Motion tracking device and radiation irradiation system

Abstract

The present invention provides a motion tracking device and a radiation irradiation system that can suppress changes in dose distribution and decreases in irradiation efficiency due to latency. [Solution] A motion tracking device that determines the position of the tracked object 55 and generates a signal to permit radiation irradiation to the target 50 when it is determined that the tracked object 55 is inside the gate range, wherein the gate range is different at the time when the tracked object 55 enters the gate range from outside to inside and at the time when it exits the gate range from inside to outside.

Description

Technical Field

[0001] The present invention relates to a radiation irradiation system for treating a diseased part such as a tumor by irradiating it with radiation such as a particle beam, and a moving body tracking device suitable for such a radiation irradiation system.

Background Art

[0002] Patent Document 1 discloses an accelerator that generates and emits a charged particle beam, an irradiation device that has a scanning electromagnet for scanning the charged particle beam and irradiates the charged particle beam onto an irradiation target, a target monitoring device that measures the position of the irradiation target, a tracking irradiation that corrects the excitation current value of the scanning electromagnet based on a signal from the target monitoring device and irradiates the charged particle beam onto the irradiation target, and a control device that performs gate irradiation for irradiating the charged particle beam when the irradiation target is within a predetermined emission permission range based on a signal from the target monitoring device. The control device performs tracking irradiation when the position of the irradiation target measured by the target monitoring device is within the emission permission range of the gate irradiation.

[0003] Non-Patent Document 1 describes a workflow of a trial operation and daily and monthly QA procedures at a target center as part of guidelines regarding methods for trial operation and quality assurance of RGPT when tracking implanted fiducial markers using the pulse fluoroscopy method in real-time gated proton beam therapy.

Prior Art Documents

Patent Documents

[0004] <00000​​​​​​​​​​​​HQ Tan et al., “Real-time gated proton therapy with a reduced source to imager distance: Commissioning and quality assurance”, Physica Medica,(2024) 122, 103380. [Overview of the project] [Problems that the invention aims to solve]

[0006] Methods of irradiating patients with cancer and other conditions with radiation such as particle beams and X-rays are known. Particle beams include proton beams and carbon beams. The radiation irradiation system used for irradiation is fixed to a patient bed called a couch and forms a dose distribution suitable for the shape of the target, such as a tumor, within the patient's body.

[0007] As a method for forming dose distributions in radiation irradiation systems, scanning irradiation, which involves scanning a narrow particle beam with an electromagnet to form the dose distribution, is beginning to become widespread.

[0008] When targets such as tumors move due to respiration or other factors, accurate irradiation with particle beams becomes difficult. Therefore, gated irradiation, which irradiates the target only when it is within a predetermined range (gate range), has been realized in recent years. Patent document 1, mentioned above, describes a method called motion tracking irradiation, which performs gated irradiation based on the position of a marker embedded near the affected area.

[0009] On the other hand, Non-Patent Document 1 reports that a time called latency occurs between the measurement of the marker position and the determination of the gate.

[0010] Specifically, when a marker moves outside the gate range, the irradiation permission state may continue due to latency, even though the marker is actually outside the gate range. In this case, particle beams may be irradiated while the marker is outside the gate range, leaving room for improvement in the dose distribution.

[0011] Conversely, when a marker moves from outside the gate range into the gate range, the marker may actually be within the gate range, but the irradiation prohibition state may continue due to latency. In this case, since the particle beam is not irradiated despite the marker being within the gate range, there is room to shorten the irradiation time.

[0012] The object of the present invention is to provide a motion tracking device and a radiation irradiation system that can suppress changes in dose distribution and decreases in irradiation efficiency due to latency compared to conventional methods. [Means for solving the problem]

[0013] The present invention includes multiple means for solving the above problems, but one example is a motion tracking device that determines the position of a target to be tracked and generates a signal to permit radiation irradiation to a target when it is determined that the target to be tracked is inside the irradiation permission range, wherein the irradiation permission range differs at the timing when the target to be tracked enters the irradiation permission range from outside to inside and at the timing when it exits the irradiation permission range from inside to outside. [Effects of the Invention]

[0014] According to the present invention, changes in dose distribution and decreases in irradiation efficiency due to latency can be suppressed compared to conventional methods. Other problems, configurations, and effects will be clarified by the following description of the examples. [Brief explanation of the drawing]

