WO2017179091A1

WO2017179091A1 - Particle beam therapy system

Info

Publication number: WO2017179091A1
Application number: PCT/JP2016/061678
Authority: WO
Inventors: 裕介坂本; 奈津子大塚; 卓紀角尾
Original assignee: 三菱電機株式会社
Priority date: 2016-04-11
Filing date: 2016-04-11
Publication date: 2017-10-19
Also published as: JP6582128B2; TW201735966A; JPWO2017179091A1; TWI635884B

Abstract

A particle beam therapy system which includes: a particle beam generation device (30) that generates a particle beam with which an affected part of a patient to be irradiated is irradiated; and an x-ray imaging device (50) that emits an X-ray to the subject being irradiated and captures an X-ray image. This particle beam therapy system has a therapy beam emittable period during which the particle beam can be emitted to the subject being irradiated, and a therapy beam non-emittable period during which the particle beam cannot be emitted to the subject being irradiated. The x-ray imaging device (50) uses a first frame rate for the imaging frame rate of the X-ray image of the subject being irradiated in an X-ray imaging period which is a period that includes at least a part of the therapy beam emittable period, and uses, in periods other than the X-ray imaging period, an imaging frame rate that is lower than the first frame rate.

Description

Particle beam therapy system

The present invention relates to a particle beam therapy system using image guidance based on an X-ray image.

In radiation therapy, image-guided radiation therapy (IGRT: Image Guided Radiation) is used to accurately irradiate the affected area with radiation for treatment while confirming the position of the affected area with an image such as an X-ray image. Therapy) has been proposed (for example, Patent Document 1). When using X-ray images in IGRT, the patient will be exposed to X-rays for image acquisition in addition to therapeutic radiation. It is desirable that this exposure be as low as possible.

In image-guided radiation therapy in which therapeutic radiation is irradiated while confirming an organ position using an X-ray imaging apparatus, the frequency of imaging with imaging X-rays, particularly in the case of an irradiation target in a range that moves due to patient respiration, such as the lungs and liver It is possible to grasp the organ position in real time the higher, the trade-off is that the exposure dose also increases.

Among the radiation treatments, particle beam therapy for irradiating the affected organs with a beam of carbon ions or protons, that is, a particle beam, has recently attracted attention. In particle beam therapy, particle accelerators are used to generate particle beams that are bundles of high energy charged particles. Many of these accelerators have a configuration in which the irradiated particle beam cannot be continuously generated.

JP 2013-252420 A

As described above, when an IGRT using an X-ray image includes a region including a moving part due to patient respiration, it is desired to grasp an organ position in real time while reducing the X-ray exposure as much as possible. .

An object of the present invention is to reduce the exposure dose by X-ray imaging without impairing the accuracy of organ position determination by X-ray imaging in the particle beam therapy system.

The particle beam therapy system of the present invention includes a particle beam generator that generates a particle beam that irradiates an affected area of a patient who is an irradiation object, an irradiation nozzle that irradiates the irradiation object with a particle beam generated by the particle beam generator, Analyzing an X-ray image captured by an X-ray imaging device, an apparatus control device that controls a particle beam generation device and an irradiation nozzle, an X-ray imaging device that irradiates an irradiation target with X-rays to capture an X-ray image And an X-ray image analysis organ position estimation device for estimating the position of an organ having an affected part of a patient, and the device control apparatus has preset the position of the organ estimated by the X-ray image analysis organ position estimation device In a particle beam therapy system that controls a particle beam generator and an irradiation nozzle to irradiate a target with a particle beam when in a range position, the particle beam therapy system emits a particle beam to the target The X-ray imaging apparatus has a period including at least a part of the therapeutic beam extraction possible period. The imaging frame rate of the X-ray image to be irradiated is set as the first frame rate during the imaging period, and the imaging frame rate is reduced below the first frame rate during the period other than the X-ray imaging period.

According to the present invention, it is possible to provide a particle beam therapy system that can reduce the exposure dose by X-ray imaging without impairing the accuracy of organ position grasping by X-ray imaging.

