JP2018134282A - Qa method and system of radiotherapy apparatus and diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for achieving position confirmation of patient positioning laser beams in a short time.SOLUTION: Patient positioning laser beams 20 compose a square detector by arranging two photo diodes 22A and 22B of a rectangular equilateral triangle alternately, and combining them. The laser beams are irradiated in a fan shape in a certain angle range on a plane. The posture of the patient and the position of a couch are corrected so that a marker line coincides with a position error Δy from the center and the position of the laser beams with an angle error θ.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a radiation irradiation system, a diagnostic apparatus, and a quality assurance method for performing treatment by irradiating an affected area such as a tumor with radiation such as charged particles or X-rays.

  A method for irradiating a patient with radiation such as charged particles or X-rays for the treatment of cancer or the like is known. Charged particles include proton beams and carbon beams. The radiation irradiation system used for this irradiation forms a dose distribution suitable for the shape of a target such as a tumor in the body of a patient fixed on a patient bed called a couch.

During treatment, a patient is roughly positioned using a patient positioning laser installed in a treatment room, and then X-ray images and CT images are taken and positioned precisely. After positioning is completed, therapeutic radiation is applied.
A radiotherapy device is used for treatment after confirming its soundness by a quality assurance test of a device called QA (Quality Assurance). Non-Patent Document 1 shows QA guidelines, in which it is recommended that the confirmation of the patient positioning laser position be performed daily. Non-Patent Document 2 shows a QA method of MD Anderson Cancer Center, and confirmation of a patient positioning laser position is carried out every day.

: Task Group 142 report: Quality assurance of medical acceleratorsa : Bijan Arjomandy, “An overview of the comprehensive proton therapy machine quality assurance procedures implemented at The University of Texas M. D. Anderson Cancer Center Proton Therapy Center-Houston”, Medical Physics 36, 2269 (2009)

  In Non-Patent Document 1, there is no particular designation as to the method for confirming the patient positioning laser position. Therefore, a method of providing a mark such as a marking line on a measuring instrument installed at a reference position and visually confirming the position of the patient positioning laser using a ruler or the like is conceivable. However, when such a method is taken, there is a problem that confirmation takes time as the number of patient positioning lasers increases. In addition, there is a problem that measurement results may vary for each measurer.

  An object of the present invention is to provide a method for realizing position confirmation of a patient positioning laser in a short time.

  In order to achieve the above object, a measuring instrument for measuring a laser used for patient positioning, wherein a detector configured by combining two triangular photodetectors is installed.

  According to the present invention, it is possible to shorten the time required for confirming the position of the patient positioning laser.

1 is an overall configuration diagram of a radiotherapy system in a first embodiment. It is a conceptual diagram explaining the detection principle of the laser position by a detector. It is a block diagram of the laser position measuring device 30 in a 1st Example. FIG. 3 is a conceptual diagram showing a connection between a detector 21 and a control device 35. FIG. 3 is a conceptual diagram showing a method for installing a laser position measuring device 30. It is a block diagram of the laser position measuring device 30 in a 2nd Example. It is a whole block diagram of the radiotherapy system in a 3rd Example. It is an inspection flow by a laser position measuring instrument.

  Embodiments of the present invention will be described with reference to the drawings.

  Hereinafter, a first embodiment of the present invention will be described.

  The present invention can be applied to radiation irradiation systems such as an X-ray irradiation system and a particle beam irradiation system, and radiation diagnostic systems such as an X-ray CT system and an MRI system. Particle beams include proton beams and carbon beams.

  An embodiment of the present embodiment will be described with reference to FIG.

  The radiation therapy system of this embodiment includes a therapeutic radiation generator 10, a therapeutic radiation irradiation nozzle 11, an X-ray generator 12, an X-ray receiver 13, a gantry 14, a couch 15, a patient positioning laser oscillator 16, and a controller. 17 and console 18. The control device 17 is connected to the therapeutic radiation generating device 10, the therapeutic radiation irradiation nozzle 11, the X-ray generating device 12, the X-ray image receiving device 13, the gantry 14, the couch 15, and the console 18, and controls these devices. The operator operates the radiotherapy system by operating the console 18. The patient positioning laser 20 is irradiated toward the isocenter as a linear laser from the patient positioning laser oscillator 16 installed in the wall or ceiling of the treatment room or in the gantry 14. The isocenter is a coordinate in space corresponding to the intersection of the central axis of the rotating gantry 14 and the axis of the beam irradiated from the therapeutic radiation irradiation nozzle 11 rotating with the gantry 14, for example.

