[Title of Invention]

MEDICAL IMAGE PROCESSING APPARATUS, TREATMENT SYSTEM, AND MEDICAL IMAGE PROCESSING PROGRAM

[Technical Field]

[0001]

Embodiments of the present invention relate to a medical image processing apparatus, a treatment system, and a medical image processing program.

[Background Art]

[0002]

Radiotherapy is a treatment method whereby a lesion within the body of a patient is irradiated to destroy the lesion. In radiotherapy, it is necessary to irradiate the position of the lesion accurately. This is because if normal tissue in the body of the patient is irradiated with a radio beam, it can be damaged. For that reason, when radiotherapy is to be performed, computed tomography (CT) is performed beforehand at the treatment planning stage to obtain a three-dimensional grasp of the position of the lesion within the body of the patient. Based on the grasped position of the lesion, the direction and intensity when the radio beam is radiated can be planned so as to reduce the irradiation of normal tissue. At the subsequent treatment stage, the patient is placed so as to match the position of the patient at the treatment planning stage, and the lesion is irradiated with the radio beam, following the direction and intensity of the irradiation established at the treatment planning stage.

[0003] In the positioning of the patient at the treatment stage, image matching done between a perspective image of the inside of the patient's body captured with the patient placed on the bed immediately before the start of treatment and a digitally reconstructed radiograph (DRR) image, which is a virtually reconstructed perspective image, from a three-dimensional computer tomography (CT) image captured at the time of treatment planning so as to determine the offset of the position of the patient between these images. By moving the bed based on the determined offset, the position of the lesion and the bones or the like within the body of the patient are adjusted to the positions thereof at the time of treatment planning.

[0004]

The offset of the patient position is determined by searching for the position in the CT image so that the DRR image most similar to the perspective image is reconstructed. A large number of methods have been proposed for computer automating the search for the patient position. The user (a physician or the like) verifies the result of the automatic search by visually comparing the perspective image with the DRR image.

[0005]

When this is done, there have been cases in which visual verification of the position of the lesion appearing in the perspective image is difficult. This is because the lesion does not appear clearly in the perspective image because, compared with bones and the like, it has a high X-ray transmissivity. Given this, when treatment is done, a CT image is sometimes used in place of the perspective image to verify the position of the lesion. In this case, the offset of the position of the patient is determined by an image comparison between the CT image captured at the time of treatment planning and the CT image captured at the treatment stage, that is, by a comparison between CT images.

[0006]

In the image matching between CT images, the position of one of the CT images is shifted as the position of greatest similarity to the other CT image is determined. An example of a method of performing an image matching between CT images is the one disclosed in Patent Reference 1. In the method disclosed in Patent Reference 1, an image of the area surrounding the lesion included in the CT image captured at the time of treatment planning is prepared as a template. In the method disclosed in Patent Reference 1, by performing template matching with respect to the CT image captured at the treatment stage, the position of the image of greatest similarity is searched for as the position of the lesion. Based on the searched for position, the offset of the patient's position is determined, and the bed is moved in accordance with the offset, similar to the method noted above, thereby adjusting the position of thepatient to the same attitude as at the time of treatment planning.

[0007]

The radio beam used in radiotherapy loses energy as it passes through a substance. For that reason, in the treatment planning, based on the captured CT image, the irradiation method is determined by doing a virtual calculation of the energy loss amount of the radio beam to be radiated. When adjusting the position of the patient at the treatment stage, it is important that there is also coincidence of the tissue within the body of the patient in the path through which the radiated beam passes.

[0008] However, with the method disclosed in Patent Reference 1, emphasis is placed on the adjustment of the position surrounding the lesion of interest in the CT image of the lesion area prepared as a template. For that reason, with the method disclosed in Patent Reference 1, there is no assurance of accuracy of the alignment of the position of the body tissue of the patient outside the area surrounding the lesion. That is, when positioning the patient by the method disclosed in Patent Reference 1 , even if the radiated beam reaches the lesion, there have been cases in which, depending upon the tissue in the body of the patient though which the radio beam passes, it has not been possible to impart the planned radio beam energy to the lesion. .

[Citation List]

[Patent Literature]

[0009]

[Patent Reference 1] Japanese Patent No. 5693388

[Summary of Invention]

[Solution to Problem]

[0010]

In some embodiments, a medical image processing apparatus of an

embodiment may include, but is not limited to, include a first image acquirer, a second image acquirer, a path acquirer, and a searcher. The first image acquirer acquires a three-dimensional first image of an object to be treated. The second image acquirer acquires a three-dimensional second image of the object to treated, captured at a time different from the first image. The path acquirer acquires the path of a radio beam set in the first image. The searcher, based on first integrated values of the integrated pixel values of the three-dimensional first pixels through which the radiation path passes within the first image and on second integrated values of the integrated pixel values of the three-dimensional second pixels through which the path corresponding to the radiation path within the second image passes, outputs a movement amount signal that indicates an amount of movement of the second image to adjust the position of the object to be treated appearing in the second image to the position of the object to be treated appearing in the first image.

[0011]

In some embodiments, a treatment system may, but is not limited to, include a medical image processing apparatus; and a treatment apparatus that includes a ray irradiator radiating the object to be treated with the treatment beam, the radiographic imaging apparatus capturing the first image and the second image, and a treatment bed controller controlling the movement of a treatment bed onto which the object to be treated is placed and fixed, in accordance with the movement amount signal.

[Brief Description of the Drawings]

[0012]

FIG. 1 is a block diagram showing the general constitution of a treatment system that has a medical image processing apparatus of a first embodiment.

FIG. 2 is a block diagram showing the general constitution of a medical image processing apparatus of the first embodiment.

FIG. 3 is a flowchart showing the flow of search processing in the medical image processing apparatus of the first embodiment.

FIG. 4 is a drawing describing an example of the relationship between radiation and the object of irradiation by a radio beam in a treatment system having the medical image processing apparatus of the first embodiment. FIG. 5 is a block diagram showing the general constitution of a medical image processing apparatus of a second embodiment.

FIG. 6 is a block diagram showing the general constitution of a medical image processing apparatus of a third embodiment.

[0013]

[Description of Embodiments]

A medical image processing apparatus, a treatment system, and a medical image processing program of embodiments are described below, with references made to drawings.

[0014]

(First Embodiment)

FIG. 1 is a block diagram showing the general constitution of a treatment system that has a medical image processing apparatus of the first embodiment. The treatment system 1 shown in FIG. 1 has a medical image processing apparatus 100 and a treatment apparatus 10.

[0015]

First, the treatment apparatus 10 of the treatment system 1 will be described. The treatment apparatus 10 has a treatment bed 1 1, a computed tomography (CT) apparatus 12 (hereinafter "CT imaging apparatus 12"), and a treatment beam irradiation gantry 13.

[0016]

The treatment bed 11 is a bed onto which an object to be treated (patient) P who will be treated by a radio beam is placed in a reclining posture and held in place, for example, with holding fixtures. The treatment bed 11 can move the patient P fixed thereto within the annular CT imaging apparatus 12, which has an aperture. In FIG. 1, the treatment bed controller that controls the movement of the treatment bed 11 is not shown.

[0017]

The CT imaging apparatus 12 is an imaging apparatus for performing three-dimensional computed tomography. The CT imaging apparatus 12 has a plurality of ray irradiators inside an annular aperture, and radiates radio beams for viewing inside the body of the patient P from each of the ray irradiators. That is, the CT imaging apparatus 12 irradiates radio beams from the periphery of the patient P. The radio beams from each of the ray irradiators of the CT imaging apparatus 12 are, for example, X-rays. The CT imaging apparatus 12 also has plurality of ray detectors on the inside of the annular aperture, which detect the radio beams that are radiated from the ray irradiators and pass through the body of the patient P and which generate a CT image of the inside of the body of the patient P, based on the size of the energy of the detected radio beam. The CT image of the inside of the body of the patient P generated by the CT imaging apparatus 12 is a three-dimensional digital image represented by digital values of the intensity of radio beam energy. The CT imaging apparatus 12 outputs the generated CT image to the medical image processing apparatus 100. In FIG. 1, the controller for the radiation of a radio beam from each of the ray irradiators of the CT image radiographic imaging apparatus 12 and for the generation of the CT image based on the radio beams detected by each of the ray detectors, that is, for three-dimensional imaging of the inside of the boy of the patient P, is not shown.

[0018] The treatment beam irradiation gantry 13 radiates as a treatment beam B a radio beam for destroying an irradiated target (lesion existing within the body of the patient P) within the body of the patient P. The treatment beam B, for example, an X-ray beam, a γ-ray beam, an electron beam, a proton beam, a neutron beam, a heavy particle beam, or the like. In FIG. 1, a controller that controls the irradiation with the treatment beam B by the treatment beam irradiation gantry 13 is not shown.

[0019]

FIG. 1 shows a constitution of the treatment apparatus 10 that is provided with one treatment beam gantry 13. However, the treatment apparatus 10 is not restricted to a constitution having only one treatment beam irradiation gantry 13 and may have a constitution having a plurality of treatment beam irradiation gantries. For example, although FIG. 1 shows the constitution of a treatment apparatus 10 having a treatment beam irradiation gantry 13 that irradiates by the treatment beam B from the vertical direction to the patient P, the treatment system 1 may be constituted to include a treatment apparatus further having a treatment beam irradiation gantry that irradiates by a treatment beam from the horizontal direction to the patient P.

[0020]

The medical image processing apparatus 100 performs processing, based on a CT image output from the CT imaging apparatus 12, to adjust the position of the patient P when performing radiotherapy. More specifically, the medical image processing apparatus 100 outputs information for adjustment of the position of a lesion or tissue within the body of the patient P to be treated by radiotherapy. The processing in the medical image processing apparatus 100 to position the lesion or tissue is performed based on a CT image of the patient P captured before performing radiotherapy such as at the treatment planning stage and a current CT image of the patient P output from the

CT imaging apparatus 12.

[0021]

When this is done, the medical image processing apparatus 100, after virtually moving the position of the lesion or tissue in the body of the patient P, determines the tissue on the path of the treatment beam B to reach the lesion. That is, the medical image processing apparatus 100 determines whether or not there is coincidence of the tissue in the body of the patient P on the path (radiation path) through which the treatment beam B passes. This is to give notification of whether or not the amount of energy that is lost by the radiated treatment beam B passing through the tissue in the body of the patient P (the energy loss amount) is within an allowed range with respect to the energy loss amount calculated at the treatment planning stage. Stated differently, this is to make notification that the position of the peak part of the Bragg curve of the radiated treatment beam B (the Bragg peak) is not offset from the position of the lesion that is the target of treatment. The determination of the tissue on the path through which the treatment beam B in the medical image processing apparatus 100 passes is done by comparing the tissue up to the lesion included in the CT image of the patient P captured before performing radiotherapy and the tissue up to the lesion included in the current CT image of the patient P. The medical image processing apparatus 100 outputs information that indicates the result of comparing the tissue on the path through which the treatment beam B passed.

[0022] The medical image processing apparatus 100 and the CT imaging apparatus 12 of the treatment apparatus 10 may be connected by a LAN (local area network) or a WAN (wide area network).

[0023]

The constitution of the medical image processing apparatus 100 of the treatment system 1 will now be described. FIG. 2 is a block diagram showing the general constitution of the medical image processing apparatus 100 of the first embodiment. The medical image processing apparatus 100 shown in FIG. 2 has a first image acquirer 101, a second image acquirer 102, a path acquirer 110, and a searcher 120. The searcher 120 has an integrated image calculator 121, a comparator 122, a determiner 123, and a movement unit 124.

[0024]

The first image acquirer 101 acquires a first image regarding the patient P before treatment. The first image acquirer 101 outputs the acquired first image to the searcher 120. In this case, the first image is the CT image used for establishing the direction (path, including the inclination and distance) and intensity of the treatment beam B radiated at the treatment planning stage in performing radiotherapy. The first image is captured with the patient P maintaining a fixed attitude by fixing to the treatment bed 11. At the treatment planning stage, the direction and intensity of the treatment beam B to be radiated are planned so as to reduce the irradiation by the treatment beam B of the normal tissue in the body of the patient P. The first image acquirer 101 may include an interface for connecting to the CT imaging apparatus 12 of the treatment apparatus 10.

[0025] The second image acquirer 102 acquires a second image regarding the patient P immediately before the start of treatment. The second image acquirer 102 outputs the acquired second image to the searcher 120. In this case, the second image is the CT image of the inside of the body of the patient P captured immediately before the start of treatment for the purpose of positioning of the patient P. That is, the second image is a CT image captured and generated by the CT imaging apparatus 12 in the state of the treatment beam B not being radiated by the treatment beam irradiation gantry 13. The second image is captured in a state of an attitude made to approach an attitude the same as the attitude when the first image was captured. The second image acquirer 102 may include an interface for connected to the CT imaging apparatus 12 of the treatment apparatus 10.

[0026]

The path acquirer 110 acquires information of the path of the radiation of the treatment beam B established at the treatment planning stage. The information of the path of the radiation of the treatment beam B is, for example, referenced to the three-dimensional coordinates of a reference position set beforehand in the treatment room in which the treatment system 1 is installed. The region (range) of a lesion existing in the body of the patient P is irradiated by scanning (raster scanning) of one radio beam (hereinafter "treatment beam b") or by irradiating with a plurality of treatment beams b. That is, there are a plurality of paths of radiating the treatment beam B for each treatment beam b actually irradiating the lesion within the body of the patient P. The path acquirer 110 acquires information of each of the paths of the treatment beam b representing the treatment beam B irradiating the lesion within the body of the patient P. The path acquirer 110 outputs information of each of the acquired paths of the treatment beam b to the searcher 120. Additionally, the path acquirer 110 may acquire information of intensity of each of the treatment beams b planned at the treatment planning stage.