It is a block diagram which shows the structure of the particle beam therapy system by Embodiment 1 of this invention. It is a time chart which shows an example of operation | movement of the particle beam therapy system by Embodiment 1 of this invention. It is a time chart which shows the other example of operation | movement of the particle beam therapy system by Embodiment 1 of this invention. It is a time chart which shows an example of operation | movement of the particle beam therapy system by Embodiment 2 of this invention. It is a block diagram which shows the structure of the particle beam therapy system by Embodiment 3 of this invention. It is a time chart which shows an example of operation | movement of the particle beam therapy system by Embodiment 3 of this invention. It is a time chart which shows the other example of operation | movement of the particle beam therapy system by Embodiment 3 of this invention. It is a time chart which shows the further another example of operation | movement of the particle beam therapy system by Embodiment 3 of this invention. It is a time chart which shows an example of operation | movement of the particle beam therapy system by Embodiment 4 of this invention. It is a block diagram which shows an example of the computer structure of the particle beam therapy system by each embodiment of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram conceptually showing the structure of an example of a particle beam therapy system according to Embodiment 1 of the present invention. A particle beam 2 emitted as a high-energy charged particle beam from an accelerator 1 that accelerates charged particles passes through a vacuum duct 3 that is a particle beam transport path and is transported to an irradiation nozzle 4 provided downstream of the vacuum duct 3. Is done. Here, a bending electromagnet for changing the traveling direction of the particle beam 2 is provided at a portion where the vacuum duct 3 is bent, but is omitted in FIG. The particle beam 2 is scanned in a two-dimensional direction perpendicular to the traveling direction of the particle beam 2 by a scanning electromagnet provided in the irradiation nozzle 4. The scanned particle beam 2a is irradiated to the affected part 60 of the patient 6 as an irradiation target placed on the treatment table. Various irradiation parameters at the time of irradiation are set by the treatment planning device 10, and parameters of each device of the accelerator 1 and the irradiation nozzle 4 for irradiation with the irradiation parameters are transmitted to the device control device 21. A command is output to each device such as the irradiation nozzle 4.

On the other hand, in order to acquire an X-ray image and confirm the movement of the affected part 60 of the patient 6 to be irradiated, X-rays constituted by

X-ray tubes

51a and 51b and flat panel detectors (FPD) 52a and 52b. An imaging device 50 is installed. X-rays emitted from the X-ray tube 51a are detected by the FPD 52a, and X-rays emitted from the X-ray tube 51b are detected by the FPD 52b. The

X-ray tubes

51a and 51b and the

FPDs

52a and 52b are controlled by the X-ray imaging control / image information acquisition device 22 to acquire X-ray image information.

A method for treating an affected area such as a tumor by irradiating the affected area 60 of the patient 6 with a particle beam as a therapeutic radiation by the above particle beam therapy system will be briefly described. First, in the treatment planning device 10, the irradiation dose to be irradiated to the affected part 60 is determined. The irradiation dose is determined as a three-dimensional distribution matched to the shape of the affected part 60, that is, an irradiation dose distribution. When the irradiation dose distribution is determined, the treatment planning apparatus 10 can determine irradiation parameters that are a set of various parameters of the accelerator 1 and the irradiation nozzle 4 for giving the irradiation dose distribution to the affected part 60. However, the set of irradiation parameters cannot be uniquely determined by the intensity of the particle beam or the beam diameter. For this reason, an irradiation parameter that a user such as a doctor considers appropriate is determined.

In the case of particle beam therapy, the particle beam irradiation to the affected area 60 is performed once a day and in several tens of times. On the day of irradiation, for example, a preset patient isocenter in the image of the affected part 60 of the patient 6 acquired by the X-ray imaging control / image information acquisition device 22 is the isocenter of the device determined by the irradiation nozzle 4. The position of the patient on the treatment table is positioned by controlling the position of the treatment table. When positioning is completed, each device is controlled via the device control device 21 according to predetermined parameters of the accelerator 1 and the irradiation nozzle 4, and the affected part 60 is irradiated with the particle beam. At this time, the image analysis / organ position estimation device 23 analyzes the X-ray image acquired by the X-ray imaging control / image information acquisition device 22 in real time, and the position of the affected part 60 falls within a predetermined range. The device controller 21 is instructed to irradiate the particle beam only at certain times. Here, the specific range generally refers to the position of the organ having the affected part 60 in the respiratory phase at which, for example, the moving speed of the affected part 60 becomes small at the time of planning a treatment (doctor, radiologist or medical physicist ). When the irradiation dose scheduled for the day is irradiated to the affected part 60, the irradiation of the day is completed.

