Method, device and storage medium for determining isocenter of electron linear accelerator

Abstract

The present invention discloses a method, device and storage medium for determining the isocenter of an electron linear accelerator, which relates to the field of medical information technology, and is mainly capable of improving the accuracy and efficiency of determining the isocenter of an electron linear accelerator. The method includes: determining the first radiation field axis corresponding to the beam limiting device based on the rotation trajectory corresponding to a preset marker that rotates with the beam limiting device; determining the second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle based on the first position relationship between the center of the preset marker and the first radiation field axis; determining the circumscribed spheres corresponding to multiple first reference points respectively; and determining the isocenter position of the electron linear accelerator based on the multiple circumscribed spheres. The present invention is suitable for determining the isocenter position of an electron linear accelerator.

Description

Technical Field

[0001] The present invention relates to the field of medical information technology, and in particular to a method, device and storage medium for determining an isocenter of an electron linear accelerator. Background Art

[0002] Radiotherapy is one of the three main methods of clinical tumor treatment. Radiotherapy equipment includes medical electron linear accelerators. Medical electron linear accelerators use X-rays and other radiation to irradiate tumors to achieve therapeutic effects, that is, to concentrate the radiation on the tumor site while avoiding damage to healthy tissues as much as possible. The principle of concentrating the radiation on the tumor site is to make the isocenter of the electron linear accelerator coincide with the tumor site. Based on this, in order to achieve precise radiotherapy of the tumor site, it is necessary to determine the isocenter position of the electron linear accelerator.

[0003] At present, the cross cursor at the center of the beam limiting device of the electron linear accelerator is usually projected onto the coordinate paper to determine the axis of the beam limiting device, and auxiliary tools such as pointers are fixed on the frame, the frame is rotated, and the offset of the axis of the beam limiting device is determined by visual inspection, so as to estimate the position of the isocenter. However, this method requires the use of light to illuminate the cross cursor at the center of the beam limiting device so that the cross cursor is projected onto the coordinate paper, which reduces the efficiency of determining the isocenter of the electron linear accelerator. At the same time, the naked eye observation cannot quantify the deviation within 1mm, and due to the negligence of the staff, wrong judgments will be made, resulting in low accuracy in determining the isocenter of the electron linear accelerator. Summary of the invention

[0004] The present invention provides a method, device and storage medium for determining an isocenter of an electron linear accelerator, which are mainly capable of improving the determination accuracy and efficiency of the isocenter of an electron linear accelerator.

[0005] According to a first aspect of the present invention, there is provided a method for determining an isocenter of an electron linear accelerator, comprising:

[0006] When the gantry is perpendicular to the floor of the treatment room, a first radiation field axis corresponding to the beam limiting device is determined based on a rotation trajectory corresponding to a preset marker that rotates with the beam limiting device;

[0007] Based on a first positional relationship between the center of the preset marker and the first radiation field axis, determining a second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle;

[0008] Determine the feet of perpendiculars corresponding to the perpendicular lines between the plurality of first reference points and the respective second radiation field axes, and based on the feet of the perpendiculars, draw the circumscribed spheres corresponding to the plurality of first reference points respectively;

[0009] The isocenter position of the electron linear accelerator is determined according to a plurality of circumscribed spheres.

[0010] According to a second aspect of the present invention, there is provided a device for determining an isocenter of an electron linear accelerator, comprising:

[0011] A first determining unit is used to determine a first radiation field axis corresponding to the beam limiting device based on a rotation trajectory corresponding to a preset marker that rotates with the beam limiting device when the gantry is perpendicular to the floor of the treatment room;

[0012] A second determining unit is used to determine, based on a first positional relationship between the center of the preset marker and the first radiation field axis, a second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle;

[0013] A drawing unit, used to determine the feet of perpendiculars corresponding to the perpendicular lines between the plurality of first reference points and the axes of the second radiation fields, and based on the feet of the perpendiculars, draw the circumscribed spheres corresponding to the plurality of first reference points;

[0014] The third determining unit is used to determine the isocenter position of the electron linear accelerator according to a plurality of circumscribed spheres.

[0015] According to a third aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the following steps:

[0016] When the gantry is perpendicular to the floor of the treatment room, a first radiation field axis corresponding to the beam limiting device is determined based on a rotation trajectory corresponding to a preset marker that rotates with the beam limiting device;

[0017] Based on a first positional relationship between the center of the preset marker and the first radiation field axis, determining a second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle;

[0018] Determine the feet of perpendiculars corresponding to the perpendicular lines between the plurality of first reference points and the respective second radiation field axes, and based on the feet of the perpendiculars, draw the circumscribed spheres corresponding to the plurality of first reference points respectively;

[0019] The isocenter position of the electron linear accelerator is determined according to a plurality of circumscribed spheres.

[0020] According to a fourth aspect of the present invention, there is provided a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the following steps are implemented:

[0021] When the gantry is perpendicular to the floor of the treatment room, a first radiation field axis corresponding to the beam limiting device is determined based on a rotation trajectory corresponding to a preset marker that rotates with the beam limiting device;

[0022] Based on a first positional relationship between the center of the preset marker and the first radiation field axis, determining a second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle;

[0023] Determine the feet of perpendiculars corresponding to the perpendicular lines between the plurality of first reference points and the respective second radiation field axes, and based on the feet of the perpendiculars, draw the circumscribed spheres corresponding to the plurality of first reference points respectively;

[0024] The isocenter position of the electron linear accelerator is determined according to a plurality of circumscribed spheres.