[0015] [Figure 1] This is an overall configuration diagram of the proton beam irradiation system in Example 1. [Figure 2] This is a conceptual diagram showing how a motion tracking and illumination device acquires captured images. [Figure 3] This is a flowchart showing how the motion tracking irradiation device in the proton beam irradiation system of Example 1 determines whether irradiation is possible from the captured image. [Figure 4] This figure shows the display portion of the console used to set the parameters for determining whether or not irradiation is possible in the motion tracking irradiation device of Example 1. [Figure 5] FIG. is a diagram showing an example of a screen that shows the current status displayed on the console during irradiation in the proton beam irradiation system of Example 1. [Figure 6] It is a conceptual diagram explaining the shift of the irradiation position due to the latency by the conventional method. [Figure 7] It is a conceptual diagram explaining the suppression effect of the irradiation position shift by the moving object tracking irradiation device of Example 1. [Figure 8] It is a conceptual diagram explaining the suppression effect of the irradiation position shift by the moving object tracking irradiation device of Example 2.

BEST MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, examples of the moving object tracking device and the radiation irradiation system of the present invention will be described with reference to the drawings.

[0017] In the drawings used in this specification, the same or corresponding components are denoted by the same or similar reference numerals, and repeated explanations of these components may be omitted.

[0018] <Example 1> Example 1 of the moving object tracking device and the radiation irradiation system of the present invention will be described with reference to FIGS. 1 to 7.

[0019] The present invention can be applied to radiation irradiation systems such as X-ray irradiation systems and proton beam irradiation systems. In this example, the proton beam irradiation system will be described as an example with reference to FIG. 1.

[0020] First, the overall configuration of the proton beam irradiation system 1 and the configuration for acquiring a fluoroscopic image will be described with reference to FIGS. 1 and 2. FIG. 1 is an overall configuration diagram of the proton beam irradiation system of Example 1, and FIG. 2 is a conceptual diagram in which the moving object tracking irradiation device acquires an imaging image.

[0021] One embodiment of the present invention, the proton beam irradiation system 1, as shown in Figure 1, comprises a proton beam generator 10, a beam transport system 20, an irradiation nozzle 22, a motion tracking control device 41, a couch 27, and an irradiation control device 40. The proton beam irradiation device (radiation irradiation device) for irradiating a target 50 with a proton beam comprises a proton beam generator 10, a beam transport system 20, and an irradiation nozzle 22.

[0022] The proton beam generator 10 comprises an ion source 12, a linac 13, and a synchrotron 11. The synchrotron 11 comprises a deflection magnet 14, a quadrupole magnet (omitted for illustrative purposes), a high-frequency accelerator 18, a high-frequency emitter 19, and an emitter deflector 17.

[0023] The ion source 12 is connected to the linac 13, which is connected to the synchrotron 11. In the proton beam generator 10, protons generated from the ion source 12 are pre-accelerated by the linac 13 and then injected into the synchrotron 11. The proton beam, further accelerated in the synchrotron 11, is emitted into the beam transport system 20.

[0024] The beam transport system 20 is equipped with multiple deflection magnets 21 and a quadrupole magnet (not shown) and is connected to the synchrotron 11 and the irradiation nozzle 22. In addition, a part of the beam transport system 20 and the irradiation nozzle 22 are installed in a cylindrical gantry 25 and can rotate together with the gantry 25. The proton beam emitted from the synchrotron 11 passes through the beam transport system 20, is focused by the quadrupole magnet, and has its direction changed by the deflection magnets 21 before being incident on the irradiation nozzle 22.

[0025] The irradiation nozzle 22 is equipped with two scanning electromagnets, a dose monitor, and a position monitor. The scanning electromagnets are positioned perpendicular to each other and generate a magnetic field by excitation current, which can deflect the proton beam so that it reaches a desired position in a plane perpendicular to the beam axis at the location of the target 50. The dose monitor measures the amount of irradiated proton beam. The position monitor can detect the position through which the proton beam has passed. The proton beam that has passed through the irradiation nozzle 22 reaches the target 50 within the irradiation target 26. When treating patients with cancer or the like, the irradiation target 26 represents the patient, and the target 50 represents a tumor or the like.

[0026] The bed on which the irradiation target 26 is placed is called the couch 27. Based on instructions from the irradiation control device 40, the couch 27 can move in the direction of three orthogonal axes and can also rotate around each axis. These movements and rotations allow the position of the irradiation target 26, including the target 50, to be moved to a desired position.

