CN115200512A - Method and device for determining isocenter of electron linear accelerator and storage medium - Google Patents
Method and device for determining isocenter of electron linear accelerator and storage medium Download PDFInfo
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Abstract
The invention discloses a method and a device for determining an isocenter of an electronic linear accelerator and a storage medium, relates to the technical field of medical information, and mainly aims to improve the determination precision and the determination efficiency of the isocenter of the electronic linear accelerator. The method comprises the following steps: determining a first radiation field axis corresponding to a beam limiting device based on a rotation track corresponding to a preset marker rotating along with the beam limiting device; determining second radiation field axes corresponding to the beam limiting device when the frame is at each first rotation angle based on a first position relation between the center of the preset marker and the first radiation field axes; determining external balls corresponding to the first reference points respectively; and determining the isocenter position of the electron linear accelerator according to a plurality of circumscribed balls. The method is suitable for determining the isocenter position of the electron linear accelerator.
Description
Technical Field
The invention relates to the technical field of medical information, in particular to a method and a device for determining an isocenter of an electron linear accelerator and a storage medium.
Background
Radiotherapy is one of three main means for treating tumor clinically, and the radiotherapy equipment includes a medical electron linear accelerator, which irradiates tumor with X-ray to reach treating effect, i.e. to concentrate the ray to the tumor part while avoiding damage to health tissue. Based on this, in order to achieve accurate radiotherapy of the tumor position, it is necessary to determine the isocenter position of the electron linac.
At present, the position of the isocenter is usually estimated by projecting a cross cursor at the center of the beam limiting device on the electron linear accelerator onto a piece of coordinate paper to determine the axis of the beam limiting device, fixedly mounting an auxiliary tool such as a pointer on a frame, rotating the frame, and determining the offset of the axis of the beam limiting device by means of visual inspection. However, in this method, the cross-shaped cursor at the center of the beam limiting device needs to be illuminated by light so that the cross-shaped cursor is projected on the coordinate paper, which reduces the efficiency of determining the isocenter of the electron linear accelerator, and meanwhile, the deviation within 1mm cannot be quantified by visual observation, and due to the negligence of workers, an erroneous judgment can be made, thereby resulting in low accuracy of determining the isocenter of the electron linear accelerator.
Disclosure of Invention
The invention provides a method and a device for determining an isocenter of an electron linear accelerator and a storage medium, and mainly aims to improve the determination accuracy and the determination efficiency of the isocenter of the electron linear accelerator.
According to a first aspect of the present invention, there is provided a method for determining an isocenter of an electron linear accelerator, comprising:
when the machine frame is vertical to the ground of a treatment room, determining a first radiation field axis corresponding to the beam limiting device based on a rotating track corresponding to a preset marker rotating along with the beam limiting device;
determining second radiation field axes corresponding to the beam limiting device when the frame is at each first rotation angle based on a first position relation between the center of the preset marker and the first radiation field axes;
determining the drop feet of the plurality of first reference points corresponding to the vertical lines between the second radiation field axes respectively, and drawing external balls corresponding to the plurality of first reference points respectively based on the drop feet;
and determining the isocenter position of the electron linear accelerator according to a plurality of external balls.
According to a second aspect of the present invention, there is provided an apparatus for determining the isocenter of an electron linear accelerator, comprising:
the first determining unit is used for determining a first radiation field axis corresponding to the beam limiting device based on a rotating track corresponding to a preset marker rotating along with the beam limiting device when the machine frame is vertical to the ground of the treatment room;
the second determining unit is used for determining a second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle based on the first position relation between the center of the preset marker and the first radiation field axis;
the drawing unit is used for determining the drop legs corresponding to the vertical lines between the first reference points and the second radiation field axes respectively, and drawing the external ball corresponding to the first reference points respectively based on the drop legs;
and the third determining unit is used for determining the isocenter position of the electron linear accelerator according to a plurality of external balls.
According to a third aspect of the present invention, there is provided a computer-readable storage medium, having stored thereon a computer program which, when executed by a processor, performs the steps of:
when the machine frame is vertical to the ground of a treatment room, determining a first radiation field axis corresponding to the beam limiting device based on a rotating track corresponding to a preset marker rotating along with the beam limiting device;
determining second radiation field axes corresponding to the beam limiting device when the frame is at each first rotation angle based on a first position relation between the center of the preset marker and the first radiation field axes;
determining the plurality of first reference points and the vertical feet corresponding to the vertical lines between the second radiation field axes respectively, and drawing the external ball corresponding to the plurality of first reference points respectively based on each vertical foot;
and determining the isocenter position of the electron linear accelerator according to a plurality of external balls.
