Angle calculation device Technical field

The present invention relates to the mechanical field, and in particular to an angle calculation device and an apparatus comprising the same.

Background art

When an examination subject is being imaged using an X-ray computed tomography (CT) system, it is necessary to perform rotation or tilting, for example when a TOPO scan is performed at a specific angle, and during this process it is necessary to know the rotation angle and tilt angle of the gantry. A CT gantry comprises a rotating part and a stationary part. At present, the rotation angle of a CT gantry is principally obtained by the following method: a number of uniformly distributed electronic contacts are positioned on the rotating part of the CT gantry, each electronic contact representing a different rotation angle; when these elec ^¬ tronic contacts are in contact with a contact on the station- ary part of the gantry, the current rotation position of the gantry can be obtained, but when the electronic contacts of the rotating part are not in contact with the contact on the stationary part of the gantry, there is no way of knowing the current position of the gantry. Therefore the number of elec- tronic contacts on the rotating part determines the precision of gantry rotation. For example, if the rotating part of the CT gantry is provided with 24 uniformly distributed elec ^¬ tronic contacts, the maximum precision of gantry rotation will be 15°. In the case of the two electronic contacts at the 0° and 15° positions, if the contact on the stationary part of the gantry is located between these two electronic contacts when the gantry stops, the current position of the gantry will be considered to be either 0° or 15° at this time, hence it is impossible to obtain the exact current po ^¬ sition. If the measurement of the current position of the gantry is not precise, for example the gantry tilt angle is not accurate, it is possible that scanning will extend to a region beyond that for which scanning is planned.

At the present time, the precision of measurement of the cur ^¬ rent position of the gantry may be improved by increasing the number of electronic contacts on the rotating part of the gantry in high-end CT equipment, for example by increasing the number of electronic contacts to as many as a thousand, so that the error can be controlled at about 0.5°.

In recent years, the development of accelerometers (also re- ferred to as gravity sensors) has been steadily gathering pace, and these are now widely used in phones with an Apple system (iphone) or Android system installed therein, for ex ^¬ ample for automatic screen-switching or the flip-over mute function in cell phones.

The invention patent application with publication number CN102156204A has disclosed a method for measuring the accel ^¬ eration of a car using a cell phone, the method comprising the following steps: 1) the cell phone is laid in a stable position inside the car, and when the car is stationary or moving forward at constant speed, a processor in the cell phone reads components of gravitational acceleration in X, Y or Z-axis directions from a gravitational acceleration sen ^¬ sor; 2) the processor calculates cell phone position informa- tion on the basis of the components of gravitational accel ^¬ eration from step 1); 3) when the car is accelerating, the processor reads components of gravitational acceleration in the X, Y or Z-axis directions from the gravitational accel ^¬ eration sensor at fixed intervals; 4) the processor calcu- lates the current acceleration of the car on the basis of the cell phone position information from step 2) and the compo ^¬ nents of gravitational acceleration from step 3) , and dis ^¬ plays this acceleration by way of a user interface. Compared with the prior art, the present invention has advantages such as low cost and convenient operation.

Content of the invention

The object of the present invention is to provide an angle calculation device and an apparatus comprising the same in order to improve the precision of measurement of the current position of a gantry.

In view of this, the present invention provides an angle cal ^¬ culation device, comprising an angle calculation component and an accelerometer which can be installed on a rotating part of a gantry, wherein the accelerometer is used for ac- quiring acceleration component values of the rotating part of the gantry in at least two directions at a current position; and the angle calculation component is used for calculating the angle between the current position and an initial posi ^¬ tion on the basis of the acceleration component values. This enables the precision of measurement of the current position of the gantry to be improved without increasing the number of electronic contacts in the gantry.

According to one embodiment of the present invention, the ac- celerometer is fixed to a surface of the rotating part of the gantry .

