JP2023183289A - Particle beam therapy system, range measurement device, and beam monitoring method - Google Patents

Abstract

To provide a particle beam therapy system, a range measurement device, and a beam monitoring method that can determine the presence/absence of a deviation from a predetermined beam irradiation position with higher accuracy than before.SOLUTION: A range measurement device 80 in a particle beam therapy system executes irradiation control of a particle beam by an accelerator 20, a beam transport system 30, and an irradiation nozzle 40 while checking a signal of a multi-pixel type gamma ray detector 83 at the time of irradiation of each spot 103 set in an affected part 101 with the particle beam.SELECTED DRAWING: Figure 9

Description

The present invention relates to a particle beam therapy system, a range measuring device, and a beam monitoring method that perform treatment by irradiating a charged particle beam accelerated by a particle beam accelerator to a cancerous area.

Patent Document 1 describes an example of a moving object tracking device that can track a tracking object without false detection even when a structure similar to the tracking object is in the vicinity of the tracking object. It is described that gradation processing is performed on the image, the position of the marker is measured using the captured image after the gradation processing, and a signal for controlling radiation irradiation is generated based on the position of the marker.

Non-Patent Document 1 describes that the position at which the particle beam stops in the body is measured from the characteristic count distribution formed on the detector by prompt gamma rays whose direction and position are limited by a slit collimator. There is.

Japanese Patent Application Publication No. 2017-196036

I.Perali, et al., “Prompt gamma imaging of proton pencil beams at clinical dose rate”, Phys.Med.Biol. 59 (2014) 5849-5871.

In particle beam therapy, a charged particle beam is accelerated using an accelerator called a synchrotron, cyclotron, or synchrocyclotron, transported to the treatment room by a beam transport system, and irradiated to the affected area of the patient lying on the bed in the treatment room. , perform cancer treatment.

The charged particle beam is appropriately shaped and irradiated by an irradiation nozzle so that it can irradiate different cancer affected areas depending on the patient. An irradiation method in which a charged particle beam accelerated by an accelerator is directly scanned and irradiated is called scanning irradiation, and it has been recently developed because it can create a dose distribution that concentrates the dose on the affected area compared to conventional irradiation methods. It is becoming the mainstream irradiation method for particle beam therapy.

In scanning irradiation, the affected area is divided into layers, and a Bragg peak point called a spot with the highest dose concentration is placed in each layer. Spots arranged laterally within each layer are illuminated by scanning a narrow beam from an accelerator with a scanning electromagnet. In order to continue irradiation by changing the layers divided in the depth direction, the energy of the accelerator or the thickness of an energy absorber called a range shifter placed in the irradiation nozzle is changed, and the charged particle beam incident on the patient is changed. adjust the energy of

Here, the Bragg peak is defined as the peak of the dose distribution when the energy of the charged particle beam is expressed by the dose distribution in the depth direction. The position of the Bragg peak corresponds to the arrival position of the charged particle beam.

In the above-described scanning irradiation, a plan for uniformly scanning and irradiating the affected area is created in a process called treatment planning before the actual irradiation is performed. In treatment planning, special software called treatment planning software calculates spot positions and the energy of the charged particle beam to irradiate each spot to irradiate only the affected area with a high dose based on the patient's X-ray CT image. .

The charged particle beam is used for therapeutic irradiation based on the results of the treatment plan. At this time, moving body tracking irradiation as described in Patent Document 1 is performed on the affected area that moves during respiration. A marker is embedded near the affected area, the position of the marker is confirmed using an X-ray fluoroscopic image, and a three-dimensional affected area position is calculated from the marker position specified on the two pairs of X-ray fluoroscopic images. By irradiating the charged particle beam only when the three-dimensional position of the affected area is within a predetermined range, it is possible to administer a concentrated dose only to the affected area, even when the affected area moves while breathing. . Furthermore, in recent years, in order to reduce the physical burden on patients who insert markers into their bodies, markerless moving body tracking irradiation that does not involve implanting markers into their bodies has been developed.

A method for determining the Bragg peak point during irradiation with a charged particle beam is to detect the passage of the charged particle beam when the human body is irradiated with the charged particle beam, as described in Non-Patent Document 1. There is a technology that measures gamma rays, called prompt gamma rays, that are generated along their path to accurately determine the depth within the body where the beam stops.