[0027]

The searcher 120 searches for the amount of movement for adjusting the current position of the patient P to the position at the time of the treatment planning stage, based on information of each of the paths of the treatment beams b output from the path acquirer 110, the first image output from the first image acquirer 101, and the second image output from the second image acquirer 102. The searcher 120 searches for the amount of movement for positioning the patient P so that the energy imparted to the lesion in the body of the patient P by irradiation with the treatment beam B approaches the energy planned at the treatment planning stage.

[0028]

The integrated image calculator 121 generates an integrated image representing the irradiation range of the treatment beam B, based on information of each of the paths of the treatment beam b output from the path acquirer 110. The integrated image calculator 121 generates

an integrated image corresponding to the first image output from the first image acquirer 101 (hereinafter "first integrated image") and an integrated image

corresponding to the second image output from the second image acquirer 102

(hereinafter "second integrated image"). The integrated image calculator 121 outputs each of the generated integrated images to the comparator 122.

[0029] The general method of the integrated image calculator 121 generating an integrated image will now be described, taking the example of the generation of the first integrated image corresponding to the first image. In the generation of the first integrated image by the integrated image calculator 121, from the three-dimensional pixels (voxels) included in the first image output from the first image acquirer 101, voxels that positioned on the path through which the treatment beam b passes are extracted. In this case, the voxel pixel values are values that differ, depending upon the tissue (substance), such as flesh and bone, making up the body of the patient P. If there is air in the body of the patient P, the voxel pixel value is different than for tissue (substance) such as flesh and bone. The integrated image calculator 121, based on information of the paths of the treatment beam b output from the path acquirer 110, extracts the voxels positioned on the path for each of the paths of the treatment beam b. The integrated image calculator 121, for each path of the treatment beam b, integrates (linearly integrates) the pixel values (hereinafter "CT values") of the extracted voxels. The integrated image calculator 121 may integrate (linearly integrate) the CT values of voxels up to the position of the Bragg peak, in accordance with the intensity of each of the treatment beams b planned at the treatment planning stage. The integrated image calculator 121 generates the first integrated image by placing (arranging) the integrated CT values for each path of the treatment beams b at positions that correspond to within the range of the irradiation by the treatment beam B. Doing this, the integrated image calculator 121 generates a first integrated image of the irradiation range of the treatment beam B, in which the pixel values of each of the pixels making up the integrated image is the integrated (linearly integrated) values (hereinafter "voxel data") of the CT values that are integrated (linearly integrated) for each of the paths of the treatment beams b. In the same manner, the integrated image calculator 121 generates the second integrated image, in which the voxel data, which are the integrated (linearly integrated) CT values of voxels on each of the paths of the treatment beams b extracted from the second image are arranged in the irradiation range of the treatment beam B. In this manner, the integrated image calculator 121 generates each of the integrated images that each include the voxel data that are the integrated (linearly integrated) CT values of only voxels through which each of the treatment beams b pass when the treatment beam B irradiates with planned intensity at the treatment planning stage.

[0030]

When the integrated image calculator 121 generates each of the integrated images, it can be envisioned that the path of some treatment beam b passes through a voxel boundary. In this case, the integrated image calculator 121, for example, may use the CT value of some one voxel of adjacent paths of the treatment beam b in the integration (linear integration) of the CT value when generating the integrated image as the voxel CT value on the path of the treatment beam b, that is, for the calculation of the voxel data. Also, the integrated image calculator 121, for example, may use the arithmetic mean CT value of two adjacent voxel CT values in the treatment beam b path as the voxel CT value on the path of the treatment beam b in calculating the voxel data when generating the integrated image.

[0031]

Although the integrated image calculator 121 has been described for the constitution that generates and outputs an integrated image by arranging voxel data in the irradiation range of the treatment beam B, the integrated image calculator 121 is not restricted to a constitution that outputs voxel data in the format of an image. For example, the integrated image calculator 121 may output the integrated values of each of the voxel data itself, that is, (linearly integrated) integrated CT values for each path of the treatment beam b.

[0032]

When each of the integrated images is generated, the integrated image calculator 121 may generate each of the integrated images, by using the

water-equivalent thickness that converts the CT values of each voxel positioned on the path of the treatment beam b to a water thickness of the energy loss amount of the radio beam. As described above, the treatment beam b (treatment beam B) loses energy when passing through a substance (tissue). When this occurs, the energy lost by each of the treatment beams b is an energy amount in accordance with the CT value of the voxel through which the treatment beam b passes, and it different depending upon the individual path of the treatment beam b. That is, the energy loss amount of the treatment beam B is not uniform, but rather is the loss of an amount of energy that differs for each treatment beam b path. The water-equivalent thickness is a value that expresses the amount of energy loss of a radio beam that differs for each tissue

(substance), expressed as a value of the thickness of water, which is also a substance, and it can be converted based on the voxel CT value. For example, if the CT value is a value that represents bone, because the energy loss value when the radio beam passes through bone is great, the water-equivalent thickness is a large value. Also, for example, if the CT value is a value that represents air, since the energy loss value when the radio beam passes through air is small, the water-equivalent thickness is a small value. When the integrated image calculator 121 generates an integrated image, by converting voxel CT values to water-equivalent thicknesses, the energy loss amounts for each of the paths through which the treatment beam b passes in the treatment beam

B can be expressed with the same reference.

[0033]

After converting each of the voxel CT values located on the path of the treatment beam b to water-equivalent thicknesses for each path, the integrated image calculator 121 integrates (linearly integrates) the water-equivalent thicknesses to calculate each of the voxel data and generate the integrated image. By integrating (linearly integrating) the water-equivalent thicknesses, the water depth (equivalent water depth) can be expressed. In the integrated image, the equivalent water depth represents the depth from the surface of the body of the patient P to the lesion. That is, the integrated image calculator 121 can, by converting the voxel CT values on each treatment beam b path extracted from the first image to water-equivalent thicknesses and then integrating (linearly integrating), expresses as the first integrated image the distance (equivalent water depth) from the surface of the body of the patient P up to the lesion verified at the treatment planning stage. Also, by integrating (linearly integrating) after converting to the water-equivalent thicknesses the voxel CT values on each of the treatment beam b paths extracted from the second image, the integrated image calculator 121 can express as the second integrated image the distance

(equivalent water depth) from the surface of the body of the patient P verified at the treatment stage, that is, the current position of the patient P, to the lesion.

[0034]

By comparing the distances (equivalent water depths) from the surface of the body of the patient P to the lesion between the first integrated image and the second integrated image, a determination can be made as to whether or not each of the treatment beams b radiated in the irradiation range of the treatment beam B imparts to the lesion in the body of the patient P the energy planned at the treatment planning stage. If one of the treatment beams b cannot impart to the lesion in the body of the patient P the energy planned at the treatment planning stage, appropriate action can be taken, such as changing that treatment beam b path. For example, if air that did not exist at the treatment planning stage currently exists in one of the treatment beam b paths, because the energy loss amount when the radio beam passes through air is small, as described above, the water-equivalent thickness is a small value, and this is

accompanied by a small value of equivalent water depth. In this case, the second integrated image voxel data in that treatment beam b path will be a value smaller than the voxel data in the corresponding first integrated image. That is, the position of the Bragg peak in that treatment beam b path is deeper than at the treatment planning stage. If the position of the Bragg peak of the treatment beam b path is deeper than at the treatment planning stage, it can be envisioned that the treatment beam b will reach an important organ that it is not desired to destroy by the radio beam located at a part in the body of the patient P deeper than the lesion, referred to as an organ at risk. In such a case, it is necessary to provide an appropriate strategy such that the treatment beam b does not reach the organ at risk. In the medical image processing apparatus 100, in such cases, an appropriate strategy can be applied so that the energy planned at the treatment planning stage is imparted to the lesion in the body of the patient P, by radiating the treatment beam b so as to detour around the path, that is, so that treatment beam b is radiated so as to avoid the path in which air exists that did not exist at the treatment planning stage. In the medical image processing apparatus 100, the comparison of the first integrated image and the second integrated image is performed by the comparator 122. In the medical image processing apparatus 100, the determiner 123 determines whether or not each of the treatment beams b radiated in the irradiation range of the treatment beam B can impart to the lesion within the body of the patient P the energy planned at the treatment planning stage. In the medical image processing apparatus 100, the movement unit 124 determines the amount of change when the path of the treatment beam b is to be changed.

[0035]

The integrated image calculator 121 outputs to the comparator 122 the first integrated image and the second integrated image that are constituted by voxel data representing the values of equivalent water depth for each path through which the treatment beam b passes. That is, the integrated image calculator 121 outputs to the comparator 122

the first integrated image of the irradiation range of the treatment beam B representing for each path of the treatment beam b information of the distance from the surface of the body of the patient P to the lesion calculated from the first image and the second integrated image of the irradiation range of the treatment beam B representing for each path of the treatment beam b information of the distance from the surface of the body of the patient P to the lesion calculated from the second image.

[0036]

By applying to the equivalent water depth the range data, which is the arrival distance of the treatment beam b determined from the Bragg curve corresponding to the strength of the radiated treatment beam b, the radiation dose of the treatment beam b for each of the paths, that is, the radiation dose of the treatment beam b with respect to the lesion, can be calculated. For that reason, the constitution may be such that the integrated image calculator 121 output to the comparator 122 each of the first integrated image and the second integrated image, in which the radiation dose of the treatment beam b in the irradiation range of the treatment beam B is made to be the voxel data.

[0037]

The comparator 122 compares the first integrated image and the second integrated image output from the integrated image calculator 121 and outputs information indicating the comparison result to the determiner 123. In this case, the comparator 122 outputs to the determiner 123 information indicating the result of comparing voxel data of the same positions in the first integrated image and the second integrated image, that is, distances (equivalent water depths) from the surface of the body of the patient P in the same treatment beam b path to the lesion. More specifically, the comparator 122 calculates the difference between the voxel data (equivalent water depth value) of a certain treatment beam b path included in the first integrated image and the voxel data (equivalent water depth value) of the corresponding same treatment beam b path included in the second integrated image. The comparator 122 outputs to the determiner 123 as comparison results the difference (equivalent water depth difference) of the voxel data calculated in each of the treatment beam b paths. Stated differently, the comparator 122 outputs to the determiner 123 the result of comparing the energy loss amount for each treatment beam b path in the treatment beam B calculated from the first image, and the energy loss amount for each treatment beam b path in the treatment beam B calculated from the second integrated image.

[0038]

The determiner 123, based on information of the comparison result output from the comparator 122, determines the offset between the first integrated image and the second integrated image. In this case, the determination of the offset between the first integrated image and the second integrated image in the determiner 123 is performed for the path of each treatment beam b in the first integrated image and the second integrated image. More specifically, the determiner 123 verifies, for each voxel data difference representing the comparison results output from the comparator 122, whether or not the difference is within a pre-established allowable range. -That is, the determiner 123 determines whether or not the difference of the equivalent water depth represented by the comparison results output from the comparator 122 is within a pre-established allowable range for each treatment beam b path. Stated differently, the determiner 123 determines whether or not energy loss amount for each treatment beam b path in the treatment beam B calculated from the second image is within a pre-established allowable range with respect to the energy loss amount for each treatment beam b path in the treatment beam B calculated from the first image. In this case, if all of the differences of voxel data in the treatment beam B irradiation range are within the pre-established allowable range, the determination is made that the first integrated image and the second integrated image are not offset, that is, that the current position of the patient P matches the position at the treatment planning stage. If, however, some voxel data in the treatment beam B irradiation range is not within the pre-established allowable range, the determiner 123 determines that the first integrated image and the second integrated image are offset, that is, that the current position of the patient P does not match the position at the treatment planning stage. The determiner 123 outputs a determination signal indicating the result of the determination of the offset between the first integrated image and the second integrated image. The determination signal is, for example, output to a result presenter (not shown) that presents the determination result, and presented to the user (a physician or the like) of the treatment system 1. The determiner 123 outputs to the movement unit 124 information of the determination result for each treatment beam b path.

[0039]

The movement unit 124, based on the information of the determination result of each treatment beam b path output from the determiner 123, establishes the amount of movement to move the current position of the patient P. More specifically, the movement unit 124, based on the equivalent water depth difference represented by the determination result of each of the treatment beam b paths output from the determiner 123, establishes the amount of movement, including the direction (inclination) of movement in a prescribed three-dimensional space of the current position of the patient P (that is, the second image) so as to cause movement in the direction in which the equivalent water depth difference is smaller. The movement unit 124 outputs to the integrated image calculator 121 information indicating the established amount of movement. Stated differently, the movement unit 124 calculates the position and direction of the patient P for the treatment beam b (treatment beam B) to reach the lesion with an energy loss amount within a pre-established allowable range and outputs to the integrated image calculator 121 information of the amount of movement for adjusting the position of (moving) the patient P with the calculated position and direction. Doing this, the integrated image calculator 121 virtually moves the second image based on the information indicating the movement amount output from the movement unit 124, and generates and outputs the second integrated image in that state to the comparator 122.

[0040] In the searcher 120, the generation of the second integrated image by the integrated image calculator 121, the determination of the offset between the second integrated image and the first integrated image by the comparator 122 and the determiner 123 and the establishment of the movement amount to move the position of the patient P by the movement unit 124 as described above are repeated until the determination is made that the current position of the patient P matches the position at the treatment planning stage. In the searcher 120, when the determiner 123 determines that the current patient P position matches the position at the treatment planning stage, a movement amount signal representing the amount of movement (including inclination, distance, and the like) ultimately established by the movement unit 124 is output, and the patient P is actually moved, so as to adjust the patient P position to the position at the treatment planning stage. That is, if the energy loss amount for each treatment beam b path in the treatment beam B calculated from the second image is within a pre-established allowable range with respect to the energy loss amount for each treatment beam b path in the treatment beam B calculated from the first image, the searcher 120 outputs information to adjust the patient P position finally to that position. For example, the movement amount signal is output to a treatment bed controller (not shown), which performs control to move the treatment bed 11, and the treatment bed controller (not shown) actually moves the patient P position by moving the treatment bed 11 based on the movement amount signal.

