CN114146328A - Automatic QA method of accelerator system based on combined die body - Google Patents
Automatic QA method of accelerator system based on combined die body Download PDFInfo
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Abstract
The invention provides an automatic QA method of an accelerator system based on a combined die body, wherein the combined die body comprises a tungsten ball central point module, a dose monitoring module and an image analysis module which are integrated into a whole, and the method comprises the following steps: placing a tungsten ball central point module at a theoretical isocenter position, controlling a mechanical part of an accelerator to move to a specific position by introducing a prefabricated plan, acquiring images while outputting beams, and calculating corresponding mechanical deviation by acquiring a field center, a tungsten ball position and a field boundary; guiding the prefabricated plan into an accelerator system, realizing the positioning of a dose detection module by moving a treatment couch, and monitoring the change of dose rate along with time and the final beam output dose in the beam output process of the accelerator; the image analysis module comprises a Las Vegas hole and line pairs representing different resolutions, the prefabricated plan is guided into the accelerator system, the positioning of the image analysis module is realized by moving the treatment couch, the accelerator is controlled to emit beams and acquire images, and images comprising the hole or the line pairs are obtained.
Description
Technical Field
The invention relates to the field of radiotherapy, in particular to an automatic QA method of an accelerator system based on a combined die body.
Background
As a main device of radiotherapy, the accelerator and all parts of components thereof need to ensure extremely high stability in use after being delivered from a factory. The operation condition of each component assembly needs to be detected regularly to ensure that the components meet the treatment requirement.
Before the accelerator leaves a factory, a specific project needs to be checked and verified to ensure that the accelerator meets the use requirement. In daily use of a hospital, the accelerator also needs to be checked regularly, if a problem exists, the accelerator needs to be stopped for maintenance immediately, and the accelerator can be used subsequently after being recovered to an ideal state.
These items to be tested cover mechanics, dose, raster, image, etc. The actual implementation process varies slightly according to specific requirements.
The detection of the accelerator system is one of the most important works before the accelerator leaves the factory, and is also the content that needs to be executed regularly in the actual use process of the hospital. Although the technical scheme and the coverage content provided by each family are slightly different, the verification of machines such as a rack, a small machine head, a bed board and the like is basically included; verification of dose linearity and stability; the verification of grating in-place precision, in-place repeatability and transmission, and the verification of image contrast, resolution and artifacts.
The mechanical part is usually verified by determining a physical isocenter by using a front pointer, and then respectively controlling the motion of each mechanical part by taking the physical isocenter as a standard center to compare the coincidence degree of the mechanical motion center and the physical isocenter. For the verification of the dose part, a dosimeter or an ionization chamber and the like are needed to be used for recording the beam-out process of the accelerator, dose data are obtained through executing a specific test plan for calculation, and whether the calculation result meets a set threshold value or not is checked. The optical field is generally adopted for verification of the grating, and whether the boundary and the size of the grating are consistent with a set value or not is confirmed by forming the shapes of the optical fields with different sizes and assisting with visual observation. The image is verified by directly using an image plate to collect images, and whether the image quality meets the requirements or not is confirmed by observing a specific area through naked eyes.
Whether the inspection before the factory leaves or the regular inspection after the factory leaves, the project is various, and the inspection is a systematic and complex process. Various auxiliary devices are needed to be borrowed, and the quality requirement on operators is high. Performing the entire inspection process completely takes a lot of time and the operator needs to be mentally focused, needs to replace various devices and record various execution data.
Disclosure of Invention
In order to solve the technical problems, the invention discloses an automatic QA method of an accelerator system based on a combined die body, which integrates the detection contents of various parts of machinery, dosage and accessories into a fully automatic process, reduces the use of auxiliary equipment and the work of operators, and further shortens the overall execution time.
