JP4362569B2 - Pencil type ion beam forming method for high precision 3D irradiation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a method for forming an ion beam for high-precision three-dimensional irradiation. The fields of application of the present invention are as follows. In the treatment with an ultra-high precision microbeam, it can be applied to cancer and other local diseases, so that a minute lesion in the body can be treated only by irradiation without surgery.
[0002]
In addition, by irradiating a minute area with high precision while controlling the ion beam three-dimensionally, it is possible to control the induction of mutations necessary for ion beam plant breeding, which is expected to make a dramatic improvement in breeding. Can be used in the agricultural field.
[0003]
Furthermore, by applying the irradiation technology while controlling the ion implantation position with an accuracy of nm to μm for material modification and creation of new materials, functionality such as nano / micro machining and high aspect ratio micropores. It can be used in the field of nanotechnology and materials, such as creating materials.
[0004]
[Prior art]
The conventional ion microbeamformer uses a precision object collimator and a beam divergence limiting collimator to limit the beam, and then passes the beam through a small hole with a diameter of several to several tens of microns to form a microbeam. There are a collimation method and a lens method for focusing the beam electromagnetically, such as a quadrupole electromagnet.
[0005]
[Problems to be solved by the invention]
Since all the microbeamformers that have been developed so far have only been used to transport the beam in a straight line, secondary charged particles generated by both collimators and the like when forming a microbeam with high-energy ions. It was difficult to eliminate the effects of radiation damage caused by radiation such as gamma rays and neutron rays.
[0006]
In addition, the beam diameter of the microbeam was kept constant or an arbitrary diameter was formed while continuously changing the energy, and at the same time, irradiation was not possible while arbitrarily changing the position of the microbeam. In addition, the conventional microbeam formation has the following problems.
[0007]
(1) When an object collimator or beam divergence limited collimator used in conventional microbeam formation is applied to a high energy ion beam, the quality on the optical axis is good due to transmission and scattering of the beam at the tip of the collimator. The function of passing only the beam and cutting other beams cannot be performed sufficiently.
[0008]
On the other hand, when the collimator material is made thick enough not to transmit the beam, the thickness will be from several centimeters to several meters, which is not practical as a practical device, and ions generated by the collimator edge when passing through the collimator gap The influence of the increase in beam size and energy width due to scattering cannot be ignored.
[0009]
(2) A large amount of radiation (γ rays, neutron rays, secondary ions, etc.) is generated due to the interaction between the collimator material and the high energy ions in addition to the large amount of transmitted ions that have passed through the collimator material. . The transmitted ions and the generated radiation have problems such as radiation damage to the sample irradiated with the ion beam and radiation damage to the human body.
[0010]
(3) In order to irradiate an ion beam three-dimensionally using a pencil beam, that is, while changing the depth, it is necessary to maintain or control the beam size while changing the beam energy. Especially for the purpose of treatment, it is essential to control the irradiation depth according to the shape of the diseased part inside the human body, but this technology has not been realized in the conventional microbeam.
[0011]
[Means to solve the problem]
The method for forming a pencil beam for high-precision three-dimensional irradiation according to the present invention is performed based on the following steps.
[0012]
(1) Using the difference between the energy of the beam that has passed through the gap between the precision beam object collimator and beam divergence limiting collimator necessary for forming the pencil beam and the energy of the beam that has passed through the collimator material, Analyze and separate the beam. By deflecting the beam with a deflecting electromagnet, the influence of radiation (secondary charged particles, gamma rays, neutron rays, etc.) simultaneously generated by the interaction between the collimator material and the incident high energy ions from the accelerator is eliminated.
[0013]
(2) By deflecting the beam using a deflecting electromagnet, the optical chromatic aberration of the generated beam is canceled by a combination of two or more deflecting electromagnets (achromatic optical system).
[0014]
(3) An energy attenuator is installed in front of the object collimator or divergence limiting collimator of the pencil beam forming apparatus, thereby changing the energy of the beam. The beam energy attenuation is performed by using a plate-like or “wedge” -like carbon or metal whose thickness is adjusted to control the beam energy.
[0015]
As shown in FIGS. 1 and 2, the energy attenuator is composed of a pair of carbon, plastic material, or metal material having a wedge shape or a foil shape. In the case of the wedge shape, it is inserted from two directions to control its position, and the thickness of the portion through which the ion beam is transmitted is arbitrarily set. In the case of the foil shape, several types of foils having different thicknesses can be inserted independently, and the total thickness is set by the combination of the inserted foils. When ions pass through the damping material, energy is lost inside the damping material depending on the thickness of the damping material, so the energy of ions after passing through the energy attenuator can be changed by controlling the thickness of the damping material. Can do.