This technology makes it possible to measure the irradiation depth for each spot and compare it with the position planned in the treatment plan, thereby reducing errors caused by uncertainties in the density information of the X-ray CT images used in the treatment plan. You can. In addition, since the particle beam stop position can be predicted with high accuracy, the amount of margin given to the affected area during treatment planning can be reduced, which can be expected to reduce the dose to normal tissue around the affected area.

However, the stopping position of a charged particle beam is determined by the sum of the water equivalent thickness along its path inside the human body, so when it is determined to be at a predetermined position by an X-ray motion tracking device, it is certain that it will reach the affected area. There was no way to confirm that the beam was being irradiated.

In other words, it is known that the actual movement of the patient's organs is slow and deviates from the predetermined position due to respiratory movement, but similarly, the water equivalent thickness on the beam passage path may vary depending on the tissue in front of the affected area. There was a possibility that a deviation in relative positional relationship would occur, resulting in deviation from a predetermined beam irradiation position. However, the method of Non-Patent Document 1 mentioned above does not take this shift into consideration, and there is no means to confirm the shift.

The present invention provides a particle beam therapy system, a range measuring device, and a beam monitoring method that are capable of determining the presence or absence of deviation from a predetermined beam irradiation position with higher precision than in the past.

The present invention includes a plurality of means for solving the above problems, and to give one example, an irradiation device that generates and irradiates a particle beam, a central control unit that controls the irradiation device, and three parts to be tracked. A moving body tracking device that determines a dimensional position and tracks its movement, and a range measuring device that has a detector that measures secondary radiation generated when the particle beam is irradiated by the irradiation device, The apparatus controls the irradiation of the particle beam by the irradiation device while checking the detector signal when each spot set in the target is irradiated with the particle beam.

According to the present invention, it is possible to determine the presence or absence of deviation from a predetermined beam irradiation position with higher precision than in the past. Problems, configurations, and effects other than those described above will be made clear by the description of the following examples.

FIG. 1 is a diagram showing the overall configuration of a particle beam therapy system according to an example. FIG. 3 is a diagram showing affected areas and spots divided into layers by scanning irradiation. FIG. 3 is a diagram showing the configuration of a scanning irradiation nozzle. FIG. 3 is a diagram showing the formation of dose distribution in the depth direction. FIG. 1 is a diagram showing an outline of a moving body tracking device. FIG. 2 is a diagram illustrating the operating principle of a moving body tracking device. It is a figure showing the measurement principle of a range measuring device. It is a figure showing a range measuring device. It is a figure which shows the arrangement|positioning of the range measuring device and count distribution in the particle beam therapy system of an Example. FIG. 3 is a diagram showing the arrangement of a range measuring device during moving body tracking treatment in the particle beam therapy system of the example. It is a figure which shows the moving body tracking control, range measurement control, and control of a particle beam therapy system in the particle beam therapy system of an Example. It is a figure showing the control contents of the range measuring device in the particle beam therapy system of an example. It is a figure showing the flow of moving body tracking treatment in the particle beam therapy system of an example.

Embodiments of the particle beam therapy system, range measuring device, and beam monitoring method of the present invention will be described with reference to FIGS. 1 to 13. In the drawings used in this specification, the same or corresponding components are given the same or similar symbols, and repeated description of these components may be omitted.

First, in order to explain particle beam scanning irradiation, the overall configuration of a particle beam therapy system will be explained using FIG. 1. FIG. 1 is a diagram showing the overall configuration of a particle beam therapy system according to an embodiment.

As shown in FIG. 1, the particle beam therapy apparatus includes an accelerator 20 that generates and irradiates particle beams, a beam transport system 30, an irradiation nozzle 40, a treatment table 50, and the like.

The accelerator 20 is composed of an injector 21 and a synchrotron accelerator 22, but may also be an accelerator such as a cyclotron. It may be a linear accelerator, a cyclotron accelerator, or even a synchrocyclotron accelerator, and is not particularly limited.

The beam transport system 30 and the irradiation nozzle 40 are installed on a pedestal called a rotating gantry that can rotate around the patient, and irradiate the patient 5 lying on the treatment table 50 with the charged particle beam 104 from any direction. It is now possible.

The treatment table 50 is a bed on which the patient 5 is placed. Based on instructions from the overall control device 2, the treatment table 50 can move in the directions of three orthogonal axes, and can further move in the so-called six-axis directions, rotating around each axis. These movements and rotations allow the patient 5 to be moved to a desired position.

The treatment planning device 1 considers the irradiation direction and calculates the spot position, energy, and irradiation amount of the charged particle beam 104 to irradiate the affected area 101 with the prescribed dose determined by the doctor while avoiding important organs that do not want to receive the dose. be done.