Among the irradiation methods that irradiate the particle beam, in the scanning irradiation method, it is necessary to change the energy of the particles multiple times during one irradiation of the patient. When the accelerator 1 is a synchrotron, the particle beam accumulated in the ring of the synchrotron is decelerated and discarded, a new particle beam is generated again by the ion source, and accelerated to the next energy, and the synchrotron There is a method to adjust the particle beam accumulated in the ring of the ring as it is to the next energy, but in the former case, the latter accelerates and decelerates until the next acceleration is completed. Until the adjustment is completed, the particle beam cannot be emitted to the affected part 60 of the patient 6 to be irradiated.

When the accelerator 1 is a cyclotron, energy is not changed by the accelerator 1, and an energy absorber called a degrader is inserted in the particle beam transport path or in the irradiation nozzle, and the energy is adjusted by adjusting the thickness of the degrader. do. Also in this case, the particle beam cannot be emitted to the affected part 60 of the patient 6 to be irradiated while the degrader is operating. Thus, in the particle beam therapy system including the accelerator, the particle beam transport path, and the irradiation nozzle, the particle beam cannot be emitted for a period during which the particle beam can be emitted to the affected part 60 of the patient 6 to be irradiated for some reason. There is often a period. In this text, for the sake of convenience, the time when the particle beam therapy system is in a period in which the particle beam can be emitted from the irradiation target is referred to as being in a state where the treatment beam can be emitted. In addition, a period during which the particle beam can be emitted from the irradiation target is referred to as a treatment beam extraction enabled period, and a period during which the particle beam cannot be output is referred to as a treatment beam extraction disabled period.

FIG. 2 shows an example of a time chart of treatment beam irradiation in IGRT irradiation by the particle beam treatment system of the present invention. As described above, the particle beam therapy system has a period during which the particle beam can be emitted (treatment beam extraction is possible on, treatment beam emission is possible period) and a period during which the particle beam is not available (treatment beam emission is off, treatment beam emission is not possible period). Exists. At this time, the X-ray imaging period is synchronized with the treatment beam extraction period, and X-ray imaging is performed only during the treatment beam extraction period. Strictly speaking, one X-ray imaging is instantaneous, and the imaging is repeated at a preset frame rate (imaging frequency), for example, 7.5 to 30 fps (frame per second). Although it should be written in pulses, in FIG. 2, a period in which X-ray imaging is performed at a preset frame rate is expressed as an X-ray imaging on period (X-ray imaging period).

The X-ray imaging control / image information acquisition device 22 acquires an X-ray image at a preset frame rate during X-ray imaging on, analyzes the acquired image by the image analysis / organ position estimation device 23, and The current position of the organ having the affected part 60 is estimated. When the current position of the organ is within a predetermined irradiation range (organ position signal on), a treatment beam irradiation signal is sent to the device control apparatus 21. The device controller 21 controls devices such as the accelerator 1 and the irradiation nozzle 4 so that the affected part 60 is irradiated with the particle beam only when the irradiation signal is received.

In the above, X-ray imaging is performed only when the treatment beam extraction is enabled, and the frame rate is set to 0 so that X-ray imaging is not performed during other periods. However, if X-ray imaging is not performed for a certain period of time, depending on the organ, the image analysis / organ position estimation device 23 may lose sight of the organ position. In such a case, as shown in FIG. 3, during the X-ray imaging off period, the frame rate is lowered and the imaging frequency is lowered than the frame rate (also referred to as the first frame rate) of the X-ray imaging period. X-ray imaging is preferably performed.

