JP2006294575A - Low-temperature charged particle beam treatment accelerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-temperature charged particle beam treatment accelerator for reducing the weight of the component of an accelerator and reducing costs greatly by accelerating, storing, and taken out low-emittance beams that are strong "cold ion beams". <P>SOLUTION: A beam size is reduced greatly in an electron beam cooling device 6 by a low-emittance EBIS-type ion source or hollow beams. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The invention of this application is a field related to a cancer treatment device by mainly suppressing the increase of cancer cells in the human body by utilizing physical and biological characteristics due to the ionization action of charged particles.

When charged particle beams (hereinafter referred to as ion beams) such as protons and carbon ions have a beam cross-sectional area exceeding a certain level, there is a physical phenomenon called Bragg peak. This is a phenomenon in which when a substance such as water or the human body is irradiated with an ion beam, strong ionization occurs at a depth corresponding to the energy. Accelerator physicist Robert Wilson believes that using this Bragg peak to irradiate a deep cancer with an ion beam can be used to treat the ideal cancer without surgical pain or side effects of anticancer drugs. Proposed this. In response to this, a therapeutic test was conducted in the heavy ion synchrotron accelerator of the Lawrence Berkeley Laboratory of the University of California attached research laboratory. It has been shut down. After this, a part of the proton accelerator of the Institute for High Energy Physics in Japan (currently the High Energy Accelerator Research Organization) was tested by the University of Tsukuba for proton experiments, and the effect was demonstrated. Independent of this proton therapy, the National Institute of Radiological Sciences built a heavy ion beam therapy device (referred to as HIMAC) dedicated to cancer treatment and treated more than 2200 cancer patients in early 2005. The effect was remarkable, and we were able to obtain many cases where cancer difficult to treat with other treatments was completely cured with carbon ions. In response to this result, Hyogo Prefecture also started treatment by constructing a reduced version of HIMAC. Since then, it has been clearly recognized that heavy particle beams have a great effect on biological cells in addition to the physical properties of Bragg Peak, and there are countries in Europe that are trying to introduce it. Above all, Germany understood the effects of carbon ions most clearly, and its construction started at the University of Heidelburg. The therapeutic effect of heavy particle beams has been demonstrated theoretically and clearly in clinical practice. Although there has been a strong movement to popularize this, the size of the device and its high price are a major obstacle. How to solve this problem of cost and size technically is a big issue for the spread of heavy ion radiotherapy, but who has a national project, who has a technical solution to solve this problem? However, no proposal has been made. An initial solution to this problem is disclosed by the present invention.

Reference 1

M.M. Kumada and V.K. V. Parkhomchuk, to be announced at the 2005 International Conference on Accelerators in Knoxville, USA. It will be announced at the particle beam workshop PTCOG42 in Tokyo in 2005. First and international academic papers and presentations of the scientific logic of the present invention.

Reference 2

V. V. Parkhomchuk. New insights in the theory of electro cooling. Nucl. Instr. Meth. Phys. Res. , A441 (2000).
An academic paper on the electronic cooling device used in the present invention.

Reference 3

D. A. Swenson, Compact Injector Linacs for Proton Therapy Synchrotrons,
A paper detailing the injectors used in the present invention.

Reference 4

C. Bieth et al. , Reent results with SUPERNANOGAN ECR ion source for Hadrontherapy, PANTECHNIC, ISN Grenoble.
Distributor of ion source with low emittance used in the present invention.

Reference 5

D. A Swenson “BNCT Neutrons from Carbon Ion Injector Linacs”, to bepublished in Proc. of PTCOG04.
An academic paper on the application of the injector linac to the BNCT treatment that is optionally possible with the present invention.

There are two types of particle beam medical accelerators: electron accelerators and proton / heavy particle accelerators. Among these, those using the Bragg Peak proposed in the present invention are classified into a proton / heavy particle linear accelerator (linac) and a circular accelerator. The cost is too high for linac alone to make the energy needed for treatment. A circular accelerator is roughly classified into a cyclotron, a FFAG (Fixed Field Alternating Gradient accelerator), and a synchrotron. Of these, cyclotron and FFAG are too large to accelerate carbon ions and are not suitable for heavy ion radiotherapy. One of the problems to be solved in order to spread the heavy ion radiotherapy is cost reduction. To reduce costs, it is necessary to reduce the size of the accelerator or reduce the price of the components of the device. In order to realize the former miniaturization, there is no choice but to increase the magnetic field strength of the deflection electromagnet in the circular accelerator. However, in a normal electromagnet, when the magnetic field strength is increased, a phenomenon of magnetic saturation occurs in the electromagnet of the magnet material, the performance of the accelerator is deteriorated, and the power conversion efficiency is also lowered, which is uneconomical. At present, there is no concrete solution. However, in the present invention, the components of the circular accelerator can be greatly reduced.
It is achieved by implementing a cold charged particle beam therapy accelerator (CBS) with a “cold ion beam”.