[0041]

According to this constitution, the medical image processing apparatus 100, based on a first image of the patient P captured at the treatment planning stage or the like and a second image captured before performing radiotherapy at the treatment stage, determines the offset between the patient P position at the treatment planning stage and the current patient P position. The medical image processing apparatus 100 outputs as the determination signal the result of determining the offset between the patient P position at the treatment planning stage and the current patient P position. The medical image processing apparatus 100, based on the result of determining the offset, establishes the amount of movement to move the patient P position, and virtually moves the current patient P position. The medical image processing apparatus 100 outputs a movement amount signal for moving the current patient P position to the position ultimately established as matching the treatment planning stage. Doing this, in the treatment system 1 that has the medical image processing apparatus 100, for example, by moving the treatment bed 11 based on the movement amount signal, the treatment bed controller (not shown) controlling the movement of the treatment bed 11 actually moves the patient P position. In the treatment system 1 that has the medical image processing apparatus 100, this enables radiotherapy to be performed by adjustment of the current patient P position to the state at which it is possible to irradiate the lesion in the body of the patient P with the treatment beam B of the energy planned at the treatment planning stage.

[0042]

A part of the functional elements of the above-described medical image processing apparatus 100 may be, for example, a software function element that functions by execution of a program stored in storage device by a processor, such as a CPU (central processing unit) or GPU (graphic processing unit). In this case, the storage device may be implemented by a ROM (read-only memory), a RAM

(random-access memory), a HD (hard disk) drive, or a flash memory or the like. The program executed by the processor such as a CPU or GPU may be stored beforehand in a storage device of the medical image processing apparatus 100, or may be downloaded from another computer via a network. A program stored in a removable storage device may be installed into the medical image processing apparatus 100. A part or all of the functional elements of the above-noted medical image processing apparatus 100 may be hardware operational units such as an FPGA (field-programmable gate array), an LSI (large-scale integration) device, or an ASIC (application-specific integrated circuit) or the like.

[0043]

In the medical image processing apparatus 100 of the treatment system 1, the flow of the processing (search processing) to establish the amount of movement for movement to adjust the current patient P position to the position at the treatment planning stage of the treatment system 1 will now be described. The search processing in the medical image processing apparatus 100 is processing to search, by determining the offset occurring between the first integrated image and the second integrated image, for a position of the patient P at which the lesion can be irradiated by the treatment beam B with the energy planned at the treatment planning stage. FIG. 3 is a flowchart showing an example of the flow of search processing in the medical image processing apparatus 100 of the first embodiment. Before the medical image processing apparatus 100 performs the search processing, that is, before performing radiotherapy (for example, one week before), a treatment plan is established, based on a captured first image. Immediately before the medical image processing apparatus 100 performs search processing, that is, immediately before the start of radiotherapy, the second image is captured. The description to follow is for the case of the capturing of the second image in the treatment system 1 having already been completed and the first image acquirer 101 and second image acquirer 102 having already acquired the first and second images, respectively. The description is also for the path acquirer 110 having already acquired the path for radiating of the treatment beam b (treatment beam B) established at the treatment planning stage.

[0044]

In the radiotherapy, to treat a given patient P, there are cases in which irradiation by the treatment beam B is done a plurality of times (including not on the same day). For that reason, on the second and subsequent radiotherapies with respect to the given patient P, the second image in which the patient P position has been adjusted in the previous treatment is taken as the first image, and the treatment beam b (treatment beam B) path in the previous treatment is taken as the treatment beam b (treatment beam B) path for the current treatment.

[0045]

First, when the medical image processing apparatus 100 starts the search processing, the integrated image calculator 121 of the searcher 120 acquires the information of each of the treatment beam b paths output from the path acquirer 110 (step SI 00).

[0046]

Next, the integrated image calculator 121 applies the information of each treatment beam b path acquired from the path acquirer 110 to the first image and generates the first integrated image that represents the irradiation range of the treatment beam B (step S200). In this case, the integrated image calculator 121 uses the water-equivalent thickness converted from the each of the voxel CT values positioned on the treatment beam b path in the first image to generate a first integrated image representing the values of the equivalent water depth for each path through which the- . _ treatment beam b passes. The method of the integrated image calculator 121 using the water-equivalent thickness converted from the CT values to generate the first integrated image will be described later in detail. The integrated image calculator 121 outputs the generated first integrated image to the comparator 122.

[0047]

Next, the integrated image calculator 121 sets each of the treatment beam b paths acquired from the path acquirer 110 into the second image (step S300). When this is done, the integrated image calculator 121, without virtually moving the second image, for example, sets the three-dimensional directions representing each of the treatment beam b paths into the second image, using as a reference the

three-dimensional coordinates of a reference position set beforehand in the treatment room in which the treatment system 1 is installed. That is, each of the treatment beam b paths is set with respect to the current state of the patient P (attitude, including position, direction, and the like).

[0048]

Next, the integrated image calculator 121, based on each of the paths of the set treatment beam b, generates a second integrated image representing the irradiation range of the treatment beam B (step S400). In this case, the integrated image calculator 121, using the equivalent water depth converted from each of the voxel CT values positioned on each treatment beam b path set in the second image, generates a second integrated image representing the values of equivalent water depth for each path through which the set treatment beam b passes. In the second image, although it can be envisioned that the voxel CT values of each position on each of the treatment beam b paths differ, the method of the integrated image calculator 121 generating the second integrated image is the same as the method of the integrated image calculator 121 generating the first integrated image. Therefore, the detailed description regarding the method of the integrated image calculator 121 generating the second integrated image will be described later, along with the method of generating the first integrated image. The integrated image calculator 121 outputs the generated second integrated image to the comparator 122.

[0049]

Next, the comparator 122 compares the first integrated image and second integrated image output from the integrated image calculator 121 and outputs to the determiner 123 information representing the result of the comparison (step S500). In this case, the comparator 122 outputs to the determiner 123 the comparison result (equivalent water depth difference) between the equivalent water depth values corresponding to the treatment beam b of the same positions in the first integrated image and the second integrated image, as the comparison result corresponding to each of the treatment beams b.

[0050]

Next, the determiner 123 determines, based on the comparison result for each of the treatment beams b output from the comparator 122, whether the offset between the first integrated image and the second integrated image is within a pre-established allowed range for each treatment beam b (step S600).

[0051] If, as a result of the determination at step S600, the determination is made that there is ah offset between the first integrated image and the second integrated image (NO at step S600), the determiner 123 outputs a determination signal indicating that there is an offset between the first integrated image and the second integrated image, that is, the current position of the patient P does not match the position at the treatment planning stage. The determiner 123 outputs to the movement unit 124 information of the determination result for each treatment beam b path (including the difference in equivalent water depth).

[0052]

Next, the movement unit 124, based on the information of the determination result for each treatment beam b path output from the determiner 123, establishes the amount of movement of the second image (step S610). More specifically, as described above, based on the difference in the equivalent water depth included in the

determination result for each of the treatment beam b paths output from the determiner 123, the amount of movement to move the second image (including rotation), that is, the current position of the patient P is established to reduce the equivalent water depth difference in the treatment beam b paths. The movement unit 124 outputs the established amount of movement of the second image to the integrated image calculator 121. If the second image is the center, that is, if the position of the second image is fixed, the amount of second image movement established by the movement unit 124 at step S610 corresponds to the path change amount that includes the direction (inclination and the like) and the intensity (distance and the like) of each of the treatment beams b.

[0053] After virtually moving the second image based on the amount of movement of the second image output from the movement unit 124, the integrated image calculator 121, similar to step S310, sets each of the treatment beam b paths acquired from the path acquirer 110 after movement thereof into the second image (step S620). If the amount of change of each treatment beam b path is output from the movement unit 124, each of the paths of the treatment beam b to be radiated that are virtually changed, that is, the treatment beam b paths after changing with respect to the current state of the patient P (attitude, including position, direction, and the like) are set into the second image.

[0054]

After that, the search processing by the medical image processing apparatus 100 returns to step S400, and the processing from step S400 to step S600 is repeated. That is, in the search processing by the medical image processing apparatus 100, the generation of a new second integrated image corresponding to the second image after movement and the comparison and determination of the offset between the new second integrated image and the first integrated image are repeated.

[0055]

However, if the result of the determination at step S600 is that there is no offset between the first integrated image and the second integrated image (or new second integrated image) (YES at step S600), the determiner 123 outputs a determination signal indicating that there is no offset between the first integrated image and the second integrated image, that is, that the current patient P position matches that at the treatment planning stage. The determiner 123 outputs to the movement unit 124 determination results information indicating that there is no offset between the first integrated image and the second integrated image.

[0056]

Next, the movement unit 124 outputs a movement amount signal representing the final amount of movement of the second image (step S700). In this case, if the movement unit 124 has not performed the processing of step S610, because the second image acquired by the second image acquirer 102 is not moved, the movement amount signal output by the movement unit 124 includes information indicating that the captured second image is not to be moved. If, however, the movement unit 124 has performed the processing of step S610, the movement amount signal output by the movement unit 124 includes information indicating the amount of movement of the second image determined in the final processing of step S610. In the processing of step S610 in the movement unit 124, if the amount of movement of the second image is always established with the three-dimensional coordinates of a pre-established reference position as the reference, the information of the movement amount of the second image established finally in the processing of step S610 is indicated by the movement amount signal. However, in the processing of step S610 in the movement unit 124, if, for example, the amount of movement of the second image is to be further determined with the amount of movement of the second image established at the previous time of step S610 processing as the reference, information of the amount of movement of the second image that is the calculated sum of the past amounts of movement of the second image is indicated by the movement amount signal.

[0057] After that, in the treatment system 1, a treatment bed controller (not shown) moves the treatment bed 11 based on a movement amount signal output from the medical image processing apparatus 100 (more specifically, the movement unit 124 of the searcher 120), so as to actually move the position of the patient P.

[0058]

At this point, an example of the processing (processing method) performed by the constituent elements of the medical image processing apparatus 100 in the search processing by the medical image processing apparatus 100 of the treatment system 1 will be described.

[0059]

First, the treatment planning performed before performing the search processing in the medical image processing apparatus 100 will be described. In the treatment planning, for example, the energy, radiation direction, and shape of the radiation range of the treatment beam B (radio beam) with which the patient P is irradiated, and the distribution of the dose when the treatment beam B is to be radiated a plurality of times is established. More specifically, first, the proposer of the treatment plan (a physician or the like) specifies, for example, with respect to the CT image (first image) captured at the treatment planning stage, the boundary between the regions of a tumor (lesion) and of normal tissue, and the boundary between the tumor and important organs in the surrounding area. Then, in the treatment planning, based on the depth to the position of the tumor from the surface of the body of the patient P and the size of the tumor, calculated from the information specified regarding the tumor, the intensity, direction (path), and the like of the treatment beam B to be used in irradiation are determined. [0060]

The above-described specification of the boundary between the regions of the tumor and of the normal tissue corresponds to specification of the tumor position and volume. The volume of the tumor is variously referred to as, for example, the gross tumor volume (GTV), the clinical target volume (CTV), the internal target volume (ITV), the planning target volume (PTV). The GTV is the tumor volume that can be verified from an image by the naked eye, which is the volume that requires irradiation by a sufficient dose by the treatment beam B in radiotherapy. The CTV is the volume that includes the GTV and the latent tumor to be treated. The ITV is the volume in which a pre-established margin is added to the CTV, giving consideration to the movement of the CTV by the expected physiological movement of the patient P. The PTV is the volume in which a margin is added to the ITV, giving consideration to the error in positioning the patient P when treatment is performed. These volumes are such that they satisfy the following relationship (1).

[0061]

[Equation 1]

[0062]

The volume of important organs positioned in the area surrounding the tumor, which have susceptibility to a radio beam and are greatly influenced by the radiation dose from the radiated radio beam is known an organ at risk (OAR). The planning organ at risk volume (PRV) that is the OAR with a pre-established margin added thereto is specified as the volume. These volumes have the following relationship (2).

[0063] [Equation 2]

OAR e PRV . . . ₍₂₎

[0064]

At the treatment planning stage, the direction (path) and intensity of the treatment beam B (radio beam) to be radiated to the patient P are established, based on a margin of error that could occur in actual treatment.

[0065]

When search processing is performed in the medical image processing apparatus 100, the first image acquirer 101 acquires and outputs to the integrated image calculator 121 of the searcher 120 a first image regarding the patient P immediately before starting treatment. The second image acquirer 102 acquires and outputs to the integrated image calculator 121 of the searcher 120 a second image. As described above, the first image and the second image are both CT images. When capturing the second image, the attitude of the patient P is made to approach the attitude the same as when the first image was captured. However, it is difficult to capture the second image with the completely same attitude as when the first image was captured. That is, it is difficult to suppress a change in the state of the inside of the patient P and to maintain the same attitude, even if a holding device is used. For that reason, even if the first image and the second image are disposed virtually the same in a prescribed three-dimensional space, a small amount (for example several millimeters) of offset occurs, so that it is difficult by just capturing the second image to reproduce the attitude of the patient P at the time that the first image was captured. Given this, in the medical image processing apparatus 100, the searcher 120, using the water-equivalent thickness, adjusts the positions of the first image and the second image (reduces the difference between the two images), that is, searches for a movement amount for adjusting the current attitude of the patient P to the attitude at the time that the first image was captured. The prescribed three-dimensional space takes as a reference the

three-dimensional coordinates of a reference position set beforehand in the treatment room, such as the treatment beam irradiation gantry 13 or the treatment bed 11.