[0025] According to a method, device and storage medium for determining the isocenter of an electron linear accelerator provided by the present invention, compared with the current method of manually observing the change range of the cross cursor on the coordinate paper when the beam limiting device is rotated at various angles to determine the isocenter of the electron linear accelerator, the present invention determines the first radiation field axis corresponding to the beam limiting device based on the rotation trajectory corresponding to the preset marker that rotates with the beam limiting device when the frame is perpendicular to the floor of the treatment room; and determines the second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle based on the first positional relationship between the center of the preset marker and the first radiation field axis; then determines the feet of perpendiculars corresponding to the perpendiculars between multiple first reference points and each second radiation field axis, and draws a perpendicular line based on each foot of the perpendicular. The circumscribed spheres respectively corresponding to the multiple first reference points are formed; finally, the isocenter position of the electron linear accelerator is determined according to the multiple circumscribed spheres, thereby determining the first target radiation field corresponding to the beam limiting device when the frame is perpendicular to the floor of the treatment room, and determining the first positional relationship between the center of a preset marker fixed on the beam limiting device and the first target radiation field, the second radiation field axis corresponding to the beam limiting device is determined, and finally, based on the positional relationship between each second radiation field axis and the preset marker, the isocenter position corresponding to the electron linear accelerator is determined. This method improves the efficiency of determining the isocenter of the electron linear accelerator, while avoiding observation errors due to negligence of the staff, thereby improving the accuracy of determining the isocenter of the electron linear accelerator. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0027] Figure 1A flow chart of a method for determining an isocenter of an electron linear accelerator provided by an embodiment of the present invention is shown;

[0028] Figure 2 A flow chart of another method for determining the isocenter of an electron linear accelerator provided by an embodiment of the present invention is shown;

[0029] Figure 3 A schematic diagram showing the structure of a device for determining an isocenter of an electron linear accelerator provided by an embodiment of the present invention is shown;

[0030] Figure 4 A schematic diagram of the physical structure of a computer device provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0032] At present, the isocenter of an electron linear accelerator is determined by manually observing the range of changes in the cross cursor on the coordinate paper when the beam limiting device is rotated at various angles. This results in low efficiency in determining the isocenter of an electron linear accelerator. At the same time, due to negligence of the staff, wrong judgments may be made, resulting in low accuracy in determining the isocenter of an electron linear accelerator.

[0033] In order to solve the above problems, an embodiment of the present invention provides a method for determining the isocenter of an electron linear accelerator, such as Figure 1 As shown, the method includes:

[0034] 101. When the gantry is perpendicular to the floor of the treatment room, a first radiation field axis corresponding to the beam limiting device is determined based on a rotation trajectory corresponding to a preset marker that rotates along with the beam limiting device.

[0035] Among them, the electron linear accelerator is composed of components such as a frame, a radiation head and a treatment bed. The radiation head is fixedly installed on the frame and can generate high-energy rays. The frame of the electron linear accelerator can usually rotate 360° in a vertical plane. The treatment bed usually has 4-6 degrees of freedom, including 3 translational degrees of freedom and 1 or 3 rotational degrees of freedom. The radiation head includes a beam limiting device. In a typical medical electron linear accelerator, the beam limiting device is composed of components such as a beam collimator, a tungsten gate, and a multi-leaf grating to form radiation fields of various shapes required for radiotherapy. The beam limiting device can rotate at least 270°. Ideally, its rotation axis is a straight line, which is the radiation field axis. This radiation field axis points to the rotation axis of the electron linear accelerator frame and intersects it vertically. Due to the influence of various mechanical errors, in addition to the rotational motion, the beam limiting device will also undergo a small translational motion relative to the fixed reference system when it rotates. At the same time, the frame will also undergo a small translational motion relative to the fixed reference system when it rotates.

[0036] For the embodiment of the present invention, in order to overcome the problems of low efficiency and low accuracy in the process of determining the isocenter of an electron linear accelerator in the prior art, the embodiment of the present invention determines the first target radiation field corresponding to the beam limiting device when the frame is perpendicular to the floor of the treatment room, and determines the first position relationship between the center of the preset marker fixed on the beam limiting device and the first target radiation field, determines the second radiation field axis corresponding to the beam limiting device, and finally determines the isocenter position corresponding to the electron linear accelerator based on the position relationship between each second radiation field axis and the preset marker. This method improves the efficiency of determining the isocenter of the electron linear accelerator, and avoids observation errors due to negligence of the staff, thereby improving the accuracy of determining the isocenter of the electron linear accelerator. The embodiment of the present invention is mainly used in the scene of determining the isocenter of the electron linear accelerator. The execution subject of the embodiment of the present invention is a device or equipment capable of determining the isocenter of the electron linear accelerator, which can be specifically set on the client or server side.

[0037] Specifically, first prepare an optical imaging device and a preset marker, on which a plurality of infrared markers are mounted, and the plurality of infrared markers can be 3-5 infrared reflective balls. The design of the preset marker should make the infrared markers asymmetrically distributed, and the infrared markers have sufficient spacing, such as the spacing between each infrared marker is 5-10 cm, and at least 3 infrared markers can be completely captured by the optical imaging device during the isocenter determination process. The optical imaging device is calibrated in advance so that it knows the directions of the three coordinate axes of the fixed reference system (Xf, Yf, Zf) of the treatment room. It should be noted that the present invention does not require the optical imaging device to be strictly calibrated to the coordinate system origin Of of the fixed reference system. If the operator needs to determine the relative relationship between the test results and the fixed reference system, the center of the preset marker described in the embodiment of the present invention can be placed at the known fixed reference system origin for calibration.