[0027] The irradiation control device 40 is a device for controlling the irradiation and stopping of the proton beam based on information transmitted from the motion tracking device (details will be described later), and is electrically connected to the proton beam generator 10, beam transport system 20, irradiation nozzle 22, motion tracking control device 41, couch 27, console 42, etc., in order to control the equipment such as the proton beam generator 10, beam transport system 20, and irradiation nozzle 22.

[0028] The motion tracking device comprises a first X-ray imaging device, a second X-ray imaging device, and a motion tracking control device 41.

[0029] Of the motion tracking devices, the first X-ray imaging device includes an imaging X-ray generator 23A and an X-ray measuring instrument 24A that capture fluoroscopic images including a tracking target 55 (see Figure 2) for tracking the position of a target 50 within the irradiation target 26. The second X-ray imaging device includes an imaging X-ray generator 23B and an X-ray measuring instrument 24B that capture fluoroscopic images including the tracking target 55.

[0030] As shown in Figure 2, the first X-ray imaging device and the second X-ray imaging device are installed so that their respective X-ray paths intersect. It is preferable that the two pairs of imaging X-ray generators 23A, 23B and X-ray measuring instruments 24A, 24B be installed in directions perpendicular to each other, but this is not required. Furthermore, the imaging X-ray generators 23A, 23B and X-ray measuring instruments 24A, 24B do not necessarily have to be located inside the gantry 25; they may be placed in fixed locations such as the ceiling or floor.

[0031] Furthermore, the tracking target 55 is one or more of the following: artificial objects such as gold markers, living tissue within the irradiation target 26 such as bone or diaphragm, or the target 50 itself.

[0032] The motion tracking control device 41 determines the position of the target 55 from the images captured by the imaging X-ray generators 23A and 23B and the X-ray detectors 24A and 24B. When it is determined that the target 55 is inside the gate range (permitted irradiation range), it generates a signal (permitted irradiation signal) that permits the irradiation of the proton beam to the target 50. When it is determined that the target 55 is outside the gate range (permitted irradiation range), it generates a signal (denied irradiation signal) that does not permit the irradiation of the proton beam to the target 50. The generated signals are then transmitted to the irradiation control device 40. Based on the input signals, the irradiation control device 40 performs the irradiation of the proton beam to the target 50.

[0033] Alternatively, the system may output only a signal that permits proton beam irradiation and irradiate only when that signal is input, or it may output only a signal that does not permit proton beam irradiation and not irradiate when that signal is not input.

[0034] More specifically, as shown in Figure 2, the motion tracking control device 41 irradiates the area including the tracking target 55 with X-rays generated from the imaging X-ray generator 23A, and images the tracking target 55 by measuring the two-dimensional dose distribution of the X-rays that have passed through the irradiated object 26, which includes the tracking target 55, using the X-ray measuring instrument 24A. In addition, the tracking target 55 is imaged by irradiating the tracking target 55 with X-rays generated from the imaging X-ray generator 23B, and measuring the two-dimensional dose distribution of the X-rays that have passed through the irradiated object 26 using the X-ray measuring instrument 24B.

[0035] The motion tracking control device 41 calculates the three-dimensional position of the tracking target 55 embedded within the irradiation target 26 from the image acquired by the X-ray measuring instruments 24A and 24B, and determines the position of the tracking target 55 (i.e., the target 50) based on the result.

[0036] The motion tracking control device 41 also determines whether the position of the tracked target 55 is within the gate range. If it determines that the position of the tracked target 55 is within the gate range, it transmits a gate-on signal to the irradiation control device 40 to permit emission. Conversely, if it determines that the position of the tracked target 55 is not within the gate range, it transmits a gate-off signal to deny emission. The irradiation control device 40 controls the emission of the proton beam based on the gate-on and gate-off signals generated by the motion tracking control device 41. This gate range is set by the user considering the irradiation time and irradiation accuracy.

[0037] The acquisition of images using the first and second X-ray imaging devices is performed at regular intervals, for example, 30 Hz, but may be performed at higher or lower frequencies, and is not particularly limited.

[0038] The irradiation control device 40 and the motion tracking control device 41 described above may each have a central processing unit (CPU) and memory connected to this CPU, or they may be configured as a single computer, and are not particularly limited.

[0039] Furthermore, the control processes for the actions to be performed may be combined into a single program, divided into multiple programs, or a combination of these.

