JP2000221300A - Charged particle beam irradiator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to measure the dose of a charged particle beam accurately without affecting the flow of the charged particle beam under normal conditions by revolving a shield on a specified axis in synchronization with the drive control of the deflection of the charged particle beam. SOLUTION: A charged particle beam 1 that has been incident is revolved on a specified axis and is scanned like a charged particle beam 5 by deflecting electromagnets 2 and 3. The charged particle beam 5 passes through a slit 21a of a shield 21 that is revolved in synchronization with the deflecting electromagnets 2 and 3, is scattered by being irradiated with a scatterer 7 and forms a required irradiated field 9 on an irradiated surface 8 as an expanded charged particle beam 10. On this occasion, the charged particle beam 5 passes through the slit 21a without suffering interference, so that the charged particle beam 5 does not stagnate in the shield 21. Therefore, an electric current does not flow from a brush put in contact with the side face of the shield 21. The measurement of the electric current makes it possible to judge whether a position where the charged particle beam 1 is incident, the operation of the electromagnets 2 and 3 and the like are normal or abnormal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle beam irradiation device used for a charged particle beam therapy device or the like.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing a conventional charged particle beam irradiation apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 10-33697. In this example, a charged particle beam irradiation apparatus is used as a charged particle beam treatment apparatus. It shows the case where it was used. In the figure,
1 is a charged particle beam, 2 and 3 are 90 degrees out of phase with each other,
The deflection electromagnet deflects the charged particle beam 1 so that the charged particle beam 1 is rotated about a predetermined axis 4 by a current having the same amplitude. 5 is a deflected charged particle beam, 6 is a shield formed of lead or the like, and shields the charged particle beam 5; 6a is a ring-shaped slit provided around the predetermined axis 4 in the shield 6; Is a scatterer that is formed of lead or the like, scatters and expands the charged particle beam 5 that has passed through the slit 6a, and generates a required irradiation field 9 on an irradiation surface 8 such as a body surface of a patient. Numeral 6 denotes a member placed on the scatterer 7. Reference numeral 10 denotes a charged particle beam scattered by the scatterer 7.

Next, the operation will be described. In the case of a treatment device, the charged particle beam obtained from a charged particle beam accelerator or the like passes through a beam transport system and a charged particle beam on / off device, etc.
The charged particle beam 1 is incident on the deflection electromagnets 2 and 3 of the irradiation system. The predetermined axis 4 is a path of the charged particle beam 1 when the amount of deflection by the deflection electromagnets 2 and 3 is zero. Bending electromagnets 2, 3
Is normal, the charged particle beam 1 is deflected by currents having phases different from each other by 90 degrees and having the same amplitude so that the charged particle beam 1 is rotated about the predetermined axis 4. Those bending electromagnets 2,
The charged particle beam 5 deflected by 3 passes through a ring-shaped slit 6 a provided around the predetermined axis 4 in the shield 6, and irradiates the scatterer 7. In addition, the charged particle beam 5 irradiated to the scatterer 7 is scattered by the scatterer 7 and is irradiated as an enlarged charged particle beam 10 to an irradiation surface 8 such as a body surface of a patient.

When the deflection electromagnets 2 and 3 are not normal, for example, when the power of the deflection electromagnets 2 and 3 is turned off, the charged particle beam 1 is not deflected at all and the upper part of the shield 6 is Is irradiated. Shield 6 made of lead etc.
Is charged to a sufficiently large thickness, the charged particle beam 1 traveling straight without being deflected is stopped by the central portion of the shield 6. Therefore, when the bending electromagnets 2 and 3 are not normal, erroneous irradiation of the irradiation surface 8 of the charged particle beam 1 can be avoided. Further, by detecting the current from the shield 6, it is determined whether the charged particle beam 5 has normally passed through the slit 6a and has generated the required irradiation field 9 on the irradiation surface 8.

