JPH1015087A - Method for charged particle nuclear therapy and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always exactly irradiate a lesion with particle beams only when an eyelid is opened and to provide therapy while reducing the burden on a patient by measuring the action of the eyelid of the patient, eyeball or the both and synchronizing the operating parameter of a charged particle nuclear irradiating device with this action. SOLUTION: An accelerator system 1 generates particle beams required for therapy, an irradiation field forming device 5 adjusts beam form and energy distribution and sets them corresponding to the position and form of the lesion at the eyebottom of a patient 6, and head is fixed by a fixer 7. A monitor camera 8 monitors the action on te eyeball or the opening/closing of the eyelid of the patient 6, sends image information to a glance monitor 9 and outputs image signals to a judging device 1. The judging device 21 compares these signals with information in a storage device 22 and, when they are settled within the allowable range, a signal is sent from the judging device 21 to a beam extraction controller 10 so that the lesion can be irradiated with beams. An irradiation dose rate is monitored by a dose monitor, a synchrotron operation controller 24 accumulates the dose rate and, when the total irradiation dose is achieved, irradiation is finished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a charged particle beam therapy method and a charged particle beam therapy device.

[0002]

2. Description of the Related Art As a prior art, Japanese Patent Laid-Open Publication No. Sho 59-88160 describes a radiation control apparatus for measuring a three-dimensional position of an affected part by an ultrasonic tomography apparatus and controlling a radiation irradiation range. Japanese Patent Application Laid-Open No. 1-2232959 discloses a corneal treatment apparatus that irradiates a predetermined position with a treatment laser beam following the movement of an eyeball.

[0003]

Generally, charged particle beam therapy using a proton beam or a heavy particle beam has an advantage that the positional resolution of dose irradiation is good and the dose can be accurately irradiated to an affected part. This property is particularly effective in the treatment of eye cancer (melanoma) because the nerve tissue and the brain immediately behind the affected area are less exposed. However, in the case of eye treatment, if the patient blinks, the charged particle beam irradiation position shifts by the thickness of the eyelid. Further, if the patient's line of sight deviates and the eyeball moves, the charged particle beam irradiation position shifts accordingly. However, it is not easy to change the irradiation position and range of the charged particle beam, and it is difficult to change the irradiation range quickly and appropriately because a complicated and huge device is required and it is difficult to realize the change. Therefore, conventionally, the eyeballs and eyelids necessary for the treatment are fixed, and the position of the affected part of the cancer and the depth to the part are fixed. Since this fixation gives the patient discomfort, there is a demand for the development of a treatment method with less burden on the patient.

[0004]

A first means for solving the above-mentioned problem is to measure the movement of the patient's eyelids and eyeballs, and to minimize the deviation of the patient's line of sight, and to measure whether the eyelids are open or not. Irradiating the charged particle beam only during the closed state.

[0005] The second means is to change the energy of the charged particle beam in front of the patient depending on whether the patient's eyelid is open or closed.

According to the first means, since the depth and the position to the affected part are constant during the irradiation of the charged particle beam, the affected part can always be accurately irradiated. There is no need to fix the patient's eyeballs and eyelids, and a treatment with less burden on the patient can be realized. In addition, since the irradiation range is not changed, accurate dose irradiation can be realized with a simple device and control.

According to the second means, by changing the energy of the charged particle beam, the depth to the affected part can be adjusted to be constant regardless of the opening and closing of the eyelid, and the affected part can always be accurately irradiated. There is no need to fix the patient's eyeballs and eyelids, and a treatment with less burden on the patient can be realized.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention for controlling the operation of a synchrotron in accordance with the condition of the eyelids and eyeballs of a patient and controlling the timing of irradiation of a particle beam to the patient.
1 shows an apparatus configuration of the embodiment. 1 in the figure is an ion source,
This is an accelerator system composed of a pre-stage accelerator and a synchrotron 2, and generates a high energy particle beam required for treatment. The particle beam accelerated by the synchrotron is extracted out of the synchrotron using a method called a slow extraction method using a perturbed electromagnetic field. The following describes the extraction method. The particle beam orbiting inside the synchrotron makes an oscillatory motion called betatron oscillation in the direction perpendicular to the traveling direction. When the acceleration is completed, the intensity of the magnetic field of the electromagnet in the synchrotron is adjusted to bring the betatron oscillation motion closer to the resonance state. Next, by applying a perturbation electromagnetic field having a frequency close to the frequency of the betatron oscillation by the perturbation electromagnetic field applying device 3, the amplitude of the betatron oscillation of the particle beam increases, and the particle beam is taken out of the synchrotron through the emitter 4. The particle beam is continuously supplied while the perturbation electromagnetic field is continuously applied, but when the application of the perturbation electromagnetic field is temporarily stopped, the particle beam is also temporarily stopped.
The beam extraction control device 10 controls the time structure of the particle beam extracted from the synchrotron by turning on and off the perturbation electric field in response to an external signal input.