[0040] Some or all of the programs contained within each device may be implemented using dedicated hardware, or they may be modularized. Furthermore, various programs may be installed on each device via a program distribution server or external storage media, or existing devices may be updated.

[0041] Furthermore, each device may be an independent device connected by a wired or wireless network, or two or more devices may be integrated into a single unit.

[0042] Next, the method for determining whether irradiation is permitted will be explained in more detail using Figures 3 and 4. Figure 3 is a flowchart showing how the motion tracking irradiation device in the proton beam irradiation system of Example 1 determines whether irradiation is permitted from the captured image, and Figure 4 shows the display portion of the console used when setting the parameters used to determine whether irradiation is permitted in the motion tracking irradiation device of Example 1.

[0043] In this embodiment, the motion tracking control device 41 is configured with a planned position and two types of gate widths prior to the start of irradiation. Specifically, the gate range differs depending on whether the tracked object 55 is moving from outside the gate range to inside or from inside to outside. In this embodiment, the gate range is specifically set to differ depending on whether the tracked object 55 is determined to be approaching the irradiation plan position or to be moving away from the irradiation plan position. More specifically, the gate range when it is determined to be approaching is wider than the gate range when it is determined to be moving away.

[0044] The gate range is defined as a spherical area centered on the planned position with a radius equal to the gate width. The gate width is defined for both the approach phase and the departure phase. The approach phase refers to the phase in which the tracked object 55 approaches the planned position and includes the timing when the tracked object 55 moves from outside the gate range to inside. Conversely, the departure phase refers to the phase in which the tracked object 55 moves away from the planned position and includes the timing when the tracked object 55 moves from inside the gate range to outside.

[0045] Figure 3 illustrates the parameter setting screen 60 displayed on the console 42. As shown in Figure 3, the setting screen 60 displays an approach phase gate width input field 62 for entering the approach phase gate width, and an exit phase gate width input field 64 for entering the exit phase gate width. The settings are configured by the user entering predetermined values ​​into these fields. However, it is desirable to reject the setting if the values ​​entered in the approach phase gate width input field 62 and the exit phase gate width input field 64 are the same, and to reject the setting if the value entered in the approach phase gate width input field 62 is smaller than the value entered in the exit phase gate width input field 64.

[0046] Furthermore, the gate area does not need to be spherical. For example, it is possible to define the gate area as a cubic region where the distance from the planned position in three perpendicular directions is within the gate width.

[0047] Figure 4 is a flowchart for determining whether irradiation is permissible. When the determination of whether irradiation is permissible is started in step S101, a fluoroscopic image is acquired in step S102 and the position of the tracking target 55 is measured.

[0048] In step S103, the phase is determined based on the measured position of the tracking target 55. Specifically, by comparing it with the position of the tracking target 55 on the perspective image measured just before, if the tracking target 55 is approaching the planned position, it is determined to be the approach phase, and if the tracking target 55 is moving away from the planned position, it is determined to be the departure phase.

[0049] In step S104, the gate range is set based on the determined phase. In step S105, it is determined whether the target 55 is inside or outside the gate range. If it is inside the gate range, irradiation is permitted; if it is outside the gate range, irradiation is prohibited, and the irradiation permission decision is completed in step S106.

[0050] Here, the determination of the position of the tracked object 55 can be performed by including the position of the tracked object 55 at one or more previous determination timings, including the one immediately preceding it. Specifically, the position of the tracked object 55 evaluated in step S105 may be the average of multiple measured values ​​measured immediately before.

[0051] Since measurement errors are inevitably included in the measured values, if the movement of the tracked object 55 fluctuates only slightly, the phase may change frequently due to fluctuations in the measured values ​​caused by measurement errors. Therefore, by determining the average of multiple immediately preceding measurements as the measured value, these fluctuations can be suppressed.

[0052] Furthermore, the motion tracking control device 41 can output signals to the console 42 that display a graph of time on one axis and a graph of the gate range and the position of the tracked object 55 on the other axis.

[0053] Figure 5 illustrates a gate determination screen 70 that shows the current status displayed on the console 42 during irradiation. As shown in Figure 5, the gate determination screen 70 on the console 42 displays the current status, an image display area 72 that shows the current measured position of the tracking target 55, an image display area 74 that shows a translucent image 1 showing the planned position, a result display area 76 that shows the gate determination result, and irradiation determination result display areas 77 and 78 that show the current irradiation feasibility status, all of which are updated in real time.