[0038] Furthermore, the frame of the electron linear accelerator is rotated to a position perpendicular to the floor of the treatment room, at which time the frame of the electron linear accelerator is at 0°, and then a preset marker is fixed at the beam limiting device of the electron linear accelerator so that the center of the preset marker is located near the visually estimated isocenter, wherein the visually estimated isocenter can be determined based on the laser intersection point irradiated by the laser lamp in the treatment room. In an embodiment of the present invention, the preset marker can be aligned with the laser lamp in the treatment room to obtain the relative relationship between the measurement result and the known spatial position. The preset marker should be tightly fixed to the beam limiting device to ensure a rigid connection to ensure that the two do not move relative to each other during the rotation process of the beam limiting device. At this time, the movement of the preset marker can be equivalent to the movement of the beam limiting device. Then, from a certain starting angle of the beam limiting device, such as 0°, the beam limiting device is rotated to 4 or more angles, and these angles should be roughly evenly distributed within the rotation range of the beam limiting device. At each of the above rotation angles, an optical imaging device is used to detect the spatial coordinates corresponding to each infrared marker, and a fitting method is used. The algorithm determines the direction of the radiation field axis corresponding to the beam limiting device. At the same time, multiple second reference points are selected in space at the starting position relative to the center of the preset marker, and the coordinates of the multiple second reference points at each rotation angle are calculated. Then, according to the coordinates corresponding to the multiple second reference points, the circumscribed circles corresponding to the multiple second reference points are drawn. Finally, based on the centers of the multiple circumscribed circles, a point through which the radiation field axis corresponding to the beam limiting device passes is determined. Finally, based on the point through which the radiation field axis passes and the direction information corresponding to the radiation field axis, the first radiation field axis corresponding to the beam limiting device is determined. At the same time, when the rack is kept at 0° and the beam limiting device is rotated to 0°, the coordinates of each infrared marker on the preset marker are measured using an optical imaging device. The position and direction of the first radiation field axis of the beam limiting device relative to the preset marker, that is, the first position relationship between the center of the preset marker and the first radiation field axis, are calculated, and the first radiation field axis of the beam limiting device at this time is determined as the radiation field axis of the rack at an angle of 0°.

[0039] 102. Based on a first positional relationship between the center of the preset marker and the first radiation field axis, determine a second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle.

[0040] For an embodiment of the present invention, the rack is rotated to several other angles for measurement. These angles are roughly evenly distributed within the rotation range of the rack. For example, for a rack with a rotation range of 360°, a measurement is performed every 45°, and there are a total of 8 measurement angles. At each rack angle, an optical imaging device is used to measure the coordinates of each infrared marker on a preset marker. Based on the first positional relationship between the center of the preset marker and the first radiation field axis, the second radiation field axis corresponding to the beam limiting device at each rack angle is calculated.

[0041] 103. Determine the feet of perpendiculars corresponding to the perpendicular lines between the plurality of first reference points and the respective second radiation field axes, and based on the feet of the perpendiculars, draw the circumscribed spheres corresponding to the plurality of first reference points.

[0042] Among them, each of the second radiation field axes includes the first radiation field axis. For the embodiment of the present invention, multiple first reference points are arbitrarily determined in the spatial coordinate system corresponding to the treatment device, wherein the positions of the multiple first reference points are known, and perpendicular lines between the multiple first reference points and the second radiation field axes are drawn respectively, and the foot of the perpendicular corresponding to each perpendicular line is determined at the same time, and the distance between the multiple first reference points and the corresponding foot of the perpendicular is calculated, that is, the distance between the multiple first reference points and the second radiation field axes obtained in the previous step, to obtain the respective distances corresponding to the multiple first reference points, determine the maximum distance among the respective distances, and obtain the maximum target distances corresponding to the multiple first reference points, and use a search algorithm to search for the coordinate change direction that reduces the above-mentioned maximum target distance with a predetermined step size, such as a step size of 0.01mm, until a point is determined among the multiple first reference points so that The above-mentioned maximum target distance is the minimum value of all the maximum target distances that have been searched. At this time, when the frame is at various rotation angles, the foot of the perpendicular corresponding to the point and the perpendicular between each second radiation field axis is determined, and each perpendicular foot is used as a point set to draw the circumscribed sphere corresponding to the point set, and the center of the circumscribed sphere is determined as the isocenter position corresponding to the electron linear accelerator. At the same time, the embodiment of the present invention can also determine the foot of the perpendicular corresponding to the multiple first reference points respectively and the perpendicular between each second radiation field axis, that is, determine the foot point set corresponding to the multiple first reference points respectively, and then draw the circumscribed spheres corresponding to the multiple foot point sets respectively, that is, obtain the circumscribed spheres corresponding to the multiple first reference points respectively, and calculate the radii corresponding to the multiple circumscribed spheres respectively, determine the minimum radius among the multiple radii, and determine the center of the circumscribed ball corresponding to the minimum radius as the isocenter corresponding to the electron linear accelerator.

[0043] 104. Determine the isocenter position of the electron linear accelerator according to a plurality of circumscribed spheres.