As described above, since the imaging frame rate of X-ray imaging is reduced in the period during which treatment beam extraction is not possible (including the case where the frame rate is 0, that is, when imaging is not performed) than the period during which treatment beam extraction is possible, Compared with the case of X-ray imaging at a frame rate, the patient exposure dose by X-rays can be reduced, and the organ position is always confirmed by X-ray imaging during a period when the treatment beam can be emitted. Therefore, it is possible to irradiate the treatment beam with high positional accuracy.

Embodiment 2. FIG.
FIG. 4 is an example of a time chart of treatment beam irradiation of the particle beam therapy system according to the second embodiment. In reality, the X-ray image analysis / organ position estimation apparatus 23 estimates the organ position and determines whether or not the treatment beam can be irradiated until it is actually started or stopped. There is a delay. In the second embodiment, in consideration of this time delay, the start time and end time of the X-ray imaging period are set earlier than the start time and end time of the treatment beam extraction possible period.

By setting the start time of the X-ray imaging period earlier, in the case where the organ is already within the irradiation range at the start of the treatment beam extraction period, the treatment beam can be irradiated from the beginning of the treatment beam extraction period. It becomes possible. Moreover, useless X-ray irradiation can be reduced by setting the end time of the X-ray imaging period earlier.

Embodiment 3 FIG.
FIG. 5 is a block diagram showing the configuration of the particle beam therapy system according to the third embodiment of the present invention. In the third embodiment, in addition to the configuration of the particle beam therapy system in the first embodiment, a body surface position detector 53 that detects the body surface position of the patient 6 without using X-rays is provided. The body surface position detector 53 can acquire position information on the body surface of the abdomen of the patient 6 in real time by means such as an infrared sensor.

FIG. 6 shows a time chart of treatment beam irradiation in the third embodiment. In the third embodiment, when the position of the body surface is within a specific range determined in advance, it is expressed as body surface position on, and this period is set as an X-ray imaging period, and X-ray imaging is performed only during this period. Is done. Alternatively, X-ray imaging may be performed at a predetermined first frame rate during the X-ray imaging period, and X-ray imaging may be performed at a frame rate lower than the first frame rate during a period other than the X-ray imaging period. Good. As in the first embodiment, the image analysis / organ position estimation device 23 analyzes the captured X-ray image and estimates the current position of the organ having the affected part 60. When the current position of the organ is within a predetermined irradiation range, a treatment beam irradiation signal is sent to the device control apparatus 21. However, as described above, since the particle beam generating apparatus 30 can emit the treatment beam only when the treatment beam emission is enabled, as a result, both the organ position on which X-ray imaging was performed and the treatment beam emission enabled on are simultaneously satisfied. Only when will the treatment beam be irradiated.

The above-mentioned specific range for determining the body surface position on corresponds to the range for determining whether or not treatment beam irradiation is possible based on the organ position of the X-ray image, and is determined by the practitioner. The practitioner uses the body surface position detector 53, the X-ray imaging control / image information acquisition device 22, and the image analysis / organ position estimation device 23 equivalent to those used for treatment at the time of patient diagnosis. It is desirable to know in advance the correlation between the body surface position acquired by the detector 53 and the organ position having the affected part 60 in the body estimated by X-ray imaging. Considering that the correlation between the body surface position and the organ position is not always completely reproduced, an appropriate margin is set when determining the range for determining the body surface position on, and X It is desirable to set a wider range than the range for determining whether or not treatment beam irradiation is possible based on the organ position of the line image.

The correlation between the body surface position and the organ position in the body is not completely reproducible, but in many cases it is expected to have a certain degree of reproducibility. Since the X-ray imaging is not performed when the organ position having the position is not within a specific range, it can be expected that the exposure dose of the patient due to the X-ray is reduced.

Further, as shown in FIG. 7, by performing X-ray imaging only when the treatment beam can be emitted and the body surface position is within a predetermined range determined in advance, the operation shown in FIG. It can be expected to reduce the patient's exposure dose by X-rays. Here, as described in the second embodiment, the time set as the start time and end time of the treatment beam extraction allowance may be set earlier than the start time and end time of the actual treatment beam extraction enable period. Good.