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 on the memory and executable on the processor, the processor implementing the following steps when executing the program:
when the rack is vertical to the ground of a treatment room, determining a first radiation field axis corresponding to the beam limiting device based on a rotation track corresponding to a preset marker which rotates along with the beam limiting device;
determining second radiation field axes corresponding to the beam limiting device when the frame is at each first rotation angle based on a first position relation between the center of the preset marker and the first radiation field axes;
determining the drop feet of the plurality of first reference points corresponding to the vertical lines between the second radiation field axes respectively, and drawing external balls corresponding to the plurality of first reference points respectively based on the drop feet;
and determining the isocenter position of the electron linear accelerator according to a plurality of circumscribed balls.
According to the method, the device and the storage medium for determining the isocenter of the electron linear accelerator, compared with the mode that the isocenter of the electron linear accelerator is determined by manually observing the change range of a cross cursor on coordinate paper when the beam limiting device rotates at each rotation angle at present, when the rack is perpendicular to the ground of a treatment room, a first radiation field axis corresponding to the beam limiting device is determined on the basis of the rotation track corresponding to a preset marker rotating along with the beam limiting device; determining second radiation field axes corresponding to the beam limiting devices when the frame is at each first rotation angle based on a first position relation between the centers of the preset markers and the first radiation field axes; then determining the plurality of first reference points and the vertical feet corresponding to the vertical lines between the second radiation field axes respectively, and drawing external balls corresponding to the plurality of first reference points respectively based on the vertical feet; finally, according to a plurality of external balls, the isocenter position of the electron linear accelerator is determined, so that when the rack is perpendicular to the ground of the treatment room, a first target radiation field corresponding to the beam limiting device is determined, a first position relation between the center of a preset marker fixed on the beam limiting device and the first target radiation field is determined, a second radiation field axis corresponding to the beam limiting device is determined, and finally the isocenter position corresponding to the electron linear accelerator is determined on the basis of the position relation between each second radiation field axis and the preset marker.
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The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
fig. 1 is a flowchart illustrating a method for determining an isocenter of an electron linear accelerator according to an embodiment of the present invention;
FIG. 2 is a flow chart of another method for determining the isocenter of an electron linear accelerator according to an embodiment of the invention;
fig. 3 is a schematic structural diagram illustrating an apparatus for determining an isocenter of an electron linear accelerator according to an embodiment of the present invention;
fig. 4 shows a physical structure diagram of a computer device according to an embodiment of the present invention.
Detailed Description
The invention will be described in detail hereinafter with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
At present, the mode of manually observing the change range of a cross cursor on coordinate paper when a beam limiting device is at each rotation angle to determine the isocenter of an electronic linear accelerator results in low efficiency of determining the isocenter of the electronic linear accelerator, and meanwhile, due to the negligence of workers, wrong judgment can be made, and the accuracy of determining the isocenter of the electronic linear accelerator is low.
In order to solve the above problem, an embodiment of the present invention provides a method for determining an isocenter of an electron linear accelerator, as shown in fig. 1, the method including:
101. when the machine frame is perpendicular to the ground of the treatment room, the first radiation field axis corresponding to the beam limiting device is determined based on the rotating track corresponding to the preset marker rotating along with the beam limiting device.
The electron linear accelerator comprises a frame, a radiation head, a treatment couch and the like, wherein the radiation head is fixedly arranged on the frame and can generate high-energy rays, the frame of the electron linear accelerator can usually rotate 360 degrees on a vertical plane, the treatment couch usually has 4-6 degrees of freedom and comprises 3 translational degrees of freedom and 1 or 3 rotational degrees of freedom, the radiation head comprises a beam limiting device, in a typical medical electron linear accelerator, the beam limiting device comprises a beam collimator, a tungsten gate, a multi-leaf grating and the like and is used for forming radiation fields of various shapes required by radiotherapy, the beam limiting device can rotate at least 270 degrees, the rotation axis of the beam limiting device is ideally a straight line, namely a radiation field axis, and the radiation field axis points to the rotation axis of the frame of the electron linear accelerator and is vertically crossed with the rotation axis, and the beam limiting device can generate small-amplitude translational motion relative to a fixed reference system when rotating under the influence of various mechanical errors, and meanwhile, the frame can also generate small-amplitude translational motion relative to the fixed reference system when rotating.
For the embodiment of the invention, in order to solve the problems of low efficiency and low accuracy of the process of determining the isocenter of the electron linear accelerator in the prior art, the embodiment of the invention determines a first target radiation field corresponding to the beam limiting device when the frame is perpendicular to the ground of the treatment room, determines a first position relationship between the center of a preset marker fixed on the beam limiting device and the first target radiation field, determines a 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. The embodiment of the invention is mainly applied to a scene of determining the isocenter of the electronic linear accelerator, and the execution main body of the embodiment of the invention is a device or equipment capable of determining the isocenter of the electronic linear accelerator, and can be specifically arranged at a client side or a server side.