Information on the position, energy, and irradiation amount of each spot is sent to the overall control device 2, where treatment is performed. The overall control device 2 sends information on the spot position and irradiation amount to the irradiation nozzle control device 3, and the spot energy information is sent to the accelerator/beam transport system control device 4. The irradiation nozzle control device 3 irradiates each layer, and when the irradiation of the layer is completed, it sends a completion signal to the overall control device 2. The overall control device 2 sends an energy change signal to the accelerator/beam transport system control device 4, and the next A charged particle beam 104 having an energy corresponding to the layer is irradiated.

The overall control device 2 is connected to a treatment planning device 1, an accelerator/beam transport system control device 4, an irradiation nozzle control device 3, a moving object tracking control device 70, a range measuring device 80 (see FIG. 8), and a treatment table 50. and controls the operation of each device.

The accelerator/beam transport system control device 4 controls the operation of each device constituting the accelerator 20 and the beam transport system 30.

The irradiation nozzle control device 3 controls the operation of each device that constitutes the irradiation nozzle 40.

The moving body tracking device determines the position of the marker embedded in the affected area 101, the affected area 101, or the high-density area, determines the three-dimensional position of the tracking target from the position of the determined marker, the affected area 101, or the high-density area, and tracks its movement. The details will be explained later using FIG. The moving object tracking control device 70 is a device that controls the operation of the moving object tracking device.

The treatment planning device 1 implements a treatment plan, creates a prescription, and transfers the created prescription to the overall control device 2.

The overall control device 2, the accelerator/beam transport system control device 4, the irradiation nozzle control device 3, and the treatment planning device 1 each have a central processing unit (CPU) and a memory connected to the CPU.

Note that the control processing of the executed operations may be summarized into one program, each may be divided into a plurality of programs, or even a combination thereof may be used.

A part or all of the programs possessed by each device may be realized by dedicated hardware or may be modularized. Furthermore, various programs may be installed in each device by a program distribution server or an external storage medium, or existing devices may be updated.

Further, each device may be an independent device connected via a wired or wireless network, or two or more devices may be integrated.

FIG. 2 is a diagram showing how the affected area 101 is divided into layers 102 by scanning irradiation and spots 103 are arranged in each layer. The charged particle beam 104 irradiates each spot while moving so as to fill each spot. A high dose portion called a Bragg peak of the charged particle beam 104 corresponds to the spot position, and the spot is irradiated with the highest dose. After irradiating each spot with the irradiation amount determined in the treatment plan, the charged particle beam 104 moves to the next spot and irradiates it. When the spot on the same layer 102 is irradiated, the energy of the charged particle beam 104 is changed by the accelerator/beam transport system to irradiate the spot on the next layer 102.

FIG. 3 is a diagram schematically showing an irradiation nozzle 40 for particle beam scanning. In the irradiation nozzle 40, the charged particle beam 104 is scanned in a two-dimensional plane by horizontal and vertical scanning electromagnets 41A and 41B. The charged particle beam 104 scanned by the scanning electromagnets 41A and 41B is irradiated onto the affected area 101.

The dose monitor 42 measures the dose of the charged particle beam 104 irradiated to each irradiation spot. The dose monitor control device 52 controls the amount of irradiation applied to each irradiation spot. The position monitor 43 measures the beam position (for example, the position of the center of gravity) of each irradiation spot. The position monitor control device 53 calculates the position and width of the irradiation spot based on the beam position data measured by the position monitor 43, and confirms the irradiation position of the charged particle beam 104.

The ridge filter 44 is used when necessary to thicken the Bragg peak. Alternatively, a range shifter 45 may be inserted to adjust the arrival position of the charged particle beam 104. Figure 4 shows the dose distribution in the depth direction. In the depth direction, Bragg curves are superimposed to form a uniform dose distribution.

When the energy of the beam changes, the location where the beam reaches the body changes. The charged particle beam 104 with high energy reaches a deep position inside the body, and the charged particle beam 104 with low energy reaches only a shallow position inside the body.

In particle beam scanning irradiation, the SOBP ( Spread Out Bragg Peak). By appropriately distributing the irradiation amount of each energy, the Bragg curves 61 of each energy are superimposed to form a uniform dose distribution SOBP 62 in the depth direction as shown in FIG. In order to perform treatment with a particle beam therapy device, the position, energy, and irradiation amount of each spot to be irradiated with the beam are determined in advance by the treatment planning device 1 prior to the treatment.