According to another embodiment of the present invention, the accelerometer is used for acquiring a tangential acceleration component value and radial acceleration component value of the rotating part of the gantry at the current position when the rotating part of the gantry rotates in a clockwise direc ^¬ tion from the initial position to the current position. According to yet another embodiment of the present invention, the angle calculation component calculates the rotation angle between the current position and the initial position accord ^¬ ing to the following formula: wherein a is the minimum rotation angle through which the ro- tating part of the gantry rotates in a clockwise direction from the initial position to the current position, x is the tangential acceleration component value at the current posi ^¬ tion, and y is the radial acceleration component value at the current position.

According to yet another embodiment of the present invention, when the rotating part of the gantry tilts from a first posi ^¬ tion to a second position, the accelerometer is used for acquiring a tangential acceleration component value, radial ac- celeration component value and Z-direction acceleration component value of the rotating part of the gantry at the second position, wherein the Z direction is perpendicular to both the tangential direction and the radial direction.

According to yet another embodiment of the present invention, the angle calculation component calculates the tilt angle of the rotating part of the gantry according to the following formula :

wherein β is the minimum tilt angle through which the rotating part of the gantry tilts in a clockwise direction from a first position to a second position, x is the tangential ac- celeration component value at the second position, y is the radial acceleration component value at the second position, and z is the Z-direction acceleration component value at the second position.

The present invention also provides an apparatus including a rotating part of a gantry and the angle calculation device, wherein the angle calculation device is installed on the ro ^¬ tating part of the gantry.

According to one embodiment of the present invention, the ap- paratus is a CT apparatus.

It can be seen from the above solution that since the present invention provides an angle calculation device comprising an angle calculation component and an accelerometer, so that ac- celeration component values of the rotating part of the gan ^¬ try at a current position can be acquired by way of the ac ^¬ celerometer and the angle between the current position and an initial position can be calculated by way of the angle calcu ^¬ lation component, the precision of measurement of the current position of the gantry when it is in a stationary or low- speed state is improved without increasing the number of electronic contacts in the gantry. In addition, the present invention also provides an apparatus comprising the angle calculation device.

Description of the accompanying drawings

Preferred embodiments of the present invention will be de ^¬ scribed in detail below with reference to the accompanying drawings, to give those skilled in the art a clearer under ^¬ standing of the above and other features and advantages of the present invention; in the drawings:

Fig. 1 is a schematic diagram of X, Y and Z axis acceleration component values when the rotating part of the gantry is at

0°, 90°, 180° and 270° and the tilt angle of the CT gantry is 0. Fig. 2 is a schematic diagram showing how the gantry rotation angle is determined in the XY plane using the angle calcula ^¬ tion device of the present invention. Fig. 3 is a schematic diagram showing how the gantry tilt angle is determined in an XYZ plane using the angle calculation device of the present invention.

Reference signs in the accompanying drawings

1- Rotating part of gantry

2- Accelerometer

Particular embodiments The present invention provides an angle calculation device and an apparatus comprising the same, in order to improve the precision of measurement of the rotation position of a gantry when it is in a stationary or low-speed state without in ^¬ creasing the number of electronic contacts in the gantry.

The method and device of the present invention are described in detail below using CT equipment as an example.

The present invention provides an angle calculation device, comprising an angle calculation component and an accelerome ^¬ ter which can be installed on a rotating part of a gantry, wherein the accelerometer is used for acquiring acceleration component values of the rotating part of the gantry in at least two directions at a current position; and the angle calculation component is used for calculating the angle be ^¬ tween the current position and an initial position on the ba ^¬ sis of the acceleration component values.

Fig. 1 is a schematic diagram of X, Y and Z axis acceleration component values when the rotating part of the gantry is at

0°, 90°, 180° and 270° and the tilt angle of the CT gantry is 0. The CT gantry 1 in Fig. 1 comprises a rotating part, an accelerometer 2 being fixed at the 0° position of the rotat- ing part, and the tilt angle of the gantry 1 at this time be ^¬ ing 0°; the accelerometer 2 is capable of measuring a gravity component value in each of the three directions given by the X, Y and Z axes (it is assumed that the maximum component of gravity in each direction g = 9.80) . Here, the X-axis direc ^¬ tion is the direction of a tangent, the Y-axis direction is the radial direction, and the Z direction is perpendicular to both the X-axis direction and the Y-axis direction, so that the coordinates of the rotating part of the gantry at a rota- tion angle of 0° are (0, 9.8, 0), the coordinates at a rota ^¬ tion angle of 90° are (9.8, 0, 0), the coordinates at a rota ^¬ tion angle of 180° are (0, -9.8, 0), and the coordinates at a rotation angle of 270° are (-9.8, 0, 0) . When the accelerome ^¬ ter uses the coordinate system shown in Fig. 1, the XZ plane is parallel to a horizontal plane when the CT apparatus is in position, while the XY plane is perpendicular to the horizontal plane.