Specifically, firstly, an optical imaging device and a preset marker are prepared, wherein a plurality of infrared markers are installed on the preset marker, the plurality of infrared markers can be 3-5 infrared reflective balls, the preset marker is designed to enable the infrared markers to be in asymmetric distribution, the infrared markers have enough spacing, for example, the spacing between every two infrared markers is 5-10 cm, at least 3 infrared markers can be completely captured by the optical imaging device in the isocenter determining process, and the optical imaging device is calibrated in advance to obtain the directions of three coordinate axes of a fixed reference system (Xf, yf, zf) of a treatment room. It should be noted that the present invention does not require the optical imaging device to be strictly calibrated to the origin Of the fixed reference system, and if the operator needs to determine the relative relationship between the test result and the fixed reference system, the preset marker according to the embodiment Of the present invention may be centered on the known origin Of the fixed reference system for calibration.
Further, the frame of the electron linear accelerator is rotated to a position perpendicular to the ground of the treatment room, at this time, the frame of the electron linear accelerator is at 0 °, then a preset marker is fixed at the beam limiting device of the electron linear accelerator, and the center of the preset marker is located near the visually estimated isocenter, wherein the visually estimated isocenter can be determined based on a laser intersection point irradiated by a laser lamp in the treatment room. Rotating the beam limiting device to 4 or more than 4 angles, wherein the angles are approximately uniformly distributed in the rotation range of the beam limiting device, detecting the spatial coordinates corresponding to each infrared marker by using an optical imaging device at each rotation angle, determining the direction of the radiation field axis corresponding to the beam limiting device by using a fitting algorithm, meanwhile, selecting a plurality of second reference points from the initial position corresponding to the center of a preset marker in the space, calculating the coordinates corresponding to the plurality of second reference points at each rotation angle, then drawing circumscribed circles corresponding to the plurality of second reference points according to the coordinates corresponding to the plurality of second reference points, finally determining the point through which the radiation field axis corresponding to the beam limiting device passes based on the centers of the plurality of circumscribed circles, and finally determining the direction information corresponding to the radiation field axis based on the point through which the radiation field axis passes and the radiation field axis, determining a first radiation field axis corresponding to the beam limiting device, simultaneously determining that the frame is kept at 0 degree and when the beam limiting device rotates to 0 degree, measuring coordinates of each infrared marker on a preset marker by using optical imaging equipment, calculating the position and the direction of the first radiation field axis of the beam limiting device relative to the preset marker, namely a first position relation between the center of the preset marker and the first radiation field axis, and determining the first radiation field axis of the beam limiting device at the moment as the radiation field axis of the frame at an angle of 0 degree.
102. And determining a second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle based on a first position relation between the center of the preset marker and the first radiation field axis.
For the embodiment of the present invention, the gantry is rotated to a plurality of other angles for measurement, and the angles are approximately uniformly distributed in the rotation range of the gantry, for example, for the gantry with the rotation range of 360 °, measurement is performed every 45 °, 8 measurement angles are provided in total, at each gantry angle, an optical imaging device is used to measure the coordinates of each infrared marker on the preset marker, and according to 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 gantry angle is calculated.
103. And determining the drop feet of the plurality of first reference points corresponding to the vertical lines between the second radiation field axes respectively, and drawing the external ball corresponding to the plurality of first reference points respectively based on the drop feet.
Wherein each of the second radiation field axes includes the first radiation field axis, for the embodiment of the present invention, a plurality of first reference points are arbitrarily determined in a spatial coordinate system corresponding to the treatment apparatus, wherein positions of the plurality of first reference points are known, perpendicular lines between the plurality of first reference points and each of the second radiation field axes are respectively drawn, a foot corresponding to each of the perpendicular lines is simultaneously determined, distances between the plurality of first reference points and the corresponding feet thereof, i.e., distances between the plurality of first reference points and each of the second radiation field axes obtained in the previous step, are calculated, respective distances corresponding to the plurality of first reference points are obtained, a maximum distance is determined in each distance, a maximum target distance corresponding to each of the plurality of first reference points is obtained, a search algorithm is used, and a predetermined step size, such as 0.01mm, searching the coordinate change direction of reducing the maximum target distance until determining a point in the plurality of first reference points so that the maximum target distance is the minimum value of all the searched maximum target distances, determining a foot corresponding to a perpendicular line between the point and each second radiation field axis when the gantry is at each rotation angle, drawing an outer ball corresponding to the point set in common, and determining a ball center corresponding to the outer ball as an isocenter position corresponding to the electronic linear accelerator, and at the same time, after determining feet corresponding to perpendicular lines between the plurality of first reference points and each second radiation field axis respectively, determining a foot point set corresponding to each of the plurality of first reference points, and then drawing an outer ball corresponding to each of the plurality of foot point sets, and obtaining external balls corresponding to the first reference points respectively, calculating the radiuses corresponding to the external balls respectively, determining the minimum radius in the radiuses, and determining the external ball center corresponding to the minimum radius as the isocenter corresponding to the electronic linear accelerator.