The moving body tracking treatment to which the present invention relates will be explained using FIG. 5. In dynamic body tracking treatment, skeletal landmark points such as the affected area 101, markers inserted into the body, or characteristic epiphyseal points are detected from X-ray fluoroscopic images obtained by two pairs of X-ray tubes 72 and X-ray imager 73. 71 (the above-mentioned high-density region), and calculates and obtains the three-dimensional position of the affected part 101, marker or skeletal landmark point 71 during treatment.

In moving body tracking, the affected area 101, marker or skeletal landmark point 71 is determined by calculating the intersection between the X-ray tube 72 and the position 74 shown in FIG. Calculate the three-dimensional position of point 71.

Beam emission permission for moving object tracking calculation to which the present invention relates will be explained using FIG. 6. Assuming that the position of the affected area 101, marker or skeletal landmark point 71 calculated by calculating the intersection of two pairs of straight lines connecting the X-ray tube 72 and position 74 is found as the three-dimensional position 75 shown in FIG. Irradiation with the charged particle beam 104 is performed only when the three-dimensional position 75 of the affected area 101, marker or skeletal landmark point 71 is within a predetermined irradiation permission range 76. As a result, the charged particle beam 104 is irradiated only when the affected area 101, marker or skeletal landmark point 71 exists at a predetermined position, and the charged particle beam 104 is applied to organs that move due to respiration. Highly accurate irradiation with suppressed positional deviations is achieved.

The permitted irradiation range 76 of the charged particle beam 104 in FIG. 6 may be assumed to be, for example, a cube with sides of 2 mm or 1 mm. The accuracy of determining the position of the marker or landmark point is determined depending on the size of the irradiation permission range 76. Since an X-ray fluoroscopic image is taken approximately 30 times per second, this technique is capable of tracking the respiratory movement of the human body and the affected area 101 almost in real time.

Control of the moving body tracking device will be explained using FIG. 7. The moving body tracking control device 70 performs irradiation with the X-ray tube 72, image acquisition with the X-ray imager 73, and extraction of the position 74 of the affected part 101, marker or skeletal landmark point 71 based on image processing.

In addition, the moving body tracking control device 70 calculates the intersection of the positions 74 of the affected part 101 and the markers or skeletal landmark points 71 found from the two pairs of X-ray fluoroscopic images, and after determining the three-dimensional position 75, as shown in FIG. Determine whether it is within the emission permission range.

As a result of the determination, if the three-dimensional position 75 of the affected area 101, marker or skeletal landmark point 71 is within a predetermined irradiation permission range 76, the moving body tracking control device 70 sends a message to the overall control device 2 of the particle beam therapy system. An emission permission signal is sent that allows the charged particle beam 104 to be irradiated. On the other hand, if the three-dimensional position 75 of the marker or landmark point is outside the predetermined irradiation permission range 76, a signal is sent to the overall control device 2 to disallow the emission of the charged particle beam 104.

The overall control device 2 irradiates the charged particle beam 104 and progresses the treatment only during the period in which it receives a beam emission permission signal from the moving body tracking device.

The measurement principle of the range measuring device to which the present invention relates will be explained with reference to FIG.

The range measuring device 80 checks the distribution of the detector 83 signal when each spot 103 set in the affected area 101 is irradiated with the particle beam, and measures the particle output by the accelerator 20, the beam transport system 30, and the irradiation nozzle 40. This is a device for controlling ray irradiation, and uses gamma rays called prompt gamma rays 81 as secondary radiation generated when the charged particle beam 104 is irradiated to the affected area 101 by the accelerator 20, beam transport system 30, and irradiation nozzle 40. It is composed of a multi-pixel type gamma ray detector 83 that measures gamma rays, and a slit collimator 82 that limits the direction in which gamma rays come to the detector 83.

In FIG. 8, when a charged particle beam 104 enters from the left and stops at an affected area 101 located at the center of the field of view of a detector 83, prompt gamma rays 81 are generated by a nuclear reaction on the path the beam travels. Almost no prompt gamma rays 81 are generated in the area after the charged particle beam 104 stops at the affected area 101. In this way, the prompt gamma rays 81 are generated only from the beam passage path.

By arranging the slit collimator 82 for the prompt gamma rays 81 generated in this manner, the prompt gamma rays 81 generated from the beam passage path go straight through the shaded area 85 in FIG. 8 and enter the detector 83.

