CN111773563A

CN111773563A - Medical electron linear accelerator quality control system based on camera

Info

Publication number: CN111773563A
Application number: CN202010726888.2A
Authority: CN
Inventors: 梁月强; 李洪升; 陈进琥; 马长升; 李宝生
Original assignee: Zhangjiagang Medical Instrument Co ltd
Current assignee: Zhangjiagang Medical Instrument Co ltd
Priority date: 2020-07-26
Filing date: 2020-07-26
Publication date: 2020-10-16

Abstract

The invention discloses a quality control system of a medical electronic linear accelerator based on a camera, which consists of the camera, a quality control die body, computing resources and quality control software running on the computing resources. The quality control module body contains fluorescent substances to replace the film, and the fluorescent substances can be repeatedly exposed and used, so that the workload caused by film replacement is avoided. The camera can replace eyes of people, and can establish a coordinate system according to a binocular vision principle to finish distance measurement, so that the automation level of related quality control is greatly improved.

Description

Medical electron linear accelerator quality control system based on camera

And controlling the quality of the medical electron linear accelerator.

Background

The medical electron linear accelerator is the most mainstream radiotherapy equipment at present. Quality control of the accelerator is particularly important to ensure accurate delivery of radiation therapy. In 11 months in 2019, the national cancer center/national tumor quality control center issued "quality control guidelines for medical electronic linear accelerators" to provide guidance for the standardized quality control of accelerators, wherein the quality control of mechanical properties relates to laser lamps, range rulers, crosshairs, light fields, radiation fields and the like. The quality control adopts a manual measurement and analysis method, so that the workload is high, and accidental errors are difficult to avoid. Thus, some tools for quality control automation have been developed. For example, the onboard EPID is used for field-related quality control, but the onboard EPID cannot perform quality control work outside the field such as an optical range rod, a laser lamp and the like.

Disclosure of Invention

The invention discloses a medical electronic linear accelerator quality control system based on a camera, which can replace human eyes and can establish a coordinate system according to a binocular vision principle to complete distance measurement, thereby greatly reducing the workload of related quality control.

The invention discloses a quality control system of a medical electronic linear accelerator based on a camera, which is characterized by comprising the camera, a quality control die body, computing resources and quality control software running on the computing resources.

The camera is used to capture images during the execution of the detection scheme, and may be a video camera (the camera and the video camera are not conceptually distinguished here). The camera can be fixed in the treatment room and does not rotate along with the accelerator frame. The camera may be mounted on the accelerator frame, rotating with the frame. The camera can be installed on the small head of the accelerator, and rotates along with the small head when rotating along with the random frame. The small handpiece refers to the part of the accelerator handpiece that rotates with the collimator. The camera shoots towards a quality control die body placed near the isocenter.

The quality control mold body comprises a semitransparent thin plate. The quality control mold body contains fluorescent substances. The fluorescent substance generates visible light upon irradiation with accelerator rays, and the generated visible light disappears upon completion of the irradiation. The fluorescent substance may be a translucent plastic scintillator, a scintillator crystal, a fluorescent paint, or the like. When the field quality control is performed, the accelerator emission ray hits on the fluorescent substance, and the camera shoots the shape of the fluorescent substance exposed by the ray. The fluorescent substance acts like a film at this time, but since the irradiation is completed, the fluorescent substance stops emitting light, and thus the exposure can be repeated. Avoiding the workload brought by changing the film.

The computing resource may be a computer, a mobile phone, or a cloud-side distributed computing resource.

And the quality control software controls the camera to shoot images in the execution process of the detection scheme through the control interface. And the quality control software generates a detection result by analyzing the image shot by the camera in the execution process of the detection scheme. And the quality control software gives an alarm to the detection result which does not meet the requirement. And the quality control software stores the shot original image, the analysis data and the detection result. And the quality control software controls the accelerator to execute a specified detection scheme through the control interface. The control interface comprises the control of the treatment bed, the on-off control of the square, the on-off control of the field, the on-off control of the single laser lamp and the on-off control of the light of the treatment room besides the normal accelerator control. The console is not controlled by a light square, a light field, a single laser lamp and a light switch of a treatment room, and the control can be realized by connecting a controlled normally closed relay in the loop of the light-emitting element in series.