[0066]

When search processing is performed by the medical image processing apparatus 100, the path acquirer 110 acquires and outputs to the integrated image calculator 121 of the searcher 120 information of a path of the radiation of the treatment beam B (radio beam) established based on the first image at the treatment planning stage. The direction of radiation of the treatment beam B is a direction within the three-dimensional space oriented toward the tumor (lesion) within the body of the patient P from the exit port of the treatment beam irradiation gantry 13. For that reason, if the position of the exit port of the treatment beam irradiation gantry 13 is known within the prescribed three-dimensional space, the path of the treatment beam B passing through each voxel in the first image and the second image can be determined, with the position of this exit port as the origin point. The path of the treatment beam B can be expressed as three-dimensional coordinates. The path of the treatment beam B may be expressed as a three-dimensional vector with its origin point at the

three-dimensional coordinates of the position of the exit port.

[0067]

The treatment beam B radiated from the treatment beam irradiation gantry 13 in the treatment system 1 will now be described. In the description to follow, the path of the treatment beam B is expressed as a three-dimensional vector. [0068]

As described above, the treatment beam B, by scanning of one treatment beam b or radiating a plurality of treatment beams b, irradiates the entire region (range) of a lesion existing within the body of the patient P. FIG. 4 describing an example of the relationship between exiting and the irradiated target (a lesion existing within the body of the patient P) of the radiation beam (treatment beam b) in a treatment system 1 having the medical image processing apparatus 100 of the first embodiment. FIG. 4 shows one example of a path over which the treatment beam B that is radiated from the treatment beam irradiation gantry 13 and reaches the lesion that is the irradiated object travels. FIG. 4 (a) shows an example of the treatment beam B in a constitution in which the treatment beam irradiation gantry 13 radiates a plurality of treatment beams b, and FIG. 4 (b) shows an example of the treatment beam B in a constitution in which the treatment beam irradiation gantry 13 radiates and scans one treatment beam b.

[0069]

In the case of a constitution in which the treatment beam irradiation gantry 13 in the treatment system 1 radiates a plurality of treatment beams b, the treatment beam irradiation gantry 13, as shown in FIG. 4 (a), has a planar exit port. Each of the treatment beams b exiting from the treatment beam irradiation gantry 13 reaches the lesion that is the irradiated target, via a collimator 13-1. That is, of the plurality of treatment beams b exiting simultaneously from the treatment beam irradiation gantry 13, only the treatment beams b passing through the collimator 13-1 reach the lesion that is the irradiated target. In this case, the collimator 13-1 is a metal device for the purpose of blocking unnecessary treatment beams b. In addition to a metal device, there is a multi-leaf collimator that can mechanically change the region of blocking the unnecessary treatment beams b as a collimator. The irradiation range of the treatment beam B radiated from the treatment beam irradiation gantry 13 in the treatment system 1 is adjusted by the collimator 13-1, for example, so that the range through which the treatment beam b passes matches the shape of the lesion, which is the irradiated target, thereby not irradiating a region outside the lesion in the body of the patient P with any treatment beam b. FIG. 4 (a) shows, in schematic form, an example for the case of the treatment beam b of the treatment beams b _\ to ½ passing through the collimator 13-1 and irradiating the lesion that is the irradiated target in the first image. In this case, the origin point of each of the paths of the treatment beams b _\ to is the position of the point of exit of each of the treatment beams b positioned within the range of the planar exit port of the treatment beam irradiation gantry 13. The three-dimensional position of the treatment beam irradiation gantry 13 in this constitution is, for example, the center position (coordinates) of the plane of the exit port.

[0070]

The path acquirer 110 acquires information of the paths of each of the treatment beams b _\ to b^up to the lesion that is the irradiated target in the first image, taking the position of the point of exit of the treatment beam b as the origin point, as information of the paths of each of the treatment beams b in the treatment beam B radiated within a prescribed three-dimensional space. Each of the treatment beam b paths in the treatment beam B in this case can be discretely represented by the following Equation (3) by a set of three-dimensional vectors.

[0071]

[Equation 3] [0072]

If the constitution is one in which the treatment beam irradiation gantry 13 emits and scans one treatment beam b in the treatment system 1, the treatment beam irradiation gantry 13, as shown in FIG. 4 (b), does not have the collimator 13-1, and has one exit port. The direction of one treatment beam b exiting from the one exit port of the treatment beam irradiation gantry 13 is deflected by a magnet or the like to perform scanned irradiation so as to fill in (scan) the entire region of the lesion that is the irradiated target. FIG. 4 (b) shows, in schematic form, an example of the case in which one treatment beam b is deflected so that it becomes the treatment beams b to the treatment beam t>N to irradiate the lesion of the irradiated target in the first image. In this case, the origin point of each of the treatment beams b ₁ to the treatment beam b>N paths is the position of the exit port of the treatment beam irradiation gantry 13. The three-dimensional position of the treatment beam irradiation gantry 13 in this constitution is the position (coordinates) of the one exit port.

[0073]

The path acquirer 110 acquires information of the paths of the treatment beam b _\ to the treatment beam t>N deflected from the position of the origin point and reaching up to the lesion that is the irradiated target in the first image, taking the position of the exit port of the treatment beam irradiation gantry 13 as the origin point, as information of the paths of each of the treatment beams b in the treatment beam B radiated within a prescribed three-dimensional space. Each of the treatment beam b paths in the treatment beam B in this case can be discretely represented as shown in the above Equation (3) by a set of three-dimensional vectors.

[0074] (Integrated Image Generation Method)

Next, the method of the integrated image calculator 121 generating the first integrated image and the second integrated image in the search processing in the medical image processing apparatus 100 will be described. First, the method of the integrated image calculator 121 generating an integrated image will be described.

[0075]

In the following description, one point in the prescribed three-dimensional space will be represented as point x. The pixel values (CT values) of a

three-dimensional pixel (voxel) corresponding to the point x included in the first image that has been placed virtually in the prescribed three-dimensional space will be represented as Ii(x, Θ). In the same manner, the pixel values (CT values) of a three-dimensional pixel (voxel) corresponding to the point x included in the second image that has been placed virtually in the prescribed three-dimensional space will be represented as I ₂ (x, Θ). The CT value when a voxel does not exist in correspondence to the point x in the first image or second image will be made 0. In this case, Θ is a parameter that represents the positional orientation in the first image or the second image in a three-dimensional space. The position of the exit port of the treatment beam irradiation gantry 13 in treatment beam B, that is, the vector from the origin point of o to the point x can be represented as shown in the following Equation (4).

[0076]

[Equation 4]

b (x ) = X - O ' ^{* *} (4)

[0077] In this case, the pixel values (voxel data) Si (x, Θ) of pixels of the first integrated image, which are the accumulations of the CT values of each of the voxels positioned on the path of the treatment beam B up to the point x in the first image can be calculated by the following Equation (5).

[0078]

[Equation 5]

[0079]

In Equation (5), t is a parameter.

[0080]

In the same manner, the pixel values (voxel data) S ₂ (x, Θ) of pixels of the second integrated image, which are the accumulations of the CT values of each of the voxels positioned on the path of the treatment beam B up to the point x in the second image can be calculated by the following Equation (6).

[0081]

[Equation 6]

[0082]

If the integrated image of the first image corresponds to some treatment beam bj be S^O), this integrated image Si/G) can be expressed as in the following Equation

(7).

[0083] [Equation 7]

^S U (0) = fci (¾ (¾ ^), · · · , 5j (x _M , Θ)}

. . . ( ₇ )

[0084]

In this case, the following Equation (8) is a set of the coordinate positions in the three-dimensional space through which the treatment beam b _\ passes.

[0085]

[Equation 8]

[0086]

In this manner, the integrated image S _1; j(9) is expressed as a vector that is the arrangement of Mj integrated pixel values. The first integrated image S^G) is expressed by the following Equation (9), taking together the integrated images S _1; j(0) of the first image corresponding to N treatment beams bi.

[0087]

[Equatio

[0088]

In the same manner, the second integrated image S ₂ (6) is expressed by the following Equation (10).

[0089]

[Equation 10 ( 1 0 ) [0090]

In this case, the set X; is a set of the position of pixels corresponding to the PTV. The set Xi may, for example, include the range of a pre-established margin included in the volume specified at the treatment planning stage of PRV or the like. The set X, may include all the positions through which the treatment beam bi passes in the body of the patient P. In the set ¾ the treatment beam bj may reach the lesion that is the irradiated target in the first image and the second image.

[0091]

By this method of generating an integrated image, the integrated image calculator 121 outputs to the comparator 122 the first integrated image and the second integrated image, which are expressed by the above Equations (9) and (10),

respectively.

[0092]

When the integrated image calculator 121 generates each of the integrated images, as described above, as the CT values of each of the voxels positioned on the path of the treatment beam b in the first image or the second image, and it generates the first integrated image and the second integrated image, using the water-equivalent thickness that converts the radio beam energy loss to a thickness of water. In this case, as a method of converting each of the voxel CT values included in the first image and the second image to water-equivalent thicknesses, the integrated image calculator 121 uses, for example, a regression formula based on empirically determined non-linearly converted data, such as shown in Reference 1 noted below. As another method, the integrated image calculator 121 may use, for example, a prepared conversion table to convert the CT values to water-equivalent thicknesses. As described above, by integrating (linearly integrating) the water-equivalent thickness, the water depth (equivalent water depth), that is, the distance to the tumor (lesion) from the surface of the body of the patient P can be determined. Reference 1 also shows the empirical determination of the relationship between the depth (water thickness) when a heavy-particle beam passes through a water medium and the imparted dose. The integrated image calculator 121 may use the relationship of the water thickness and the imparted dose indicated in Reference 1 to convert each of the voxel data in the integrated image to the imparted dose at each pixel position.

[0093]

[Reference 1] O. Jakel, et al., "Relationship between carbon ion ranges and x-ray CT numbers", Med. Phys. 28 (4), 701-703, 2001.

[0094]

The integrated image calculator 121 outputs to the comparator 122 an integrated image in which voxel CT values of each position on the path of the treatment beam b included in the first image and the second image are converted to

water-equivalent thicknesses and expressed by integrated equivalent water depths or an integrated image in which each voxel data in the integrated image is converted to imparted dose.

[0095]

Next, the method of the comparator 122 comparing the first integrated image and the second integrated image in the search processing in the medical image processing apparatus 100 will be described.

[0096] The comparator 122 uses the cost function such as shown by the following Equation (11) to compare the first integrated image with the second integrated image.

[0097]

[Equation 11]

[0098]

The comparator 122, using the above-noted Equation (11), determines the ΔΘ that minimizes the squared error of the integrated image pixel values (voxel data). The comparator 122 minimizes the cost function using an optimization method such as gradient method, the Newton method, the Lucas-Kanade method (LK method), or the like. The comparator 122 outputs to the determiner 123 the minimized cost function value E and ΔΘ as information of the comparison results of comparing the first integrated image and the second integrated image.

[0099]

The cost function used by the comparator 122 to compared the first integrated image and the second integrated image can be a cost function such as shown in the following Equation (12).

[0100]

[Equation 12]

Ε(ΑΘ) = λΕ _ρτν {Αθ) + (1 - λ)Ε _ρχν (ΑΘ)

• • • ( 1 2 )

[0101]

In the above Equation (12), Ε _Ρ χν represents the squared error of the integrated image constituted by only pixel positions included in the PTV, and EPRV represents the squared error of the integrated image constituted by only pixel positions included in the PRV. In the above Equation (12), λ is a parameter and, if the comparison is done with emphasis on position adjustment in the PTV, λ is a value of, for example, 0.5 or greater. Even if a cost function such as the above Equation (12) is used to perform the comparison, the comparator 122 outputs to the determiner 123 the cost function value E and ΔΘ as information of the comparison results of comparing the first integrated image and the second integrated image.

[0102]

By this type of comparison method, the comparator 122 outputs to the determiner 123 information of the comparison results of comparing the first integrated image and the second integrated image.

[0103]

Next, the method of the determiner 123 determining the offset between the first integrated image and the second integrated image in the search processing in the medical image processing apparatus 100 will be described.

[0104]

The determiner 123 determines whether or not the comparison results output from the comparator 122 is within a pre-established allowable range. Conditions such as the following are set in the determiner 123.

[0105]

(Determination condition 1): The ΔΘ included in the comparison results output from the comparator 122 does not exceed a pre-established threshold. (Determination condition 2): The cost function value E included in the comparison results output from the comparator 122 does not exceed a pre-established threshold.

[0106]

A determination condition such as the following is set in the determiner 123.

[0107]

(Determination condition 3): The number of determinations with respect to the comparison results output from the comparator 122 is at least a pre-established number.

[0108]

The determiner 123 performs a determination based on the above-described determination condition 1 to determination condition 3 and, if at least one or more determination conditions are satisfied, determines that there is no offset between the first integrated image and the second integrated image. If none of the above-described determination condition 1 to the determination condition 3 are satisfied, the determiner 123 determines that there is an offset between the first integrated image and the second integrated image. The determiner 123 outputs a determination signal that indicates the results of the determination of offset between the first integrated image and the second integrated image.

[0109]

The determiner 123 calculates the difference between the thresholds in the above-described determination condition 1 and determination condition 2 and the comparison results output from the comparator 122, that is, the amount of offset, and outputs to the movement unit 124 information of the calculated offset amount. [0110]

By doing this, the movement unit 124, based on the information of the offset amount output from the determiner 123, establishes the amount of movement (including rotation) to move the second image in the three-dimensional space so that the current position of the patient P is moved in the direction in which the offset amount becomes smaller. The movement unit 124 outputs information indicating the established amount of movement of the second image to the integrated image calculator 121.