104. And determining the isocenter position of the electron linear accelerator according to a plurality of external balls.
For the embodiment of the present invention, after the circumscribed balls corresponding to the plurality of first reference points are drawn, the radii corresponding to the plurality of circumscribed balls are determined, the minimum radius is determined among the plurality of radii, the target sphere center coordinate information of the circumscribed ball 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.
According to the method for determining the isocenter of the electronic linear accelerator, compared with the mode that the isocenter of the electronic linear accelerator is determined by manually observing the change range of a cross cursor on coordinate paper when a beam limiting device rotates at each rotation angle at present, the method determines a first radiation field axis corresponding to the beam limiting device when a rack is vertical to the ground of a treatment room on the basis of the rotation track corresponding to a preset marker rotating along with the beam limiting device; determining second radiation field axes corresponding to the beam limiting devices when the frame is at each first rotation angle based on a first position relation between the centers of the preset markers and the first radiation field axes; then, determining the drop feet of the plurality of first reference points corresponding to the vertical lines between the second radiation field axes respectively, and drawing external balls corresponding to the plurality of first reference points respectively based on the drop feet; finally, the isocenter position of the electron linear accelerator is determined according to the plurality of external balls, so that when the rack is perpendicular to the ground of the treatment room, a first target radiation field corresponding to the beam limiting device is determined, a first position relation between the center of a preset marker fixed on the beam limiting device and the first target radiation field is determined, a second radiation field axis corresponding to the beam limiting device is determined, and finally the isocenter position corresponding to the electron linear accelerator is determined based on the position relation between each second radiation field axis and the preset marker, so that the isocenter determination efficiency of the electron linear accelerator is improved, meanwhile, the condition that wrong judgment is made due to negligence of workers is avoided, and the isocenter determination precision of the electron linear accelerator is improved.
Further, in order to better explain the above process of determining the isocenter of the linac, as a refinement and an extension of the above embodiment, an embodiment of the present invention provides another method for determining the isocenter of the linac, as shown in fig. 2, where the method includes:
201. when the frame is perpendicular to the ground of the treatment room, based on the rotating track corresponding to the preset marker rotating along with the beam limiting device, the radiation field axis direction information corresponding to the beam limiting device is determined, and the radiation field axis position information corresponding to the beam limiting device is determined.
For the embodiment of the present invention, in order to determine the isocenter position of the electron linear accelerator, first, it needs to determine a first radiation field axis corresponding to a beam limiting device of the electron linear accelerator when a gantry of the electron linear accelerator is at 0 °, and in order to determine the first radiation field axis, first, it needs to determine radiation field axis direction information corresponding to the beam limiting device, and based on this, step 201 specifically includes: determining planes through which the plurality of infrared markers pass respectively when rotating along with the beam limiting device; determining common corresponding normal direction information of a plurality of planes; and determining the normal direction information as the radiation field axis direction information corresponding to the beam limiting device.
In particular, the spatial coordinates of the individual infrared markers in a fixed reference system are detected using an optical imaging device and these coordinates are marked as
Wherein i is the serial number of the infrared marker, j is a second rotation angle corresponding to the beam limiting device, and then according to the coordinates of each infrared marker obtained by measurement, the radiation field axis direction information corresponding to the beam limiting device is determined by using a fitting algorithm i Wherein i corresponds to the serial number of the infrared marker, determining the distance between each infrared marker and the corresponding plane at each second rotation angle, and when each infrared marker is at each second rotation angleWhen the sum of squares of the distances reaches the minimum, the direction and the position of each plane are determined at the moment, normal direction information corresponding to each plane is fitted, and the normal direction corresponding to each plane is the direction information of the radiation field axis.
Further, 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 which step 201 further includes: determining first position information of the center of the preset marker when the beam limiting device is at each second rotation angle, and determining an angle change value of the preset marker when the beam limiting device is at each second rotation angle; determining a plurality of second reference points in the preset marker, and determining 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 relation between the center of the preset marker and the plurality of second reference points, and each first position information and each angle change value; and determining circumscribed circles corresponding to the second reference points respectively based on the second position information, and determining the position information of the radiation field axis corresponding to the beam limiting device based on the position information of the centers of the circumscribed circles.
Specifically, the optical imaging device is capable of detecting coordinate information corresponding to each second rotation angle of each infrared marker at the beam limiting device, and calculating, according to the coordinate information corresponding to each infrared marker, coordinate information corresponding to a preset marker center, that is, first position information corresponding to each second rotation angle of the preset marker center, and an angle change value of each second rotation angle of the preset marker with respect to a starting position, where the starting position is a rotation angle of the preset marker around three coordinate axes of a fixed reference system when the beam limiting device is at 0 ° (when the beam limiting device is not rotated), and then selecting a plurality of second reference points in the preset marker, where the starting coordinates of the plurality of second reference points are as follows:
wherein,
representing the corresponding first spatial coordinates of the second reference point at the starting position,
a second spatial coordinate representing a correspondence of the preset marker center at the start position,
representing a coordinate difference between the first space coordinate and the second space coordinate, wherein the coordinate difference is a second position relationship between the preset identifier center and the plurality of second reference points
Further, after determining the second position relationship between the preset marker center and the plurality of second reference points, and the first position information and the angle change value of the preset marker center at each second rotation angle, second position information of the plurality of second reference points at each second rotation angle of the beam limiting device needs to be determined, based on which the method includes: determining a position conversion matrix corresponding to the plurality of second reference points based on the angle change values; and determining second position information of the plurality of second reference points when the beam limiting device is at the second rotation angles based on the position conversion matrix, the second position relation and the first position information.