[0044] For an embodiment of the present invention, after drawing the circumscribed spheres corresponding to multiple first reference points respectively, the radii corresponding to the multiple circumscribed spheres are determined, the minimum radius is determined among the multiple radii, and the target sphere center coordinate information of the circumscribed sphere corresponding to the minimum radius is determined, and the target sphere center coordinate information is determined as the isocenter coordinate information corresponding to the electron linear accelerator.

[0045] According to a method for determining the isocenter of an electron linear accelerator provided by the present invention, compared with the current method of manually observing the change range of the cross cursor on the coordinate paper at each rotation angle of the beam limiting device to determine the isocenter of the electron linear accelerator, the present invention determines the first radiation field axis corresponding to the beam limiting device when the frame is perpendicular to the floor of the treatment room based on the rotation trajectory corresponding to the preset marker that rotates with the beam limiting device; and determines the second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle based on the first position relationship between the center of the preset marker and the first radiation field axis; then determines the feet of perpendiculars corresponding to the perpendicular lines between multiple first reference points and each second radiation field axis, and draws the perpendicular lines based on each foot of the perpendicular. The circumscribed spheres respectively correspond to the multiple first reference points; finally, the isocenter position of the electron linear accelerator is determined according to the multiple circumscribed spheres, thereby determining the first target radiation field corresponding to the beam limiting device when the frame is perpendicular to the floor of the treatment room, and determining the first positional relationship between the center of a preset marker fixed on the beam limiting device and the first target radiation field, the second radiation field axis corresponding to the beam limiting device is determined, and finally, based on the positional relationship between each second radiation field axis and the preset marker, the isocenter position corresponding to the electron linear accelerator is determined, which improves the efficiency of determining the isocenter of the electron linear accelerator and avoids the situation where the staff makes an erroneous judgment due to negligence, thereby improving the accuracy of determining the isocenter of the electron linear accelerator.

[0046] Further, in order to better illustrate the above process of determining the isocenter of the linear accelerator, as a refinement and extension of the above embodiment, the embodiment of the present invention provides another method for determining the isocenter of the electron linear accelerator, such as Figure 2 As shown, the method includes:

[0047] 201. When the gantry is perpendicular to the floor of the treatment room, based on a rotation trajectory corresponding to a preset marker that rotates with the beam limiting device, determine the radiation field axis direction information corresponding to the beam limiting device, and determine the radiation field axis position information corresponding to the beam limiting device.

[0048] For the embodiment of the present invention, in order to determine the isocenter position of the electron linear accelerator, it is first necessary to determine the first radiation field axis corresponding to the beam limiting device of the electron linear accelerator when the frame of the electron linear accelerator is at 0°. In order to determine the first radiation field axis, it is first necessary to determine the radiation field axis direction information corresponding to the beam limiting device. Based on this, step 201 specifically includes: determining the planes through which the multiple infrared markers pass respectively when rotating with the beam limiting device; determining the normal direction information corresponding to the multiple planes; and determining the normal direction information as the radiation field axis direction information corresponding to the beam limiting device.

[0049] Specifically, an optical imaging device is used to detect the spatial coordinates of each infrared marker in a fixed reference system, and these coordinates are marked as Where i is the serial number of the infrared marker, j is the second rotation angle corresponding to the beam limiting device, and then the fitting algorithm is used to determine the radiation field axis direction information corresponding to the beam limiting device according to the measured coordinates of each infrared marker. The fitting algorithm in the embodiment of the present invention is to generate a series of planes in a fixed reference system, the number of these planes is equal to the number of infrared markers, and these planes are recorded as P i , where i corresponds to the serial number of the infrared marker. The distance between each infrared marker and its corresponding plane at each second rotation angle is determined. When the sum of the squares of each distance reaches the minimum, the direction and position of each plane is determined, and the normal direction information corresponding to each plane is fitted. The normal direction corresponding to these planes is the direction information of the radiation field axis.

[0050] Furthermore, after determining the direction information of the radiation field axis, it is also necessary to determine the position information of the radiation field axis. Based on this, step 201 also includes: determining the first position information of the center of the preset marker when the beam limiting device is at each second rotation angle, and determining the angle change value of the preset marker when the beam limiting device is at each second rotation angle; determining multiple second reference points in the preset marker, and based on the second position relationship between the center of the preset marker and the multiple second reference points, as well as each first position information and each angle change value, determining the second position information of the multiple second reference points when the beam limiting device is at each second rotation angle; based on each second position information, determining the circumscribed circles corresponding to the multiple second reference points respectively, and based on the center point position information of the multiple circumscribed circles, determining the radiation field axis position information corresponding to the beam limiting device.

[0051] Specifically, the optical imaging device can detect the coordinate information corresponding to each infrared marker at each second rotation angle of the beam limiting device, and according to the coordinate information corresponding to each infrared marker, the coordinate information corresponding to the center of the preset marker can be calculated, that is, the first position information corresponding to the center of the preset marker at each second rotation angle, and the angle change value of the preset marker at each second rotation angle relative to the starting position, wherein the starting position is the position of the preset marker when the beam limiting device is at 0° (not rotated), and the angle change corresponds to the rotation angle of the three coordinate axes around the fixed reference system, and then multiple second reference points are selected from the preset marker, and the starting coordinates of the multiple second reference points are as follows:

[0052]

[0053] in, represents the first spatial coordinate of the second reference point at the starting position, Indicates the second spatial coordinate corresponding to the center of the preset marker at the starting position, represents the coordinate difference between the first spatial coordinate and the second spatial coordinate, wherein the coordinate difference is the second position relationship between the center of the preset marker and the plurality of second reference points

[0054] Furthermore, after determining the second position relationship between the center of the preset marker and the multiple second reference points, as well as the first position information and angle change value corresponding to the center of the preset marker at each second rotation angle, it is also necessary to determine the second position information of the multiple second reference points when the beam limiting device is at each second rotation angle. Based on this, the method includes: determining a position conversion matrix corresponding to the multiple second reference points based on the various angle change values; determining the second position information of the multiple second reference points when the beam limiting device is at each second rotation angle based on the position conversion matrix, the second position relationship and the various first position information.