[0005]

Since the conventional charged particle beam irradiation apparatus is configured as described above, the charged particle beam 5 normally passes through the slit 6a by detecting the current from the shield 6. Then, it is determined whether the required irradiation field 9 is generated on the irradiation surface 8. Here, when the power of the bending electromagnets 2 and 3 is turned off, the charged particle beam 1 is irradiated to the upper center of the shield 6 without receiving any deflection. , Must be detected from the upper center of the shield 6. Because the shield 6 is provided with the ring-shaped slit 6a, the bending electromagnets 2, 3 are provided.
Of the charged particle beam 1 irradiated to the upper center of the shield 6 after the power supply of the
This is because the flow to the outer periphery of the shield 6 is blocked by a. However, when a current detection element is installed at the upper center of the shield 6 and a current is detected by connecting a measurement cable to the current detection element, the measurement cable is connected to the ring-shaped slit 6 a of the shield 6. , And adversely affect the flow of the charged particle beam 5 in a normal state, or adversely affect the detected current value of the flow of the charged particle beam 5.

[0006] The shield 6 is placed on the scatterer 7. Here, the thickness of the shield 6 is several cm in a charged particle beam therapy apparatus using a proton beam or the like. For example, when treating a deep tumor, the beam energy of the required proton beam is about 230 MeV. Therefore, when the shield 6 is made of lead, the thickness is about 5 cm. On the other hand, the thickness of the scatterer 7 is about several mm or less for the same lead made to spread the proton beam and generate the required irradiation field 9 on the irradiation surface 8. In addition, the thickness of the scatterer 7 needs to be changed in a range from several hundred μm to several mm according to the required size of the irradiation field 9. Therefore, a heavy shield 6 having a thickness of several centimeters must be supported by a thin scatterer 7 having a thickness of several millimeters or less.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and can accurately measure a charged particle dose without affecting the flow of a charged particle beam in a normal state. An object is to obtain a highly charged charged particle beam irradiation device.

[0008]

The charged particle beam irradiation apparatus according to the present invention controls the driving so that the charged particle beam is deflected about a predetermined axis by the deflecting means, and synchronizes with the driving control. Driving control means for driving the shielding means about a predetermined axis so that the charged particle beam deflected by the deflecting means passes through an opening provided in the shielding means; and deflecting means, shielding means, and scattering. It is provided with a holding means for holding the means at a predetermined position, and a measuring means for measuring the dose of charged particles applied to the shielding means.

The charged particle beam irradiation apparatus according to the present invention includes, as measuring means, a brush that comes into contact with a side surface of the shielding means, and an ammeter that measures current from the brush.

In the charged particle beam irradiation apparatus according to the present invention, the drive control means controls the drive so that the charged particle beam is rotated and deflected about a predetermined axis by the deflecting means, and is synchronized with the drive control. Then, drive control is performed such that the shielding means is rotated about a predetermined axis.

[0011] In the charged particle beam irradiation apparatus according to the present invention, the drive control means controls the drive so that the charged particle beam vibrates and is deflected about a predetermined axis by the deflecting means, and is synchronized with the drive control. Then, the shielding means is driven and controlled so as to be vibrated about a predetermined axis.

The charged particle beam irradiation apparatus according to the present invention is provided with a retracting means which is held by the holding means and makes it possible to retreat the shielding means from the passage area of the charged particle beam deflected by the deflecting means.

In the charged particle beam irradiation apparatus according to the present invention, as the shielding means, a charged particle beam deflected by the deflecting means whose thickness other than near a predetermined axis and near the opening is thinned is used. .

In the charged particle beam irradiation apparatus according to the present invention, as the shielding means, a charged particle beam deflected by the deflecting means having a reduced thickness other than near a predetermined axis is used.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing a charged particle beam irradiation device according to Embodiment 1 of the present invention, and FIG. 2 is a configuration diagram showing details around a shield. In Embodiment 1, the charged particle beam irradiation device is charged. This shows a case where the present invention is used for a particle beam therapy system. FIGS. 1A and 1B show a shield 2 to be described later.
The position of the slit 21a and the position of the charged particle beam 5 are each rotated by about 180 degrees. FIG.
In the figure, 1 is a charged particle beam such as an electron, a proton or an ion, and 2 and 3 are different in phase by 90 degrees from each other, and the sine wave current of the same amplitude makes the charged particle beam 1 a predetermined radius around a predetermined axis 4. Is a deflection electromagnet (deflecting means) that deflects the light so that it is rotated with the angle. Such a bending electromagnet 2,
3 is called a wobbling electromagnet. 5 is the deflected charged particle beam, 21 is lead, iron,
Alternatively, it is a shield (shielding means) formed of copper or the like, which is rotated about the predetermined axis 4 and shields the charged particle beam 5. The shield 21 has a thickness capable of completely stopping the charged particle beam 5. It has been molded. Reference numeral 21a denotes a slit (opening) passing through the charged particle beam 5 provided at one place on the shield 21 as shown in FIG.
Is cylindrical in FIG. 2, but may be arbitrary. A scatterer 7 is formed of lead, iron, copper, or the like, scatters and expands the charged particle beam 5 passing through the slit 21a, and forms a required irradiation field 9 on an irradiation surface 8 such as a body surface of a patient. (Scattering means). 10 is the scatterer 7
Is a charged particle beam scattered by