Specifically, based on the angle change values, a formula for determining a position conversion matrix corresponding to the second reference points in common is as follows:
wherein,
representing the angle change value of the preset marker in each second rotation angle relative to the starting position, m 11 ，m 12 ，m 13 ，m 21 ，m 22 ，m 23 ，m 31 ，m 32 ，m 33 And respectively representing each matrix element in the position conversion matrix.
Further, 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:
wherein,
the second position information is represented by a second position information,
and the first position information of the centers of the preset markers corresponding to each second rotation angle is represented, and the second position information of a plurality of second reference points when the beam limiting device is positioned at each second rotation angle can be determined according to the formula.
Furthermore, based on each second position information corresponding to each second reference point, drawing an circumscribed circle corresponding to each second reference point track, determining a target circumscribed circle with the smallest radius from the plurality of circumscribed circles, determining a spatial coordinate corresponding to a target circle center of the target circumscribed circle, and finally determining the spatial coordinate corresponding to the target circle center as a point through which the radiation field axis corresponding to the beam limiting device passes, i.e., determining the radiation field axis position information corresponding to the beam limiting device.
202. And determining 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.
For the embodiment of the present invention, after the radiation field axis direction information and the radiation field axis position information are determined, the first radiation field axis corresponding to the beam limiting device may be determined based on the radiation field axis direction information and the radiation field axis position information. It should be noted that, according to the above method, the rotation axis of the gantry corresponding to the gantry in the electron linear accelerator and the rotation axis of the treatment couch corresponding to the treatment couch can also be determined, and when the rotation axis of the treatment couch is determined, the preset identifier may be fixed on the treatment couch.
203. And determining a second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle based on a first position relation between the center of the preset marker and the first radiation field axis.
For the embodiment of the present invention, the gantry of the electronic linear accelerator is maintained at 0 °, that is, the gantry is perpendicular to the ground of the treatment room, the beam limiting device is rotated to 0 °, coordinates of each infrared marker on the preset marker are measured by using the optical imaging device, and the position and the direction of the first radiation field axis of the beam limiting device relative to the preset marker are calculated, that is, a first positional relationship between the center of the preset marker and the first radiation field axis is determined, for example, the first positional relationship between the center of the preset marker and the first radiation field axis is that the first radiation field axis is 10mm in the x-axis positive direction, 5mm in the y-axis negative direction, and 3mm in the z-axis positive direction of the preset marker, and meanwhile, the first positional relationship further includes an angular relationship, for example, the angle between the first radiation field axis and the preset marker in the x-axis positive direction is 20 °, the y-axis negative direction is 50 °, and the z-axis negative direction is 30 °.
Further, after determining the first positional relationship between the preset marker and the first radiation field axis, it is necessary to determine, based on the first positional relationship, a second radiation field axis corresponding to the beam limiting device when the frame of the electron linear accelerator is at each first rotation angle, and based on this, step 203 specifically includes: determining third position information corresponding to the center of the preset marker when the rack is positioned at each first rotation angle; and determining a second radiation field axis corresponding to the beam limiting device when the rack is at each first rotation angle based on each third position information and the first position relation.
Specifically, the frame is rotated to a plurality of other first rotation angles for measurement, the angles are approximately uniformly distributed in the rotation range of the frame, for example, for a frame with a rotation range of 360 °, measurement is performed every 45 °, 8 first rotation angles are provided in total, an optical imaging device is used to measure coordinates of each infrared marker on a preset marker in the first rotation angle corresponding to each frame, and a coordinate corresponding to the center of the preset marker, that is, third position information, is determined when the frame of the electron linear accelerator is at each first rotation angle, and 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 frame of the electron linear accelerator is at each first rotation angle can be calculated. It should be noted that, in the embodiment of the present invention, a known fixed initial point may be arbitrarily determined in the spatial coordinate system where the electron linear accelerator is located, a first positional relationship between the known fixed initial point and the first radiation field axis is determined, and according to the above manner, based on the first positional relationship, the second radiation field axis corresponding to the beam limiting device when the gantry is at each first rotation angle is determined.
204. And determining the drop feet of the preset marker, which correspond to the vertical lines between the first reference points and the second radiation field axes, respectively, and drawing the external ball corresponding to the first reference points on the basis of the drop feet.