The problem the invention was trying to solve

As cost reduction of heavy ion accelerator is an issue to be solved, synchrotron is assumed as a circular accelerator. To reduce costs, we want to make the electromagnet, which is the main component, smaller. The size of the electromagnet can be reduced by shortening the magnetic field strength and the length and width of the magnetic pole gap (gap) that houses the vacuum chamber for accelerating and accumulating the ion beam. That is, the size of the ion beam may be reduced. The size of the ion beam depends on factors such as the beta function (twice parameter), dispersion function, and equilibrium orbit distortion (COD) determined by the beam engineering of the accelerator, and the beam emittance that is a property of the ion beam itself ( beam energy) and energy spread. In general, the smaller the emission, the better. In the case of a multi-stage compound device such as an ion source, injector, main synchrotron, high energy beam transport system, and beam irradiation system such as an ion synchrotron, this beam emittance is normalized by the energy of the beam. When considering emittance, the value at the outlet of the first ion source is not exceeded. This is determined by the basic laws of physics. The first solution of the present invention is to select the ion source having the smallest emittance from among the obtained ion sources. The lowest emittance obtained is an EBIS type ion source, which greatly reduces the low cost problem of the device that the present invention has revealed. The second solution is to reduce the beam emittance by beam cooling after leaving the ion source. These include stochastic cooling, statistical cooling, and electron beam cooling. The beam cooling method avoids the previous emittance conservation law in a clever way by human knowledge. Of these, the best method is a special electron beam cooling method using a hollow beam invented by Parkhomchuk. The reason is that the cooling time is short and a high-intensity ion beam can be cooled. With this hollow beam electron cooling method, it is possible to cool the beam emittance in both the vertical and horizontal directions. (The vertical direction is the area of the momentum phase space, and the horizontal direction is the area of the horizontal and vertical phase spaces.)

The invention's effect

By using the CBS that generates a cold ion beam as referred to in the present invention, it is possible to extremely reduce the size of the components of the accelerator, and as a result, the cost of the entire apparatus can be greatly reduced. The amount of beam emittance reduction depends on the beam intensity to be accelerated. For example, when the lateral beam emittance is cooled to 1/25, the size of the ion beam becomes 1/10 in the horizontal and vertical directions. In this case, the gap of the magnet is 1/5, and the lateral width of the magnet is also 1/5. As a result, the amount of current required to produce the same magnetic field strength may be 1/5. In this case, the cross-sectional area of the electromagnet can be reduced to about 1/10. As a result, the weight of the electromagnet becomes 1/10, and the power source of the high-power electromagnet that excites the electromagnet requires 1/5 power. Thanks to this, it is possible to reduce the size of the substation equipment, which contributes to the reduction of the initial cost. The current voltage of the deflection electromagnet power source of a typical popular heavy particle synchrotron is 4 kA and 1.2 kV, and the power is 4.8 MVA. If a quadrupole electromagnet or the like is included, the magnet-related alone exceeds 5 MVA. The ion beam extracted from the synchrotron consists of a string of magnets that is as long as or longer than the synchrotron and has the same level of power consumption. The heavy particle ion apparatus of the present invention significantly reduces the electric power, so that the power cost can be reduced by a large proportion of the operation and maintenance cost.
CBS's cold intense ion beam also provides various benefits, including:
(1) Since the beam size is small when the ion beam is extracted, it is possible to reduce the gap of the extraction device, and facilitate the extraction of the beam with high energy, which has been difficult in the past.
(2) It is possible to reduce the weight of the magnet of the rotating gantry, which has conventionally been difficult to design and manufacture because the device is too heavy.

Embodiment

The inventive cold beam particle beam therapy accelerator (CBS) according to the present application is implemented as shown in FIG.

FIG. 1 shows the whole image including a part of the beam line. Each device constituting the whole is: Ion source 2. 2. RFQ (Radio Frequency Quadrupole) RFI (Radio frequency Inter digital) 4. Electronic cooler 5. Booster Synchrotron Main synchrotron 7. It consists of a heavy particle beam line. There are two options for the ion source. In the case where electron cooling can be performed, an EBIS type ion source that generates fully ionized carbon ions that can obtain a cold intense ion beam is used. In this case, a single beam injection method is performed on the main accelerator. That is, an ion beam for one pulse is injected from the injector per cycle of the main accelerator. When using electronic cooling, use SUPERNANOGUN manufactured by PANTECNIC or an equivalent or higher carbon ion beam. The purpose is to suppress the space charge effect and increase the beam intensity. Then, the electron cooling is performed at a time of about 0.1 second per pulse, the beam is narrowed, the next pulse is incident on the vacant gap, the cooling is performed again, and this cycle is repeated to obtain about 2.5 × ^{10 10.} / Inject, accelerate, store, and extract carbon ions up to the cycle. FIG. 1 shows a configuration different from that of other heavy particle beam synchrotrons. That is, there is a booster synchrotron between the injector linac and the main synchrotron. The method of increasing the beam intensity at the final energy by inserting a booster synchrotron is a known knowledge, and adopting such a configuration makes it possible to relax the space charge limit of the main accelerator and improve the performance. The invention makes it possible to perform two types of acceleration of a carbon ion beam and a proton beam in one cycle of the main synchrotron. The RINAC system RFI is introduced as an injector in this equipment, so it is possible to accelerate high-intensity protons and carbon ions under CBS operating conditions. The dream cancer treatment BNCT (neutron capture therapy) is made possible with a small additional budget.

Explanation of symbols

1. Ion source 2. RFQ
3. RFI
4). 4. Booster synchrotron 5. Proton beam line Electronic cooling device (Electron Cooler)
7). Heavy particle beam line

Claims (4)

By using a cold ion beam with a small beam emittance in a cancer treatment device by suppressing the increase of cancer cells in the human body mainly by utilizing physical and biological characteristics by the ionization action of charged particles. A method of ion beam supply that significantly reduces the volume of accelerator components.   2. The method of claim 1, wherein a hollow electron beam is generated to enable acceleration, storage, and extraction of a high intensity ion beam.   2. The method according to claim 1, wherein a booster synchrotron is inserted between the injector linac and the main accelerator synchrotron, so that carbon ion therapy and proton beam therapy can be performed almost simultaneously in an independent treatment room.   The combination of claims 1, 2, and 3 makes it possible to increase the beam intensity of carbon ions by 10 times that of a conventional accelerator, thereby increasing the number of treatment rooms by 10 times, and the cost performance of the treatment apparatus. This is a way to improve significantly.