The extracted particle beam is adjusted in beam shape and energy distribution by an irradiation field forming device 5.
The irradiation field forming device 5 is set in accordance with the position and shape of the affected part on the fundus of the patient 6 at the time of treatment planning. During treatment, the patient's head is fixed by the fixture 7. Surveillance camera 8
Monitors the movement of the patient's eyeballs and the open / closed state of the eyelids,
The image information is sent to the eye monitor 9. The eye gaze monitor 9 processes the image information and outputs to the determination device 21 a signal that quantitatively represents the positions and directions of the eyelids and the eyeball. Judgment device 2
1 compares the signal with information in the storage device 22 that stores conditions set at the time of treatment planning, and determines whether the signal is within an allowable range. If it exceeds the allowable range, a signal is sent to the beam extraction control device 10 to temporarily stop the application of the perturbation electromagnetic field and temporarily stop the beam irradiation. If the positions and orientations of the eyelids and the eyeball return to the allowable range again, the determination device 2
From 1, a signal is sent to the beam extraction control device 10, a perturbation electromagnetic field is applied again, and beam irradiation is restarted. The dose rate irradiating the patient is measured by the dose monitor 23, and the measured value is output to the synchrotron operation control device 24. The synchrotron operation control device 24 accumulates the dose rates, and ends the irradiation when the accumulated dose reaches the total irradiation dose set in the treatment plan. FIG. 10 is a flowchart showing the operation of the apparatus in this embodiment.

FIG. 2 shows a state of a patient's eye and a beam irradiation portion. FIG. 2A shows an irradiation state when the positions and orientations of the patient's eyelids and eyeballs are within an allowable range. The energy of the particle beam from the synchrotron and the scatterer 5a, which is a part of the irradiation field forming device, are set so that the dose distribution becomes higher in the affected part 12 located behind the eyeball 11 of the patient.
And a collimator 5b. The dose rate applied to the patient is measured by the dose monitor 23. FIG.
2B shows the case where the eyelid 13 is closed, and FIG. 2C shows the case where the eyeball moves and the line of sight is deviated. In order to suppress the irradiation of the normal tissue, the particle beam from the synchrotron is temporarily stopped. . FIGS. 8A and 8B show how the irradiation range shifts when the particle beam is irradiated with the eyelids closed. FIG. 3 shows an example of a signal output from the line-of-sight monitor 9 and a temporal change of the particle beam current from the synchrotron. The “line of sight” and “opening amount of the eyelid” in the figure are signals representing the direction of the line of sight and the state of the eyelid, respectively, of the signals output from the line-of-sight monitor 9. The permissible range set at the time of treatment planning is indicated by a dotted line parallel to the time axis. The line of sight is within an allowable range between two dotted lines sandwiching the time axis. The lower limit of the eyelid opening below one dotted line is an allowable range. Beyond this range, the perturbation field strength becomes zero
To set the particle beam current to zero. That is, the particle beam irradiation is temporarily stopped. The relationship between the respective timings is shown by a dotted line perpendicular to the time axis.

The beam may be temporarily stopped by cutting off the low energy particle beam supplied from the ion source in the case of an accelerator such as a cyclotron which generates a beam in a quasi-continuous manner.

A method for measuring eyelid and eye movement of a patient includes contacting the electrodes around the eyes of the patient's head,
A method of taking an electromyogram or a method of monitoring the reflectance of light such as a laser may be used.

FIG. 4 shows the configuration of an apparatus according to a second embodiment of the present invention, which controls a beam breaker in accordance with the state of the eyelids and eyes of a patient and controls the timing of beam irradiation on the patient. The beam shape and the energy distribution of the particle beam supplied from the accelerator 1 are adjusted by the irradiation field forming device 5, and the particle beam is irradiated on the affected part on the fundus of the patient 6. During treatment, the head of the patient 6 is fixed by the fixture 7. The monitoring camera 8 monitors the movement of the eyeball of the patient 6 and the open / closed state of the eyelids, and sends image information to the eye gaze monitor 9. Eye gaze monitor 9
Processes the image information and outputs to the determination device 21 a signal quantitatively representing the positions and orientations of the eyelids and the eyeball. The determination device 21 compares the signal with information in a storage device 22 that stores conditions set at the time of treatment planning, and determines whether the signal is within an allowable range. If it exceeds the allowable range, a signal is sent to the beam breaker control device 14 and the beam breaker 15
Is closed to suspend the particle beam irradiation. When the positions and orientations of the eyelids and the eyeball return to the allowable ranges again, a signal is sent from the determination device 21 to the beam breaker control device 14, and the breaker 15 is opened again to restart the particle beam irradiation. The dose rate irradiating the patient is measured by the dose monitor 23, and the measured value is output to the accelerator operation control device 25.
The accelerator operation control device 25 accumulates the dose rates, and terminates the irradiation when the accumulated dose reaches the total irradiation dose set in the treatment plan.