In order to achieve the purpose, the technical scheme of the invention is as follows: an automated QA method for an accelerator system based on a combined die body, said combined die body comprising an integrated tungsten ball center point module, a dose monitoring module and an image analysis module, said method comprising the steps of:
when the tungsten ball central point module is used, the tungsten ball central point module is placed at a theoretical isocenter position, a mechanical part of an accelerator is controlled to move to a specific position through a prefabricated plan led into the accelerator, an image is acquired through an image plate while the accelerator emits a beam, and a corresponding mechanical deviation is calculated through acquiring a field center, a tungsten ball position and a field boundary;
when the dose monitoring module is used, the corresponding prefabricated plan is guided into an accelerator system according to a detection project, the accelerator system automatically realizes the positioning of the dose monitoring module by moving a treatment couch, automatically controls the accelerator to output beams, and monitors the change of the dose rate along with time and the final beam output dose in the beam output process of the accelerator;
the image analysis module comprises Las Vegas holes and line pairs representing different resolutions, when the image analysis module is used, a corresponding prefabricated plan is led into the accelerator system according to a detection item, the accelerator system automatically realizes the positioning of the image analysis module by moving the treatment couch, and then the accelerator is controlled to emit beams and images are acquired through the image plate, so that images comprising the holes or the line pairs are obtained.
In a further technical scheme, the tungsten ball center point module comprises a tungsten ball mounting seat, a connecting rod embedded with a tungsten ball and a three-dimensional manual fine adjustment sliding table, and an object detected by the tungsten ball center point module comprises at least one of the following items: the deviation of the mechanical center and the isocenter of the radiation field, the deviation of the rotating center of the frame and the isocenter, the deviation of the rotating center of the treatment bed and the isocenter, the in-place precision of the grating and the in-place repeatability of the grating.
In a further technical scheme, when detecting the deviation between the mechanical center and the field isocenter, the pre-prepared plan includes 8 fields, the angle positions of the gantry and the treatment couch of each field are different, and the angle positions are respectively: 60 DEG, treatment bed: 0 DEG, frame: 60 DEG, treatment bed: 338 °, gantry: 130 °, treatment couch: 0 DEG, frame: 130 °, treatment couch: 338 °, gantry: 230 °, treatment couch: 0 DEG, frame: 230 °, treatment couch: 22 degrees, frame: 300 ° treatment couch: 0 DEG, frame: 300 ° treatment couch: 22 degrees;
the method comprises the steps of obtaining a field center and a tungsten ball center on a returned image of an image plate corresponding to each field through a field center obtaining method and a tungsten ball position obtaining method, calculating corresponding deviation, and judging whether a threshold value is met through three-dimensional deviation of a mechanical center and a field isocenter calculated through a Winston Lutz method according to a frame angle, a treatment bed angle and two-center deviation.
In a further technical scheme, when detecting the deviation between the rotation center of the gantry and the isocenter, the pre-planning includes 6 fields, and the gantry angle position of each field is different and respectively: 0 °, 45 °, 90 °, 200 °, 245 °, 290 °;
the method comprises the steps of respectively obtaining a field center and a tungsten ball center on a returned image of an image plate corresponding to each field through a field center obtaining method and a tungsten ball position obtaining method, calculating corresponding deviation, and calculating three-dimensional deviation of the deviation between a rotating center and an isocenter of a rack through a Winston Lutz method according to the angle of the rack and the deviation between the two centers so as to judge whether a threshold value is met.
In a further technical scheme, when detecting the deviation between the rotation center and the isocenter of the treatment couch, the pre-prepared plan includes 5 fields, and the angle positions of the treatment couch of each field are different and respectively: 0 °, 10 °, 20 °, 350 °, 340 °;
by the method of obtaining the position of the tungsten ball, the center of the tungsten ball on the returned image of the image plate corresponding to each field is respectively obtained, a square area with the center of the image as the center is taken, each pixel in the area is respectively taken as the center point, the distance between the center point and the center of different tungsten balls is calculated, the variance of all 5 distances is calculated, the center point when the variance is calculated is obtained, the maximum value of the distance between the center point and the center of the tungsten ball is taken as the deviation, and whether the deviation meets the threshold value is judged.