Doing this, the integrated image calculator 121 generates a new second integrated image, by the above-described method of generating an integrated image.

[0111]

By processing such as this, in the search processing of the medical image processing apparatus 100, based on the first integrated image generated from the first image and the second integrated image generated from the second image, the offset between the attitude of the body of the patient P at the treatment planning stage and the current attitude of the body of the patient P is determined. That is, in the search processing of the medical image processing apparatus 100 the offset of the path of the treatment beam B is determined based on the first integrated image and the second integrated image. In the search processing of the medical image processing apparatus 100, based on the determined amount of offset, the amount of movement to move the attitude of the patient P so that the current attitude of the patient P approaches the attitude of the patient P at the treatment planning stage is determined. Stated differently, in the search processing of the medical image processing apparatus 100, the amount of movement for positioning of the patient P is determined so that it is possible to radiate the lesion within the body of the patient P with a treatment beam B having an energy amount that is close to the energy established at the treatment planning stage. In the treatment system 1 that has the medical image processing apparatus 100, doing this actually moves the patient P in accordance with the amount of movement established by the search processing in the medical image processing apparatus 100, thereby enabling irradiation of the lesion by a treatment beam B having an energy amount that was established at the treatment planning stage and enabling radiotherapy according to the plan.

[0112]

As described above, in the medical image processing apparatus 100 of the first embodiment, the first image acquirer 101 acquires a first image of the patient P captured before treatment and the second image acquirer 102 acquires a second image of the patient P captured immediately before starting treatment. In the medical image processing apparatus 100 of the first embodiment, the path acquirer 110 acquires information of the path of the treatment beam B established at the treatment planning stage, based on the first image. In the medical image processing apparatus 100 of the first embodiment, the searcher 120 (integrated image calculator 121), based on the information of the path of the treatment beam B, generates a first integrated image corresponding to the first image and a second integrated image corresponding to the second image. In the medical image processing apparatus 100 of the first embodiment, the searcher 120 (comparator 122 and determiner 123) determine the offset of the path of the treatment beam B between the first integrated image and the second integrated image and output a determination signal indicating the result of the determination. In the medical image processing apparatus 100 of the first embodiment, the searcher 120 (movement unit 124), based on the determined offset amount, establishes the amount of movement for making the current attitude of the patient P approach the attitude of the patient P at the treatment planning stage and, if the offset in the path of the treatment beam B between the first integrated image and the second integrated image is within a pre-established allowable range, outputs a movement amount signal indicating the final amount of movement of the patient P. In the treatment system 1 that has the medical image processing apparatus 100 of the first embodiment, for example, this enables a treatment bed controller (not shown) that controls movement of the treatment bed 11, by moving the treatment bed 11 based on the movement amount signal, to actually move the position of the patient P. In the treatment system 1 that has the medical image processing apparatus 100 of the first embodiment, this enables the current position of the patient P to be adjusted to a state enabling the irradiation of a lesion in the body of the patient P with the treatment beam B having an energy amount that is close to the energy amount established at the treatment planning stage, thereby enabling

radiotherapy according to plan.

[0113]

As described above, the medical image processing apparatus 100 has a first image acquirer 101 that acquires a three-dimensional first image of a patient P captured by a CT radiographic imaging apparatus 12, a second image acquirer 102 that acquires a three-dimensional second image of the patient P captured by the radiographic imaging apparatus 12 at a time different from the first image, a path acquirer 110 that acquires a radio beam path set in the first image, and

a searcher that, based on first integrated values (first integrated image) of the integrated pixel values (CT values) of the three-dimensional first pixel through which the radiation path passes and included in the first image and on second integrated values (second integrated image) of the integrated pixel values (CT values) of the three-dimensional second image through which the path corresponding to the radiation path within the second image passes, outputs a movement amount signal that indicates an amount of movement of the second image to adjust the position of the patient P appearing in the second image to the position of the patient P appearing in the first image. By doing this, the medical image processing apparatus 100, based on the first image acquired by the first image acquirer 101, the second image acquired by the second image acquirer 102, and the path (radiation path) of the treatment beam B (treatment beam b) acquired by the path acquirer 110, can search for an amount of movement for adjusting the current position of the patient P to the position at the time the first image was captured.

[0114]

As described above, the searcher 120 may have

an integrated image calculator 121 that generates a first integrated image by calculating the first integration values and representing the calculated first integrated values within a irradiation range in which the treatment beam B (treatment beam b) is radiated, and a second integrated image by calculating the second integrated values and representing the calculated second integrated values within a irradiation range, a comparator 122 that compares the first integrated values (voxel data) included in the first integrated image and the second integrated values (voxel data) corresponding to the first integrated values included in the second integrated image, respectively, a determiner 123 that, based on the comparison results of the comparator 122, determines the offset of the radiation paths appearing in the first integrated image and the second integrated image, and a movement unit 124 that establishes the amount of movement based on the

determination result of the determiner 123 and outputs the movement amount signal representing the established amount of movement. By doing this, the medical image processing apparatus 100 can, based on the result of comparing the first integrated values in which voxel CT value included in the first image and is integrated and the second integrated values in which voxel CT value included in the second image is integrated, determine the offset between the current position of the patient P that is virtually moved and the position of the patient P when the first image was captured and establish the amount of movement for finally moving the patient P.

[0115]

As described above, the integrated image calculator 121 may calculate each of the first integrated value and the second integrated value by converting a pixel value (CT value) of the first pixel (voxel) positioned on the radiation path and a pixel value (CT value) of the second pixel (voxel) positioned on a path corresponding to the radiation path, by a pre-established non-linear conversion (empirically determined non-linear conversion data) and then performing integration thereof. By doing this, the medical image processing apparatus 100 can, for example, based on a first integrated image and a second integrated image integrated after converting voxel CT value included in the first image and a voxel CT value included in the second image by a regression formula based on the on-linear conversion data determined empirically as shown in the above-noted Reference 1, establish the amount of movement to move the current patient P position.

[0116]

As described above, the integrated image calculator 121 may, by a non-linear conversion (empirically determined non-linear conversion data), convert a pixel value (CT value) of the first pixel (voxel) positioned on the radiation path and a pixel value (CT value) of the second pixel (voxel) positioned on a path corresponding to the radiation path to values (for example water-equivalent thicknesses) that represent the energy loss amount when the radio beam passes therethrough. By doing this, the medical image processing apparatus 100 can establish the amount of movement to move the current patient P position, based on a first integrated image and a second integrated image obtained by converting to, for example, equivalent water depths and then integrating a voxel CT value included in the first image and a voxel CT value included in the second image.

[0117]

As described above, the integrated image calculator 121 may calculate the first integrated image value and the second integrated value by integrating the energy loss amounts (water-equivalent thicknesses) that have been converted from the pixel value (CT value) of a first pixel (voxel) on a radiation path reaching up the region (lesion) that is the irradiated target of the treatment beam B (treatment beam b) and the pixel value (CT value) of a second pixel (voxel) on a path corresponding to the radiation path reaching up to the region (lesion) that is the irradiated target of the treatment beam B (treatment beam b). By doing this, the medical image processing apparatus 100 can reduce the processing (computation) amount when generating the first integrated image and the second integrated image.

[0118]

As described above, the movement amount signal may be transmitted to a treatment bed controller (not shown) that controls the movement of the treatment bed 11 provided in the treatment apparatus 10. By doing this, the treatment bed controller can control the movement of the treatment bed 11 based on the movement amount signal output by the medical image processing apparatus 100 to actually move the position of the patient P.

[0119]

As described above, the irradiated target region (lesion) of the radio beam is the region of a tumor (lesion) existing in the body of the patient P, and the radiation path may include the region of the tumor (lesion).

[0120]

As described above, if the second image has been moved by the amount of movement searched by the searcher 120, the path corresponding to the radiation path may include a region that avoids irradiation by the treatment beam B (treatment beam b) (for example, a region of air that did not exist at the treatment planning stage). By doing this, in the medical image processing apparatus 100, by the difference of the position of the Bragg peak of the treatment beam B (treatment beam b), it is possible to provide an appropriate strategy for not being able with the radiated treatment beam B (treatment beam b) to impart to the lesion in the body of the patient P the energy planned at the treatment planning stage or the possibility that an organ at risk (OAR) that is not to be irradiated by the treatment beam B (treatment beam b) is irradiated.

[0121]

As described above, the treatment system 1 may have a medical image processing apparatus 100, and a treatment apparatus 10 that has a ray irradiator

(treatment beam irradiation gantry 13) irradiating the patient P with the treatment beam B (treatment beam b), the radiographic imaging apparatus capturing the first image and the second image, and a treatment bed controller controlling the movement of a treatment bed 11 onto which the patient P is placed and fixed, in accordance with the movement amount signal. By doing this, the treatment system 1 can adjust the current position of the patient P to that state in which it is possible to irradiate a lesion in the body of the patient P with the treatment beam B (treatment beam b) having an energy amount close to the energy established at the treatment planning stage.

[0122]

The medical image processing apparatus 100 may be an apparatus having a processor such as a CPU or GPU and a storage device such as a ROM, a RAM, a HD drive, or a flash memory, and the storage apparatus may store a program to cause the processor to function as a first image acquirer 101 that acquires a three-dimensional first image of a patient P captured by a CT radiographic imaging apparatus 12, a second image acquirer 102 that acquires a three-dimensional second image of the patient P captured by the CT radiographic image apparatus 12 at a time different from the first image, a path acquirer 110 that acquires a radiation path (a path through which a radiated treatment beam B (treatment beam b) passes) set in the first image, and a searcher 120 that, based on first integrated values (first integrated image) of the integrated pixel values (CT values) of three-dimensional first pixels (voxels) through which the radiation path passes and which are included in the first image and on second integrated values (second integrated image) of the integrated pixel values (CT values) of three-dimensional second pixels (voxels) through which the path corresponding to the radiation path within the second image passes, outputs a movement amount signal that indicates the result of searching for an amount of movement of the second image to adjust the position of the patient P appearing in the second image to the position of the patient P appearing in the first image.

[0123] The medical image processing apparatus 100 may be an apparatus having a processor such as a CPU or GPU and a storage device such as a ROM, a RAM, a HD drive, or a flash memory, and the storage apparatus may store a program to cause the processer to function as a searcher 120 having an integrated image calculator 121 that calculates first integration values and generates the first integrated image, in which the calculated first integrated values are represented within an irradiation range to be irradiated by a radio beam, and that calculates second integrated values and generates the second integrated image, in which the calculated second integrated values are represented within a irradiation range, a comparator 122 that compares the first integrated values (voxel data), which are the integrated (linearly integrated) values of pixel values (CT values) of first pixels (voxel data) included in the first integrated image, and the second integrated values (voxel data), which are integrated (linearly integrated) values of pixel values (CT values) of the second pixels (voxel data) corresponding to the first integrated values (voxel data) included in the second integrated image, a determiner 123 that, based on the comparison results of the comparator 122, determines the offset of the radiation paths appearing in the first integrated image and the second integrated image, and a movement unit 124 that establishes the amount of movement based on the determination result of the determiner 123 and outputs a movement amount signal representing the established amount of movement.

[0124]

(Second Embodiment)

The second embodiment will now be described. The constitution of the treatment system that has a medical image processing apparatus of the second embodiment has, in the treatment system 1 that has the medical image processing apparatus 100 of the first embodiment shown in FIG. 1, the medical image processing apparatus of the second embodiment (hereinafter "medical image processing apparatus 200") in place of the medical image processing apparatus 100. The treatment system that has the medical image processing apparatus 200 will be referred to as the treatment system 2.

[0125]

In the description to follow, in the constituent elements of the treatment system 2 that has the medical image processing apparatus 200, constituent elements that are the same as constituent elements of the treatment system 1 that has the medical image processing apparatus 100 of the first embodiment are assigned the same reference symbols, and the detailed descriptions thereof will be omitted. In the following description, only the constitution, operation, and processing of the medical image processing apparatus 200, which is a constituent element differing from the medical image processing apparatus 100 of the first embodiment, will be described.

[0126]

The medical image processing apparatus 200, similar to the medical image processing apparatus 100 of the first embodiment, based on a CT image output from the CT radiographic imaging apparatus 12, outputs a determination signal indicating the result of determining the offset between the attitude of the patient P at the treatment planning stage and the current attitude of the patient P. The medical image processing apparatus 200, similar to the medical image processing apparatus 100 of the first embodiment, based on the result of determining the offset of the patient P attitude, outputs a movement amount signal representing the amount of movement to move the state (attitude, including position and direction) of the patient P at the time of performing radiotherapy so as to approach the attitude of the patient P at the treatment planning stage. However, with the medical image processing apparatus 200, the search processing to search for the amount of movement to move the attitude of the patient P to approach the treatment planning stage is performed at a higher speed than with the medical image processing apparatus 100 of the first embodiment.

[0127]

The constitution of the medical image processing apparatus 200 of the treatment system 2 will now be described. FIG. 5 is a block diagram showing the general constitution of the medical image processing apparatus 200 of the second embodiment. The medical image processing apparatus 200 shown in FIG. 5 has a first image acquirer 101, a second image acquirer 102, a path acquirer 110, and a searcher 220. The searcher 220 has a provisional positioner 225, an integrated image calculator 121, a comparator 122, a determiner 123, and a movement unit 224.