Reference numeral 22 denotes a bearing provided on the outer periphery of the shield 21, and reference numeral 23 denotes a motor (drive control means) that rotationally drives the shield 21 via a gear 23a. 24 controls the driving of the deflection electromagnets 2 and 3 so that the charged particle beam 1 is rotated about the predetermined axis 4 by the deflection electromagnets 2 and 3 and moves the shield 21 in synchronization with the drive control. A power supply controller (drive control means) that controls the drive of the motor 23 so that the charged particle beam 5 deflected by the deflection electromagnets 2 and 3 passes through the slit 21a. . 25 is a bending electromagnet 2, 3,
This is a frame (holding unit) that holds the motor 23, the bearing 22, and the scatterer 7 at predetermined positions. Further, FIG.
, 31 is formed of carbon or the like,
A brush (measuring means) in contact with one side surface, 32 is a measurement cable connected to the brush 31, 33 is connected to the measurement cable 32, and measures the dose of charged particles emitted from the brush 31 to the shield 21. It is an ammeter (measuring means) such as a charge integration circuit.

Next, the operation will be described. First, an initial adjustment before starting irradiation is performed. The amplitude of the sinusoidal current supplied to the bending electromagnets 2 and 3 according to the size of the required irradiation field,
And the thickness of the scatterer 7 is selected. Here, the amplitude of the sinusoidal current supplied to the bending electromagnets 2 and 3 sets the turning radius of the charged particle beam 5 to be deflected, and can be set by the power supply controller 24. The scatterer 7
The thickness is selected in advance by, for example, a thickness of 1 mm.
The scatterers 7 having different thicknesses of 5 mm to 5 mm are selected and arranged at predetermined positions of the frame 25.
Then, the power supply controller 24 is turned on, and the bending electromagnets 2 and 3 are turned on.
And the motor 23 is driven to rotate the shield 21. The bending electromagnets 2 and 3 are controlled so as to be excited with a sinusoidal current of the same frequency, for example, 57 Hz. Also, the phase of the sine wave current of the deflecting electromagnets 2 and 3 and the rotation of the motor 23 are controlled by the power controller 24 so that the deflected charged particle beam 5 can always pass through the slit 21 a of the shield 21 almost without interference. Adjust with. Further, although not shown in FIG. 1, preparation for positioning the patient on the position of the irradiation surface 8, a modulator for modulating the beam energy of the charged particle beam 10 downstream of the scatterer 7, a dose, Adjust measurement equipment, patient collimator, etc.

Then, irradiation is started. A charged particle beam obtained from a charged particle beam accelerator or the like is incident on a deflection electromagnet 2 or 3 of an irradiation system as a charged particle beam 1 via a beam transport system and a charged particle beam on / off device. The predetermined axis 4 is a path of the charged particle beam 1 when the amount of deflection by the deflection electromagnets 2 and 3 is zero. When the charged particle beam therapy system is normal, the incident charged particle beam 1 is charged about a predetermined axis 4 by deflection magnets 2 and 3 which are excited in advance.
Is rotationally scanned as follows. Further, the charged particle beam 5 is shielded by a shield 21 that has been previously rotated in synchronization with the bending electromagnets 2 and 3.
Pass through the slit 21a with little interference and irradiate the scatterer 7. The charged particle beam 5 is scattered by the scatterer 7, passes through another irradiation system provided downstream of the scatterer 7 as an expanded charged particle beam 10, and forms a required irradiation field 9 on the irradiation surface 8. Form. In the charged particle beam therapy apparatus according to Embodiment 1, the irradiation dose distribution in the irradiation field 9 formed on the irradiation surface 8 mainly includes the turning radius of the charged particle beam 5, the thickness of the scatterer 7, and the scatterer 7. And the distance from the irradiation surface 8 to the irradiation surface 8. Since the thickness of the scatterer 7 and the distance from the scatterer 7 to the irradiation surface 8 are accurately set in the initial adjustment before the start of irradiation, the radius of rotation of the charged particle beam 5, that is, the charged particle beam The irradiation dose formed on the irradiation surface 8 only when the incident position 1 and the amplitude and phase relationship of the sinusoidal currents of the bending electromagnets 2 and 3 match the values set in the initial adjustment before the start of irradiation. The distribution will be the required distribution. Here, since the charged particle beam 5 passes through the slit 21 a of the shield 21 almost without interference, the charged particle beam 5 hardly accumulates on the shield 21. Therefore, the shield 2 shown in FIG.
1 from the brush 31 contacting the side
Almost no current flows through the ammeter 33 via the
Is normal, and the relationship between the amplitude and the phase of the sinusoidal currents of the bending electromagnets 2 and 3 is normal. Therefore, the charged particle beam therapy apparatus normally forms a required irradiation dose distribution on the irradiation surface 8. Can be determined.