In a further technical scheme, when calculating the grating in-place accuracy, the pre-plan includes 7 fields, and the equal center positions of the gratings of each field are different and respectively: leaf a-70 mm, leaf b-50 mm, leaf a-50 mm, leaf b-30 mm, leaf a-30 mm, leaf b-10 mm, leaf a-10 mm, leaf b-30 mm, leaf a-30 mm, leaf b-50 mm, leaf a-50 mm, leaf b-70 mm;
the method comprises the steps of obtaining left and right or upper and lower boundary positions of a field by a field boundary obtaining method, calculating deviation between a theoretical blade position and the obtained boundary positions, and judging whether the deviation meets a threshold value or not.
In a further technical scheme, when calculating the repeatability of grating in place, the pre-plan includes 12 fields, and there are 4 different equal center positions of the grating, which are respectively: leaf a-70 mm, leaf b-50 mm, leaf a-30 mm, leaf b-10 mm, leaf a-10 mm, leaf b-30 mm, leaf a-50 mm, leaf b-70 mm, each position performed 3 times;
the method comprises the steps of obtaining the positions of left and right or upper and lower boundaries of a field by a method of obtaining the field boundary, calculating the standard deviation of the boundary obtained for 3 times of the grating at the same theoretical position, and judging whether the standard deviation meets a threshold value or not.
In a further technical solution, the dose monitoring module includes a three-dimensional water phantom and a dose detector inserted into a center of the three-dimensional water phantom, and a detection item of the dose monitoring module includes one of dose repeatability and dose linearity.
In a further technical scheme, when detecting dose repeatability, the pre-prepared plan comprises 10 fields, each field is the same, the outgoing dose is 10MU, the dose accumulation in the outgoing process is recorded by a dose detector, and the actual final accumulated amount of each field is returned, wherein the method for judging the dose repeatability is to calculate the coefficient of variation: the coefficient of variation is the standard deviation of the measured dose/the mean value of the measured dose 100%;
when the detected dose is linear, the pre-plan contains 25 fields, and there are 5 different outgoing beam doses: 100MU, 300MU, 500MU, 700MU, 900MU, each dose is executed 5 times, the dose accumulation of the beam-out process is recorded by a dose detector, and the actual final accumulated amount of each field is returned, the method for judging the dose repeatability is to calculate the deviation: deviation is 100% ABS (measured dose-theoretical dose)/out beam dose.
In a further technical solution, the detection item of the image analysis module includes one of detection image contrast and detection image resolution;
when the image contrast is detected, acquiring the coverage area of each hole on the image according to the relative physical position and the aperture of the center of the image analysis module and each hole, respectively calculating the gray value average value in the coverage area of each hole, calculating the gray value average value of the coverage area of a square externally connected with each hole, and then judging whether the threshold requirement is met or not by calculating the ratio of the gray value average value to the gray value average value;
when the image resolution is detected, the covering area of each line pair on the image is obtained according to the relative physical position of the center of the image analysis module and each line pair area and the size of each line pair area, and the standard deviation of the gray level in each area is calculated to judge whether the threshold requirement is met.
The invention summarizes and integrates the detection items required by the accelerator, integrates the auxiliary equipment possibly required to be used in the detection process into a single die body, and reduces the time for replacing the auxiliary equipment in the original detection process. Because the execution plans of different detection items are built in advance, the whole execution process is completely realized by the automatic execution plan of the accelerator, and the time for manually controlling the accelerator to move out of the beam originally is reduced. In addition, the switching of each module in the module is realized by planning and controlling the bed to move to different positions, and after the whole detection execution process is started, an operator does not need to enter or exit the accelerator chamber any more, so that the execution time is shortened.