[0055] Specifically, based on the angle change values, the formula for determining the position transformation matrix commonly corresponding to the multiple second reference points is as follows:

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065] in, represents the angle change value of the preset marker at each second rotation angle relative to the starting position, m 11 , m 12 , m 13 , m 21 , m 22 , m 23 , m 31 , m32 , m 33 They are respectively the matrix elements in the position transformation matrix.

[0066] Furthermore, the calculation formula of the second position information of the second reference point when the beam limiting device is at each second rotation angle is as follows:

[0067]

[0068] in, represents the second position information, Represents the first position information of the center of the preset marker at each second rotation angle. According to the above formula, the second position information of multiple second reference points when the beam limiting device is at each second rotation angle can be determined.

[0069] Furthermore, based on the second position information corresponding to each second reference point, a circumscribed circle corresponding to the trajectory of each second reference point is drawn, and a target circumscribed circle with the smallest radius is determined among multiple circumscribed circles. At the same time, the spatial coordinates corresponding to the target center of the target circumscribed circle are determined. Finally, the spatial coordinates corresponding to the target center are determined as a point through which the radiation field axis corresponding to the beam limiting device passes, thereby determining the position information of the radiation field axis corresponding to the beam limiting device.

[0070] 202. Determine a first radiation field axis corresponding to the beam limiting device based on the radiation field axis direction information and the radiation field axis position information.

[0071] For the embodiment of the present invention, after determining the radiation field axis direction information and the radiation field axis position information, the first radiation field axis corresponding to the beam limiting device can be determined based on the radiation field axis direction information and the radiation field axis position information. It should be noted that the gantry rotation axis corresponding to the gantry in the electron linear accelerator and the treatment bed rotation axis corresponding to the treatment bed can also be determined according to the above method. When determining the rotation axis corresponding to the treatment bed, a preset marker can be fixed on the treatment bed.

[0072] 203. Based on a first positional relationship between the center of the preset marker and the first radiation field axis, determine a second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle.

[0073] For the embodiment of the present invention, the frame of the electron linear accelerator is maintained at 0°, that is, the frame is perpendicular to the floor of the treatment room, and the beam limiting device is rotated to 0°, and the coordinates of each infrared marker on the preset marker are measured using an optical imaging device, and the position and direction of the first radiation field axis of the beam limiting device relative to the preset marker are calculated, that is, the first position relationship between the center of the preset marker and the first radiation field axis is determined. For example, the first position relationship between the center of the preset marker and the first radiation field axis is that the first radiation field axis is 10 mm in the positive direction of the x-axis of the preset marker, 5 mm in the negative direction of the y-axis, and 3 mm in the positive direction of the z-axis. At the same time, the first position relationship also includes an angle relationship, such as the angle between the first radiation field axis and the preset marker in the positive direction of the x-axis is 20°, the angle in the negative direction of the y-axis is 50°, and the angle in the positive direction of the z-axis is 30°.

[0074] Furthermore, after determining the first position relationship between the preset marker and the first radiation field axis, it is necessary to determine, based on the first position relationship, the second radiation field axis corresponding to the beam limiting device when the frame of the electron linear accelerator is at each first rotation angle. Based on this, step 203 specifically includes: determining the third position information corresponding to the center of the preset marker when the frame is at each first rotation angle; based on each third position information and the first position relationship, determining the second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle.

[0075] Specifically, the gantry is rotated to several other first rotation angles for measurement, and these angles are roughly evenly distributed within the rotation range of the gantry. For example, for a gantry with a rotation range of 360°, a measurement is performed every 45°, and there are 8 first rotation angles in total. At the first rotation angle corresponding to each gantry, the coordinates of each infrared marker on the preset marker are measured using an optical imaging device, and the coordinates corresponding to the center of the preset marker when the gantry of the electron linear accelerator is at each first rotation angle are determined, that is, the third position information. Finally, according to the position and direction of the first radiation field axis relative to the preset marker, and the third position information, the position and direction corresponding to the second radiation field axis corresponding to the beam limiting device when the gantry of the electron linear accelerator is at each first rotation angle can be calculated. It should be noted that the embodiment of the present invention can also arbitrarily determine a known fixed initial point in the spatial coordinate system where the electron linear accelerator is located, and determine the first position relationship between the known fixed initial point and the first radiation field axis, and in the above manner, based on the first position relationship, determine the second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle.

[0076] 204. Determine the feet of perpendiculars corresponding to the perpendicular lines between the plurality of first reference points in the preset marker and the respective second radiation field axes, and based on the feet of the perpendiculars, draw the circumscribed spheres corresponding to the plurality of first reference points.