  The operation of each device will be described according to the procedure during treatment. First, the patient 19 is fixed to the couch 15 using a fixing tool (not shown). Subsequently, coarse positioning is performed using a patient positioning laser 20 (hereinafter referred to as a laser). At that time, the posture of the patient 19 and the position of the couch 15 are corrected in advance so that the marker line written on the body surface of the patient 19 and the fixture and the position of the laser 20 match. Thereafter, precise positioning using the X-ray generator 12 and the X-ray image receiver 13 is performed. After the positioning is completed, the gantry 14 is rotated to the treatment angle, and then the patient 19 is irradiated with the therapeutic radiation planned in advance using the therapeutic radiation generator 10 and the therapeutic radiation irradiation nozzle 11.

  A radiotherapy apparatus is used for treatment after confirming its soundness by a quality assurance test of an apparatus called QA (Quality Assurance). The QA of the radiotherapy system needs to be performed not only when the device is first made, but also periodically with a check menu that varies depending on the frequency, such as once a week every day. Especially, QA performed every morning has a high time load. .

  This embodiment is a method for measuring and confirming the position of the laser 20 in QA and a test apparatus. The principle of laser position detection will be described. As shown in FIG. 2, two square-shaped isosceles photodiodes 22 are alternately arranged to form a square detector 21. The laser 20 is irradiated in a fan shape in a certain angular range on the plane. Assume that a horizontal laser 20 having a position error Δy from the center and an angle error θ is incident on the detector 21. When the width of the detector 21 is w, the line lengths l1 and l2 of the laser 20 irradiated to the photodiodes 22A and 22B are respectively

It is expressed. Assuming that the outputs L1 and L2 of each photodiode 22 are proportional to l1 and l2, and that the position dependence of the laser intensity can be ignored.

And the left side is proportional to Δy. When w is constant, it is possible to measure the change in the laser position by measuring the outputs L1 and L2. When actually measuring the laser position, the position error Δy of the laser 20 is determined based on the equation (3) using the proportional coefficient C and the reference position error Δy0 determined in advance based on actual measurement.

  Although FIG. 2 shows the case where the vertical position of the laser 20 is measured, the horizontal position can also be measured with the same measuring instrument. Further, in FIG. 2, the square detector 21 is configured by two right-angled isosceles triangular photodiodes 22, but even if the rectangular detector 21 is configured by using two triangular photodiodes 22, the laser 20 It is possible to measure the position.

  Next, a laser position measuring device 30 using this detector 21 will be described. As shown in FIG. 3, detectors 21 are installed on three surfaces of a rectangular parallelepiped measuring instrument 30. The detector 21 is installed at the center of the surface of the measuring instrument 30. In addition, at the intersection of a straight line connecting the detectors 21A and 21C installed on the opposite side of the measuring instrument 30 and a straight line extending from the detector 21B installed on any other surface in the direction perpendicular to the surface, the height is high. A density marker 31 is placed. The marker 31 needs to be dense enough to be visually recognized in an X-ray image taken using the X-ray generator 12 and the X-ray image receiver 13. Specifically, a metal sphere or a cylindrical marker 31 can be used. The laser position measuring instrument 30 is fixed to the couch 15 using a fixing jig 32. The fixing jig 32 fixes the laser position measuring device 30 by the measuring device fixing unit 33 and fixes the position with respect to the couch 15 by the couch setting unit 34. In FIG. 3, when the patient 19 lies on his back on the couch 15, the detectors 21 are installed on the left and right surfaces and the front surface as viewed from the patient. That is, when any two opposing surfaces of the measuring device 30 are installed so as to face the longitudinal direction of the couch 15, the detectors 21 are installed on both side surfaces parallel to the long side of the couch 15 and the upper surface far from the couch. ing. However, depending on the arrangement of the laser oscillator 16 and the configuration of the laser position measuring device 30, it is possible to install the detector 21 on a different surface.

  As shown in FIG. 4, the detector 21 is connected to a control device 35, and the control device 35 is connected to a console 36. When measuring the position of the laser 20, the detector 21 transmits outputs L 1 and L 2 to the control device 35. The control device 35 calculates the change in the position of the laser 20 with respect to the reference position based on the equation (3). An allowable range is set in advance for the amount of deviation from the reference position, and a warning is displayed on the console 36 if the allowable range is exceeded.

