apparatus and an X-ray detector

TECHNICAL FIELD

The present invention relates generally to providing dose measurement in an X-ray apparatus, and in particular to an X-ray dose detection arrangement, an X-ray imaging system, and a method for measuring an X-ray dose in an X-ray imaging system. BACKGROUND

In X-ray imaging, for example in medical X-ray imaging, it is necessary to control radiation levels. Therefore, the X-ray dose is measured, for example by providing an ionization chamber. The ionization chamber may be provided as an extra-unit between the object, for example a patient, and the detector/x-ray source. However, due to the ionization chamber provided as a separate component, the setup for the X-ray imaging system consumes valuable space. Further, the ionization chamber may be displaced and exposure procedures may be performed without ionization chambers. Fig. 1 is a schematic view of a simplified X-ray source housingl OO according to prior art. The X-ray source housing 100 comprises an X-ray tube 101 , which generates X-rays 102. The X-rays 102 pass through a collimator 103 and in this case a Dose Area Product (DAP) meter 104. DAP meters are usually large-area, transmission ionization chambers and associated electronics. In use, the ionization chamber is placed perpendicular to the beam central axis and in a location to completely intercept the entire area of the x-ray beam. The DAP, in combination with information on x-ray field size can be used to determine the average dose produced by the x-ray beam at any distance downstream in the x-ray beam from the location of the ionization chamber.

DAP is defined as the integral of dose across the X-ray beam. Therefore DAP includes field non-uniformity effects such as anode-heel-effect, and the use of semi-transparent beam-equalizing shutters (lung shutter). Assuming that the incident beam is totally confined to the patient, the recorded value may essentially provide an upper limit on the X-ray energy absorbed by the patient (i.e. there is no transmission or scatter). DAP's ability to estimate stochastic risk is degraded because of the lack of dose distribution information within the patient. The best may be to assume an average weighting factor for all the tissues at risk. This may lead to an over or under estimate of risk in certain cases.

SUMMARY Thus, there is a need to provide dose measurement in X-ray imaging requiring minimized constructional space and positioning that do not interfere with the reproduced image. The solution of the present invention provides for measuring a number of X-ray parameters, amongst others total dose and ray quality. For these reasons an X-ray parameter measuring arrangement comprising a detector for measuring said parameter configured to be positioned in a position adjacent to an x-ray source arranged to generate a ray formation having a primary ray portion for radiating an object. The position is chosen in such a way that the interference with a reproduced image is reduced or eliminated. In one embodiment, the detector is configured to measure scattered radiation. In another embodiment, the detector is configured to measure a direct radiation. In one embodiment, the detector is arranged on a housing of the x-ray source and configured to detect the scattered rays through an aperture provided in the housing. The detector, according to a second embodiment, is arranged at an opening of a housing of the source from which x-rays emerge, positioned at least partly or entirely in an image field, i.e. the ray formation radiating an object to be examined. The detector may also be arranged inside a housing of the source, in a position of corresponding to a direction from where the rays leave a collimator aperture positioned at least partly or entirely in an image field, i.e. the ray formation radiating an object to be examined. In a fourth, the detector is arranged inside a housing, between the source and a collimator. In a fifth embodiment, the detector is arranged inside or on a surface of a collimator.

The X-ray parameter measuring arrangement of the present invention , may be configured to measure one or several radiological parameters including dose of scattered X-rays, total dose, dose rate, Peak Kilovoltage (kVp), half-value layer (HVL), total filtration, exposure time, pulses, pulse rate and dose/pulse. The detector, in one embodiment, comprises a housing enclosing a number of stacked diode layers, each diode layer distanced from each other and provided with a radiation filter between each diode layer and each diode layer connected to a processing unit for generating a signal corresponding to said parameter. The detector may comprise a housing enclosing one or several didoes in one layer. Moreover, the detector in one embodiment comprises a RF communication portion.