When the incident position of the charged particle beam 1 is deviated or when the deflection electromagnets 2 and 3 are abnormal, the trajectory of the deflected charged particle beam 5 is deviated and the slit 21a of the shield 21 is displaced. , And collides with the shield 21. Here, since the charged particle beam 5 collides with the shield 21, the charged particle beam 5 accumulates on the shield 21, and therefore, the measuring cable is connected to the brush 31 shown in FIG. The electric current flows significantly through the ammeter 33 through the electric current meter 32, and the charged particle beam 1 is measured by the ammeter 33.
At least one of the incident position and the amplitude and phase relationship of the sinusoidal currents of the bending electromagnets 2 and 3 is abnormal. Therefore, the charged particle beam therapy system irradiates a required irradiation dose distribution due to abnormality. It can be determined that it is not formed on the surface 8. It should be noted that the abnormality of the charged particle beam therapy apparatus is such that the charged particle beam 5 collides with the shield 21 and the slit 21
This is a direction in which the light cannot pass through a, and the irradiation dose formed on the irradiation surface 8 is a direction in which the irradiation dose is reduced, so that there is no effect on the human body.

In the first embodiment, the shield 21 is driven to rotate by the motor 23 via the gear 23a. However, for example, a belt may be used instead of the gear 23a. Further, the motor 2 is directly connected to the rotation center of the shield 21.
Alternatively, three rotating shafts may be connected. Further, when adjusting the phase of the sine wave current of the bending electromagnets 2 and 3 and the rotation of the motor 23 by the power supply controller 24, an encoder indicating the position of the slit 21a of the shield 21 is attached to the shield 21 or the motor 23. The adjustment may be performed by using
Further, in the first embodiment, by the ammeter 33,
Although the normal or abnormal state of the charged particle beam therapy system is determined, an automatic stop controller for automatically stopping the charged particle beam therapy system when an abnormality is determined by the ammeter 33 may be provided. Furthermore, the shield 2 of the bearing 22
If the bearing ring and the gear 23a on the first side are insulated from the shield 21 or the bearing ring and the gear 23a are formed of an insulator, the charged particle beam 5 accumulated in the shield 21 does not leak as a current. The measurement can be performed with higher accuracy by the ammeter 33. Further, in the first embodiment, the predetermined axis 4 is set to the vertical direction. However, the predetermined axis 4 may be set to the horizontal direction or the oblique direction, and further, the rotation that can irradiate the patient from an arbitrary angle. A charged particle beam therapy apparatus may be incorporated in a gantry-type rotary irradiation apparatus or the like. Further, the charged particle beam irradiation apparatus according to the first embodiment is not limited to the one used as a charged particle beam therapy apparatus, but may be applied to a field requiring charged particle beam irradiation or injection such as a semiconductor field or a material field. May be applied.