Drawings
FIG. 1 is a schematic structural diagram of a composite mold body according to the present invention;
FIG. 2 is a side view of a modular mold body of the present invention.
Labeled as: the method comprises the following steps of 1-a three-dimensional water mold body, 2-a positioning pin, 3-an influence analysis module, 4-a positioning plate, 5-a three-dimensional manual fine adjustment sliding table, 6-a bed plate, 7-a tungsten ball, 8-a connecting rod and 9-a tungsten ball mounting seat.
Detailed Description
The technical solution of the present invention will be further described with reference to the following specific examples, but the present invention is not limited to these examples.
In order to realize the automatic QA of the accelerator system, the invention designs an integrated phantom to be used together with an image plate, dose acquisition and image acquisition are carried out by using different parts in the phantom, data are analyzed by matching with a specific algorithm, and finally the inspection result of the system is obtained, as shown in fig. 1 and 2, the combined phantom of the invention comprises:
the image analysis module: FIG. 1 is a left-most generic image phantom including Las Vegas holes and lines of different resolution;
a dose monitoring module: FIG. 1 is a three-dimensional water mold body which is inserted with a detector and is arranged in the middle;
tungsten ball center point module: the connecting rod with tungsten ball inserted in the right-most part of figure 1.
The three parts are combined into a die body through the base groove and other mechanical parts, and the relative positions of the three parts of the die body are not changed when the three parts are integrally moved, and are fixed relative positions which are physically limited.
1. The mould body is integrally and horizontally placed on a treatment bed by using a tungsten ball central point module, and 3 mutually vertical laser lamp lines are intersected on the tungsten ball (namely the tungsten ball is placed at the theoretical isocentric position of an accelerator determined by the laser lamp) by manually adjusting the positions of the treatment bed and the mould body. And manually selecting and importing the corresponding prefabricated plan file into an accelerator system according to the difference of mechanical parts and the difference of project contents which need to be detected (the deviation of a mechanical center and a radiation field isocenter, the deviation of a rack rotating center and an isocenter, the deviation of a treatment bed rotating center and an isocenter, the in-place precision of the grating and the in-place repeatability of the grating can be detected). The accelerator system automatically controls the mechanical part to be detected to move to a corresponding position according to the content of the plan file, automatically opens the image plate at the image acquisition position (the position which is fixed relative to the die body, is positioned below the die body and is parallel to the die body), and then controls the accelerator to emit beams. The image plate returns an image after receiving the accelerator radiation, and each pixel on the image presents different gray scales according to different radiation doses of the image plate (the more the radiation is, the larger the gray scale is).
2. When detecting the deviation of the mechanical center and the field isocenter, the prefabricated plan contains 8 fields, the angle positions of the frame and the treatment couch of each field are different, and the frame is: 60 DEG, treatment bed: 0 degree; a frame: 60 DEG, treatment bed: 338 °; a frame: 130 °, treatment couch: 0 degree; a frame: 130 °, treatment couch: 338 °; a frame: 230 °, treatment couch: 0 degree; a frame: 230 °, treatment couch: 22 degrees; a frame: 300 ° treatment couch: 0 degree; a frame: 300 ° treatment couch: 22 deg.
By the method for acquiring the field center and the method for acquiring the position of the tungsten ball, the field center and the tungsten ball center on the returned image of the image plate corresponding to each field are respectively acquired, and the deviation of the field center and the tungsten ball center is calculated. And judging whether the three-dimensional deviation between the mechanical center and the field isocenter meets a threshold value or not according to the angle of the frame, the angle of the treatment bed and the deviation of the two centers, and the three-dimensional deviation between the mechanical center and the field isocenter calculated by a Winston Lutz method.
3. When the deviation between the rotation center of the rack and the isocenter is detected, the prefabricated plan comprises 6 fields, and the angle position of the rack of each field is different and is 0 degree; 45 degrees; 90 degrees; 200 degrees; 245 °; 290 deg..