The invention also relates to an X-ray detector comprising: a number of stacked diode layers, a radiation filter layer between each diode layer; and a processing unit connected each diode layer or a diode in each diode layer. The X-ray detector may further comprise a housing of a radiation blocking material. The processing unit may be realized in Application Specific Integrated Circuit (ASIC). The invention also relates to a computer network for handling radiological information, the network comprising an X-ray examination arrangement, a data collector and a database, wherein the X-ray examination arrangement is provided with an X-ray parameter measuring arrangement comprising a detector for measuring said x-ray parameter, the arrangement is configured to be positioned in a position adjacent to an x-ray source arranged to generate a ray formation having a primary ray portion for radiating an object. The position is chosen in such a way that the interference with a reproduced image is reduced or eliminated. The database may consist of a central application and a locally- installed DICOM or MWL, RDSR, MPPS, DICOMOCR data collector. BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the attached drawings, wherein elements having the same reference number designation may represent like elements throughout.

Fig. 1 illustrates schematically an exemplary X-ray source according to prior art;

Fig. 2a illustrates schematically an exemplary X-ray source according to present

invention;

Fig. 2b illustrates schematically an exaggerated portion of X-ray source of Fig. 2a; Fig. 3 is a cut through an exemplary detector according to one embodiment of the present invention; and Fig. 4 is a schematic communication system for radiography purposes incorporating present invention;

DETAILED DESCRIPTION

Fig. 2a is a schematic view of a simplified X-ray source housing 200. The X-ray source housing 200 comprises an X-ray tube 201 , which generates X-rays 202 with a certain formation (ray image). The X-rays 202 pass through a collimator 203, which narrows the beam before radiating an object 206 to be examined.

According to the invention, at least one x-ray measuring detector 205 is arranged adjacent to the x-ray source housing 200, between the tube 201 and the object (e.g. patient) 206 to be examined. The source housing comprises a housing 207. The detector 205 may be mounted adjacent to the tube on the housing, in a first position as illustrated by solid line or in position where the beam exits the housing, as illustrated by dashed line. In this way, when the tube generates a ray formation with a primary ray portion for radiating the object, the detector positioned outside the primary ray portion but inside the ray formation (ray image).

Fig. 2b illustrates a number of different positions in which the detector(s) (black boxes) may be provided. Detector 2051 is arranged on the housing 207 and is configured to detect the scattered rays 2021. In this case an aperture is provided in the housing to let through the rays.

Detector 2052 is arranged at the opening of the housing 207 from which x-rays emerge. The detector may, at least partly or entirely, be arranged in the image field, i.e. the ray formation that will radiate the object to be examined. However, due to its position on the fringe of the opening, its influence on the reproduced image will be negligible or very little.

Detector 2053 is arranged inside the housing 207, beneath the collimator 203 aperture. Although, in this embodiment, the detector may, at least partly or entirely, be arranged in the image field, i.e. the ray formation that will radiate the object to be examined. However, due to its position on the fringe of the beam formation, its influence on the reproduced image will be negligible or very little.

Detector 2054 is arranged inside the housing 207, between the tube and the collimator 5 207. In this case, the primary beam before passing the collimator will be measured and the reproduced image will not be influenced at all.

Detector 2055 is arranged inside or on a surface of the collimator 203. In this case, the primary beam before passing the collimator will be measured and the reproduced image 10 will not be influenced at all.

The consequence of positioning of the detector(s) 205 in a space adjacent to the source 201 or in small portion of sight for the primary X-ray beams 202, is that the detector will not interfere or have very small (negligible) with the rays radiating the object 206 and 15 deteriorate the reproduced image.

The X-ray measuring detector 205 (which will be detailed below) comprises a sensor, which is configured to measure radiological parameters, mainly dose of scattered X-rays. The sensor is also capable of measuring other radiological parameters such as dose rate, 20 Peak Kilovoltage (kVp), half-value layer (HVL), total filtration, exposure time, pulses, pulse rate and dose/pulse.

The output of the detector may be provided to a computer unit 208 for processing the signals.

25

The detector 205 may be assembled on the source housing separately or built in.

Fig. 3 is a cross sectional view of one exemplary detector 305 according to one embodiment of the invention. The detector comprises a sensor part 3051 and electronics 30 3052 enclosed inside a housing 3053.