As described above, according to the first embodiment, the power supply controller 24 controls the driving so that the charged particle beam 1 is rotated about the predetermined axis 4 by the bending electromagnets 2 and 3. , The shield 2 in synchronization with the drive control
1 is rotated around a predetermined axis 4 by a motor 23.
Is controlled so that the charged particle beam 5 deflected by the deflection electromagnets 2 and 3 passes through the slit 21a. The current flow due to the charged particle beam 5 colliding with 21 can flow to the side surface of the shield 21, and therefore, from the brush 31 contacting the side surface of the shield 21, the ammeter 33 via the measuring cable 32.
Current flows through the current meter 33, and it can be determined that an abnormality has occurred in the charged particle beam therapy system. In this case, the measuring cable 32 does not cross the slit 21a and adversely affects the flow of the charged particle beam 5 in a normal state, or adversely affects the current value at which the irradiation of the charged particle beam 5 is detected. Can be prevented, and the charged particle dose can be accurately measured. Further, it is possible to form an irradiation field 9 having a required irradiation dose distribution such that the irradiation field 9 is rotated about the predetermined axis 4 on the irradiation surface 8. Further, since the bending electromagnets 2 and 3, the motor 23, the bearing 22 provided on the outer periphery of the shield 21, and the scatterer 7 are held at predetermined positions by the frame 25, the heavy shield 21 is thinned. There is no need to support with the scatterer 7, and the structure can be strengthened.

Embodiment 2 FIG. FIG. 3 is a configuration diagram showing details around a shield of a charged particle beam irradiation apparatus according to Embodiment 2 of the present invention. In the drawing, reference numeral 41 denotes a member formed of lead, iron, copper, or the like, and has a predetermined axis 4 as a center. Shielded object (shielding means) which is linearly oscillated linearly and shields the charged particle beam 5
The shield 41 is formed to a thickness that can completely stop the charged particle beam 5. 41a is the shield 21
3 is a slit (opening) that passes through the charged particle beam 5 provided at one place, and the shape of the slit 41a is as shown in FIG.
Although the shape is inverted frustoconical, any shape may be used. Other configurations are the same as those in FIG. 2, and thus the same reference numerals are given and duplicate explanations are omitted.

Next, the operation will be described. In the first embodiment, the power supply controller 24 controls the bending electromagnets 2 and 3
To control the charged particle beam 1 to rotate about the predetermined axis 4 and to drive the motor 23 to rotate the shield 21 about the predetermined axis 4 in synchronization with the driving control. A required irradiation dose distribution such that the charged particle beam 5 deflected by the deflection electromagnets 2 and 3 passes through the slit 21a and is rotated on the irradiation surface 8 about the predetermined axis 4 In the second embodiment, the charged particle beam 1 is linearly and simply oscillated about the predetermined axis 4 by the deflection electromagnets 2 and 3 by the power supply controller 24 in the second embodiment. In addition to the drive control, the motor 41 drives and controls the shield 41 so that the shield 41 is linearly oscillated linearly around the predetermined axis 4 in synchronization with the drive control. Particle beam 5 Configured to pass through the slit 41a, and forms an irradiation field 9 having the required irradiation dose distribution as linearly simple harmonic motion about a predetermined axis 4 to the irradiation surface 8.

Charged particle beam 5 scanned linearly with a single vibration
Is obtained by controlling the bending electromagnets 2 and 3 by the power supply controller 24 so as to be excited by sine wave currents of the same amplitude synchronized with each other. Further, the shield 41 which is linearly vibrated in a straight line can be provided by providing a rack on a side surface or a lower surface of the shield 41 and making the rack a single vibration by the motor 23 via the gear 23a. Then, the charged particle beam 5 deflected by the power supply controller 24 so as to be scanned in a single vibration is always in the slit 4 of the shield 41.
The driving of the phase of the sinusoidal currents of the bending electromagnets 2 and 3 and the rotation of the motor 23 are controlled so that the motor 1 can pass through the motor 1a almost without interference. In the second embodiment, the charged particle beam 5 that is linearly scanned with a sinusoidal current in a single oscillation is obtained.
In this case, the gear 23 a
If the rack is oscillated at a constant speed through the above, an irradiation field 9 having a required irradiation dose distribution such that the irradiation surface 8 is oscillated linearly at a constant speed around the predetermined axis 4 can be formed. it can.

As described above, according to the second embodiment, the power controller 24 controls the drive so that the charged particle beam 1 is oscillated about the predetermined axis 4 by the bending electromagnets 2 and 3. , The shield 4 in synchronization with the drive control
1 is oscillated about a predetermined axis 4
Is controlled so that the charged particle beam 5 deflected by the deflection electromagnets 2 and 3 passes through the slit 41a. An irradiation field 9 having a dose distribution can be formed.