Description of the drawings:

FIG. 1 schematic diagram of example 1

FIG. 2A control mold body according to embodiment 1

FIG. 3 schematic diagram of example 2

FIG. 4 is a schematic view of example 3

The specific embodiment is as follows:

example 1

Fig. 1 illustrates one embodiment of the present invention. In the embodiment, only one camera (101) shoots towards the quality control die body (102); 103 is a medical electron linear accelerator; 104 is a treatment couch; the camera is fixed on the ceiling of the accelerator room; the quality control mold body is placed on the treatment bed. The quality control phantom in this embodiment is comprised of three panels (see fig. 2), each having markers at four corners to provide known distance information to the analysis software. Wherein 201 is a horizontal bottom plate, which is made of water equivalent material and is marked with horizontal scale marks; 202 is a vertical transverse plate, the center of which is marked with a cross mark line; 203 is a vertical longitudinal plate, and vertical scale marks are marked on the vertical longitudinal plate; the vertical transverse plates and the vertical longitudinal plates are both semitransparent plastic plates with the thickness of 0.2 mm. 204 are three vertical support bars fixed to the horizontal base plate for fixing the vertical transverse plate and the vertical longitudinal plate. When the positioning accuracy of the laser lamp is detected, the quality control software controls the treatment bed to move through the control interface to enable the isocenter to be located near a scale line of a horizontal bottom plate of the quality control die body (a cross vertical line of a light field and the laser line in the Y-axis direction of the treatment bed are intersected with the scale line), the quality control software controls the accelerator to open the light field through the control interface, the laser lamp is turned off, and the quality control software controls the camera to shoot a first picture of a bottom plate of the quality control die body through the camera control interface; closing the light field, turning on the laser lamp, and controlling the camera to shoot a second quality control die body bottom plate picture by the quality control software through the camera control interface; the quality control software controls the treatment bed to move a certain distance along the Y-axis direction of the bed through the control interface, so that the light field cross vertical line and the laser line in the Y-axis direction of the treatment bed are still intersected with the scale line, the light field is turned on, the laser lamp is turned off, and a third quality control die body bottom plate picture is shot; closing the light field, turning on a laser lamp, and taking a fourth picture of the bottom plate of the quality control die body; the quality control software analyzes the four bottom plate pictures by combining with the scale marks, and automatically identifies and calculates the distance between the first light field cross vertical line and the laser line in the Y-axis direction of the second treatment bed and the distance between the third light field cross vertical line and the laser line in the Y-axis direction of the fourth treatment bed respectively; and finally, automatically analyzing the two distance differences to evaluate the parallelism between the light field cross vertical line and the laser line in the Y-axis direction of the treatment bed.

Example 2

Fig. 3 illustrates one embodiment of the present invention. In the embodiment, the two cameras (301) are fixed on the ceiling of the accelerator room and shoot towards the quality control die body. The quality control phantom in this example is the same as that in example 1. According to the binocular vision principle, two cameras are calibrated to a fixed reference system. When the motion precision of the bed is detected, the quality control software controls the frame and the collimator to rotate to 0 degree through the control interface, the quality control software controls the treatment bed to ascend and descend through the control interface until the scale marks on the horizontal bottom plate of the die body are located on an isocentric plane (namely, coordinate values of a certain scale point on the scale marks of the horizontal bottom plate in a fixed reference system are calculated in real time through binocular vision of two cameras, the ascending and descending of the bed are controlled in a feedback mode, the z coordinate value of the fixed reference system of the scale marks of the horizontal bottom plate is 0), and then the quality control software controls the treatment bed to enter the bed by 20cm, 40cm, 60cm and 70cm, move the bed by 10cm and 20cm left and right and move the bed by 20cm through. Meanwhile, the binocular vision of the two cameras calculates the moving distance of the corresponding scale points on the scale lines of the horizontal bottom plate under the fixed reference system in real time as the moving actual value, and compares the deviation between the actual value and the specified value.

Example 3

Fig. 4 illustrates an embodiment of the present invention. In this embodiment there are two cameras (401), both fixed to the accelerator frame, shooting towards the isocenter, rotating together with the frame. The quality control phantom in this example was identical in structure to that in example 1 except that the vertical transverse plates and the vertical longitudinal plates were each a thin translucent plastic scintillator plate having a thickness of 0.2 mm. According to the binocular vision principle, the two cameras are calibrated to a frame coordinate system. When the rack rotation concentricity monthly inspection is carried out, the quality control software enables the rack and the collimator to rotate to 0 degree through the control interface, the quality control software controls the treatment bed to move through the control interface until the cross center on the vertical transverse plate of the die body is positioned at the position of a rack coordinate system (0, 0, 0), the rack is rotated to 90 degrees, 180 degrees and 270 degrees, meanwhile, the coordinate values of the cross center on the angle vertical transverse plate under the rack coordinate system are respectively calculated through binocular vision of the two cameras, and then the deviation between the four coordinate values and the average value of the four coordinate values is calculated. When the rack rotation concentricity annual inspection is carried out, the quality control software enables the rack and the collimator to rotate to 0 degree through the control interface, the X-direction collimator is set to be the minimum width of the central position, the Y-direction collimator is 30 cm in width, rays are emitted at rack angles of 0 degree, 60 degrees, 120 degrees, 150 degrees, 210 degrees and 270 degrees respectively, meanwhile, the quality control software controls the camera to shoot fluorescence images on the angle vertical transverse plate through the control interface, and the radius of a long axis inscribed circle of each fluorescence area is analyzed and calculated.