Fig. 2 is a schematic diagram showing how the gantry rotation angle is determined in the XY plane using the angle calcula ^¬ tion device of the present invention. The accelerometer 2 in Fig. 2 is fixed to a surface of the rotating part of the gan ^¬ try. When the rotating part of the gantry rotates through an angle from the initial position 0° and stops when it reaches the current position, or when it rotates through an angle from the initial position 0° to the current position at a very low speed, the accelerometer 2 rotates through this angle together with the gantry to arrive at the current posi ^¬ tion. Since the gantry stops rotating or continues rotating at a very low speed at the current end position, the cen ^¬ tripetal force arising from the rotation of the gantry is nearly 0, and can be ignored; only the acceleration due to gravity need be taken into account. Thus the rotation angle is calculated according to the following formula (1) at the current position: wherein a is the minimum rotation angle through which the rotating part of the gantry rotates in a clockwise direction from the initial position to the current position, x is the tangential acceleration component value at the current posi ^¬ tion, and y is the radial acceleration component value at the current position. When an examination subject such as a spinal column is being scanned in slices, the CT gantry must be tilted, for example from a first position to a second position; the accelerometer 2 is used for acquiring acceleration component values of the rotating part of the gantry at the second position in three directions - acceleration component values in the directions of the X axis, Y axis and Z axis - and calculating the tilt angle of the rotating part of the gantry on the basis of the three acceleration component values. At this time the accel ^¬ erometer 2 fixed to the rotating part of the gantry tilts with the gantry through an angle to the second position.

Fig. 3 is a schematic diagram showing how the gantry tilt angle is determined in an XYZ plane using the accelerometer. The tilt angle of the gantry is calculated according to the following formula (2) :

wherein β is the minimum tilt angle through which the rotat ing part of the gantry tilts in a clockwise direction from first position to a second position, x is the tangential ac celeration component value at the second position, y is the radial acceleration component value at the second position, and z is the Z-direction acceleration component value at the second position.

Thus, the angle calculation device of the present invention enables the rotation angle and tilt angle between a current position of the rotating part of the gantry and an initial position to be acquired without increasing the number of electronic contacts on the rotating part of the gantry, so that the precision of measurement of the current position of the gantry is improved. Moreover, the present method may only require one sensor, so is cheaper than the method of adding as many as a thousand electronic contacts in high-end equip- ment .

In addition, the present invention also provides an apparatus comprising the angle calculation device and a rotating part of a gantry, wherein the angle calculation device is located on the rotating part of the gantry; the apparatus may for ex ^¬ ample be a CT apparatus, or another mechanical apparatus fa ^¬ miliar to those skilled in the art such as a DSA machine.

The present invention relates to the mechanical field, in particular to an angle calculation device, comprising an angle calculation component and an accelerometer which can be installed on a rotating part of a gantry, wherein the accel ^¬ erometer is used for acquiring acceleration component values of the rotating part of the gantry in at least two directions at a current position; and the angle calculation component is used for calculating the angle between the current position and an initial position on the basis of the acceleration component values. The present invention also provides an appara ^¬ tus including the angle calculation device and a rotating part of a gantry. The present invention is able to improve the precision of measurement of the current position of the gantry without increasing the number of electronic contacts in the gantry. The above are merely preferred embodiments of the present in vention, and are not intended to limit it; any amendments, equivalent substitutions or improvements, etc. that are made without departing from the spirit and principle of the pre ^¬ sent invention should be included within the scope of protec tion thereof.