FIG. 5 shows the condition of the patient's eye and the degrader 1.
6 shows the open / closed state of a beam breaker 15 composed of a magnet 6, a bending electromagnet 17, and a beam damper 18 and a beam irradiation portion. During particle beam irradiation, the degrader 16 is open as shown in FIG. 5 (a), but the eyelid 13 is closed (FIG. 5 (b)) or the eye moves and the line of sight is deviated (FIG. 5 (b)).
In (c)), the degrader 16 is closed. The energy of the particle beam is reduced by passing through the closed degrader, the deflection angle at the downstream bending electromagnet 17 is increased, the trajectory is deviated, and the particle beam reaches the beam damper 18 and stops. By using a configuration using a thin degrader, a short beam cutoff reaction time is obtained. FIG. 6 shows an example of a signal output from the line-of-sight monitor 9 and a time change of the opening / closing state of the degrader, which is a part of the beam breaker, and the particle beam irradiation state. Similar to FIG. 3, the allowable range set at the time of treatment planning is indicated by a dotted line parallel to the time axis, and the timing relationship is indicated by a dotted line perpendicular to the time axis. If it exceeds the allowable range, the degrader is closed to reduce the beam current to zero. That is, the particle beam irradiation is temporarily stopped.

The beam breaker may use a degrader having a thickness enough to temporarily stop the particle beam completely, and may have a configuration in which a bending electromagnet is not disposed downstream or a configuration in which a kicker electromagnet and a beam damper are provided.

FIG. 7 shows the configuration of an apparatus according to a third embodiment of the present invention for controlling the energy of a particle beam applied to a patient in accordance with the eyelid opening / closing state of the patient. The beam shape and energy distribution of the particle beam supplied from the accelerator 1 are adjusted by the irradiation field forming device 5. The irradiation range is set so that the affected part is irradiated with the particle beam with the eyelids open and the shutter type degrader 20 closed. Irradiation is performed on the affected area on the fundus of the patient 6. During treatment, the patient's head is fixed by the fixture 7. Surveillance camera 8
Monitors the open / closed state of the patient's eyelids and sends image information to the eye monitor 9. The eye gaze monitor 9 processes the image information,
A signal quantitatively representing the state of opening and closing of the eyelid is output to the determination device 21. The determination device 21 compares the signal with information in the storage device 22 that stores conditions set at the time of treatment planning, and determines whether the signal is within an allowable range (eyelids are open). If it is determined that the permissible range is exceeded (the eyelid is closed), a signal is sent to the irradiation depth control device 19 to adjust the particle beam energy to increase the irradiation depth by the thickness of the eyelid. When the eyelids return to the allowable range again (if the eyelids are opened), a signal is sent from the determination device 21 to the irradiation depth control device 19, and the energy of the particle beam is returned again to the irradiation depth, and the depth of the eyelids is opened. Put it back. The judgment device 21
Measure the time from when the eyelid opening exceeds the allowable range,
If the amount of eyelid opening does not return to the allowable range even after the length of time set in advance, the beam irradiation is temporarily stopped.
The dose rate at which the patient is irradiated with the beam energy is measured by the dose monitor 23, and the measured value is output to the accelerator operation control device 25. The accelerator operation control device 25 accumulates the dose rates, and terminates the irradiation when the accumulated dose reaches the total irradiation dose set in the treatment plan.

FIG. 8 shows a state of a patient's eye, a beam energy changer using a shutter type degrader 20, and a beam irradiation portion. If the eyelids are open, see FIG.
As shown in FIG. 8C, when the shutter type degrader 20 is closed and the eyelid 13 is closed (FIG. 8D), the shutter type degrader 20 is opened. The thickness of the shutter type degrader 20 is set so that the energy lost when the particle beam passes through the shutter type degrader is equal to the energy lost when the particle beam passes through the eyelid 13. The irradiation range is set so that the affected part is irradiated with the particle beam with the eyelids open and the shutter type degrader closed. Since the energy loss in the shutter-type degrader is equal to the energy loss in the eyelid, the particle beam passes through the shutter-type degrader and does not pass through the eyelid, and the particle beam passes through the eyelid and does not pass through the shutter-type degrader. The range is equal and the irradiation range is equal.