For the embodiment of the present invention, a plurality of first reference points are determined on the preset marker, and when the gantry is at each rotation angle, perpendicular lines are respectively drawn from the plurality of first reference points to each second radiation field axis, and then the drop feet corresponding to each perpendicular line are determined, at this time, each first reference point corresponds to each drop foot, the number of the drop feet corresponding to each first reference point is the same as the number of the second radiation field axis, each drop foot corresponding to each first reference point forms a point set, so that the plurality of first reference points respectively have a corresponding point set, further, after the point set corresponding to each first reference point is determined, an external 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 external sphere corresponding to the first reference point, thereby the external sphere corresponding to the plurality of first reference points can be obtained, and finally, the isocenter position corresponding to the electronic linear accelerator is determined based on the plurality of external spheres.
205. And determining the isocenter position of the electron linear accelerator according to a plurality of external balls.
For the embodiment of the present invention, after drawing the external balls corresponding to the first reference points, the isocenter position corresponding to the electronic linear accelerator needs to be determined according to the sphere center position information of the external balls, and based on this, step 205 specifically includes: and determining a minimum external ball in the plurality of external balls, and determining a target sphere center position corresponding to the minimum external ball as the isocenter position of the electron linear accelerator.
Specifically, a target external ball with the smallest radius is determined from the external balls, a target center coordinate corresponding to the target external ball is determined, and finally the target center coordinate is determined as the isocenter position corresponding to the electron linear accelerator.
Further, the rotation axis of the treatment couch can be determined according to the method, after the rotation axis corresponding to the treatment couch is determined, each rotation angle of the treatment couch is set to be 0 °, the optical imaging device is used for measuring the coordinates of each infrared marker on the preset marker, the point on the surface of the preset marker corresponding to the rotation axis of the treatment couch is calculated, the pitch angle ψ t, the roll angle Φ t or the combination of the pitch angle ψ t and the roll angle Φ t of the treatment couch is set, the treatment couch is operated to complete corresponding rotation, the optical imaging device is used for measuring the coordinates of each preset marker on the preset marker after the treatment couch is rotated, the pitch angle and the roll angle of the preset marker and the displacement of the point on the surface of the preset marker corresponding to the rotation axis of the treatment couch are calculated, the preset marker is placed on the treatment couch surface, the position change of the preset marker before and after the treatment couch is moved is measured by the optical imaging system, and the position indication of the treatment couch is compared, so that the quality control of the movement distance of the treatment couch can be completed.
According to another method for determining the isocenter of the electron linear accelerator, compared with the mode that the isocenter of the electron linear accelerator is determined by manually observing the change range of a cross cursor on coordinate paper when the beam limiting device rotates at each rotation angle at present, when the rack is perpendicular to the ground of a treatment room, the first radiation field axis corresponding to the beam limiting device is determined according to the rotation track corresponding to the preset marker which rotates along with the beam limiting device; determining second radiation field axes corresponding to the beam limiting devices when the frame is at each first rotation angle based on a first position relation between the centers of the preset markers and the first radiation field axes; then, determining the drop feet corresponding to the vertical lines between the first reference points in the preset marker and the second radiation field axes respectively, and drawing external balls corresponding to the first reference points respectively based on the drop feet; finally, the isocenter position of the electron linear accelerator is determined according to the plurality of external balls, so that when the rack is perpendicular to the ground of the treatment room, a first target radiation field corresponding to the beam limiting device is determined, a first position relation between the center of a preset marker fixed on the beam limiting device and the first target radiation field is determined, a second radiation field axis corresponding to the beam limiting device is determined, and finally the isocenter position corresponding to the electron linear accelerator is determined based on the position relation between each second radiation field axis and the preset marker, so that the isocenter determination efficiency of the electron linear accelerator is improved, meanwhile, the condition that wrong judgment is made due to negligence of workers is avoided, and the isocenter determination precision of the electron linear accelerator is improved.
Further, as a specific implementation of fig. 1, an embodiment of the present invention provides an apparatus for determining an isocenter of an electron linear accelerator, as shown in fig. 3, where the apparatus includes: a first determining unit 31, a second determining unit 32, a rendering unit 33 and a third determining unit 34.
The first determining 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 rotating with the beam limiting device when the gantry is perpendicular to the treatment room floor.
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.
The drawing unit 33 may be configured to determine that the plurality of first reference points in the preset marker respectively correspond to the vertical lines between the second radiation field axes, and draw the external ball corresponding to the plurality of first reference points respectively based on each of the vertical feet.
The third determining unit 34 may be configured to determine an isocenter position of the electron linear accelerator according to a plurality of circumscribed balls.