  Next, a laser position measurement method will be described with reference to FIG.

  First, the laser position measuring device 30 is fixed to the couch 15 using the fixing jig 32 (S101). Next, the couch 15 is moved to a predetermined position (S102). FIG. 5 is a diagram in the case where the laser position measuring device 30 is placed at an approximately correct position with respect to the laser 20. The laser 20 is irradiated in a fan shape in a certain angular range on two planes perpendicular to each other. Since three laser oscillators 16 are provided so as to face the three surfaces on which the detectors 21 of the laser position measuring device 30 are installed, a cross is formed so that two linear laser traces intersect the three surfaces. The line of light appears. The predetermined position for moving the couch is set when the reference position of the laser 20 is set, and as long as the position of the laser 20 is not greatly shifted, as shown in FIG. The center of the detector 21 approximately coincides with the intersection of the lines. Subsequently, the position of the laser 20 is measured (S103). The position is measured by turning on only the laser 20 to be measured. At that time, by turning off the illumination in the treatment room, light other than the laser 20 incident on the detector 21 can be reduced, so that the measurement position accuracy is improved. The position of all the lasers 20 is measured by repeatedly measuring the laser position, turning off the laser 20, and turning on the next laser 20 to be measured. By the above method, the fluctuation of the relative position between the couch 15 and the laser 20 can be measured.

  Next, the position of the marker 31 on the X-ray image is measured using the X-ray generator 12 and the X-ray image receiver 13 (S104). Then, the couch 15 is moved so that the position of the marker 31 coincides with the center of the X-ray image (S105). In this state, each laser position is measured again (S106). The measurement method is the same as when the laser position with respect to the couch 15 is measured. By the above method, the fluctuation of the center of the X-ray image and the laser relative position can be measured.

  Although the case where the relative position between the center of the X-ray image and the laser 20 is measured after measuring the relative position between the couch 15 and the laser 20 has been described above, the relative position between the center of the X-ray image and the laser 20 is measured first. May be. Further, only the position with respect to the couch 15 or only the position with respect to the center of the X-ray image may be measured.

  In addition, by irradiating the laser 20 to two perpendicular planes, a cross light line appears on each surface of the laser position measuring device 30, but this causes a positional error in two directions, not only left and right. Can also be detected.

  A second embodiment of the present invention will be described. The same components as those in FIGS. 1 to 5 are denoted by the same reference numerals, and description thereof is omitted. The same applies to the following embodiments.

  The difference between the second embodiment of the present invention and the first embodiment lies in the installation method of the detector 21 with respect to the laser position measuring device 30.

  FIG. 6 shows the configuration of the laser position measuring instrument 30 of this embodiment. There may be a case where the detector 21 cannot be installed at a point where the laser 20 irradiated to two perpendicular planes intersects, for example, because a therapeutic radiation detector (not shown) is installed in the laser position measuring device 30. . In that case, as shown in FIG. 6, it is possible to measure each position by using two sets of detectors 21 for the lasers 20 in the horizontal direction and the vertical direction. At this time, by measuring one laser 20 with the two detectors 21, not only the position error of the laser 20 but also the angle error can be measured. For example, the detector 21 is installed at a position on one surface of the laser position measuring device 30 that is centered in one direction and far from the center in the other direction, specifically, a position that is substantially in contact with the side of the measuring device 30. As a result, the accuracy of inclination detection can be improved.

  A third embodiment of the present invention will be described. The feature of the present embodiment resides in a control device that executes laser position measurement in a certain procedure in the radiotherapy system.

FIG. 7 shows the configuration of the radiation therapy system of this embodiment. In addition to the configuration of the first embodiment, a laser oscillator 16, treatment room illumination, and a control device 35 are connected to the control device 17.
Next, a method for measuring the laser position will be described. The description of the same part as that in FIG. 8 is omitted.

  First, the laser position measuring device 30 is fixed to the couch 15 using the fixing jig 32. Next, the couch 15 is moved to a predetermined position. In order to start measuring the position of the laser 20, the operator presses a laser position measurement start button (not shown) on the console 36. The control device 17 turns off the illumination of the treatment room and turns on the laser 20 to be measured first. After the measurement of the laser position, the measurement result is transmitted to the control device 35, and the determination result of the positional deviation amount is displayed on the console 36. Subsequently, the first laser 20 is turned off and the second laser 20 is turned on. Thereafter, the positions of all the lasers 20 are sequentially measured according to a predetermined order.