FIG. 9 shows an example of a signal output from the line-of-sight monitor 9, a shutter-type degrader opening / closing state, and a temporal change in particle beam energy and beam current in front of the patient. Similar to FIG. 3, the allowable range set at the time of treatment planning is indicated by a dotted line parallel to the time axis, and the timing relationship is indicated by a dotted line perpendicular to the time axis. If the allowable range is exceeded, the shutter degrader opens and the energy of the beam increases. The arrow in the figure is the allowable elapsed time set at the time of treatment planning,
If the signal from the line-of-sight monitor does not return within the allowable range even if the length of time has elapsed since the signal exceeded the allowable range, the particle beam is temporarily stopped. To pause irradiation,
The method described in the first and second embodiments may be used.

The direction of the line of sight may be measured and used together with the first and second embodiments.

According to the first embodiment, the particle beam continues to circulate around the synchrotron and is not lost while the irradiation of the affected part is not performed, so that the utilization efficiency of the particle beam is improved. At the same time, the amount of radiation is small because the beam loss is small.
Further, since on / off of the particle beam is controlled by the perturbation electromagnetic field, quick beam switching can be realized by a simple device configuration and control.

According to the second embodiment, quick beam switching can be realized with the accelerator operating in a steady state.

According to the third embodiment, since the irradiation can be continued even while the patient temporarily closes the eyelids, the utilization efficiency of the particle beam is improved. Since the irradiation range is changed by opening and closing the shutter-type degrader, accurate dose irradiation can be realized with a simple device and control.

[0023]

According to the present invention, the eyelid opening / closing state of the patient and the movement of the eyeball (line of sight) are monitored, and the particle beam is radiated only while the patient's line of sight is small and the eyelid is open. Thus, the affected area can always be accurately irradiated. There is no need to fix the patient's eyeballs and eyelids, and a treatment with less burden on the patient can be realized. In addition, since the irradiation range is not changed, accurate dose irradiation can be realized with a simple device and control.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the operation principle of the device in the first embodiment.

FIG. 3 is a timing chart showing an operation procedure of the device in the first embodiment.

FIG. 4 is a block diagram of an apparatus according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing the operation principle of the device according to the second embodiment.

FIG. 6 is a timing chart showing an operation procedure of the device in the second embodiment.

FIG. 7 is a block diagram of an apparatus according to a third embodiment of the present invention.

FIG. 8 is a block diagram showing the operation principle of the device according to the third embodiment.

FIG. 9 is a timing chart showing an operation procedure of the device in the third embodiment.

FIG. 10 is a flowchart showing the operation of the apparatus according to the first embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Accelerator system, 2 ... Synchrotron, 3 ... Perturbation field applying device, 4 ... Ejector, 5 ... Irradiation field forming device, 6 ... Patient, 7 ... Fixture, 8 ... Surveillance camera, 9 ... Eye gaze monitor, 1
0: Beam extraction control device, 21: Judgment device, 22:
Storage device, 24: synchrotron operation control device.

Claims (6)

[Claims] 1. A charged particle beam irradiation method characterized by measuring the movement of a patient's eyelid and / or eyeball, and synchronizing an operation parameter of the charged particle beam irradiation device with the movement. 2. The charged particle beam irradiation timing according to claim 1, wherein the patient's eyelid opening / closing state and the amount of deviation of the line of sight are measured, and the measured amount is compared with a predetermined judgment condition. Charged particle beam irradiation method. 3. The charged particle beam irradiation method according to claim 1, wherein the energy of the charged particle beam in front of the patient is changed depending on whether the patient's eyelid is open or closed. 4. A degrader according to claim 3, wherein energy lost when said charged particle beam passes is substantially equal to energy lost when passing through the eyelid,
A charged particle beam irradiation method in which the degrader is closed while the eyelid is open and opened while the eyelid is closed. 5. A charged particle beam irradiation apparatus according to claim 2, wherein a synchrotron is used as a radiation source, and switching of charged particle beam irradiation timing is realized by turning on / off beam extraction. 6. A charged particle beam irradiation apparatus according to claim 5, wherein a perturbation electromagnetic field having a frequency close to the frequency of betatron oscillation of the beam is applied to the beam to extract the beam.