In a specific application scenario, in order to determine a first radiation field axis corresponding to a beam limiting device in the electronic linear accelerator, the first determining unit 31 may be specifically configured to determine, based on a rotation trajectory corresponding to a preset marker that rotates with the beam limiting device, radiation field axis direction information corresponding to the beam limiting device, and radiation field axis position information corresponding to the beam limiting device; and determining 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.
In a specific application scenario, in order to determine the axis direction information of the radiation field corresponding to the beam limiting device, the first determining unit 31 may be specifically configured to determine planes through which the plurality of infrared markers pass respectively when rotating with the beam limiting device; determining common corresponding normal direction information of a plurality of planes; and determining the normal direction information as the radiation field axis direction information corresponding to the beam limiting device.
In a specific application scenario, in order to determine the position information of the radiation field axis corresponding to the beam limiting device, the first determining unit 31 may be further configured to 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; determining a plurality of second reference points in the preset marker, and determining 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 relation between the center of the preset marker and the plurality of second reference points, and each first position information and each angle change value; and determining circumscribed circles corresponding to the second reference point tracks respectively based on the second position information, and determining the position information of the radiation field axis corresponding to the beam limiting device based on the position information of the centers of the circumscribed circles.
In a specific application scenario, in order to determine second position information of the plurality of second reference points when the beam limiting device is at each second rotation angle, the first determining unit 31 may be further configured to determine, based on the each angle variation value, a position conversion matrix to which the plurality of second reference points correspond in common; and determining second position information of the plurality of second reference points when the beam limiting device is at the second rotation angles based on the position conversion matrix, the second position relation and the first position information.
In a specific application scenario, in order to determine a second radiation field axis corresponding to the beam limiting device when the gantry of the electron linear accelerator is at each first rotation angle, the second determining unit 32 may be specifically configured to determine third position information corresponding to the center of the preset marker when the gantry is at each first rotation angle; and determining a second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle based on each third position information and the first position relation.
In a specific application scenario, in order to determine the isocenter position corresponding to the electron linear accelerator, the third determining unit 34 may be specifically configured to determine a minimum circumscribed ball among the multiple circumscribed balls, and determine a sphere center position corresponding to the minimum circumscribed ball as the isocenter position of the electron linear accelerator.
It should be noted that other corresponding descriptions of the functional modules involved in the determination apparatus for an isocenter of an electronic linear accelerator according to an embodiment of the present invention may refer to the corresponding description of the method shown in fig. 1, and are not described herein again.
Based on the method shown in fig. 1, correspondingly, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the following steps: when the machine frame is vertical to the ground of a treatment room, determining a first radiation field axis corresponding to the beam limiting device based on a rotating track corresponding to a preset marker rotating along with the beam limiting device; determining second radiation field axes corresponding to the beam limiting device when the frame is at each first rotation angle based on a first position relation between the center of the preset marker and the first radiation field axes; determining the drop feet of the preset marker, which correspond to the vertical lines between the first reference points and the second radiation field axes, and drawing external balls corresponding to the first reference points based on the drop feet; and determining the isocenter position of the electron linear accelerator according to a plurality of external balls.
Based on the above embodiments of the method shown in fig. 1 and the apparatus shown in fig. 3, an embodiment of the present invention further provides an entity structure diagram of a computer device, as shown in fig. 4, where the computer device includes: a processor 41, a memory 42, and a computer program stored on the memory 42 and executable on the processor, wherein the memory 42 and the processor 41 are both arranged on a bus 43 such that when the processor 41 executes the program, the following steps are performed: when the rack is vertical to the ground of a treatment room, determining a first radiation field axis corresponding to the beam limiting device based on a rotation track corresponding to a preset marker which rotates along with the beam limiting device; determining second radiation field axes corresponding to the beam limiting device when the frame is at each first rotation angle based on a first position relation between the center of the preset marker and the first radiation field axes; determining the drop feet of the preset marker, which correspond to the vertical lines between the first reference points and the second radiation field axes, and drawing external balls corresponding to the first reference points based on the drop feet; and determining the isocenter position of the electron linear accelerator according to a plurality of circumscribed balls.
According to the technical scheme, when the frame is perpendicular to the ground of the treatment room, the first radiation field axis corresponding to the beam limiting device is determined based on the rotating track corresponding to the preset marker rotating along with the beam limiting device; determining second radiation field axes corresponding to the beam limiting devices when the frame is at each first rotation angle based on a first position relation between the centers of the preset markers and the first radiation field axes; then, determining the drop feet corresponding to the vertical lines between the first reference points in the preset marker and the second radiation field axes respectively, and drawing external balls corresponding to the first reference points respectively based on the drop feet; finally, the isocenter position of the electron linear accelerator is determined according to the plurality of external balls, so that when the rack is perpendicular to the ground of the treatment room, a first target radiation field corresponding to the beam limiting device is determined, a first position relation between the center of a preset marker fixed on the beam limiting device and the first target radiation field is determined, a second radiation field axis corresponding to the beam limiting device is determined, and finally the isocenter position corresponding to the electron linear accelerator is determined based on the position relation between each second radiation field axis and the preset marker, so that the isocenter determination efficiency of the electron linear accelerator is improved, meanwhile, the condition that wrong judgment is made due to negligence of workers is avoided, and the isocenter determination precision of the electron linear accelerator is improved.