[0077] For the embodiment of the present invention, multiple first reference points are determined on the preset marker, and when the frame is at various rotation angles, vertical lines are drawn from the multiple first reference points to the respective second radiation field axes, and then the feet of the perpendiculars corresponding to the respective vertical lines are determined. At this time, each first reference point corresponds to a respective foot of the perpendicular, and the number of the feet of the perpendiculars corresponding to each first reference point is the same as the number of the second radiation field axes. A point set is composed of the feet of the perpendiculars corresponding to each first reference point, so that the multiple first reference points respectively have their corresponding point sets. Further, after determining the point set corresponding to each first reference point, a circumscribed sphere corresponding to the point set is drawn based on the point set corresponding to each first reference point, wherein the longest vertical line segment corresponding to each point set is the radius of the circumscribed sphere corresponding to the first reference point, thereby the circumscribed spheres corresponding to the multiple first reference points can be obtained, and finally the isocenter position corresponding to the electron linear accelerator is determined based on the multiple circumscribed spheres.

[0078] 205. Determine the isocenter position of the electron linear accelerator according to a plurality of circumscribed spheres.

[0079] For the embodiment of the present invention, after drawing the circumscribed spheres corresponding to the multiple first reference points respectively, it is necessary to determine the isocenter position corresponding to the electron linear accelerator based on the center position information of the multiple circumscribed spheres. Based on this, step 205 specifically includes: determining the minimum circumscribed sphere among the multiple circumscribed spheres, and determining the target center position corresponding to the minimum circumscribed sphere as the isocenter position of the electron linear accelerator.

[0080] Specifically, a target circumscribed sphere with the smallest radius is determined among multiple circumscribed spheres, and the target sphere center coordinates corresponding to the target circumscribed sphere are determined, and finally the target sphere center coordinates are determined as the isocenter position corresponding to the electron linear accelerator.

[0081] Furthermore, according to the above method, the rotation axis of the treatment bed can be determined. After the rotation axis corresponding to the treatment bed is determined, each rotation angle of the treatment bed is set to 0°, and the coordinates of each infrared marker on the preset marker are measured using an optical imaging device, and the point on the surface of the preset marker corresponding to the rotation axis of the treatment bed is calculated, and the pitch angle ψt, roll angle φt or a combination of the two of the treatment bed are set, and the treatment bed is operated to complete the corresponding rotation, and the optical imaging device is used to measure the coordinates of each preset marker on the preset marker after the treatment bed is rotated, and the pitch angle and roll angle of the preset marker, as well as the displacement of the point on the surface of the preset marker corresponding to the rotation axis of the treatment bed are calculated. At the same time, the preset marker is placed on the treatment bed surface, and the optical imaging system is used to measure the position change of the preset marker before and after the treatment bed moves, and the position indication of the treatment bed is compared, so as to complete the quality control of the movement distance of the treatment bed.

[0082] According to another method for determining the isocenter of an electron linear accelerator provided by the present invention, compared with the current method of manually observing the change range of the cross cursor on the coordinate paper at each rotation angle of the beam limiting device to determine the isocenter of the electron linear accelerator, the present invention determines the first radiation field axis corresponding to the beam limiting device when the frame is perpendicular to the floor of the treatment room based on the rotation trajectory corresponding to the preset marker that rotates with the beam limiting device; and determines the second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle based on the first position relationship between the center of the preset marker and the first radiation field axis; then determines the feet of perpendiculars corresponding to the perpendiculars between multiple first reference points in the preset marker and each second radiation field axis, and based on each foot of the perpendicular , draw circumscribed spheres corresponding to the multiple first reference points respectively; finally, determine the isocenter position of the electron linear accelerator based on the multiple circumscribed spheres, thereby determining the first target radiation field corresponding to the beam limiting device when the frame is perpendicular to the floor of the treatment room, and determining the first position relationship between the center of a preset marker fixed on the beam limiting device and the first target radiation field, determine the second radiation field axis corresponding to the beam limiting device, and finally determine the isocenter position corresponding to the electron linear accelerator based on the position relationship between each second radiation field axis and the preset marker, thereby improving the efficiency of determining the isocenter of the electron linear accelerator and avoiding the situation where the staff makes an erroneous judgment due to negligence, thereby improving the accuracy of determining the isocenter of the electron linear accelerator.

[0083] Further, as Figure 1 In a specific implementation, an embodiment of the present invention provides a device for determining the isocenter of an electron linear accelerator, such as Figure 3 As shown, the device includes: a first determining unit 31, a second determining unit 32, a drawing unit 33 and a third determining unit 34.

[0084] The first determination unit 31 may be configured to determine a first radiation field axis corresponding to the beam limiting device based on a rotation trajectory corresponding to a preset marker that rotates along with the beam limiting device when the gantry is perpendicular to the floor of the treatment room.

[0085] The second determining unit 32 may be configured to determine, based on a first positional relationship between the center of the preset marker and the first radiation field axis, a second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle.

[0086] The drawing unit 33 may be used to determine the feet of perpendiculars corresponding to the perpendicular lines between the plurality of first reference points in the preset marker and the second radiation field axes, and based on the feet of the perpendiculars, draw the circumscribed spheres corresponding to the plurality of first reference points.

[0087] The third determination unit 34 may be configured to determine the isocenter position of the electron linear accelerator according to a plurality of circumscribed spheres.

[0088] In a specific application scenario, in order to determine the first radiation field axis corresponding to the beam limiting device in the electron linear accelerator, the first determination unit 31 can be specifically used to determine the radiation field axis direction information corresponding to the beam limiting device based on the rotation trajectory corresponding to a preset marker that rotates with the beam limiting device, and determine the radiation field axis position information corresponding to the beam limiting device; based on the radiation field axis direction information and the radiation field axis position information, determine the first radiation field axis corresponding to the beam limiting device.