By the method for acquiring the field center and the method for acquiring the position of the tungsten ball, the field center and the tungsten ball center on the returned image of the image plate corresponding to each field are respectively acquired, and the deviation of the field center and the tungsten ball center is calculated. And calculating the three-dimensional deviation of the deviation between the rotation center and the isocenter of the rack by a Winston Lutz method according to the angle of the rack and the deviation between the two centers, and judging whether the deviation meets a threshold value.
4. When the deviation between the rotation center and the isocenter of the treatment couch is detected, the prefabricated plan comprises 5 radiation fields, and the angle position of the treatment couch of each radiation field is different and is 0 degree; 10 degrees; 20 degrees; 350 degrees; 340 deg.
And respectively obtaining the center of the tungsten ball on the returned image of the image plate corresponding to each field by a method of obtaining the position of the tungsten ball. And taking the center of the image as a center, and taking a square area with the side length of 3mm (which can be modified according to actual conditions). And respectively taking each pixel in the area as a central point, calculating the distance between the central point and the centers of different tungsten balls, calculating the variance of all 5 distances, obtaining the central point when the calculated variance is minimum, taking the maximum value of the distance between the central point and the center of the tungsten ball as a deviation, and judging whether the maximum value meets a threshold value.
5. When the in-place accuracy of the grating is calculated, the prefabrication plan comprises 7 fields, the equal center positions of the grating of each field are different, and the equal center positions are leaf A-70 mm and leaf B-50 mm respectively; leaf A-50 mm, leaf B-30 mm;
LeafA＝-30mm、LeafB＝-10mm；LeafA＝-10mm、LeafB＝10mm；
LeafA＝10mm、LeafB＝30mm；LeafA＝30mm、LeafB＝50mm；
LeafA＝50mm、LeafB＝70mm。
the method for acquiring the field boundary can acquire the left and right (or upper and lower) boundary positions of the field (the field is a square field), calculate the deviation between the theoretical blade position and the acquired boundary position, and judge whether the deviation meets the threshold value
6. When the in-place repeatability of the grating is calculated, the prefabrication plan comprises 12 fields, and the equal center positions of 4 different gratings are-70 mm and-50 mm respectively; leaf A-30 mm, leaf B-10 mm;
leaf A is 10mm, leaf B is 30 mm; each position was performed 3 times with a leaf a of 50mm and a leaf b of 70 mm.
The method for acquiring the portal boundary can acquire the position of the left and right (or upper and lower) boundaries of the portal (the portal is a square portal), calculate the standard deviation of the boundaries acquired for 3 times of the grating at the same theoretical position, and judge whether the standard deviation meets the threshold value
7. The method for acquiring the portal boundary comprises the following steps: the gray values of all pixels on the image are sorted from large to small, the average value of the gray values of the first 10 percent (which can be modified according to the actual condition) of the pixels is calculated, the image is subjected to binarization processing by taking 50 percent (which can be modified according to the actual condition) of the average value as a threshold value, and the boundary of a binarization bright area is the portal boundary.
The method for acquiring the shot center comprises the following steps: calculating the geometric center of the field region defined by the field boundary, namely the field center
The method for acquiring the position of the tungsten ball comprises the following steps: the center of the radiation field is taken as the circle center, and 3mm (which can be modified according to the actual situation) is taken as the area of the diameter. And respectively taking each pixel point in the area as the center of a circle and 3mm as the radius, calculating the gray level variance of all the pixel points in the new circular area, and obtaining the center position when the variance is minimum as the center of the tungsten ball.
8. The dose detection module in the phantom comprises a 30cmX30cmX30cm cubic water model (a cube with density equal to water), a dose detector inserted into the center of the cube (for receiving radiation), and a dose monitoring display connected to the outside of the machine room through a connecting line (capable of reflecting the radiation dose received by the detector in real time). When the module is used, the die body is placed according to a method of using a tungsten ball central point module, then a corresponding prefabricated plan execution file is imported into an accelerator system according to different detection items (detectable dose repeatability and dose linearity), the accelerator system automatically realizes the positioning of a dose detection module by moving a treatment bed, a dose detector moves to an isocenter position, then an image plate is closed, a rack is automatically controlled to move to 0 degree, a grating moves to 10cmX10cm for field opening, and the accelerator is automatically controlled to beam out.