[0128]

The medical image processing apparatus 200 is constituted to have the searcher 120 of the medical image processing apparatus 100 of the first embodiment replaced by the searcher 220. The searcher 220 has a constitution in which the provisional positioner 225 is added to the searcher 120 provided in the medical image processing apparatus 100 of the first embodiment. Accompanying this, in the medical image processing apparatus 200, the movement unit 124 in the searcher 120 provided in the medical image processing apparatus 100 of the first embodiment is replaced by the movement unit 224. The other constituent elements provided in the medical image processing apparatus 200 are the same as constituent elements provided in the medical image processing apparatus 100 of the first embodiment. In the following description, therefore, in the constituent elements of the medical image processing apparatus 200, those constituent elements that are the same as one in the medical image processing apparatus 100 of the first embodiment are assigned the same reference symbols, and the detailed descriptions thereof will be omitted. In the following description, only the constituent elements that differ from the medical image processing apparatus 100 of the first embodiment will be described.

[0129]

The searcher 220, similar to the searcher 120 provided in the medical image processing apparatus 100 of the first embodiment, searches for the amount of movement for adjusting the current position of the patient P to the position at the time of the treatment planning stage, based on information of each of the paths of the treatment beams b output from the path acquirer 110, the first image output from the first image acquirer 101, and the second image output from the second image acquirer 102. The searcher 220, similar to the searcher 120 provided in the medical image processing apparatus 100 of the first embodiment, searches for the amount of movement for positioning the patient P so that the energy imparted to the lesion in the body of the patient P by irradiation with the treatment beam B approaches the energy planned at the treatment planning stage.

[0130]

However, in the medical image processing apparatus 200, as described above, the search processing for searching for the amount of movement to adjust the position of the patient P is faster than that of the medical image processing apparatus 100 of the first embodiment. This is because, although in the medical image processing apparatus 100 of the first embodiment the searcher 120 searches for the amount of movement for adjusting the current position of the patient P to the position at the treatment planning stage, in the medical image processing apparatus 100 of the first embodiment, if the offset between the first image and the second image, that is, the offset between the patient P position at the treatment planning stage and the current patient P position is large, it can be envisioned that time is required for the search processing in the searcher 120. More specifically, this is because it can be envisioned that, in the flowchart of the search processing in the medical image processing apparatus 100 of the first embodiment shown in FIG. 3, the number of repetitions of the processing of searching for the final amount of movement of the second image at step S400 to S600 becomes large. Given this, the searcher 220 is provided with the provisional positioner 225. In the medical image processing apparatus 200, in order to reduce the offset between the first image and the second image to within a

pre-established offset amount, the provisional positioner 225 provisionally establishes the amount of movement of the second image and, by searching for an amount of movement for adjusting the current patient P position from this state to the position at the treatment planning stage, reduces the time required for search processing. That is, in the medical image processing apparatus 200, by provisionally moving the second image beforehand based on a provisionally established amount of movement, the range for determining the offset between the first integrated image and the second integrated image in the search processing is narrowed beforehand to the region surrounding irradiated target (lesion exiting in the body of the patient P) to be irradiated by the treatment beam B (radio beam), the speed of the search processing is increased.

[0131] The provisional positioner 225, based on the first image output from the first image acquirer 101 and the second image output from the second image acquirer 102, provisionally established the amount of movement for adjusting the current patient P position to the position at the treatment planning stage. More specifically, the provisional positioner 225, so as to reduce the offset between the first image and the second image to a pre-established amount, provisionally establishes the amount of movement that includes the direction (inclination) of movement of the second image in a prescribed three-dimensional space. The provisional positioner 225 outputs to the integrated image calculator 121 the second image after moving it based on the provisionally established amount of movement. The provisional positioner 225 outputs to the movement unit 224 information indicating the provisionally established amount of movement.

[0132]

The integrated image calculator 121, rather than the second integrated image corresponding to the second image output from the second image acquirer 102, generates and outputs to the comparator 122 a second integrated image corresponding to the second image output from the provisional positioner 225 after being provisionally moved (hereinafter "provisionally moved second image").

[0133]

The movement unit 224, similar to the movement unit 124 in the searcher 120 of the medical image processing apparatus 100 of the first embodiment, based on information of the determination result output from the determiner 123 for each treatment beam b path, establishes the amount of movement for movement of the provisionally moved second image in a prescribed three-dimensional space, and outputs to the integrated image calculator 121 information indicating the established amount of movement. However, the movement unit 224, when outputting a movement amount signal for movement of the current patient P position to the final position determined to match treatment planning stage, also outputs the amount of movement output from the provisional positioner 225. That is, the movement unit 224 outputs a movement signal as the final amount of movement of the second image, which is the amount of movement adjusted to the amount of movement already applied to the provisionally moved second image of the second integrated image to be generated by the integrated image calculator 121.

[0134]

The method of the provisional positioner 225 provided in the searcher 220 in the medical image processing apparatus 200 provisionally establishing the amount of movement of the second image will now be described. In the following description as well, one point in the prescribed three-dimensional space will be represented as point x.

[0135]

The provisional positioner 225 using a cost function such as the following Equation (13) to compare the first integrated image and the second integrated image.

[0136]

[Equation 13

• • ^■ ( 1 3 )

[0137]

In the above Equation (13), Ii(x, Θ) represents the CT value of a

three-dimensional voxel corresponding to the point x included in the first image virtually disposed in the prescribed three-dimensional space, and I ₂ (x, Θ) represents the CT value of a three-dimensional voxel corresponding to the point x included in the second image virtually disposed in the prescribed three-dimensional space. In the above Equation (13), X is the set of pixel positions. In Equation (13), the set X includes the CT values at the positions of all the pixels included in the first image and the second image. The set X, similar to the case of the integrated image calculator 121 generating the first integrated image and the second integrated image, is not restricted to the positions of pixels corresponding to, for example, the PTV or the PRV.

[0138]

The provisional positioner 225, by the above Equation (13), determines the ΔΘ that minimizes the squared error of the difference of the pixel image values (CT values) included in the first image and the second image. The provisional positioner 225 minimizes the cost function, using an optimization method such as the gradient method, the Newton method, the LK method, or the like. The provisional positioner 225 compares the first image and the second image and, based on the minimized cost function value E _k and ΔΘ, determines the provisional amount of movement p for moving the second image.

[0139]

The cost function used by the provisional positioner 225 to compare the first integrated image and the second integrated image may be the cost function shown in Equation (14).

[0140]

E _k (ΑΘ) = M _k (ΑΘ, X _x )+ (1 - X)E _k (ΑΘ, X ₂ )

^{• ■} - ( 1 4 ) [0141]

In the above Equation (14), X _\ represents, for example, the set of pixels included in the PTV, and X ₂ represents, for example, the set of pixels included in the PRV. In Equation (1 ^' 4), λ is a parameter and, if the comparison is done with emphasis on position adjustment in the PTV, λ is a value of, for example 0.5 or greater. Even if a cost function such as the above Equation (14) is used to compare the first image and the second image, the provisional positioner 225, based on the cost function value Ek and ΔΘ, determines the provisional amount of movement p for moving the second image.

[0142]

The provisional positioner 225 outputs the second image moved based on the determined provisional movement amount p to the integrated image calculator 121 as the provisionally moved second image. The provisionally moved second image output by the provisional positioner 225 to the integrated image calculator 121 is expressed by the following Equation (15).

[0143]

[Equation 15]

Ε(ΑΘ) = (Θ) -¼(0+/? + ΑΘ)} ²

^• · - ( 1 5 )

[0144]

By this type of comparison method, the provisional positioner 225 compares the first image and the second image and outputs to the integrated image calculator 121 a provisionally moved second image that is the second image moved based on the provisionally determined . provision movement amount p. After that, the searcher 220, similar to the searcher 120 provided in the medical image processing apparatus 100 of the first embodiment, performs search processing and outputs a movement amount signal that indicates the final amount of movement of the patient P.

[0145]

By this constitution and operation, the medical image processing apparatus 200, based on the first image of the patient P captured at the treatment planning stage or the like and the second image of the patient P captured before performing radiotherapy at the treatment stage, outputs as a determination signal the result of determining the offset between the position of the patient P at the treatment planning stage and the current position of the patient P. The medical image processing apparatus 200 also outputs a movement amount signal for moving the current patient P position to the position virtually established based on the result of the offset determination. By doing this, in the treatment system 2 that has the medical image processing apparatus 200, similar to the treatment system 1 that has the medical image processing apparatus 100 of the first embodiment, a treatment bed controller (not shown) that controls the movement of the treatment bed 11 actually moves the position of the patient P by moving the treatment bed 11 based on the movement amount signal. In the treatment system 2 that has the medical image processing apparatus 200, similar to the treatment system 1 that has the medical image processing apparatus 100 of the first embodiment, this enables radiotherapy according to plan, with the actual state (position) of the patient P adjusted to the state (position) enabling irradiation of the lesion in the body of the patient P with a treatment beam B having the energy planned at the treatment planning stage.

[0146] Furthermore, in the medical image processing apparatus 200, by the provisional positioner 225 provided in the searcher 220 moving the second image by a provisional movement amount established provisionally so as to reduce the amount of offset down to the amount of the prescribed offset between the first image and the second image, the search processing can be done from a state in which the range over which the search processing is done has been narrowed beforehand to the area surrounding the lesion in the body of the patient P being irradiated with the treatment beam B. In the medical image processing apparatus 200, this enables the search processing to search for the amount of movement for moving the state (position) of the patient P to approach that at the treatment planning stage can be performed faster than in the medical image processing apparatus 100 of the first embodiment.

[0147]

The search processing in the medical image processing apparatus 200 can be easily thought of as the search processing of the medical image processing apparatus 100 of the first embodiment shown in FIG. 3, with the addition of the processing by the provisional positioner 225. More specifically, it is easy to think of this as the addition processing whereby the provisional positioner 225 provisionally establishes a movement amount of, and moves the second image added before step SI 00 or between step S200 and step S300. The detailed description regarding the flow of search processing in the medical image processing apparatus 200 will therefore be omitted.

[0148]

As described above, in the medical image processing apparatus 200 of the second embodiment, the first image acquirer 101 acquires the first image of the patient P captured before treatment, and the second image acquirer 102 acquires the second image of the patient P captured immediately before the start of treatment. In the medical image processing apparatus 200 of the second embodiment, the path acquirer 110 acquires information of a path of irradiation with the treatment beam B established at the treatment planning stage, based on the first image. In the medical image processing apparatus 200 of the second embodiment, after the searcher 220 (provisional positioner 225), provisionally moves the second image to reduce the offset between the first image and the second image, the searcher 220 (integrated image calculator 121) generates the first image corresponding to the first integrated image and the second image corresponding to the second integrated image based on information of the treatment beam B path. In the medical image processing apparatus 200 of the second embodiment, the searcher 220 (comparator 122 and determiner 123) determines the offset in the treatment beam B paths between the first integrated image and the second integrated image, and outputs a determination signal indicating the result of the determination. In the medical image processing apparatus 200 of the second embodiment, the searcher 220 (movement unit 224), based on the determined amount of offset, establishes the amount of movement for causing the current attitude of the patient P to approach the attitude of the patient P at the treatment planning stage and, when the offset between the treatment beam B paths in between the first integrated image and the second integrated image has reached to within a pre-established allowable range, outputs a movement amount signal representing the final amount of movement of the patient P adjusted to the amount of movement already applied. By doing this, in the treatment system 2 that has the medical image processing apparatus 200 of the second embodiment, similar to the treatment system 1 that has the medical image processing apparatus 100 of the first embodiment, for example, a treatment bed controller (not shown) that controls the movement of the treatment bed 11, based on the movement amount signal, actually moves the position of the patient P by moving the treatment bed 11. In the medical image processing apparatus 200 of the second embodiment, similar to the treatment system 1 that has the medical image processing apparatus 100 of the first embodiment, this enables radiotherapy according to plan, with the current position of the patient P adjusted to the state enabling irradiation of the lesion in the body of the patient P with a treatment beam B having an energy amount close to the energy established at the treatment planning stage. Furthermore, in the treatment system 2 that has the medical image processing apparatus 200 of the second embodiment, the position of the patient P can be adjusted and the radiotherapy performed faster than with the treatment system 1 that has the medical image processing apparatus 100 of the first embodiment.

[0149]

As described above, in the medical image processing apparatus 200, the searcher 220 further has a provisional positioner 225 that, based on the difference between pixel values (CT values) of the first pixels (voxels) included in the first image and pixel values (CT values) of the second pixels (voxels) included in the second image, determines the offset between the first image and the second image and, based on provisional movement amount (provisionally established movement amount) established based on the determination result, outputs a provisionally moved second image in which the position of the patient P appearing in the second image adjusted beforehand to the patient P position appearing in the first image, and wherein the integrated image calculator 121 generates the first integrated image corresponding to the first image and the second integrated image corresponding to the second provisionally moved image. By doing this, the medical image processing apparatus 200 can, from the state in which the patient P position has been provisionally moved by the provisional positioner 225 beforehand, search for the amount of movement for adjusting the current patient P position to the position when the first image was captured, thereby enabling a shortening of the time required for the search processing.

[0150]

(Third Embodiment)

The third embodiment will now be described. The constitution of the treatment system that has a medical image processing apparatus of the third

embodiment has, in the treatment system 1 that has the medical image processing apparatus 100 of the first embodiment shown in FIG. 1, the medical image processing apparatus of the third embodiment (hereinafter "medical image processing apparatus 300") in place of the medical image processing apparatus 100. The treatment system that has the medical image processing apparatus 300 will be referred to as the treatment system 3.