Embodiment 3 FIG. FIG. 4 is a configuration diagram showing a charged particle beam irradiation apparatus according to Embodiment 3 of the present invention. In the figure, reference numerals 25a and 25b denote two divided frames, and the frame 25a includes bending electromagnets 2, 3,. The scatterer 7 is held at a predetermined position, and the frame 25b holds the motor 23 and the bearing 22 at a predetermined position. Then, the shield 21, the bearing 22, the motor 2
3. The movable shield 50 is constituted by the gear 23a and the frame 25b. A bolt 51 is connected to the movable shield 50 to allow the movable shield 50 to retreat from the passage area of the charged particle beam 5, a nut 52 is screwed to the bolt 51, and a nut whose outer periphery is formed into a gear, 53 is a gear 53a
Is a motor that rotates the nut 52 through the shaft and slides the bolt 51 and the movable shield 50.
1, a retracting means is constituted by the nut 52, the motor 53, and the gear 53a. Reference numeral 54 denotes a dosimetry device arranged at the time of initial setting before the start of irradiation. Other configurations are the same as those in FIG. 1, and thus the same reference numerals are given and duplicate explanations are omitted.

Next, the operation will be described. In the initial setting before the start of irradiation shown in the first embodiment, the scatterer 7
There is a case where the beam energy of the charged particle beam 5 is measured downstream of and the beam energy is adjusted. In this case, a dose measuring device 54 is arranged between the scatterer 7 and the irradiation surface 8 to measure the beam energy of the charged particle beam 5 output from the bending electromagnets 2 and 3. In this case, Since the charged particle beam 5 output from the bending electromagnets 2 and 3 may be interfered by the shield 21,
Cannot measure accurately. Therefore, at the time of initial setting before the start of irradiation, the motor 53 is rotationally driven,
The nut 52 is rotated via the gear 53a to slide the bolt 51 and the movable shield 50, and the movable shield 50 is retracted from the passage area of the charged particle beam 5. After the beam energy is adjusted by the dosimeter 54, the motor 53 is driven to rotate in the reverse direction, the nut 52 is rotated via the gear 53a, and the bolt 51 and the movable shield 50 are slid in the reverse direction. The movable shield 50 can be arranged at a predetermined position.

As described above, according to the third embodiment, since the movable shield 50 can be retracted from the passage area of the charged particle beam 5, the deflection by the dose measuring device 54 in the initial setting before the start of irradiation is performed. Since the beam energy of the charged particle beam 5 output from the electromagnets 2 and 3 can be measured accurately without interference by the shield 21, the beam energy of the charged particle beam 5 can be adjusted with high reliability. . In particular, in a cancer treatment apparatus using a proton beam, a carbon beam, or the like, the adjustment of the beam energy is important, and a remarkable effect can be obtained by being able to accurately measure the beam energy.

Embodiment 4 FIGS. 5, 6, and 7 are configuration diagrams showing details around a shield of a charged particle beam irradiation apparatus according to a fourth embodiment of the present invention.
Reference numeral 1 denotes a shielding object, 61a denotes a slit, and the dimensions indicate the most suitable numerical values for implementation. Also, in FIG.
Reference numeral 2 denotes a shielding member (shielding means) formed thin except for the vicinity of the predetermined axis 4 of the charged particle beam 5 and other than the vicinity of the slit (opening) 62a. It is. Further, in FIG. 7, reference numeral 63 denotes a shielding object (shielding means) formed thin except for the vicinity of the predetermined axis 4 of the charged particle beam 5, and 63a denotes a slit, the size of which is an optimum numerical value for implementation. It is. Other configurations are
Since they are the same as those in FIG. 1, the same reference numerals are given and duplicate explanations are omitted.