9. In examining dose reproducibility, the pre-plan contained 10 fields, each field being identical, with an exit dose of 10 MU. The dose accumulation for the exit process will be recorded by the dose detector and the actual final accumulated amount for each field returned. The method for judging the repeatability of the dosage is to calculate the coefficient of variation and judge whether the coefficient meets the requirement of a threshold value. The coefficient of variation is the standard deviation of the measured dose/mean of the measured dose 100%.
10. When the detection dose is linear, the pre-preparation plan comprises 25 radiation fields, and the total number of different beam-emitting doses in 5 is 100 MU; 300 MU; 500 MU; 700 MU; 900MU, 5 times per dose. The dose accumulation for the exit process will be recorded by the dose detector and the actual final accumulated amount for each field returned. The method for judging the repeatability of the dose is to calculate the deviation of the dose and judge whether the deviation meets a threshold value. Firstly, calculating the average value of actually measured doses of the radiation fields with the same beam-out dose for 5 times, taking the beam-out dose as X and the average value as Y, and calculating a fitting straight line by adopting a least square method. And substituting 5 outgoing beam doses into the fitting straight line to obtain 5 theoretical doses. Deviation is 100% ABS (measured dose-theoretical dose)/out beam dose.
11. The image analysis module for the phantom contains a set (28) of Las Vegas holes (with different combinations of hole diameter and depth) and line pairs of different (12) densities. When the module is used, the die body is placed according to a method of using a tungsten ball center point module, then a corresponding prefabricated plan execution file is imported into an accelerator system according to different detection items (detectable image contrast and image resolution), the accelerator system automatically realizes the positioning of an image analysis module by moving a treatment bed, the center position of the image analysis module is moved to the isocenter, an image plate is opened to a drawing position, then the frame is automatically controlled to move to 0 degree, the grating is automatically controlled to move to 26cmX26cm for field opening, and the accelerator is automatically controlled to beam out. The image is collected through the image plate, the image containing Las Vegas holes and line pairs is obtained, the number of holes and the line pair density which are considered to be clear are analyzed and identified through an algorithm, and whether the contrast and the resolution of the image meet the requirements or not can be judged.
12. When the contrast of the image is detected, the coverage area of each hole on the image is obtained according to the relative physical position and the aperture of the module center (namely the image center) and each hole, the gray value average value in the coverage area of each hole is respectively calculated, and the gray value average value in the coverage area of a square externally connected with each hole is calculated. And calculating the ratio of the two, and judging whether the ratio meets the threshold requirement.
13. When the resolution of the image is detected, the covering area of each line pair on the image is obtained according to the relative physical position of the module center (namely the image center) and each line pair area and the size of each line pair area, the standard deviation of the gray level in each area is calculated, and whether the standard deviation meets the threshold requirement or not is judged.
When different detection items are detected, corresponding prefabricated plans need to be introduced, after an operator puts a die body and introduces the plans of the detection items into an accelerator system, the accelerator automatically opens or closes the image plate, automatically executes the corresponding plans, and acquires corresponding images or monitors the beam dosage. And calculating whether the result meets a threshold value by using a corresponding algorithm according to the obtained image or the actually measured dose. If the detected items include the use conditions of different modules, the switching among the different modules of the die body is realized through the automatic control movement of the holding plate.
By designing the integrated die body and designing an automatic execution flow, the invention has the following beneficial technical effects:
the invention summarizes and integrates the detection items required by the accelerator, integrates the auxiliary equipment possibly required to be used in the detection process into a single die body, and reduces the time for replacing the auxiliary equipment in the original detection process.