The housing 3053, e.g. made of tin or other suitable x-ray blocking material, has an open end (window) 30531 for allowing through radiation. The open end is however, provided with a light blocking element 30532. The housing comprises a bottom portion 30533 and a 35 upper portion 30534. The sensor part 3051 comprises a number of stacked solid state (silicon) diodes 30511 (four rows in this case). Diodes in each row are arranged on a carrier (PCB) (not numbered) connected to a conductor 30512.

A filtering layer 30513, e.g. made of copper or other suitable material, is arranged between each row comprising diodes and carrier. The rows are distanced using distancing elements 30514 (at each side), e.g. arranged as a frame for each row. The filter layers function as filters between each diode row such that they block radiation from sides but allow radiation falling through the open end 30531 of the housing.

The electronic portion comprises 3052 a signal processing unit 30521 (e.g. realized as Application Specific Integrated Circuit (ASIC)). Each row is connected to input of processing unit by means of conductors 30512 as a channel. The output of the signal processing unit may be connected to external processing elements (not shown) through a cable 30522. Instead or in combination with the cable 30522, the electronic portion may also be provided with a RF transmitter/receiver 30523 for transmitting processed data to a receiver. The electronics may be provided with power using onboard power source or external power source.

The number of diodes in rows and number of layers depends on application are. The detector may comprise only one diode, e.g. for the applications where the sensor is incorporated with the collimator as described above. However, a preferred embodiment comprises at least three or more layers.

As mentioned earlier, the senor comprises stacked diodes, in which each diode layer is radiated by same source radiation. The filter layers between each diode layer changes energy content of the source radiation, i.e. each diode layer is radiated by spectrally different radiation although having a common source radiation. Each diode layer generates a current depending on the radiation intensity and energy. The diode currents are connected to an amplifier (e.g. transimpedance amplifier) with varying amplification and a following amplifier (e.g. voltage amplifier) with varying amplification. The diode specific voltage for each diode layer is then forwarded to an Analogue-to-Digital converter (ADC) for further connection to a processing unit, which processes the signals to compute one or several of dose, kVp, total filter, dose rate, expose time, HVL, etc., for the source radiation.

Fig. 4 illustrates a schematic of a network 400, which may incorporate a detector and measuring teachings of the present invention. The network according to this embodiment comprises an X-ray examination arrangement 401 , such an X-ray machine, CT, radiography machine, etc., provided with at least one detector 405 as described earlier. The examination arrangement 401 and the detector 405 may be connected to RIS/PACS 406 and/or a data collector 407. The information from data collector 407 may be provided to a database 408 in the computer network.

The database may consist of a cloud-based application and a locally-installed DICOM or similar (MWL, RDSR, MPPS, DICOMOCR) data collector. Users such as, operator 4091 , RSO physicist 4092, radiologist 4093 etc., may access the information form the examination arrangement or detector, for example through a web browser. This enables all individuals in the workflow easy access to the solution without any troublesome software installations. The data collector may be a software solution that may be installed at examination site. The data collector connects the X-ray machines and/or RIS/PACS systems using the DICOM network.

The foregoing description of embodiments of the present invention, have been presented for purposes of illustration and description. The foregoing description is not intended to be exhaustive or to limit embodiments of the present invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of various embodiments of the present invention. The

embodiments discussed herein were chosen and described in order to explain the principles and the nature of various embodiments of the present invention and its practical application to enable one skilled in the art to utilize the present invention in various embodiments and with various modifications as are suited to the particular use

contemplated. The features of the embodiments described herein may be combined in all possible combinations of methods, apparatus, modules, systems, and computer program products. It should be noted that the word "comprising" does not exclude the presence of other elements or steps than those listed and the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements. It should further be noted that any reference signs do not limit the scope of the claims, that the invention may be

implemented at least in part by means of both hardware and software, and that several "means", "units" or "devices" may be represented by the same item of hardware.

Software and web implementations of various embodiments of the present invention can be accomplished with standard programming techniques with rule-based logic and other logic to accomplish various database searching steps or processes, correlation steps or processes, comparison steps or processes and decision steps or processes. It should be noted that the words "component" and "module," as used herein and in the following claims, is intended to encompass implementations using one or more lines of software code, and/or hardware implementations, and/or equipment for receiving manual inputs.

The various embodiments of the present invention described herein is described in the general context of method steps or processes, which may be implemented in one embodiment by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), etc. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.