The gamma ray detector 83 is composed of a large number of vertically elongated scintillator crystals. Each scintillator is shielded from light, making it possible to measure the count distribution at each position of the scintillator composing the detector 83. Each vertically long scintillator making up the detector 83 is called a channel, and the detector 83 is made up of multiple channels.

Since prompt gamma rays 81 are not generated after the beam stops, the count distribution 84 of gamma rays detected by the detector 83 is higher on the right side, which is opposite to the beam incidence direction, as shown in FIG. 8, and higher on the left side, which is the beam incidence direction. A characteristic count distribution is formed in which the count quantity in the direction is low.

The range measuring device 80 uses the slit collimator 82 to obtain an image of a count distribution that is reversed with respect to the traveling direction of the charged particle beam 104 on the same principle as a pinhole camera.

When the slit collimator 82 is a knife edge type as shown in FIG. 8, it can provide a large field of view, but there is a limit to the improvement in accuracy. On the other hand, when the vertical type is used, the field of view is narrow but the precision can be improved, so the form can be selected as appropriate depending on the measurement system and the like.

The principle when the range measuring device 80 according to the present invention is applied to moving body tracking treatment will be explained using FIG. 9.

In FIG. 9, the affected area 101 moves between positions 101A and 101B due to respiratory movement. Therefore, it is desirable that the detector 83 of the range measuring device 80 be installed so that its field of view covers the movement range of the affected part 101. Further, it is desirable that the range measuring device 80 perform counting monitoring by focusing on a specific channel of the detector 83.

In FIG. 9, the affected area 101 continues to move between positions 101A and 101B in a breathing cycle. This is done only when 101 is located.

When the charged particle beam 104 is irradiated onto the affected area 101 located at the position 101A, the passage path of the prompt gamma rays 81 passes through the shaded area in FIG. 9 due to the action of the slit collimator 82, and in FIG. A count distribution 84A is obtained in which the count in the right end channel region 83A is high. Conversely, when the moving body tracking treatment is progressing without problems, the affected area 101 is always located at the position 101A, so the count distribution of the detector 83 is a count distribution 84A in which the count in the right end channel region 83A is high. can get. When the right end channel region 83A has a count distribution 84A with a high count, the left channel region 83B has a low count and has a count that is the background plus a noise component.

Therefore, if a count distribution such as the count distribution 84B shown by the broken line in FIG. 9 is obtained during the moving body tracking treatment, it can be determined that the stopped position of the charged particle beam 104 is outside the affected area 101.

The arrangement of the range measuring device 80 in the moving body tracking treatment according to the present invention will be explained using FIG. 10. As described in the method of using the range measuring device according to the present invention in FIG. It is necessary that the affected area 101 be located at the time when the radiation is applied.

In FIG. 10, the affected area 101 is located at a position 101A when the left end of the field of view of the detector 83 is irradiated with the charged particle beam 104. It is assumed that the affected part 101 periodically moves in an area from position 101A to position 101B due to respiratory movement. By arranging the detector 83 at the position shown in FIG. 10, the present invention can reliably confirm the irradiated beam position during moving body tracking treatment based on the principle shown in FIG.

Control of a particle beam therapy system in which a range measuring device is combined with moving body tracking therapy according to the present invention will be explained using FIG. 11. As shown in FIG. 11, a range measurement control device 86 that controls the range measurement device 80 is newly added.

The control contents of the range measurement control device 86 will be explained with reference to FIG. FIG. 12 shows the detector 83 shown in FIG. 9 and the count distribution 84 of gamma rays detected by the detector.

In the present invention, the gamma ray count distribution when the moving body tracking treatment is progressing without any problem becomes a count distribution 84A. The count of the channel area 83B on the left side of the detector 83 does not become high when the motion tracking treatment is progressing without any problems, so a counting threshold for judgment is applied to the count of the left channel area 83B. Set the value to 87.

However, when the count of the detector channel in the area shown in the count distribution 84B becomes high during the motion tracking treatment, it is assumed that the charged particle beam 104 penetrating the affected area 101 located at the predetermined position 101A is irradiated with the motion tracking treatment. Determine whether there is an abnormality. When the range measurement control device 86 determines that there is an abnormality, it immediately sends a beam stop command to the overall control device 2 shown in FIG. The overall control device 2 sends a beam stop signal to the particle beam therapy system, thereby interrupting the treatment irradiation.

In this way, the range measurement control device 86 prevents the generation of particle beams by the accelerator 20, the beam transport system 30, and the irradiation nozzle 40 when the signal from a specific channel whose count should not increase exceeds a predetermined threshold. make it stop.