[0016]
(4) In order to keep the pencil beam diameter constant while changing the beam energy, or to form an arbitrary beam diameter, it is linked with energy attenuation by an energy attenuator to excite the bending magnet and quadrupole electromagnet. Precision control of current.
[0017]
(5) While changing the beam energy and keeping the pencil beam diameter constant or controlling the formation of an arbitrary beam diameter, the irradiation is performed with a fixed position at an arbitrary position or an arbitrary width and shape at an arbitrary position. Therefore, combined with the beam scanner by electromagnetic method.
[0018]
【Example】
Hereinafter, an example of a pencil beam forming method using the forming method of the present invention will be described with reference to FIGS.
[0019]
Example 1
As shown in FIG. 1, the apparatus of the present invention forms a pencil beam using electromagnets such as an object collimator 2, a divergence limiting collimator 3, and a precision quadrupole electromagnet 7. At this time, two deflecting electromagnets 4 are used to eliminate the influence of the ion beam transmitted through the object collimator 2 and / or the divergence limiting collimator 3 or the energy attenuated and the radiation generated by the collimator. Bend the beam transport line.
[0020]
Further, the energy of the beam is arbitrarily changed by the energy attenuator 1 installed upstream of the object collimator 2. The spread of the momentum of the beam energy generated when passing through the energy attenuator 1 and the collimators 2 and 3 is limited by the energy analysis slit 5 installed at the entrance / exit between the two deflection electromagnets. The energy analysis system is composed of two 45 ° deflection electromagnets 4 and an analysis slit 5 installed between them.
[0021]
The beam after energy analysis is focused by an electromagnetic method, for example, a quadrupole quadrupole magnet 7, and the depth of focus and the size are controlled by adjusting the excitation current. The irradiation position of the beam can be controlled and scanned by an electromagnetic method installed upstream of the quadrupole electromagnet 7, for example, the beam scanning coil 6 or the like. Further, the energy attenuator 1, the deflecting electromagnet 4, and the quadruple quadrupole electromagnet 7 are operated in an interlocked manner so that the beam size can be kept constant while changing the energy.
[0022]
(Example 2)
As shown in FIG. 2, another apparatus of the present invention arbitrarily changes the energy by using the energy attenuator 1 and passes only the beam center portion by the beam limiting collimator 3. A beam transmitted through the collimator 3, a generated secondary particle beam, radiation, and the like are limited by a collimator (slit) 5.
[0023]
Use an energy analysis system to deflect the beam in order to limit the beam energy width spread by using the energy attenuator 1 and to eliminate the effects of secondary particle beams and radiation generated in the slit 2, collimator 3, etc. Let The energy analysis system includes an energy analysis electromagnet 4 and front and rear slits and collimators 2, 3, and 5. The energy resolution of the energy analysis system depends on the configuration of the entire apparatus and the beam size to be formed. If ΔE / E = 10 ⁻⁴ or less, a pencil beam having a beam size of 1 μm can be easily formed.
[0024]
Further, the deflection electromagnet 7 is used to eliminate the influence of the scattered beam and the generated secondary radiation in the slits 2 and 5 downstream of the energy analysis electromagnet 4. The deflection angle of the deflection electromagnet 7 may be arbitrary. A pencil beam is formed by using an electromagnet such as a quadruple quadrupole magnet 9 as the deflecting electromagnet passing beam.
[0025]
The beam after energy analysis and deflection is focused by an electromagnetic method, for example, a quadruple quadrupole magnet 9, and the depth of focus and the size are controlled by adjusting the excitation current. The irradiation position of the beam can be controlled and scanned by an electromagnetic method installed upstream of the quadrupole electromagnet, for example, the beam scanner 8 or the like. Further, by operating the energy attenuator 1, the energy analysis electromagnet 4, the quadrupole electromagnet 6, the deflection electromagnet 7, and the quadruple quadrupole electromagnet 9 in an interlocking manner, the beam size can be kept constant while changing the energy. .
[0026]
In addition, the quadrupole electromagnet 6 focuses the ion beam analyzed by the devices 1 to 5 using the quadrupole electromagnet 6 so that it does not diverge in the horizontal direction or the vertical direction, and efficiently passes the deflecting electromagnet 7. At the same time, it can also serve to provide an optimum beam for forming a microbeam by the quadruple quadrupole electromagnet 9.