The camera in this embodiment is located on the body of the frame, and the camera may be located in virtually any convenient location on the frame for taking a photograph, for example, the camera may also be located on a cross arm connecting the body and the head, facing the isocenter for taking a photograph.

Example 4

In the embodiment, two cameras are arranged on the small head of the accelerator, and rotate along with the small head while rotating along with the random frame. More specifically, the camera is mounted on the tray adapter; when the device is used, the tray adapter is inserted into a tray on a small handpiece of the accelerator, and the two cameras shoot towards the isocenter direction. According to the binocular vision principle, the two cameras are calibrated to the beam limiter coordinate system. The quality control mold body in this example was identical in structure to that in example 1 except that the vertical transverse plate and the vertical longitudinal plate were both translucent plastic scintillator sheets having a thickness of 0.2mm, and the upper surface of the horizontal base plate was attached with a fluorescent paint. When the rotating concentricity of the collimator is detected, the quality control software enables the rack and the collimator to rotate to 0 degree through the control interface, the X-direction collimator is set to be the minimum width of the central position, the Y-direction collimator is 30 cm wide, then the collimator is controlled to rotate, the rays are emitted at the collimator angles of 300 degrees, 330 degrees, 0 degrees, 30 degrees, 60 degrees and 90 degrees respectively, meanwhile, the quality control software controls the camera to shoot the fluorescence images on the angle horizontal bottom plate respectively through the control interface, and the radius of a circle inscribed in the long axis of each fluorescence area is analyzed and calculated.

Because the two cameras are calibrated to the beam limiter coordinate system according to the binocular vision principle, the two cameras can replace the function of the front pointer. When the indicating accuracy of the optical moment ruler is detected, the quality control software controls the rack and the collimator to rotate to 0 degree through the control interface, the quality control software controls the treatment bed to ascend and descend through the control interface until a scale mark on a horizontal bottom plate of the mold body is located on an isocentric plane (namely, coordinate values of a certain scale point on the scale mark of the horizontal bottom plate in a beam limiter coordinate system are calculated in real time through binocular vision of two cameras, the bed is controlled to ascend and descend in a feedback mode, the z coordinate value of the beam limiter coordinate system of the scale mark of the horizontal bottom plate is 0, then the quality control software opens the optical field and the optical moment ruler through the control interface, controls the cameras to shoot images on the horizontal bottom plate, automatically extracts intersection points of cross lines of the optical field on the images and the optical moment ruler, obtains the reading of the optical moment ruler, and records the deviation of the reading of the optical. The quality control software controls the therapeutic bed to ascend and descend through the control interface until the scale marks on the horizontal bottom plate of the die body are located 20cm above and below the isocenter plane respectively, and the process is repeated.

The camera in the embodiment is arranged on the tray adapter and is convenient to take down when not in use; in fact, the camera can be positioned at any position on the small machine head convenient for shooting and can also be fixedly arranged on the small machine head.

Claims

1. The invention discloses a quality control system of a medical electronic linear accelerator based on a camera, which is characterized by comprising the camera, a quality control die body, computing resources and quality control software running on the computing resources.

2. The system of claim 1, wherein the control module comprises a translucent sheet.

3. The system of claim 1, wherein the control module comprises a fluorescent material.

4. The camera-based quality control system for the medical electronic linear accelerator as claimed in claim 1, wherein the camera is fixed in the treatment room and does not rotate with the accelerator frame.

5. The system of claim 1, wherein the camera is mounted on the accelerator frame and rotates with the frame.

6. The system of claim 1, wherein the camera is mounted on a small head of the accelerator, and rotates with the small head while rotating with the gantry.

7. The system of claim 1, wherein the control software controls the accelerator to execute a specific detection scheme via the control interface.

8. The system of claim 1, wherein the quality control software controls the camera to capture images during execution of the detection scheme via the control interface.

9. The system of claim 1, wherein the quality control software is configured to generate the testing results by analyzing images captured by the camera during execution of the testing protocol.