A modification of the control content of the range measurement control device 86 will be described.

The range measurement control device 86 can increase the intensity of the particle beam when it is determined that the irradiation accuracy of the particle beam is high. More specifically, the counting threshold value 87 shown in FIG. When the difference from the count distribution 84B is large, it is assumed that accuracy is ensured and the beam intensity is increased, and when it is small, the absolute value of the count threshold 87 can be increased to perform control to widen the irradiation OFF region.

FIG. 13 shows the flow of the moving body tracking treatment according to the present invention.

A patient enters the treatment room (process 501) and lies down on the treatment table 50, and the patient is positioned on the treatment table at a position determined by the treatment plan (process 502).

Next, in order to investigate the positions 101A and 101B shown in FIG. 10, the movement range of the affected area 101 is calculated using an X-ray fluoroscope that constitutes the moving body tracking device (process 503).

Next, based on the investigated movement range of the affected area 101, the detector 83 is installed so that the position of the affected area 101 where the charged particle beam 104 is turned on is in the left area of the field of view of the detector 83, as shown in FIG. process 504). With the detector 83 arranged, a detector channel where the count becomes high when irradiated with the charged particle beam 104 is identified, and other areas, such as the left channel area 83B shown in FIG. 12, are identified. Detector channels that do not have high counts during the count motion tracking treatment are determined (process 505).

Since the installation of the range measuring device and the pre-irradiation settings are completed through the above process, the moving object tracking treatment is started (process 506).

During the motion tracking treatment, the count of the detector channel determined in process 505 is constantly monitored (process 507), and when the threshold value is exceeded, irradiation of the charged particle beam 104 is immediately interrupted (process 509). If there are no problems, irradiation continues (process 508).

Next, the effects of this embodiment will be explained.

The particle beam therapy system of this embodiment described above includes an accelerator 20 that generates and irradiates particle beams, a beam transport system 30, and an irradiation nozzle 40, and an overall control device 2 that controls the accelerator 20, beam transport system 30, and irradiation nozzle 40. , a moving body tracking device that determines the three-dimensional position of the tracked object and tracks its movement, and a detector 83 that measures the secondary radiation generated when the particle beam is irradiated by the accelerator 20, beam transport system 30, and irradiation nozzle 40. The range measuring device 80 includes a range measuring device 80, which detects the accelerator 20, the beam while checking the detector 83 signal at the time of irradiating the particle beam to each spot 103 set in the affected area 101. Particle beam irradiation control by the transport system 30 and the irradiation nozzle 40 is executed.

Although the three-dimensional position of the affected area 101 can be grasped in the moving body tracking treatment, it is not possible to deal with changes in density due to respiratory movement in front of the affected area 101 through which the charged particle beam 104 passes, causing changes in the beam arrival position. . For example, a moving body tracking device can grasp the three-dimensional position of the affected area 101 as shown in FIG. 9, but if a change in density occurs in front of the affected area 101 due to respiratory movement, the beam may penetrate through the affected area 101. This can occur, for example, in lung treatment. Also, although it depends on the situation, the position of the Bragg peak is the sum of the densities of the internal substances existing on the beam passage path, so if a change in the beam passage path before the affected area 101 occurs due to respiratory movement, , a problem may arise in that it is not known whether a Bragg peak is formed at a predetermined position.

On the other hand, in the present invention, monitoring not only the three-dimensional position of the affected area 101 but also density changes on the beam passage path that affect the arrival position of the charged particle beam 104 is equivalent to monitoring respiratory movement. By becoming more precise, it is possible to contribute to improving the safety of moving body tracking treatment and to more accurately determine whether a Bragg peak is formed at a predetermined position.

In addition, the range measuring device 80 executes particle beam irradiation control by the accelerator 20, beam transport system 30, and irradiation nozzle 40 while checking the distribution of the detector 83 signal, thereby realizing highly accurate detection. be able to.

Furthermore, the detector 83 is installed so that its field of view covers the movement range of the affected area 101. By arranging the field of view of the detector 83 to cover the area of the affected area 101 that moves while breathing in the moving body tracking treatment, the signal distribution formed by the charged particle beam 104 is characteristic when performing the moving body tracking treatment on the affected area 101 that moves while breathing. More specifically, when the motion tracking treatment is progressing without problems, a count distribution with a characteristic that the count amount of a specific detector channel is high is created. It is possible to implement processing such as incorporating a control device into the particle beam therapy system that immediately shuts off the beam when the count becomes high, making it possible to realize safer moving body tracking therapy. Further, since the range measurement control device 86 does not need to perform position calculations, it is possible to speed up the processing.