[0054] Next, the effects obtained by this embodiment will be explained using Figures 6 and 7. Figure 6 is a conceptual diagram illustrating the shift in irradiation position due to latency in the conventional method, and Figure 7 is a conceptual diagram illustrating the effect of suppressing the shift in irradiation position by the motion tracking device of Embodiment 1.

[0055] First, Figure 6 will be used to explain the conventional method of tracking and irradiating a moving object. The horizontal axis in Figure 6 represents time, and Figure 6(A) represents the distance between the planned position and the tracking target 55, or the position of the tracking target 55 relative to the planned position in the direction of a certain axis. In Figure 6(A), the solid line represents the real-time position of the tracking target 55, the dots represent the position of the tracking target 55 recognized by the motion tracking control device 41, and the dashed line represents the gate range. As can be seen in Figure 6(A), the dots are delayed by the latency time. This latency value is determined by the calculation time from image acquisition to gate determination, and is therefore a value specific to the equipment. Figure 6(B) shows the state of the gate signal, where a low value means irradiation is prohibited, and a high value means irradiation is permitted.

[0056] In conventional methods, the gate width is constant regardless of the approach phase and departure phase. In the area indicated by the black arrow in Figure 6(A), the target object 55 is actually outside the gate range, but the gate signal may still indicate an illumination permit state.

[0057] Next, the motion tracking irradiation in this embodiment will be explained using Figure 7. The horizontal axis in Figure 7 represents time. The vertical axis in Figure 7(A) is R, which represents the distance between the planned position and the tracking target 55, or the position of the tracking target 55 relative to the planned position in the direction of a certain axis. The solid line represents the real-time position of the tracking target 55, the dots represent the position of the tracking target 55 recognized by the motion tracking control device 41, and the dashed line represents the gate range. Figure 7(B) shows the state of the gate signal, where a low value means irradiation is prohibited and a high value means irradiation is permitted. Figure 7(C) shows the change in R ΔR from the previous perspective image. Figure 7(D) shows the state of the phase, where a high value means the approach phase and a low value means the departure phase.

[0058] As shown in Figure 7, a negative change in the amount of change ΔR indicates an approach phase, while a positive change indicates an exit phase. In Figure 7, the gate width in the approach phase is the same as the value in Figure 6, but the gate width in the exit phase is set smaller than the value in Figure 6. By setting a smaller gate width in the exit phase, the time at which the gate signal prohibits irradiation is brought forward. This shortens the time during which the target 55 is outside the gate range in Figure 6 and is in an irradiation-permitted state. Similarly, by setting the gate width in the approach phase to be larger than the value in Figure 6, the time at which the gate signal permits irradiation is brought forward, making it possible to improve irradiation efficiency. In other words, according to the present invention, changes in dose distribution and decreases in irradiation efficiency due to latency can be suppressed compared to conventional methods.

[0059] Furthermore, the gate range differs depending on whether the target 55 is determined to be approaching the irradiation plan position or moving away from the irradiation plan position. In particular, the gate range when the target is determined to be approaching is wider than the gate range when the target is determined to be moving away. This allows for setting a more appropriate gate range according to the movement of the target 50, thereby achieving greater effects in shortening irradiation time and improving accuracy.

[0060] Furthermore, by determining the position of the tracking target 55 by including the position of the tracking target 55 at one or more previous determination timings, including the immediate preceding one, the influence of fluctuations in measured values ​​due to measurement errors can be further reduced, enabling more accurate determination of whether or not to fire.

[0061] Furthermore, by outputting a signal where one axis represents time and the other axis displays a graph of the gate range and the position of the tracked object 55, the user can easily grasp the current situation visually.

[0062] Furthermore, by providing imaging X-ray generators 23A, 23B and X-ray measuring instruments 24A, 24B for imaging the tracking target 55, and a motion tracking control device 41 that determines the position of the tracking target 55 from the images captured by the imaging X-ray generators 23A, 23B and X-ray measuring instruments 24A, 24B, it is possible to handle cases where the tracking target 55 or target 50 is located within the irradiation target 26.

[0063] <Example 2> The motion tracking device and radiation irradiation system of Embodiment 2 of the present invention will be described with reference to Figure 8. Figure 8 is a conceptual diagram illustrating the effect of suppressing irradiation position deviation by the motion tracking irradiation device of Embodiment 2.