[0151]

In the description to follow, in the constituent elements of the treatment system 3 that has the medical image processing apparatus 300, constituent elements that are the same as constituent elements of the treatment system 1 that has the medical image processing apparatus 100 of the first embodiment are assigned the same reference symbols, and the detailed descriptions thereof will be omitted. In the following description, only the constitution, operation, and processing of the medical image processing apparatus 300, which is a constituent element differing from the medical image processing apparatus 100 of the first embodiment, will be described. [0152]

The medical image processing apparatus 300, similar to the medical image processing apparatus 100 of the first embodiment, based on a CT image output from the CT radiographic imaging apparatus 12, outputs a determination signal indicating the result of determining the offset between the attitude of the patient P at the treatment planning stage and the current attitude of the patient P. The medical image processing apparatus 300 presents to user (a physician or the like) of the treatment system 3 that has the medical image processing apparatus 300 the result of the determination of the offset of the attitude of the patient P. The medical image processing apparatus 300 determines the offset of the attitude of the patient P in accordance with a setting by the user (a physician or the like) of the treatment system 3 that has the medical image processing apparatus 300. The medical image processing apparatus 300, similar to the medical image processing apparatus 100 of the first embodiment, based on the result of determining the offset of the patient P attitude, outputs a movement amount signal representing the amount of movement to move the state (attitude, including position and direction) of the patient P at the time of performing radiotherapy so as to approach the attitude of the patient P at the treatment planning stage.

[0153]

The constitution of the medical image processing apparatus 300 of the treatment system 3 will now be described. FIG. 6 is a block diagram showing the general constitution of the medical image processing apparatus 300 of the third embodiment. The medical image processing apparatus 300 shown in FIG. 6 has a first image acquirer 101, a second image acquirer 102, a path acquirer 110, a searcher 320, and a user interface 330. The searcher 320 has an integrated image calculator 321, a comparator 322, a determiner 323, and a movement unit 124.

[0154]

The medical image processing apparatus 300 is constituted to have the user interface 330 added to the medical image processing apparatus 100 of the first embodiment. Accompanying this, in the medical image processing apparatus 300, the searcher 320 replaces the searcher 120 provided in the medical image processing apparatus 100 of the first embodiment. In the searcher 320, the integrated image calculator 121 provided in the searcher 120 is replaced by the integrated image calculator 321, the comparator 122 is replaced by the comparator 322, and the determiner 123 is replaced by the determiner 323. The other constituent elements provided in the medical image processing apparatus 300 are the same as constituent elements provided in the medical image processing apparatus 100 of the first embodiment. In the following description, therefore, in the constituent elements of the medical image processing apparatus 300, those constituent elements that are the same as one in the medical image processing apparatus 100 of the first embodiment are assigned the same reference symbols, and the detailed descriptions thereof will be omitted. In the following description, only the constituent elements that differ from the medical image processing apparatus 100 of the first embodiment will be described.

[0155]

The searcher 320, similar to the searcher 120 provided in the medical image processing apparatus 100 of the first embodiment, searches for the amount of movement for adjusting the current position of the patient P to the position at the time of the treatment planning stage, based on information of each of the paths of the treatment beams b output from the path acquirer 110, the first image output from the first image acquirer 101, and the second image output from the second image acquirer 102. The searcher 320, similar to the searcher 120 provided in the medical image processing apparatus 100 of the first embodiment, searches for the amount of movement for positioning the patient P so that the energy imparted to the lesion in the body of the patient P by irradiation with the treatment beam B approaches the energy planned at the treatment planning stage.

[0156]

In the medical image processing apparatus 300, however, as described above, the results of determining the offset of the attitude of the patient P are presented to the user (a physician or the like) of the treatment system 3 that has the medical image processing apparatus 300. In the medical image processing apparatus 300, as described above, a determination is made of the offset of the patient P attitude in accordance with a setting made by the user (a physician or the like) of the treatment system 3 that has the medical image processing apparatus 300.

[0157]

The integrated image calculator 321, similar to the integrated image calculator 121 provided in the searcher 120 of the medical image processing apparatus 100 of the first embodiment, based on information of the paths of the treatment beam b output from the path acquirer 110, generates and outputs to the comparator 322 the first integrated image corresponding to the first image and the second integrated image corresponding to the second image. Additionally, the integrated image calculator 321 outputs the generated first integrated image and second integrated image to the user interface 330. The integrated image calculator 321, when generating the first integrated image and the second integrated image, which are virtually placed in the prescribed three-dimensional space, may output the first image and the second image to the user interface 330.

[0158]

The comparator 322, similar to the comparator 122 in the searcher 120 of the medical image processing apparatus 100 of the first embodiment, compares the first integrated image and the second integrated image output from the integrated image calculator 321. When this is done, the comparator 322 compares the first integrated image and the second integrated image based on a setting output from the user interface 330. More specifically, the comparator 322 compares the first integrated image and the second integrated image within a region corresponding to a region of interest (ROI) output from the user interface 330 in response to an operation by the user that sets a partial image region. The comparator 322 applies a parameter output from the user interface 330 in response to an operation by the user setting a parameter of a cost function to, for example, the cost function shown in Equation (11) or Equation (12), and compares the first integrated image and the second integrated image. The comparator

322 outputs information of the results of comparing the first integrated image and the second integrated image to the determiner 323.

[0159]

The determiner 323, similar to the determiner 123 in the searcher 120 of the medical image processing apparatus 100 of the first embodiment, determines the offset between the first integrated image and the second integrated image, based on the comparison result output from the comparator 322. When this is done, the determiner

323 outputs to the user interface 330 information of the determination result of the offset between the first integrated image and the second integrated image indicated by the output determination signal. The determiner 323, in accordance with an instruction indicated by user determination signal output from the user interface 330 according to the operation by the user, determines the offset between the first integrated image and the second integrated image. That is, the determiner 323, at the timing in accordance with an operation of the user interface 330 by the user, determines the offset between the first integrated image and the second integrated image. For example, if the user determination signal output from the user interface 330 indicates an instruction to execute the next determination processing, the determiner 323 executes processing to output the determination result information to the movement unit 124 and cause the determination of the amount of movement of the second integrated image, and determine the offset between the first integrated image and the new second integrated image generated by the integrated image calculator 321. Also, for example, if the user determination signal output from the user interface 330 indicates an instruction to end the determination processing, the determiner 323 either does not perform anew a determination of the offset between the first integrated image and second integrated image or ends the determination of the offset between the first integrated image and the second integrated image currently being performed and maintains he determination result output the previous time to the user interface 330. Because it can be envisioned that the user might use a previous determination result, the constitution may be such that the determiner 323 stores the history of information of the results of determining the offset between the first integrated image and the second integrated image and returns the amount of movement of the second image determined by the movement unit 124 to its original amount. The constitution may be such that the history of the determined amounts of movement of the second image is stored in the movement unit 124 and the user is able to reproduce the amount of movement of the second image obtained from the determination result that has been used.

[0160]

The user interface 330 has a display device, which presents to the user (a physician or the like) of the treatment, system 3. that has the medical image processing apparatus 300 the result of determining the offset of the attitude of the patient P, and an input device that accepts input of various operations from the user. The display device of the user interface 330 is, for example, a liquid crystal display (LCD). The user interface 330 displays on the display device the first integrated image and the second integrated image output from the integrated image calculator 321 and an image for presenting information of the result of determining the offset between the first integrated image and the second integrated image output from the determiner 323. If the first image and the second image are each output from the integrated image calculator 321, an image thereof, in which the corresponding first integrated image or the second integrated image are superimposed thereon may be displayed on the display device.

[0161]

The input device of the user interface 330 is an input device such as a keyboard, a pointing device such as a mouse or pen-type stylus, or an operating device such as buttons or switches. The user interface 330 accepts operations of the input device by the user. Specifically, it accepts setting of the region of interest (ROI) or cost function parameter and instructions expressed as a user determination signal, and outputs information representing the accepted operations to the corresponding comparator 322 or determiner 323. The user interface 330 may have a pressure sensor as an input device, which is constituted as a touch panel that is combined with the display device. In this case, the user interface 330, by the pressure sensor, detects and accepts various touch operations (tapping and flicking) made by the user on the f rst image and the second image displayed on the display device and outputs to the corresponding comparator 322 or determiner 323 information representing the accepted input operation by the user.

[0162]

The displaying information and the method of inputting settings and instructions in the user interface 330 will now be described. Because the first integrated image and the second integrated image are three-dimensional images, they cannot be directly displayed on a display device that displays in two dimensions.

Given this, the user interface 330 generates one or a plurality of cross-sectional images corresponding to the first integrated image and the second integrated image and displays them on the display device. When this is done, the user interface 330, in order to facilitate viewing of a comparison of the first integrated image and the second integrated image, displays difference images of each of the cross-sectional images. The user interface 330 may make a color map display, applying colors in accordance with the size of the difference values of the cross-sectional images. The user interface 330 may also make an overlaid display of the outline of the PTV or PRV. The user interface 330 may also display as information the cost function value for each of the PTV and PRV. By doing this, the user can verify the cross-sectional images of the first integrated image and the second integrated image and can determine the offset between the first integrated image and the second integrated image, and can judge whether or not to end the determination to adjust the position of the patient P. If the user operates the input device to input the determination result, the user interface 330 outputs to the determiner 323 a user determination signal that indicates the information input from the input device. The user can, on the cross-sectional image of the first integrated image and the second integrated image displayed on the display device, make a region of interest (ROI) setting or a costs function parameter setting. When the user operates the input device to input a region of interest (ROI) setting or a cost function parameter setting, the user interface 330 outputs to the comparator 322 information of the region of interest (ROI) setting or cost function parameter setting input by the input device.

[0163]

The method of the comparator 322 comparing the first integrated image and the second integrated image within the region corresponding to the region of interest ROI in the search processing in the medical image processing apparatus 300 will now be described. In the description to follow, the set of positions Y of a pixel (voxel) in a prescribed three-dimensional space included in the region of interest ROI output from the user interface 330 will be represented by YROI- In this case, the cost function represented as shown in the above Equation (11) is expressed, with Y=YROI, as shown in the following equation (16).

[0164]

[Equation 16]

[0165] In the above Equation (16), E OI represents the squared error of the integrated image constituted by only pixel positions included in the set YROI- [0166]

The comparator 322 determines the ΔΘ that minimizes the squared error of the difference between pixel values (voxel data) of the integrated image within the region corresponding to the region of interest ROI by the equation (16). The comparator 322 uses an optimization method such as the gradient method, the Newton method, or the LK method to minimize the cost function. The comparator 322 outputs to the determiner 323 the minimized cost function value E and ΔΘ as information of the result of comparing the first integrated image and the second integrated image within a region corresponding to the region of interest ROI.

[0167]

If the first integrated image and the second integrated image within the region corresponding to the region of interest ROI are compared by the comparator 322, the position Y of a pixel (voxel) in a three-dimensional space may be expressed by the following Equation (17).

[0168]

[Equation 17]

[0169]

In the above Equation (17), the set X is, for example, a set of positions of pixels corresponding to the PTV. When the positions Y are as in the above Equation (17) and the first integrated image and the second integrated image within a region corresponding to the region of interest ROI are also compared, the comparator 322 outputs the cost function value E and ΔΘ to the determiner 323 as information of the result of comparing the first integrated image and the second integrated image within the region corresponding to the region of interest ROI.

[0170]

By this comparison method, the comparator 322 outputs to the determiner 323 information of the result of comparing the first integrated image and the second integrated image within the region corresponding to the region of interest ROI.

[0171]

By this constitution and operation, the medical image processing apparatus 300, based on the first image of the patient P captured at the treatment planning stage or the like and the second image of the patient P captured before performing radiotherapy at the treatment stage, outputs as a determination signal the result of determining the offset between the position of the patient P at the treatment planning stage and the current position of the patient P. The medical image processing apparatus 300 presents to the user (a physician or the like) of the treatment system 3 that has the medical image processing apparatus 300 the results of determining the offset between the patient P position at the treatment planning stage and the current patient P position, by display on a display device of the user interface 330. By doing this, the user of the treatment system 3 that has the medical image processing apparatus 300 can make a determination as to whether or not to end the determination of the offset between the patient P position at the treatment planning stage and the current patient P position.

[0172]

In the medical image processing apparatus 300, the user (a physician or the like) of the treatment system 3 that has the medical image processing apparatus 300 can operate an input device of the user interface 330 to make region of interest ROI settings or cost function parameter settings on the cross-sectional images of the first integrated image and the second integrated image displayed on the display device. By doing this, the medical image processing apparatus 300 can compare the first integrated image and the second integrated image, that is, can make a determination of the offset between the patient P position at the treatment planning stage and the current patient P position, by a method set by the user.

[0173]

In the medical image processing apparatus 300, a movement amount signal is output for moving the current position of the patient P to the final position determined based on the result of the offset determination. By doing this, in the treatment system 3 that has the medical image processing apparatus 300, for example, a treatment bed controller (not shown) that controls the movement of the treatment bed 11, based on the movement amount signal, moves the treatment bed 11 so as to actually move the position of the patient P. By doing this, in the treatment system 3 that has the medical image processing apparatus 300, the current position of the patient P can be moved to a position in accordance with a judgment or instruction by the user. By doing this, in the treatment system 3 that has the medical image processing apparatus 300, radiotherapy can be performed by irradiating a lesion within the body of the patient P with a treatment beam B having an energy planned at the treatment planning stage, with the patient P in a state (position) in accordance with a judgment or instruction by the user.

[0174]

With the exception of the display by and input from the user interface 330, the search processing in the medical image processing apparatus 300 is the same as the search processing in the medical image processing apparatus 100 of the first embodiment shown in FIG. 3. More specifically, with the exception of the integrated image calculator 321 presenting the integrated images to the user and the determiner 323 presenting information of the determination result represented by the determination signal to the user by outputting them to the user interface 330, the comparison processing in the comparator 322 being done by a method set by the user using the user interface 330, and the determination processing in the determiner 323 controlling execution and ending in accordance with a judgment result of the user input at the user interface 330, the search processing in the medical image processing apparatus 300 is the same as the search processing in the medical image processing apparatus 100 of the first embodiment shown in FIG. 3. Therefore the detailed description regarding the flow of the search processing in the medical image processing apparatus 300 will be omitted.