Further, as described in FIG. 3, as shown in FIG. 8, the frame rate is lower than the X-ray imaging period in the X-ray imaging off period in FIG. 7, that is, in a period other than the X-ray imaging period. X-ray imaging may be performed. Alternatively, it goes without saying that the X-ray imaging may be performed at a lower frame rate than the X-ray imaging period in the X-ray imaging off period in FIG.

2, 3, 4, 6, 7, and 8, the particle beam therapy system is capable of emitting a treatment beam that can emit a particle beam to the affected area of the patient, and the patient. A treatment beam extraction impossible period during which the particle beam cannot be emitted from the affected area, and the X-ray imaging period is a period including at least a part of the treatment beam emission possible period.

Embodiment 4 FIG.
FIG. 9 is an example of a time chart of treatment beam irradiation of the particle beam therapy system according to the fourth embodiment. The fourth embodiment is an embodiment of a particle beam therapy system in which the particle beam generator 30 including the accelerator 1 can continuously generate a particle beam that can be irradiated to a patient. The configuration of the particle beam therapy system is the same as the configuration shown in FIG. The particle beam therapy system according to the fourth embodiment irradiates the entire affected area 60 of the patient 6 without changing the energy of the particle beam generated from the particle beam generator 30 using, for example, a bolus, so-called broad irradiation. Applicable to law.

When the position of the body surface is within a predetermined range, it is expressed as body surface position on, and X-ray imaging is performed at a preset frame rate (also referred to as a first frame rate) during this period. . In a period other than the body surface position on, the imaging frame rate for X-ray imaging is reduced below the first frame rate. The imaging frame rate in this case is 0, that is, includes the case where X-ray imaging is not performed. The image analysis / organ position estimation device 23 analyzes the captured X-ray image and estimates the current position of the organ having the affected part 60. When the current position of the organ is within a predetermined irradiation range, a treatment beam irradiation signal is sent to the device control apparatus 21.

As described in the third embodiment, the specific range for the determination of the body surface position on corresponds to the range for determining whether the treatment beam can be irradiated based on the organ position of the X-ray image, Determined by the practitioner. The practitioner uses the body surface position detector 53, the X-ray imaging control / image information acquisition device 22, and the image analysis / organ position estimation device 23 equivalent to those used for treatment at the time of patient diagnosis. It is desirable to know in advance the correlation between the body surface position of the patient 6 acquired by the detector 53 and the organ position having the affected part 60 estimated by X-ray imaging in the patient 6 body. Considering that the correlation between the body surface position and the organ position is not always completely reproduced, an appropriate margin is set when determining the range for determining the body surface position on, and X It is desirable to set a wider range than the range for determining whether or not treatment beam irradiation is possible based on the organ position of the line image.

The correlation between the body surface position and the organ position in the body is not completely reproducible, but in many cases it is expected to have some reproducibility. For this reason, in the fourth embodiment, when the position of the internal organ having the affected part 60 is clearly not within a specific range, the frequency of X-ray imaging is reduced or X-ray imaging is not performed. Therefore, even in a particle beam therapy system that can continuously generate a particle beam that can be irradiated to a patient, it can be expected to reduce the patient's exposure dose due to X-rays.

In each of the above-described embodiments, the treatment planning device 10, the device control device 21, the X-ray imaging control / image information acquisition device 22, and the image analysis / organ position estimation device 23 are each a processor 11 as shown in FIG. It is realized by a general computer including a memory 12, an input interface 13 such as a keyboard and a touch panel, a display 14 as an output interface, and the like. In addition, the treatment planning device 10, the device control device 21, the X-ray imaging control / image information acquisition device 22, and the image analysis / organ position estimation device 23 may all be configured by a single computer. Alternatively, for example, the treatment planning device 10 and the device control device 21 are configured by a single computer, and the X-ray imaging control / image information acquisition device 22 and the image analysis / organ position estimation device 23 are configured by a single computer. Any computer configuration may be used.