Further, the range measuring device 80 performs counting monitoring by focusing on a specific channel of the detector 83. In the conventional method of stopping the beam based on the beam depth using a range measurement device, the range measurement control device calculates the beam depth using a method such as fitting based on the count distribution obtained by irradiation with the charged particle beam 104. There was a problem in that it required arithmetic processing, and the processing took a long time. On the other hand, since it is possible to monitor the counts of some channels constituting the detector 83 while eliminating the arithmetic processing for determining the range from the range measuring device 80, the irradiation position of the charged particle beam 104 can be monitored. By making this determination, the configuration and processing of the control device can be simplified. Therefore, it becomes possible to perform processing in real time and at high speed.

Further, the range measurement control device 86 stops the generation of particle beams by the accelerator 20, the beam transport system 30, and the irradiation nozzle 40 when the signal from a specific channel whose count should not increase exceeds a predetermined threshold value. . The detector 83 is often composed of multiple channels (locations within the detector), but when the motion tracking treatment is progressing successfully, a characteristic signal is generated in which the count of a certain channel becomes high. The other channels have a background level signal distribution. Therefore, by monitoring the signal level by focusing on channels that do not normally have a high count, if something abnormal occurs during moving object tracking, or if a density change in the body occurs during moving object tracking treatment, The count of a channel that originally has a low count increases, and in this case, irradiation control is performed to immediately stop the beam, so for moving body tracking treatment that accurately irradiates the charged particle beam 104 to organs that are breathing and moving, By adding a simple control device, the safety of moving body tracking therapy can be further improved.

Moreover, by having the slit collimator 82, the range measuring device 80 can reduce detection of radiation other than secondary radiation generated from the beam passage path, and can further improve counting accuracy. .

Furthermore, when it is determined that the particle beam irradiation accuracy is high, the range measurement control device 86 can increase the intensity of the particle beam to realize highly accurate irradiation in a shorter time.

Moreover, the range measuring device 80 can further improve the feasibility of the detector 83 and the processing system by processing signals based on prompt gamma rays as secondary radiation.

Furthermore, the moving body tracking device determines the position of the marker embedded in the affected area 101, the affected area 101, or the high-density area, and tracks the tracking target from the determined position of the marker, the affected area 101, or the high-density area, thereby achieving more accurate tracking. Irradiation can be achieved while specifying the three-dimensional position of the affected area 101.

<Others>
Note that the present invention is not limited to the above-described embodiments, and various modifications and applications are possible. The embodiments described above are described in detail to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described.

For example, in the embodiment, a range measuring device that detects prompt gamma rays as secondary radiation is taken up, but since the intention of the present invention is to provide means for confirming the irradiation position of the charged particle beam 104 in addition to the fluoroscopic X-ray, For example, the secondary radiation may be ultrasonic waves generated when the charged particle beam 104 is irradiated, or low-energy X-rays generated when the charged particle beam 104 is irradiated. When detecting ultrasonic waves, the range measuring device 80 executes particle beam irradiation control by the accelerator 20, beam transport system 30, and irradiation nozzle 40 while checking the detector signal rather than the distribution of the detector signal. When detecting low-energy X-rays, irradiation control can be performed while checking the distribution of detector signals as in the case of prompt gamma rays.

Embodiments of the present invention may have the following aspects.

(1) An irradiation device that generates and irradiates a particle beam, a central control unit that controls the irradiation device, a moving object tracking device that determines the three-dimensional position of a tracking target and tracks its movement, and the particles produced by the irradiation device. a range measuring device having a detector that measures secondary radiation generated during irradiation of the particle beam; A particle beam therapy system that executes irradiation control of the particle beam by the irradiation device while checking a detector signal.

(2): In the particle beam therapy system described in (1), the range measuring device controls the irradiation of the particle beam by the irradiation device while checking the distribution of the detector signal.

(3): In the particle beam therapy system described in (1) or (2), the detector is installed such that its field of view covers the movement range of the target.

(4): In the particle beam therapy system according to any one of (1) to (3), the range measuring device performs counting monitoring by focusing on a specific channel of the detector.

(5): In the particle beam therapy system described in (4), the range measuring device is configured to detect the particles emitted by the irradiation device when the signal from the specific channel, which should not count too much, exceeds a predetermined threshold. Stop line generation.