It will be apparent to those skilled in the art that the modules or steps of the present invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and alternatively, they may be implemented by program code executable by a computing device, such that they may be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described may be performed in an order different than that described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple ones of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for determining the isocenter of an electron linear accelerator, the electron linear accelerator comprising a gantry and a beam limiting device, the method comprising:
when the machine frame is vertical to the ground of a treatment room, determining a first radiation field axis corresponding to the beam limiting device based on a rotating track corresponding to a preset marker rotating along with the beam limiting device;
determining second radiation field axes corresponding to the beam limiting device when the frame is at each first rotation angle based on a first position relation between the center of the preset marker and the first radiation field axes;
determining the drop feet of the plurality of first reference points corresponding to the vertical lines between the second radiation field axes respectively, and drawing external balls corresponding to the plurality of first reference points respectively based on the drop feet;
and determining the isocenter position of the electron linear accelerator according to a plurality of circumscribed balls.
2. The method according to claim 1, wherein the determining the first radiation field axis corresponding to the beam limiting device based on the rotation trajectory corresponding to the preset marker rotating with the beam limiting device comprises:
determining the axial line direction information of a radiation field corresponding to a beam limiting device and determining the axial line position information of the radiation field corresponding to the beam limiting device based on a rotating track corresponding to a preset marker rotating along with the beam limiting device;
and determining 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.
3. The method according to claim 2, wherein a plurality of infrared markers are installed on the preset marker, and the determining of the radiation field axis direction information corresponding to the beam limiting device based on the rotation track corresponding to the preset marker rotating along with the beam limiting device comprises:
determining planes through which the plurality of infrared markers pass respectively when rotating along with the beam limiting device;
determining common corresponding normal direction information of a plurality of planes;
and determining the normal direction information as the radiation field axis direction information corresponding to the beam limiting device.
4. The method according to claim 2, wherein determining the radiation field axis position information corresponding to the beam limiting device based on the rotation trajectory corresponding to the preset marker rotating with the beam limiting device comprises:
determining first position information of the center of the preset marker when the beam limiting device is at each second rotation angle, and determining an angle change value of the preset marker when the beam limiting device is at each second rotation angle;
determining a plurality of second reference points in the preset marker, and determining 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 relation between the center of the preset marker and the plurality of second reference points, and each first position information and each angle change value;
and determining circumscribed circles corresponding to the second reference points respectively based on the second position information, and determining the position information of the radiation field axis corresponding to the beam limiting device based on the position information of the centers of the circumscribed circles.
5. The method according to claim 4, wherein the determining second position information of the plurality of second reference points at the respective second rotation angles of the beam limiting device based on the second position relationship between the center of the preset identifier and the plurality of second reference points, and the respective first position information and the respective angle change values comprises:
determining a position conversion matrix corresponding to the plurality of second reference points based on the angle change values;
and determining second position information of the plurality of second reference points when the beam limiting device is at the second rotation angles based on the position conversion matrix, the second position relation and the first position information.
6. The method according to claim 1, wherein the determining a second radiation field axis corresponding to the beam limiting device at each first rotation angle of the gantry based on the first position relationship between the center of the preset marker and the first radiation field axis comprises:
determining third position information corresponding to the center of the preset marker when the frame is at each first rotation angle;
and determining a second radiation field axis corresponding to the beam limiting device when the rack is at each first rotation angle based on each third position information and the first position relation.
7. The method of claim 1, wherein determining the isocenter position of the electron linear accelerator from a plurality of circumspheres comprises:
and determining an external ball with the minimum radius from the plurality of external balls, and determining the position of the center of the ball corresponding to the external ball with the minimum radius as the position of the isocenter of the electron linear accelerator.
8. An apparatus for determining an isocenter of an electron linear accelerator, comprising:
the first determining unit is used for determining a first radiation field axis corresponding to the beam limiting device based on a rotating track corresponding to a preset marker rotating along with the beam limiting device when the machine frame is vertical to the ground of the treatment room;
the second determining unit is used for determining a second radiation field axis corresponding to the beam limiting device when the frame is at each first rotation angle based on the first position relation between the center of the preset marker and the first radiation field axis;
the drawing unit is used for determining the drop legs corresponding to the vertical lines between the first reference points and the second radiation field axes respectively, and drawing the external ball corresponding to the first reference points respectively based on the drop legs;
and the third determining unit is used for determining the isocenter position of the electron linear accelerator according to a plurality of external balls.
9. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method of any one of claims 1 to 7.
10. A computer arrangement comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the computer program realizes the steps of the method of any one of claims 1 to 7 when executed by the processor.
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