[0027]
【The invention's effect】
The pencil beam treatment technology with a beam size of 1 mm or less with high-energy ions is the world's first state-of-the-art treatment technology. In addition to the conventional malignant tumor, It can be expanded to various benign diseases such as benign tumor, pituitary tumor, paraspinal tumor AVM, neurological disease, and eye disease (senile retinopathy). Further, since it can be treated without surgery, it can be used as an epoch-making treatment technique that reduces the risk associated with surgery and minimizes the burden on the patient.
[0028]
Establishing a technology that irradiates a minute area with high precision while controlling the ion beam three-dimensionally, the target of plant breeding has expanded to all varieties such as vegetables, fruit trees, flower buds, trees, etc. Such as crops that are resistant to ultraviolet rays, dryness, high salts, fruit trees that are not defeated by pests, trees that clean the air and soil, and the like, it is expected that varieties will be greatly improved.
[0029]
By applying ion irradiation technology while controlling the ion implantation position with accuracy of nm to μm for material modification and creation of new materials, for example, ion beams are used to open fine holes with high aspect ratios in organic materials. Incorporating functional materials and semiconductor materials that adsorb atoms and molecules into membranes, creating functional materials such as membranes, nano-sized devices, biofunctional membranes, and semiconductor elements that accurately separate atoms and molecules Inventions are expected to create new industries in the field of nanotechnology and materials.
[Brief description of the drawings]
FIG. 1 is a diagram showing a pencil beam forming method using the forming method of the present invention.
FIG. 2 is a diagram showing another pencil beam forming method using the forming method of the present invention.

Claims (2)

This is a method of forming a pencil-type ion beam having a beam size of 1 mm or less using high-energy ions having an energy of several MeV or more used for treatment of local diseases including malignant tumors and benign tumors accelerated using an accelerator. And
An energy attenuator 1, an object collimator 2, a divergence limiting collimator 3, a deflection electromagnet 4, an energy analysis slit 5, a deflection electromagnet 4 ', a scanning coil 6, and a precision quadrupole electromagnet 7 are arranged in this order. Type ion beam forming device,
The energy attenuator 1 installed upstream of the object collimator 2 is used to arbitrarily change the energy of the high energy beam, and to expand the momentum of the beam energy generated when passing through the energy attenuator 1 and the collimators 2 and 3. Restricted by the energy analysis slit 5 installed between the two 45 ° deflection electromagnets 4 and 4 ′,
The beam after passing through the energy analysis slit is focused by the quadrupole electromagnet 7, the depth of focus on the sample and the beam size are controlled by adjusting the excitation current, and the beam scanning coil installed upstream of the quadrupole electromagnet 7 6. The method according to claim 6, wherein the irradiation position of the beam is controlled and scanned by 6. This is a method of forming a pencil-type ion beam having a beam size of 1 mm or less using high-energy ions having an energy of several MeV or more used for treatment of local diseases including malignant tumors and benign tumors accelerated using an accelerator. And
Energy attenuator 1, first slit 2, beam limiting collimator 3, energy analyzing electromagnet 4, second slit 2, collimator slit 5, quadrupole electromagnet 6, deflection electromagnet 7, beam scanner 8 and quadruple quadrupole electromagnet Using a pencil type ion beam forming apparatus for irradiation arranged in the order of 9,
The energy attenuator 1 is used to arbitrarily change the energy of the high energy beam, the beam limiting collimator 3 is used to pass only the center of the beam,
In order to restrict the beam transmitted through the beam limiting collimator 3, the secondary particle beam and radiation generated during the transmission by the collimator slit 5, and to limit the beam energy width spread by the energy attenuator, the first In order to eliminate the influence of the secondary particle beam and radiation generated by the second slit 2 and the beam limiting collimator 3, the energy analyzing electromagnet 4, the first and second slits 2 before and after the energy analyzing electromagnet 4, and the beam limiting collimator are used. A beam is deflected using an energy analysis system composed of a meter 3 and a collimator slit 5,
Further, the influence of the scattered beam and secondary radiation generated in the slits 2 and 5 at the rear stage of the energy analyzing electromagnet 4 is eliminated by using the deflecting electromagnet 7, and the passing beam of this deflecting electromagnet is used by the quadruple quadrupole electromagnet 9. Forming a pencil beam.

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