(6): In the particle beam therapy system according to any one of (1) to (5), the range measuring device includes a collimator.

(7): In the particle beam therapy system according to any one of (1) to (6), when the range measuring device determines that the irradiation accuracy of the particle beam is high, the range measuring device measures the intensity of the particle beam. strengthen.

(8): In the particle beam therapy system according to any one of (2) to (7), the range measuring device processes a signal based on prompt gamma rays as the secondary radiation.

(9): In the particle beam therapy system according to any one of (1) to (8), the moving body tracking device determines the position of a marker embedded in the target, and performs the tracking from the determined position of the marker. Track your target.

(10): In the particle beam therapy system according to any one of (1) to (9), the moving body tracking device determines the position of the target or high-density region, and The tracked object is tracked from its position.

1: Treatment planning device 2: Overall control device (central control section)
3: Irradiation nozzle control device 4: Accelerator/beam transport system control device 5: Patient 20: Accelerator (irradiation device)
21: Injector 22: Synchrotron accelerator 30: Beam transport system (irradiation device)
40: Irradiation nozzle (irradiation device)
41A, 41B: Scanning electromagnet 42: Dose monitor 43: Position monitor 44: Ridge filter 45: Range shifter 50: Treatment table 51A: Horizontal scanning electromagnet power supply 51B: Vertical scanning electromagnet power supply 52: Dose monitor control device 53: Position monitor control device 54 : Scanning electromagnet power supply control device 61 : Bragg curve 62 : Dose distribution SOBP
70: Moving body tracking control device 71: Affected area, marker or skeletal landmark point 72: X-ray tube 73: X-ray imager 74: Position 75: Three-dimensional position 76: Permitted irradiation range 80: Range measuring device 81: Prompt gamma ray 82: Slit collimator 83: Detector 83A: Right end channel region 83B: Channel regions 84, 84A, 84B: Count distribution detected by the detector 85: Shaded region 86: Range measurement control device 87: Judgment threshold 101 : Affected area (target)
101A, 101B: Position 102: Layer 103: Spot 104: Charged particle beam

Claims (12)

An irradiation device that generates and irradiates particle beams;
a central control unit that controls the irradiation device;
a moving object tracking device that determines the three-dimensional position of a tracked object and tracks its movement;
a range measuring device having a detector that measures secondary radiation generated during irradiation of the particle beam by the irradiation device;
The range measuring device executes irradiation control of the particle beam by the irradiation device while checking a detector signal during irradiation of the particle beam to each spot set in the target. Particle beam therapy system . The particle beam therapy system according to claim 1,
The range measuring device executes irradiation control of the particle beam by the irradiation device while checking the distribution of the detector signal. Particle beam therapy system. The particle beam therapy system according to claim 1,
The detector is installed so that its field of view covers the movement range of the target. Particle beam therapy system. The particle beam therapy system according to claim 1,
The range measuring device performs count monitoring by focusing on a specific channel of the detector. A particle beam therapy system. The particle beam therapy system according to claim 4,
The range measuring device is configured to stop the irradiation device from generating the particle beam when a signal from a specific channel whose count should not increase exceeds a predetermined threshold. The particle beam therapy system according to claim 1,
The range measuring device has a collimator. Particle beam therapy system. The particle beam therapy system according to claim 1,
The range measuring device increases the intensity of the particle beam when it is determined that the irradiation accuracy of the particle beam is high.Particle beam therapy system. The particle beam therapy system according to claim 2,
The range measuring device processes a signal based on prompt gamma rays as the secondary radiation. Particle beam therapy system. The particle beam therapy system according to claim 1,
The moving body tracking device determines the position of a marker embedded in the target, and tracks the tracking target from the determined position of the marker.Particle beam therapy system. The particle beam therapy system according to claim 1,
The moving body tracking device determines the position of the target or the high-density region, and tracks the tracking target from the determined position of the target or the high-density region. It has a detector that measures secondary radiation generated during particle beam irradiation,
A range measuring device that executes irradiation control of the particle beam by an irradiation device while checking a detector signal during irradiation of the particle beam to each spot set in a target. A beam monitoring method for determining the irradiation position of the particle beam by detecting a secondary signal emitted during irradiation with the particle beam, the method comprising:
a particle beam therapy system emits the particle beam;
A beam monitoring method, comprising controlling the irradiation of the particle beam by the particle beam therapy system while checking a detector signal when each spot set in a target is irradiated with the particle beam.

Images