[0175]

As described above, in the medical image processing apparatus 300 of the third embodiment, similar to the medical image processing apparatus 100 of the first embodiment, the searcher 320 (integrated image calculator 321), based on information of the path of the treatment beam B, generates a first integrated image corresponding to the first image and a second integrated image corresponding to the second image.

When this is done, in the medical image processing apparatus 300 of the third embodiment, by outputting the generated first integrated image and second integrated image to the user interface 330, they are presented to the user (a physician or the like) of the treatment system 3 having the medical image processing apparatus 300. In the medical image processing apparatus 300 of the third embodiment, similar to the medical image processing apparatus 100 of the first embodiment, the searcher 320 (comparator 322 and determiner 323) determines the offset of the path of the treatment beam B between the first integrated image and the second integrated image and outputs a determination signal representing the determination result. When this is done, in the medical image processing apparatus 300 of the third embodiment, the determination is performed in accordance with a setting from the user input to the user interface 330. Also, in the medical image processing apparatus 300 of the third embodiment, information indicating the determination result is presented to the user by outputting it to the user interface 330. In the medical image processing apparatus 300 of the third embodiment, in accordance with an instruction from the user input to the user interface 330, the determination of the offset of the path of the treatment beam B between the first integrated image and the second integrated image is either executed or ended. In the medical image processing apparatus 300 of the third embodiment, the movement amount signal representing the amount of movement established by the movement unit 124 based on the determination result when the offset determination was ended is output as the movement amount signal for moving the current patient P position to the finally established position. By doing this, in the treatment system 3 that has the medical image processing apparatus 300 of the third embodiment, for example, a treatment bed controller (not shown) that moves the treatment bed 11 moves the treatment bed 11 based on the movement amount signal, thereby actually moving the position of the patient P. By doing this, in the treatment system 3 that has the medical image processing apparatus 300 of the third embodiment, the user can move the current patient P position to the desired position, enabling radiotherapy by irradiation of the lesion within the body of the patient P with the treatment beam B having the energy planned at the treatment planning stage in the state (position) desired by the user.

[0176]

The user interface 330 is not restricted to a constitution in which it is provided in the medical image processing apparatus 300 of the third embodiment, and may be provided in the treatment system that has the medical image processing apparatus 300 of the third embodiment. The user interface 330 is not restricted to a constitution in which it is added to the medical image processing apparatus 100 of the first

embodiment or to the treatment system 1 that has the medical image processing apparatus 100, and may be added to the medical image processing apparatus 200 of the second embodiment or to the treatment system 2 that has the medical image processing apparatus 200.

[0177]

In the medical image processing apparatus 300 of the third embodiment, the description has been for the case in which, in the constitution of the medical image processing apparatus 300 shown in FIG. 6, the user interface 330 generates and causes display (overlaying) on the display device of images in accordance with information output from constituent elements within the searcher 320 provided in the medical image processing apparatus 300. However, the constitution is not restricted to one in which the images displayed (overlaid) in the display device of the user interface 330 are generated within the user interface 330, and they may be generated by constituent elements that input information. For example, the constitution may be one in which the medical image processing apparatus 300, the integrated image calculator 321 within the controller 320 generates cross-sectional images corresponding to the first integrated image and the second integrated image and outputs to the user interface 330 the generated cross-sectional images as the first integrated image and the second integrated image. In this case, the constitution may be. one in which the user interface 330 displays as is the cross-sectional images output from the integrated image calculator 321. Also, for example, in the medical image processing apparatus 300, the constitution may be one in which the determiner 323 in the searcher 320 generates one information display image for displaying the information of the determination result of the offset between the first integrated image and the second integrated image represented by the determination signal and outputs the generated information display image to the user interface 330 as information of the determination results represented by the

determination signal. In this case, the constitution is one in which the user interface 330 overlays the one information display image output from the determiner 323 onto the cross-sectional images as is.

[0178]

As described above, the medical image processing apparatus 300 further has the user interface 330 that has a display device that displays at least the results of determination by the determiner 323. This enables the medical image processing apparatus 300 to present to the user (a physician or the like) of the treatment system 3 that has the medical image processing apparatus 300 the determined state of the offset between the virtually moved current patient P position and the position of the patient P at the time the first image was captured.

[0179]

As described above, in the medical image processing apparatus 300, the user interface 330 further has an input device that sets the comparison regions within the irradiation range compared by the comparator 322 of the first integrated values and the second integrated values (which can be the region of interest ROI and a cost function parameter), and the comparator 322 may compare the first integrated values and the second integrated values within the comparison region corresponding to the region of interest ROI set by the input device. By doing this, the medical image processing apparatus 300, by a method set by the user (a physician or the like) of the treatment system 3 that has the medical image processing apparatus 300 can perform search processing to search for a movement amount for adjusting the current patient P position to the position when the first image was captured.

[0180]

As described above, the treatment system 3 may further have a user interface 330 that has a display device that displays information when the searcher 320 searches for the amount of movement of the second image. By doing this, the treatment system 3 can present to the user (a physician or the like) of the treatment system 3 the state of processing by the medical image processing apparatus 300 that determines the offset between the virtually moved current patient P position and the patient P position when the first image was captured.

[0181]

As described above, in the treatment system 3, the user interface 330 further has an input device that sets the searching region (which can be the region of interest ROI and a cost function parameter) for searching by the searcher 320 for the amount of movement of the second image, and the searcher 320 may, based on the first integrated values and second integrated values corresponding to the region of interest ROI set by the input device, search for the amount of movement of the second image. By doing this, the treatment system 3 can, by a method set by the user (a physician or the like), perform search processing to search for the amount of movement for adjusting the current patient P position in the medical image processing apparatus 300 to the position when the first image was captured.

[0182]

As described above, in the medical image processing apparatus of the various embodiments, the first image, which is a three-dimensional CT image of the patient P captured before treatment, the second image, which is a patient P three-dimensional CT image currently captured, and information of the path of the treatment beam B that is radiated established based on the first image are acquired. In the medical image processing apparatus of the various embodiments, the first integrated image

corresponding to the first image and the second integrated image corresponding to the second image are generated by, in the first image and the second image, converting the pixel values (CT values) of three-dimensional pixels (voxels) positioned on the path of the treatment beam B by converting the radio beam energy loss amount to a water thickness that is the water-equivalent thickness, and then integrating (by linear integration). In the medical image processing apparatus of the various embodiments, by determining the offset of the path of the treatment beam B between the first integrated image and the second integrated image, an amount of movement is searched for that adjusts the current state (attitude, including position, direction, and the like) patient P to the state at the treatment planning stage. In the medical image processing apparatus of the various embodiments, an amount of movement of the second image in accordance with an amount of offset when the offset of the path of the treatment beam B in the first integrated image and the second integrated image becomes an offset within a pre-established allowable range is established as the final amount of movement of the patient P to adjust the current patient P state to the state of the patient P at the treatment planning stage. In the medical image processing apparatus of the various

embodiments, a movement amount signal is output that represents the established final amount of movement of the patient P. By doing this, in a treatment system that has a medical image processing apparatus of the various embodiments, for example, a treatment bed controller that controls the movement of the treatment bed moves the treatment bed based on the movement amount signal, thereby actually moving the state of the patient P. In the treatment system that has a medical image processing apparatus of the various embodiments, this enables radiotherapy according to plan, with adjustment of the current patient P state to a state enabling irradiation of a lesion in the body of the patient P by a treatment beam B having an energy amount that is close to the energy established at the treatment planning stage.

[0183]

In the description of the second embodiment and the third embodiment, constituent elements that are features of those embodiments are added to the medical image processing apparatus 100 of the first embodiment. However, there is no restriction to a constitution in which the constituent elements that are features of each of the embodiments are each exclusively provided in the medical image processing apparatus. That is, the constituent elements that are the features of each of the embodiments may be provided simultaneously in the medical image processing apparatus. For example, the medical image processing apparatus may be constituted to have simultaneously the provisional positioner 225 provided in the medical image processing apparatus 200 of the second embodiment and the user interface 330 provided in the medical image processing apparatus 300 of the third embodiment. In this case, the other constituent elements provided in the medical image processing apparatus can be appropriately changed to implement the functions corresponding to each of those constituent elements.

[0184]

In each of the embodiments, the description has been for constitutions, in which the medical image processing apparatus and the treatment apparatus 10 are separated. However, the constitution is not restricted to one in which the medical image processing apparatus and the treatment apparatus 10 are separated, and the medical image processing apparatus and the treatment apparatus 10 may be constituted as one.

[0185]

In the various embodiments, the description has been for the case in which, if the result of the determination of the offset of the pixel values on the path of the treatment beam b between the first integrated image and the second integrated image made by the comparator and the determiner is such that the body tissue on the path of the treatment beam b is greatly offset, an appropriate strategy is provided for moving the current patient P position so that the body tissue coincides. However, the strategy when there is a large offset of pixel values on the path of the treatment beam b is not restricted to the method described in the various embodiment. For example, if the intensity of the treatment beam b that is radiated at the treatment planning stage can be changed, it is possible to provide a strategy that, rather than moving the current position of the patient P, changes the intensity of the treatment beam b. More specifically, if the result of comparing the distance (equivalent water depth) from the surface of the body of the patient P to the lesion represented by the first integrated image and the second integrated image is that the position of the Bragg peak in the path of some treatment beam b is offset in the direction of greater depth than at the treatment planning stage, the strategy may be to decrease the intensity of the treatment beam b. If, however, the result of comparing the distance (equivalent water depth) from the surface of the body of the patient P to the lesion represented by the first integrated image and the second integrated image is that the position of the Bragg peak in some path of the treatment beam b is offset in the direction of less depth than at the treatment planning stage, the strategy may be to increase the intensity of the treatment beam b. In this case, it can be envisioned that the change of the intensity of the treatment beam b in the medical image processing apparatus is determined by the constituent element corresponding to the movement unit.

[0186]

A medical image processing program used in the treatment system described in the above-noted embodiments causes a computer to function as a first image acquirer that acquires a three-dimensional first image of an object to be treated captured by a radiographic imaging apparatus, a second image acquirer that acquires a

three-dimensional second image of the object to be treated captured by the radiographic image apparatus at a time different from the first image, a path acquirer that acquires a radiation path set in the first image, and a searcher that, based on first integrated values of the integrated pixel values of three-dimensional first pixels through which the radiation path passes and which are included in the first image and on second integrated values of the integrated pixel values of three-dimensional second pixels through which the path corresponding to the radiation path within the second image passes, outputs a movement amount signal that indicates the amount of movement of the second image to adjust the position of the object to be treated appearing in the second image to the position of the object to be treated appearing in the first image.

[0187]

According to at least one of the above-described embodiments, by having a first image acquirer (101) that acquires a three-dimensional first image of an object to be treated (patient P) captured by a radiographic imaging apparatus (CT radiographic imaging apparatus 12), a second image acquirer (102) that acquires a three-dimensional second image of the object to be treated (patient P) captured by the radiographic imaging apparatus (CT radiographic imaging apparatus 12) at a time different from the first image, a path acquirer (110) that acquires a radiation path (path through which the radiated treatment beam B (treatment beam b) passes) set in the first image, and a searcher (120) that, based on first integrated values of the integrated pixel values (CT values) of the three-dimensional first pixels (voxels) through which the radiation path passes and included in the first image and on second integrated values of the integrated pixel values (CT values) of the three-dimensional second pixels (voxels) through which the path corresponding to the radiation path within the second image passes, outputs a movement amount signal that indicates an amount of movement of the second image to adjust the position of the object to be treated (patient P) appearing in the second image to the position of the object to be treated (patient P) appearing in the first image, the position of the patient can be adjusted to as to impart the planned radio beam energy to the lesion.

[0188]

A program for implementing the functions of each of the constituent elements of a medical image processing apparatus, such as the searcher 120, and the integrated image calculator 121, the comparator 122, the determiner 123, and the movement unit 124 and the like of the searcher 120 shown in FIG. 2 may be recorded in a

computer-readable storage medium, and a computer system may be made to read-in and execute the program stored in the storage medium, so as to implement the various above-noted functions of treatment system of the present embodiment. The term "computer system" may include an operating system and hardware such as peripheral devices. The term "computer system" also includes a WWW system having a webpage-providing environment (or webpage-displaying environment). The term "computer-readable storage medium" refers to a writable non- volatile memory such as a flexible disk, an optomagnetic disk, a ROM, a flash memory, a removable media such as a CD-ROM, or the like, or a storage device such as a hard disk or the like built into a computer system.

[0189]

Additionally, the term "computer-readable storage medium" encompasses one holding a program for a given period of time, such as a volatile memory (DRAM:

dynamic random access memory) within a computer system serving as a server or client when a program is transmitted via a network such as the Internet or via a

communication line such as a telephone line. The above-noted program may be transferred from a computer system in which the program is stored in a storage apparatus to another computer system, either via a transfer medium, or by a transfer wave in a transfer medium. In this case, the term "transfer medium" transferring a program refers to a medium having a function of transferring information, such as a network (communication network) such as the Internet, or a communication circuit (communication line) such as a telephone line. The above-noted program may be for implementing a part of the above-described functionality. Additionally, it may be a so-called difference file (difference program) enabling implementation in combination with a program that already has recorded the above-noted functionality in a computer system.

Each element for the medical image processing apparatus described above and for the treatment system described above can be implemented by hardware with or without software. In some cases, the medical image processing apparatus may be implemented by one or more hardware processors and one or more software components wherein the one or more software components are to be executed by the one or more hardware processors to implement each element for the medical image processing apparatus and for the treatment system. In some other cases, the medical image processing apparatus may be implemented by a system of circuits or circuitry configured to perform each operation of each element for the medical image processing apparatus and for the treatment system.

[0190]

While certain embodiments of the present inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.