[0089] In a specific application scenario, in order to determine the axial direction information of the radiation field corresponding to the beam limiting device, the first determination unit 31 can be specifically used to determine the planes through which multiple infrared markers pass when the beam limiting device rotates; determine the normal direction information corresponding to multiple planes; and determine the normal direction information as the axial direction information of the radiation field corresponding to the beam limiting device.

[0090] In a specific application scenario, in order to determine the radiation field axis position information corresponding to the beam limiting device, the first determination unit 31 can also be used to determine the first position information of the center of the preset marker when the beam limiting device is at each second rotation angle, and determine the angle change value of the preset marker when the beam limiting device is at each second rotation angle; determine multiple second reference points in the preset marker, and based on the second position relationship between the center of the preset marker and the multiple second reference points, as well as each first position information and each angle change value, determine the second position information of the multiple second reference points when the beam limiting device is at each second rotation angle; based on each second position information, determine the circumscribed circles corresponding to the trajectories of the multiple second reference points, and based on the center point position information of the multiple circumscribed circles, determine the radiation field axis position information corresponding to the beam limiting device.

[0091] In a specific application scenario, in order to determine the second position information of the multiple second reference points when the beam limiting device is at each second rotation angle, the first determination unit 31 can also be used to determine the position transformation matrix corresponding to the multiple second reference points based on the various angle change values; based on the position transformation matrix, the second position relationship and the various first position information, determine the second position information of the multiple second reference points when the beam limiting device is at each second rotation angle.

[0092] In a specific application scenario, in order to determine the second radiation field axis corresponding to the beam limiting device when the frame of the electron linear accelerator is at each first rotation angle, the second determination unit 32 can be specifically used to determine the third position information corresponding to the center of the preset marker when the frame is at each first rotation angle; based on each third position information and the first position relationship, determine the second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle.

[0093] In a specific application scenario, in order to determine the isocenter position corresponding to the electron linear accelerator, the third determination unit 34 can be specifically used to determine the minimum circumscribed sphere among the multiple circumscribed spheres, and determine the center position corresponding to the minimum circumscribed sphere as the isocenter position of the electron linear accelerator.

[0094] It should be noted that for other corresponding descriptions of the functional modules involved in the device for determining the isocenter of an electron linear accelerator provided in an embodiment of the present invention, reference can be made to Figure 1 The corresponding description of the method shown will not be repeated here.

[0095] Based on the above Figure 1The method shown, accordingly, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the following steps are implemented: when the gantry is perpendicular to the floor of the treatment room, based on the rotation trajectory corresponding to the preset marker that rotates with the beam limiting device, the first radiation field axis corresponding to the beam limiting device is determined; based on the first position relationship between the center of the preset marker and the first radiation field axis, the second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle is determined; the feet of perpendiculars corresponding to the perpendiculars between multiple first reference points in the preset marker and each second radiation field axis are determined, and based on each foot of the perpendicular, the circumscribed spheres corresponding to the multiple first reference points are drawn; based on the multiple circumscribed spheres, the isocenter position of the electron linear accelerator is determined.

[0096] Based on the above Figure 1 The method shown and Figure 3 The embodiment of the device shown in the figure, the embodiment of the present invention also provides a physical structure diagram of a computer device, such as Figure 4 As shown, the computer device includes: a processor 41, a memory 42, and a computer program stored in the memory 42 and executable on the processor, wherein the memory 42 and the processor 41 are both arranged on a bus 43, and the processor 41 implements the following steps when executing the program: when the gantry is perpendicular to the floor of the treatment room, based on the rotation trajectory corresponding to the preset marker that rotates with the beam limiting device, the first radiation field axis corresponding to the beam limiting device is determined; based on the first positional relationship between the center of the preset marker and the first radiation field axis, the second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle is determined; the feet of perpendiculars corresponding to the perpendiculars between the plurality of first reference points in the preset marker and the second radiation field axes are determined, and based on the feet of the perpendiculars, the circumscribed spheres corresponding to the plurality of first reference points are drawn; based on the plurality of circumscribed spheres, the isocenter position of the electron linear accelerator is determined.

[0097] Through the technical solution of the present invention, the present invention determines the first radiation field axis corresponding to the beam limiting device when the frame is perpendicular to the floor of the treatment room based on the rotation trajectory corresponding to the preset marker that rotates with the beam limiting device; and determines the second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle based on the first position relationship between the center of the preset marker and the first radiation field axis; then determines the foot of the perpendicular corresponding to the perpendicular between multiple first reference points in the preset marker and each second radiation field axis, and based on each foot of the perpendicular, draws the circumscribed spheres corresponding to the multiple first reference points; finally, determines the The isocenter position of the electron linear accelerator is determined by determining the first target radiation field corresponding to the beam limiting device when the frame is perpendicular to the floor of the treatment room, and determining the first positional relationship between the center of a preset marker fixed on the beam limiting device and the first target radiation field, thereby determining the second radiation field axis corresponding to the beam limiting device, and finally determining the isocenter position corresponding to the electron linear accelerator based on the positional relationship between each second radiation field axis and the preset marker, thereby improving the efficiency of determining the isocenter of the electron linear accelerator, and avoiding the situation where the staff makes an erroneous judgment due to negligence, thereby improving the accuracy of determining the isocenter of the electron linear accelerator.