Next, the position of the marker 31 on the X-ray image is measured using the X-ray generator 12 and the X-ray image receiver 13, and the couch 15 is moved so that the position of the marker 31 coincides with the center of the X-ray image. The In this state, the position of each laser 20 is automatically measured. The measurement method is the same as when the laser position with respect to the couch 15 is measured. After all laser positions have been measured, the treatment room lights are turned on.
The laser 20 may be switched on / off by turning on / off the power source, or may be switched by opening / closing a shutter installed in front of the light source of the laser 20.

  In addition, this invention is not limited to said Example, Various modifications are included. The above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Moreover, it is also possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  For example, in the above-described embodiment, the method for measuring the laser position with respect to the center of the X-ray image taken using the X-ray imaging apparatus has been described. However, the present invention can also be applied to a cone beam CT that images by rotating the X-ray imaging apparatus and a CT imaging apparatus that is separately installed in the treatment room.

  Furthermore, although the proton beam irradiation system was demonstrated to the example in the above-mentioned Example, the radiation irradiation system of this invention is with respect to the system which irradiates particle beams other than proton beams, such as a carbon beam, X-rays, an electron beam. Can be applied similarly. For example, when X-rays are used, the radiation irradiation apparatus includes an X-ray generation apparatus, a beam transport system, and an irradiation nozzle.

10: therapeutic radiation generator 11: therapeutic radiation irradiation nozzle 12: X-ray generator 13: X-ray image receiver 14: gantry 15: couch 16: patient positioning laser oscillator 17: controller 18: console 19: patient 20 : Patient positioning laser 21: Detector 22: Photodiode 30: Laser position measuring instrument 31: Marker 32: Fixing jig 33: Measuring instrument fixing part 34: Couch setting part 35: Control device 36: Console 37: Illumination

Claims (10)

A measuring instrument for measuring a laser used for patient positioning,
A measuring instrument comprising a detector configured by combining two triangular photodetectors. The measuring instrument according to claim 1,
The measuring instrument is a rectangular parallelepiped,
A measuring instrument, wherein a plurality of detectors configured in combination are installed on different surfaces. The measuring instrument according to claim 1, wherein
A measuring instrument comprising a fixing jig for fixing the measuring instrument to a couch. It is a measuring instrument of Claim 1 thru | or 3, Comprising:
Measuring instrument characterized by having a marker visible in an X-ray image It is a measuring instrument of Claims 1 thru | or 4, Comprising:
A control device for processing the detection result of the detector;
The control device outputs a warning when the measured position of the laser deviates from a predetermined allowable value. Fixing the laser position measuring instrument to the couch using a fixing jig;
Moving the couch to a predetermined position;
Irradiating a laser in a fan-shaped manner to a certain angular range on a plane toward the laser position measuring instrument;
Measuring the position of the laser with the measuring instrument;
Measuring the position of the marker of the measuring instrument using an X-ray imaging device;
And a step of moving the couch so that the position of the marker coincides with the center of the X-ray image. Using the measuring instrument according to claim 1 to 5,
A method for confirming a position of the laser, comprising measuring a relative position of the laser with respect to a center of a patient positioning X-ray image. A radiation generator for generating radiation;
A radiation irradiating nozzle for irradiating the target with the radiation;
An X-ray imaging device for imaging the object;
A couch that supports the subject;
A laser oscillator for irradiating the target positioning laser;
A control device that moves the couch based on a measurement result of the laser position confirmation measuring instrument installed on the couch and a measurement result of the marker included in the measuring instrument by the X-ray imaging device. Radiation therapy system. The radiotherapy system according to claim 8,
A plurality of the patient positioning laser oscillators are provided,
The control device includes (1) turning on the laser to be measured, (2) measuring the position of the laser with the laser position confirmation measuring instrument, (3) turning off the laser, and the procedures of (1) to (3) The position of each of the plurality of lasers is measured by repeating for each of the plurality of laser oscillators. The radiotherapy system according to claim 8,
The laser oscillator irradiates a laser so as to form a cross on the outer surface of the measuring instrument for laser position confirmation,
When the previous marker is installed in the vicinity of the irradiation line of the radiation irradiation nozzle, the photodetector provided on the outer surface of the laser position confirmation measuring instrument is installed on the intersection of the laser crosses. Characterized radiotherapy system.

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