[0064] The difference between the motion tracking irradiation device and radiation irradiation system of this embodiment and that of Embodiment 1 lies in the method of determining the phase.

[0065] In this embodiment, the gate range differs depending on whether the target of tracking 55 was inside the gate range and irradiation was permitted at a determination timing one or more prior to the immediately preceding tracking determination timing, or whether the target of tracking 55 was outside the gate range and irradiation was not permitted. Specifically, the gate range when irradiation was permitted is narrower than the gate range when the target of tracking 55 was outside the gate range and irradiation was not permitted.

[0066] In terms of the difference in processing flow, in step S103 shown in Figure 4, the phase is determined based on the position of the tracking target 55, i.e., the position of the target 50, at a determination timing one or more prior to the immediately preceding tracking determination timing, including the previous tracking determination timing.

[0067] Specifically, if the gate signal at the time of determination is in a state of irradiation prohibition, it is determined to be in an approach phase; if the gate signal at the time of determination is in a state of irradiation permission, it is determined to be in a close phase.

[0068] Furthermore, in this embodiment, if the difference in gate width between the approach phase and the departure phase is large, the determination of whether irradiation is permissible may change again immediately after the determination of whether irradiation is permissible has changed.

[0069] To avoid this, after the determination of whether irradiation is permissible or not changes, the irradiation permission / denial can be kept fixed for a predetermined time or for a predetermined number of tracking timing periods for the target 55 being tracked.

[0070] Specifically, it is possible to set a grace period after a change in the irradiation feasibility determination, and to control the system so that the phase does not change during this grace period. The grace period can be set by time or by the number of measurements taken at the location of the tracked object 55.

[0071] The motion tracking irradiation in this embodiment will be explained using Figure 8. The horizontal axis in Figure 8 represents time. The vertical axis in Figure 8(A) is R, which represents the distance between the planned position and the target 55, or the position of the target 55 relative to the planned position in the direction of a certain axis. The solid line represents the real-time position of the target 55, and the dots represent the position of the target 55 recognized by the motion tracking control device 41. The dashed line represents the gate range. Figure 8(B) shows the state of the gate signal, where a low value means irradiation is prohibited, and a high value means irradiation is permitted.

[0072] In this embodiment, if the gate signal at the time of determination is in the irradiation prohibition state, it is set to the approach phase, and if the gate signal at the time of determination is in the irradiation permission state, it is set to the departure phase. Therefore, in the example in Figure 8, the gate signal becomes in the irradiation permission state for the first time at the left phase x1, and thereafter it becomes the departure phase and determination is made using a narrow gate width.

[0073] Next, at phase x2 on the right, it is determined that the target 55 is outside the gate range, and thereafter it enters the close phase and is determined using a wider gate width. This shortens the time during which the target 55 is outside the gate range in Figure 8 and is in a state where irradiation is permitted.

[0074] The other configurations and operations are substantially the same as those of the motion tracking device and radiation irradiation system in Example 1 described above, and details are omitted.

[0075] As in the motion tracking device and radiation irradiation system of Embodiment 2 of the present invention, even if the gate range differs depending on whether the tracking target 55 is inside the gate range and irradiation is permitted at a determination timing one or more prior to the immediately preceding tracking determination timing, including the gate range when the tracking target 55 is outside the gate range and irradiation is not permitted, it is possible to suppress changes in dose distribution and a decrease in irradiation efficiency due to latency, similar to the motion tracking device and radiation irradiation system of Embodiment 1 described above.

[0076] Furthermore, because the gate range when irradiation is permitted is narrower than the gate range when the target 55 is outside the gate range and irradiation is not permitted, it becomes possible to set a more appropriate gate range according to the movement of the target 50, thereby achieving greater effects in shortening irradiation time and improving accuracy.

[0077] Furthermore, by calculating the difference between the gate range when irradiation is permitted and the gate range when irradiation is not permitted, and if the difference is greater than or equal to a predetermined value, the irradiation permission / denial status is kept fixed for a predetermined time or a predetermined number of tracking timing times for the target 55, it is possible to prevent the judgment result from fluctuating between the approach phase and the departure phase, and to prevent the switching between irradiation permission and denial from being abrupt and unstable.

[0078] <Other> It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications. The embodiments described above are explained in detail for the purpose of clearly illustrating the present invention, and are not necessarily limited to those having all the configurations described.