[0098] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and optionally, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order than here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for determining the isocenter of an electron linear accelerator, wherein the electron linear accelerator comprises a frame, a beam limiting device, and a treatment bed, characterized in that: include: When the gantry is perpendicular to the floor of the treatment room, the spatial coordinates of the preset marker rotating with the beam limiting device are determined, and based on the spatial coordinates, the direction information of the radiation field axis corresponding to the beam limiting device is determined, wherein the gantry can rotate 360° on a vertical plane, and the gantry is perpendicular to the floor of the treatment room, that is, the gantry is in a non-rotated state of 0°; Selecting a plurality of second reference points at a starting position relative to the center of the preset marker, determining a point through which the radiation field axis of the beam limiting device passes according to the coordinates of each of the second reference points at each rotation angle of the beam limiting device, and determining the first radiation field axis corresponding to the beam limiting device based on the point and the direction information; Determine third position information corresponding to the center of the preset marker when the rack is at each first rotation angle; Based on each third position information and based on a first positional relationship between the center of the preset marker and the first radiation field axis, determining a second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle; Arbitrarily determine a plurality of first reference points in the spatial coordinate system corresponding to the treatment bed, determine the feet of perpendiculars corresponding to the perpendicular lines between the plurality of first reference points and the axes of the second radiation fields, and draw circumscribed spheres corresponding to the plurality of first reference points based on the feet of the perpendiculars; The isocenter position of the electron linear accelerator is determined according to a plurality of circumscribed spheres.

2. The method according to claim 1, characterized in that The method for determining the first radiation field axis corresponding to the beam limiting device includes: Based on the rotation trajectory corresponding to the preset marker that rotates with the beam limiting device, determine the radiation field axis direction information corresponding to the beam limiting device, and determine the radiation field axis position information corresponding to the beam limiting device; Based on the radiation field axis direction information and the radiation field axis position information, a first radiation field axis corresponding to the beam limiting device is determined.

3. The method according to claim 2, characterized in that A plurality of infrared markers are installed on the preset marker, and the radiation field axis direction information corresponding to the beam limiting device is determined based on the rotation trajectory corresponding to the preset marker rotating with the beam limiting device, including: Determining the planes that the plurality of infrared markers respectively pass through when rotating with the beam limiting device; Determine the normal direction information corresponding to multiple planes; The normal direction information is determined as the radiation field axis direction information corresponding to the beam limiting device.

4. The method according to claim 2, characterized in that: Based on the rotation trajectory corresponding to the preset marker rotating with the beam limiting device, determining the radiation field axis position information corresponding to the beam limiting device, including: Determine first position information of the center of the preset marker when the beam limiting device is at each second rotation angle, and determine an angle change value of the preset marker when the beam limiting device is at each second rotation angle; Determine a plurality of second reference points in the preset marker, and determine second position information of the plurality of second reference points when the beam limiting device is at each second rotation angle based on a second position relationship between the center of the preset marker and the plurality of second reference points, and each first position information and each angle change value; Based on each second position information, the circumscribed circles corresponding to the multiple second reference points are determined, and based on the center position information of the multiple circumscribed circles, the radiation field axis position information corresponding to the beam limiting device is determined.

5. The method according to claim 4, characterized in that The determining, based on the second positional relationship between the center of the preset marker and the plurality of second reference points, and the respective first positional information and the respective angle change values, the second positional information of the plurality of second reference points when the beam limiting device is at each second rotation angle comprises: Based on the angle change values, determining a position transformation matrix commonly corresponding to the plurality of second reference points; Based on the position conversion matrix, the second position relationship and the respective first position information, second position information of the plurality of second reference points when the beam limiting device is at respective second rotation angles is determined.

6. The method according to claim 1, characterized in that Determining the isocenter position of the electron linear accelerator according to a plurality of circumscribed spheres comprises: A circumscribed sphere with the smallest radius is determined among the multiple circumscribed spheres, and a sphere center position corresponding to the circumscribed sphere with the smallest radius is determined as the isocenter position of the electron linear accelerator.

7. A device for determining the isocenter of an electron linear accelerator, the electron linear accelerator comprising a frame, a beam limiting device, and a treatment bed, characterized in that: include: A first determination unit is used to determine the spatial coordinates of the preset marker rotating with the beam limiting device when the gantry is perpendicular to the floor of the treatment room, and determine the direction information of the radiation field axis corresponding to the beam limiting device based on the spatial coordinates, wherein the gantry can rotate 360° on a vertical plane, and the gantry being perpendicular to the floor of the treatment room means that the gantry is in a non-rotated state of 0°; select a plurality of second reference points at a starting position relative to the center of the preset marker, determine a point through which the radiation field axis of the beam limiting device passes according to the coordinates of each of the second reference points at each rotation angle of the beam limiting device, and determine a first radiation field axis corresponding to the beam limiting device based on the point and the direction information; A second determination unit is used to determine third position information corresponding to the center of the preset marker when the gantry is at each first rotation angle; based on each third position information and based on a first position relationship between the center of the preset marker and the first radiation field axis, determine a second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle; a drawing unit, configured to arbitrarily determine a plurality of first reference points in the spatial coordinate system corresponding to the treatment bed, determine the feet of perpendiculars corresponding to the perpendiculars between the plurality of first reference points and the axes of the second radiation fields, and draw circumscribed spheres corresponding to the plurality of first reference points based on the feet of the perpendiculars; The third determining unit is used to determine the isocenter position of the electron linear accelerator according to the multiple circumscribed spheres.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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