NIRS HEAVY PARTICLE ACCELERATOR FOR MEDICAL USE
K. Kawachi, H. Matsuzawa and H. Tsunemoto
National Institute of Radiological Sciences
9-1, Anagawa 4-chome, Chiba-shi 260, Japan
research works performed at the LBL (Lawrence Berkeley
Laboratory in California) using 185-inch synchrocyclotron and BEVALAC which is a unique combination of two
accelerators, the Bevatron and the HILAC. The present
data have indicated that the heavy particle beams offer
several advantage over conventional photon beams incancer treatment, or they are at least as long as withthe best of other available methods.

ABSTRACTThis report is mainly concerned with the present
situation and future schedule of the construction of a
dedicated heavy particle accelerator for medical use atthe NIRS. The design of this machine will be speciffically optimized to meet the accelerator requirements
which are determined from the experience of theparticle radiotherapy at the NIRS and from the various
physical, biological and clinical heavy particle dataof the LBL. The conceptual design of this machine has
The fundamental andjust started from this year.
detailed design wi 11 be carried out during the next twofiscal years. The whole accelerator facilities will becompleted in 1991 and the clinical trials using heavy
particles will start in 1992.

ACCELERATOR REQUIREMENTS
The accelerator requirements of the NIRS machine
have been arranged by the planning group of heavy
particle accelerator for medical use, based on theideas of the user's working group. The construction
committee of heavy particle accelerator for medical useform.
approved the draft almost in its original
Further, the draft of the requirements was reported to
the research committee of particle radiation therapy
which involved the outside specialists and finaly
determined by the congress of the NIRS.
The outline of these requirements are listed in
the fo 11 owings.

INTRODUCTION
As a link in the chain of a national project forcancer extermination, the NIRS (National Institute ofRadiological Sciences) has a plan to construct a
dedicated heavy particle accelerator for medical use,which will contribute to the improvement of cancer
The NIRS Hospital has used high energy
treatment.
radiation, such as photons and electrons, for cancer
treatment during more than 20 years. Further, several
clinical trials using particle beams, such as fastneutrons and protons, have been also performed at theNIRS during more than 15 years.
The first stage of fast neutron radiotherapy wascarried out from May 1967 to Sptember 1975 using a Van
de Graaff. Number of treated patient were 36 during
Most of cases were far advanced andthis period.
thought hardly curable by conventional treatment, andThe results
23 patients were malignant melanoma.
indicated a marked improvement in local control
especially for the primary cases.
The second stage of fast neutron radiotherapy hasbeen carried out genuinely since November 1975 using a
medical cyclotron which is able to provide a verticalneutron beam for therapy. More than 1200 patients weretreated with this neutron radiotherapy system. The
results demonstrate that the fast neutron beam could be
effectively applied to improve the cure rate for thetumors of selected organs, such as carcinoma of thelarynx and the esophagus, Pancost's tumor of the lungand osteosarcoma.
The clinical trial of proton radiotherapy has been
done 27 patients since October 1979. This number ofpatient is rather small because of a limited machinetime available, that is a half day per week, and alimited range of 70 MeV protons which can only beapplied to the superficial region within 4 em depth intissue. However, the results have been showing good
local control and cure rate with making good use of thecharacteristics of definite range of protons.
From these results, it has been found that the useof these particles are highly expected as the effective
modalities for cancer treatment.
On the other hands, the heavy particles possess
the exquisite dose localization properties of protons
and the biological high-LET properties of neutrons.
From the above mentioned our experiences, such heavy
particles are considered as next trump ~ard in theTherefore, we proposed afuture radiation therapy.
special research program on the medical use of theheavy particle beams, which includes the constructionof a heavy particle accelerator for medical use at theNIRS. A main purpose of this accelerator involves theevaluation of heavy particle beams in the treatment ofcancer in humans, and the basic and clinical research,such as physics and biology in medicine. Preliminary

Requirements for particles extracted from main
accelerator
1. Particle species:
From He to Si and Ar (He, C, 0, Ne, Si and Ar areinvolved at least).
.
2. Accelerating energy:
The kinetic energy is continuously variable in theranges from 100 MeV/amu to 600 MeV/amu for all above
mentioned particles in principle. At least, the energy
is variable as stepwisely as the steps of 100 MeV/amu
within the above energy range. The maximum kinetic
energy of 600 MeV/amu was determined from the rangeenergy relationship of Fig.l so as to secure the rangeof 20 em in soft tissue for silicon.
I.