Next, the operation will be described. In the first and third embodiments, the shape of the shield 21 and the slit 21a is cylindrical, but may be another shape if necessary. FIG. 5 shows that the charged particle beam 1 is a proton beam of about 200 MeV for treating a deep tumor, and the deflection angle of the weaving electromagnet composed of the deflection electromagnets 2 and 3 is within a range of about 0.5 to 2.0 degrees. In a certain case, the dimensions are optimum for the case where the lead shield 61 is installed at a position about 30 cm downstream of the bending electromagnets 2 and 3. FIG. 6 shows a shield 62 having a small thickness except the vicinity of the predetermined shaft 4 and the slit 62a under the above conditions.
In the figure, the size of the charged particle beam 5 flows on the predetermined axis 4 when the power of the bending electromagnets 2 and 3 is turned off, or the charged beam deflected by the bending electromagnets 2 and 3 Even when the scanning position of the particle beam 5 is shifted in the outer peripheral direction of the shield 62, the charged particle beam 5 can be stopped at a thick portion of the shield 62. Therefore, FIG.
By shaping the shield 62 into the shape shown in FIG.
Can be reduced in weight, and the output of the motor 23 can be reduced. FIG. 7 shows that under the above conditions,
A shield 63 formed thin except for the vicinity of the predetermined shaft 4
In the case where the power of the bending electromagnets 2 and 3 is turned off and the charged particle beam 5 flows on the predetermined axis 4, the vicinity of the predetermined axis 4 where the shield 63 has a thickness is shown. The charged particle beam 5 can be stopped at a portion. Also,
When the scanning position of the charged particle beam 5 deflected by the bending electromagnets 2 and 3 is shifted in the outer circumferential direction of the shield 62, the shield 6
Although the patient slightly passes through the thin portion of No. 3, a patient collimator called a multi-leaf collimator capable of arbitrarily changing the slit shape is provided immediately before the patient, so that safety for the patient can be ensured. Therefore, by forming the shield 63 into the shape shown in FIG. 7, the shield 62 shown in FIG.
As described above, the weight can be reduced, and the output of the motor 23 can be reduced. According to the fourth embodiment,
Although all the shields are formed of a metal such as lead, the weight may be reduced while maintaining the strength by combining a metal and a resin. For example, in FIGS. 6 and 7, the thin portions of the shields 62 and 63 may be supplemented with resin to form the shield 61 in FIG.

As described above, according to the fourth embodiment, the thickness of the shielding member 62 other than the vicinity of the predetermined axis 4 and the slit 62a can be reduced, or the thickness of the shielding object 63 other than the vicinity of the predetermined axis 4 can be reduced. Are formed thinly, so that the shields 62, 63
Can be made lighter.

[0032]

As described above, according to the present invention, the driving of the charged particle beam is controlled by the deflecting means so that the charged particle beam is deflected around a predetermined axis, and the shielding means is controlled in synchronization with the driving control. Drive control means for controlling the drive around the axis so that the charged particle beam deflected by the deflecting means passes through an opening provided in the shielding means; and a deflecting means, a shielding means, and a scattering means. Since it is configured to include a holding unit for holding the position and a measuring unit for measuring the dose of the charged particles irradiated to the shielding unit, the shielding unit is detached from the opening when an abnormality occurs in the charged particle beam irradiation device. The current flow due to the charged particle beam that has collided with the shielding means can flow to the side of the shielding means. Therefore, if the dose of the charged particles irradiated to the shielding means by the measuring means from the side of the shielding means is charged, It can be determined that an abnormality has occurred in the child beam irradiation apparatus. In this case, the measuring cable used for the measuring means does not cross the opening, and adversely affects the flow of the charged particle beam in a normal state, or adversely affects the current value at which the irradiation of the charged particle beam is detected. Can be prevented, and the presence or absence of an abnormality in the charged particle beam irradiation device can be accurately measured. Further, since the deflecting means, the shielding means, and the scattering means can be held at predetermined positions by the holding means, it is not necessary to support the heavy shielding means with the thin scattering means, and there is an effect that the structure can be strengthened.

According to the present invention, as the measuring means is provided with the brush contacting the side surface of the shielding means and the ammeter for measuring the current from the brush, the measuring means is brought into contact with the side surface of the shielding means. The current from the brush can be measured by the ammeter, and the current can be accurately measured.

According to the present invention, the drive control means controls the drive so that the deflecting means rotates and deflects the charged particle beam about a predetermined axis, and the shielding means is synchronized with the drive control. Since the drive control is performed so as to rotate about the predetermined axis, an irradiation field having a required irradiation dose distribution such that the irradiation surface is rotated about the predetermined axis can be formed on the irradiation surface. There is.

According to the present invention, the drive control means controls the drive so that the charged particle beam is oscillated and deflected about the predetermined axis by the deflecting means, and the shielding means is synchronized with the drive control. Since the drive control is performed so as to be oscillated about a predetermined axis, an irradiation field having a required irradiation dose distribution such that the irradiation field is oscillated about the predetermined axis can be formed. There is.