The execution plans of different detection items are built in advance, the whole execution process is completely realized by the automatic execution plan of the accelerator, and the time for artificially controlling the accelerator to move out of the beam originally is reduced.
The switching of each module in the module is realized by planning the movement of the control bed to different positions, and after the whole detection execution process is started, an operator does not need to enter or exit the accelerator chamber any more, so that the execution time is shortened.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the inventive concept of the present invention, and these changes and modifications are all within the scope of the present invention.
Claims (10)
1. An automated QA method for an accelerator system based on a combined die body, wherein the combined die body comprises a tungsten ball center point module, a dose monitoring module and an image analysis module which are integrated into a whole, the method comprises the following steps:
when the tungsten ball central point module is used, the tungsten ball central point module is placed at a theoretical isocenter position, a mechanical part of an accelerator is controlled to move to a specific position through a prefabricated plan led into the accelerator, an image is acquired through an image plate while the accelerator emits a beam, and a corresponding mechanical deviation is calculated through acquiring a field center, a tungsten ball position and a field boundary;
when the dose monitoring module is used, the corresponding prefabricated plan is guided into an accelerator system according to a detection project, the accelerator system automatically realizes the positioning of the dose monitoring module by moving a treatment couch, automatically controls the accelerator to output beams, and monitors the change of the dose rate along with time and the final beam output dose in the beam output process of the accelerator;
the image analysis module comprises Las Vegas holes and line pairs representing different resolutions, when the image analysis module is used, a corresponding prefabricated plan is led into the accelerator system according to a detection item, the accelerator system automatically realizes the positioning of the image analysis module by moving the treatment couch, and then the accelerator is controlled to emit beams and images are acquired through the image plate, so that images comprising the holes or the line pairs are obtained.
2. The method of claim 1, wherein the tungsten ball center point module comprises a tungsten ball mounting seat, a connecting rod embedded with a tungsten ball and a three-dimensional manual fine adjustment sliding table, and the object detected by the tungsten ball center point module comprises at least one of the following objects: the deviation of the mechanical center and the isocenter of the radiation field, the deviation of the rotating center of the frame and the isocenter, the deviation of the rotating center of the treatment bed and the isocenter, the in-place precision of the grating and the in-place repeatability of the grating.
3. The method of claim 2, wherein the pre-plan includes 8 fields when detecting the deviation of the mechanical center from the field isocenter, and the gantry and treatment couch angular positions of each field are different, namely: 60 DEG, treatment bed: 0 DEG, frame: 60 DEG, treatment bed: 338 °, gantry: 130 °, treatment couch: 0 DEG, frame: 130 °, treatment couch: 338 °, gantry: 230 °, treatment couch: 0 DEG, frame: 230 °, treatment couch: 22 degrees, frame: 300 ° treatment couch: 0 DEG, frame: 300 ° treatment couch: 22 degrees;
the method comprises the steps of obtaining a field center and a tungsten ball center on a returned image of an image plate corresponding to each field through a field center obtaining method and a tungsten ball position obtaining method, calculating corresponding deviation, and judging whether a threshold value is met through three-dimensional deviation of a mechanical center and a field isocenter calculated through a Winston Lutz method according to a frame angle, a treatment bed angle and two-center deviation.
4. The method of claim 2, wherein the pre-planning comprises 6 fields when detecting the deviation of the gantry rotation center from the isocenter, and the gantry angular position of each field is different, respectively: 0 °, 45 °, 90 °, 200 °, 245 °, 290 °;
the method comprises the steps of respectively obtaining a field center and a tungsten ball center on a returned image of an image plate corresponding to each field through a field center obtaining method and a tungsten ball position obtaining method, calculating corresponding deviation, and calculating three-dimensional deviation of the deviation between a rotating center and an isocenter of a rack through a Winston Lutz method according to the angle of the rack and the deviation between the two centers so as to judge whether a threshold value is met.