[0079] Furthermore, it is possible to replace parts of the configuration of one embodiment with parts of the configuration of another embodiment, and it is also possible to add parts of the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with parts of other configurations.

[0080] For example, in the above embodiment, we described a case where two X-ray imaging devices are used to image the target, but it is not necessarily required to use two X-ray imaging devices. For example, by moving one X-ray imaging device, images of the target 55 can be acquired from two different directions. Furthermore, it is also possible to use ultrasound or MRI instead of X-ray imaging devices for imaging.

[0081] Furthermore, although the above embodiments described a proton beam irradiation system as an example, the radiation irradiation system of the present invention can be similarly applied to systems that irradiate with particle beams other than proton beams, such as carbon beams, as well as X-rays, electron beams, etc. For example, when using X-rays, the radiation irradiation apparatus consists of an X-ray generator, a beam transport system, and an irradiation nozzle.

[0082] Furthermore, in the case of a particle beam irradiation system, the particle beam generator may be a cyclotron, a synchrocyclotron, or even another type of accelerator, in addition to the synchrotron 11 described in the above embodiment. [Explanation of Symbols]

[0083] 1…Proton beam irradiation system (radiation irradiation system) 10…Proton beam generator 11... Synchrotron 12…Ion source 13...Lynack 14...Bending electromagnet 17...Dejector for ejection 18…High-frequency accelerator 19…High-frequency injection device 20... Beam transport system 21...Bending electromagnet 22... Irradiation nozzle 23A, 23B…X-ray generator for imaging (imaging device) 24A, 24B…X-ray measuring instrument (imaging device) 25…Gantry 26…Target of irradiation 27... Couch 40... Irradiation control device 41…Motion tracking control device 42… Console 50…Target 55...Target 60... Settings screen 62...Approach Phase Gate Width Input Field 64... Departure phase gate width input field 70...Gate judgment screen 72, 74… Image display area 76…Result display field 77,78…Irradiation judgment result display field

Claims

1. A motion tracking device that determines the position of a target and generates a signal to permit radiation irradiation to the target when it is determined that the target is within the permitted irradiation range, The irradiation permit range differs depending on when the tracking target enters the irradiation permit range from outside to inside and when it exits the irradiation permit range from inside to outside. Motion tracking device.

2. In the motion tracking device according to claim 1, The permitted irradiation range differs depending on whether the tracking target is determined to be approaching the irradiation plan position or has moved away from the irradiation plan position. Motion tracking device.

3. In the motion tracking device according to claim 2, The permitted irradiation range when it is determined to be approaching is wider than the permitted irradiation range when it is determined to be moving away. Motion tracking device.

4. In the motion tracking device according to claim 2, The determination of the tracking target's position is performed including the position of the tracking target at one or more previous determination timings, including the one immediately preceding it. Motion tracking device.

5. In the motion tracking device according to claim 1, If, at one or more prior determination timings including the immediately preceding tracking determination timing, the irradiation permit range differs depending on whether the tracking target was inside the irradiation permit range and irradiation was permitted, or if the tracking target was outside the irradiation permit range and irradiation was not permitted. Motion tracking device.

6. In the motion tracking device according to claim 5, The permitted irradiation range when irradiation is permitted is narrower than the permitted irradiation range when irradiation is not permitted. Motion tracking device.

7. In the motion tracking device according to claim 5, After the determination of whether irradiation is permitted or not changes, the irradiation permission / denial will remain fixed for a predetermined period of time or a predetermined number of tracking timing periods for the subject being tracked. Motion tracking device.

8. In the motion tracking device according to claim 5, The determination of the tracking target's position is performed including the position of the tracking target at one or more previous determination timings, including the one immediately preceding it. Motion tracking device.

9. In the motion tracking device according to claim 1, One axis represents time, and the other axis outputs a signal that displays a graph of the permitted irradiation range and the position of the target being tracked. Motion tracking device.

10. In the motion tracking device according to claim 1, An imaging device for capturing images of the target being tracked, The system includes a control device that determines the position of the target to be tracked from the captured image taken by the imaging device. Motion tracking device.

11. A radiation irradiation device for irradiating a target with radiation, This radiation irradiation device controls the irradiation control device, A motion tracking device according to any one of claims 1 to 10, comprising: The motion tracking device transmits the signal to the irradiation control device, The irradiation control device controls the irradiation and stopping of the radiation based on the transmitted information. Radiation irradiation system.

Images