According to the present invention, the holding member is held by the holding means,
Since the shielding means is provided with a retracting means for retreating from the passage area of the charged particle beam deflected by the deflecting means, the charged particle beam output from the deflecting means by the dose measuring device in the initial setting before the start of irradiation Beam energy can be accurately measured without interference by the shielding means, so that the beam energy of the charged particle beam can be adjusted with high reliability.

According to the present invention, as the shielding means, the charged particle beam deflected by the deflecting means having a reduced thickness other than near the predetermined axis and near the opening is used. There is an effect that the weight can be reduced.

According to the present invention, since the thickness of the charged particle beam deflected by the deflecting means other than the vicinity of the predetermined axis is reduced as the shielding means, the weight of the shielding means can be reduced. There is an effect that can be done.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a charged particle beam irradiation apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing details around a shield.

FIG. 3 is a configuration diagram showing details around a shield of a charged particle beam irradiation apparatus according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram showing a charged particle beam irradiation apparatus according to Embodiment 3 of the present invention.

FIG. 5 is a configuration diagram showing details around a shield of a charged particle beam irradiation apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram showing details around a shield of a charged particle beam irradiation apparatus according to Embodiment 4 of the present invention.

FIG. 7 is a configuration diagram showing details around a shield of a charged particle beam irradiation apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a configuration diagram showing a conventional charged particle beam irradiation device.

[Explanation of symbols]

1, 5 charged particle beam, 2, 3 bending electromagnet (deflecting means), 4 predetermined axis, 7 scatterer (scattering means), 9 irradiation field, 21, 41, 62, 63 shielding object (shielding means), 2
1a, 41a, 62a slit (opening), 23 motor (drive control means), 24 power supply controller (drive control means), 25 frames (holding means), 31 brush (measurement means), 33 ammeter (measurement means) , 51 bolts (evacuating means), 52 nuts (evacuating means), 53 motors (evacuating means), 53a gears (evacuating means).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) G21K 1/10 G21K 1/10 SF term (Reference) 2G088 EE01 FF13 GG27 JJ01 JJ12 JJ29 JJ31 JJ33 JJ37 4C082 AA01 AC04 AC05 AC06 AE01 AG11 AG12 AG22 AJ06 AP01 AP11 AP20 AR05

Claims (7)

[Claims] A shielding means provided with an opening through which the charged particle beam deflected by the deflecting means is provided; and a driving control so that the charged particle beam is deflected about a predetermined axis by the deflecting means. Drive control means for controlling the drive of the shielding means about the predetermined axis in synchronization with the drive control so that the charged particle beam deflected by the deflection means passes through the opening; and Scattering means for scattering the charged particle beam passing through the portion to form a required irradiation field, the deflecting means, the shielding means, a holding means for holding the scattering means at a predetermined position, and irradiating the shielding means. A charged particle beam irradiation apparatus comprising: a measuring unit configured to measure a charged particle particle dose. 2. The charged particle beam irradiation device according to claim 1, wherein the measuring means includes a brush that contacts a side surface of the shielding means, and an ammeter that measures a current from the brush. 3. The drive control means controls the drive so that the charged particle beam is rotated and deflected about a predetermined axis by the deflection means, and moves the shielding means in synchronization with the drive control. Drive control to rotate around the center,
3. The charged particle beam irradiation apparatus according to claim 1, wherein the charged particle beam deflected by the deflecting means passes through the opening. 4. The drive control means controls the drive so that the charged particle beam oscillates and is deflected about a predetermined axis by the deflection means, and moves the shielding means in synchronization with the drive control. Drive control so that it vibrates around the center,
3. The charged particle beam irradiation apparatus according to claim 1, wherein the charged particle beam deflected by the deflecting means passes through the opening. 5. An evacuation device which is held by the holding device and which makes it possible to retreat the shielding device from a passage area of the charged particle beam deflected by the deflecting device is provided. The charged particle beam irradiation device according to any one of the above items. 6. The shielding means according to claim 1, wherein the thickness of the charged particle beam deflected by the deflection means is reduced except in the vicinity of a predetermined axis and in the vicinity of the opening. The charged particle beam irradiation apparatus according to claim 1. 7. The shielding means according to claim 1, wherein the thickness of the charged particle beam deflected by the deflecting means other than the vicinity of a predetermined axis is reduced.
A charged particle beam irradiation apparatus according to any one of the preceding claims.