It should be noted that the present invention can be combined with each other within the scope of the present invention, and each embodiment can be appropriately modified or omitted.

1 accelerator, 2 particle beam, 3 vacuum duct, 4 irradiation nozzle, 5 irradiation target, 10 treatment planning device, 21 device control device, 21 X-ray imaging control / image information acquisition device, 22 image analysis / organ position estimation device, 30 Particle beam generator, 50 X-ray imaging device, 51a, 51b X-ray tube, 52a, 52b FPD, 53 Body surface position detector

Claims

A particle beam generator for generating a particle beam for irradiating an affected area of a patient to be irradiated; and
An irradiation nozzle for irradiating the irradiation object with the particle beam generated by the particle beam generator;
An apparatus control device for controlling the particle beam generator and the irradiation nozzle;
An X-ray imaging device that irradiates the irradiation target with X-rays to capture an X-ray image;
An X-ray image analysis organ position estimation device that analyzes an X-ray image captured by the X-ray imaging device and estimates a position of an organ having an affected part of the patient;
The device control device controls the particle beam generation device and the irradiation nozzle when the position of the organ estimated by the X-ray image analysis organ position estimation device is within a preset range. In the particle beam therapy system for irradiating the irradiation target with the particle beam,
The particle beam therapy system has a treatment beam emission enabled period during which a particle beam can be emitted to the irradiation target, and a treatment beam emission disabled period during which the particle beam cannot be emitted to the irradiation target,
The X-ray imaging apparatus sets the imaging frame rate of the X-ray image to be irradiated as a first frame rate during an X-ray imaging period that includes at least a part of the therapeutic beam extraction possible period, and performs the X-ray imaging. In a period other than the period, the particle beam therapy system is characterized in that the imaging frame rate is lower than the first frame rate.
The particle beam therapy system according to claim 1, wherein the X-ray imaging apparatus sets the imaging frame rate to 0 during a period other than the X-ray imaging period.
The particle beam therapy system according to claim 1 or 2, wherein a period including at least a part of the therapeutic beam extraction period is the therapeutic beam extraction period.
The start of the period including at least a part of the treatment beam extraction period is before the start of the treatment beam extraction period in the period including at least a part of the treatment beam extraction period. 3. The particle beam according to claim 1, wherein the end of the period including at least a part is before the end of the therapeutic beam extraction possible period in a period including at least a part of the therapeutic beam extraction possible period. Treatment system.
A body surface position detector for detecting the body surface position of the patient;
The X-ray imaging period is a period including at least a part of the treatment beam extraction possible period, and the body surface position detected by the body surface position detector is in a position in a preset range. The particle beam therapy system according to any one of claims 1 to 4, wherein the particle beam therapy system is provided.
A particle beam generator for generating a particle beam for irradiating an affected area of a patient to be irradiated; and
An irradiation nozzle for irradiating the irradiation object with the particle beam generated by the particle beam generator;
An apparatus control device for controlling the particle beam generator and the irradiation nozzle;
An X-ray imaging device that irradiates the irradiation target with X-rays to capture an X-ray image;
An X-ray image analysis organ position estimation device that analyzes an X-ray image captured by the X-ray imaging device and estimates a position of an organ including the affected part of the patient;
The device control device controls the particle beam generation device and the irradiation nozzle when the position of the organ estimated by the X-ray image analysis organ position estimation device is within a preset range. In the particle beam therapy system for irradiating the irradiation target with the particle beam to treat the affected area of the patient,
A body surface position detector for detecting the body surface position of the patient;
When the body surface position detected by the body surface position detector is within a preset range, the X-ray imaging apparatus sets the imaging frame rate of the X-ray image to be irradiated as a first frame rate. And when the body surface position detected by the body surface position detector is outside a preset range, the imaging frame rate is reduced below the first frame rate. Treatment system.
The X-ray imaging apparatus sets the imaging frame rate to 0 when the body surface position detected by the body surface position detector is outside a preset range. The described particle beam therapy system.