5. The method of claim 2, wherein the pre-plan includes 5 fields when detecting the deviation of the center of rotation of the treatment couch from the isocenter, and the angular position of the treatment couch is different for each field: 0 °, 10 °, 20 °, 350 °, 340 °;
by the method of obtaining the position of the tungsten ball, the center of the tungsten ball on the returned image of the image plate corresponding to each field is respectively obtained, a square area with the center of the image as the center is taken, each pixel in the area is respectively taken as the center point, the distance between the center point and the center of different tungsten balls is calculated, the variance of all 5 distances is calculated, the center point when the variance is calculated is obtained, the maximum value of the distance between the center point and the center of the tungsten ball is taken as the deviation, and whether the deviation meets the threshold value is judged.
6. The method according to claim 2, wherein when calculating the grating positioning accuracy, the pre-plan includes 7 fields, and the grating isocenter position of each field is different, which is: leaf a-70 mm, leaf b-50 mm, leaf a-50 mm, leaf b-30 mm, leaf a-30 mm, leaf b-10 mm, leaf a-10 mm, leaf b-30 mm, leaf a-30 mm, leaf b-50 mm, leaf a-50 mm, leaf b-70 mm;
the method comprises the steps of obtaining left and right or upper and lower boundary positions of a field by a field boundary obtaining method, calculating deviation between a theoretical blade position and the obtained boundary positions, and judging whether the deviation meets a threshold value or not.
7. The method of claim 2, wherein the pre-plan includes 12 fields for calculating the repeatability of the grating in-place, and there are 4 different positions of the isocenter of the grating, which are: leaf a-70 mm, leaf b-50 mm, leaf a-30 mm, leaf b-10 mm, leaf a-10 mm, leaf b-30 mm, leaf a-50 mm, leaf b-70 mm, each position performed 3 times;
the method comprises the steps of obtaining the positions of left and right or upper and lower boundaries of a field by a method of obtaining the field boundary, calculating the standard deviation of the boundary obtained for 3 times of the grating at the same theoretical position, and judging whether the standard deviation meets a threshold value or not.
8. The method of claim 1, wherein the dose monitoring module comprises a stereoscopic water phantom and a dose detector inserted into the center of the stereoscopic water phantom, and the detection items of the dose monitoring module comprise one of dose repeatability and dose linearity.
9. The method of claim 8, wherein in detecting dose repeatability, the pre-plan contains 10 fields, each field is the same, the dose delivered is 10MU, the dose accumulation during delivery is recorded by the dose detector, and the actual final accumulated dose for each field is returned, wherein the dose repeatability is determined by calculating the coefficient of variation: the coefficient of variation is the standard deviation of the measured dose/the mean value of the measured dose 100%;
when the detected dose is linear, the pre-plan contains 25 fields, and there are 5 different outgoing beam doses: 100MU, 300MU, 500MU, 700MU, 900MU, each dose is executed 5 times, the dose accumulation of the beam-out process is recorded by a dose detector, and the actual final accumulated amount of each field is returned, the method for judging the dose repeatability is to calculate the deviation: deviation is 100% ABS (measured dose-theoretical dose)/out beam dose.
10. The method of claim 1, wherein the detection items of the image analysis module include one of detecting image contrast and detecting image resolution;
when the image contrast is detected, acquiring the coverage area of each hole on the image according to the relative physical position and the aperture of the center of the image analysis module and each hole, respectively calculating the gray value average value in the coverage area of each hole, calculating the gray value average value of the coverage area of a square externally connected with each hole, and then judging whether the threshold requirement is met or not by calculating the ratio of the gray value average value to the gray value average value;
when the image resolution is detected, the covering area of each line pair on the image is obtained according to the relative physical position of the center of the image analysis module and each line pair area and the size of each line pair area, and the standard deviation of the gray level in each area is calculated to judge whether the threshold requirement is met.
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