::;::
0f-z

<(:I:a..

w""
f<(3::;

10w"'z<(""

300

400

600500(MeV/amu)

KINETIC ENERGY

Fig.l409

Range in water phantom for heavy particles ofinterest as a function of their kinetic energy.

high dose rate.
The synclotron has two beam extraction channels offast and slow extractions. Both beams are delivered toeach irradiation room with same beam line.
3. Use of radioactive beam:
Radioactive beams which are positron emitter areavailable for diagnosis and/or traetment planning.

Beam intensity (particle flux density):
Low intensity for counting experiments (especiallyfor diagnostic purpose) is less than 10 6 particles/sec(for all particles).
High intensty for therapy is as follows.
3.

particleparticles/sec

He

2.2 X 1010
3.7 X 109l.6x 10 9
8.4 X 108
5.0 X 108cNeSi
Ar

III. Irradiation facilities
1. Irradiation room and beam port:
Each
Treatment room: 4 rooms (A, B, C and D).
room A and B has two (horizontal and vertical) beamlines. Each room C and D has only a holizontal beamline
Biology cave one room (has a horizontal beam)
Physics cave one room (has a horizontal beam)
one room (has three or more
General use cavehorizontal beam lines)
Radioactive beam cave one room (has a horizontalbeam)
Radiographic cave : one room (has a horizontalbeam line)
2. Control system
Operation of accelerator itself, and operation oftherapy and diagnosis facilities should be separated.
The control system should be fully automated from thestart to the end of operation, so as to operate with as
few people as possible.
The system should provide self-diagnosing featuresto quickly repaire the failing components.
In order to increase the operating efficiency, ion
They can be quickly
sources should be attached.
switched one by one. Accelerating energy in the sameion source should be possible to change easily in shorttime.

These beam intensities were determined fromconsiderations of treatment volume and dose rate, which
are the dose rate of 500 rad/min and the treatment
volume for 10 em square field and 20 em depth except
silicon and argon. Further the beam losses in thescatterers and in the beam transport system from beam
extraction site to treatment site are consideredfactors of 10 in the above intensities.
4. Momentum spread and emittance:
2 x 10- 3
Momentum spread ~p/p
2 x 10- 5 m radians
Emittance
The above values indicate the guide lines. They
are not essential. The values should be within therange in which beams can be used for beam transport andpatient treatment with no trouble.
Beam requirements at therapeutic site
Maximum field size and uniformity:
30 x 30 em
Maximum field size
< ± 2 %
Dose uniformity
In order to spread the beam as required field size
double scatterer method is certainly available. Either
magnetically deforcusing system or spot beam scanning
Pencil beam irradiation
system is also available.
within 5 mm diameter is also provided.
2. Beam waveform:
Beam with long pulse and flat top intensity (~ 100ms/pulse) is extracted. Beam duty factor is more -than
25 % at the repetition rates of less than 2 Hz.
Short pulse extraction is possible at the repetition rates of 2 Hz, for the special experiments withII.
1.

PROPOSED SCHEDULE
In 1984 (Japanese fiscal year), the conceptual
design and developing study of the NIRS heavy particle
accelerator for medical use were accepted by Japanese
They have been ordered to four Japanesegovernment.
major companies which have a volition to join theconstruction and have potentials enough to make theaccelerator design. The reports will be submitted tothe NIRS by the end of February 1985.
PRE-ACCELERATOR

General purpose

Consultation room
24I
Therapy

II Contra 1 r;;'omu uv:;)J
f:::::=::=J-Power suply~MAINFig.2

Plan view of a conceptual facility layout.
410

Before the order of the conceptual design of thismachine, the NIR~ set ·up the adviser committee for
examination of the accelerator design and study. It isorganized by several staff of the NIRS and the experts
andphysics
of accelerator physics, medical
radiotherapy of other institutes. The committee will
give the careful consideration and suport to promote
this project in future.
To realize this long-term project within the 10years all-around strategy for cancer extermination, thefollowing time schedule has been proposed.
I.

Design of technical components and buildings(1984 - 1986)
1984
Conceptual design1.
1985
Fundamental design2.
1986
Detailed design
3.

II.

Construction of technical components(1987 - 1991)
Pre-accelerator and main accelerator
1.
1987 - 1989
Manufacture
1990
Installation
Beam transport and irradiation facilities
2.
1988 - 1990
Manufacture
1990 - 1991
Installation

III. Construction of Buildings (1987 - 1990)
1987 - 1990
Building structure1.
1987 - 1989
Conventiona 1 components
2.
IV.

Commissioning (1991 - 1992)v.

Research and Clincal trials with new machine)(1991 1991 1 . Dosimetry
1991 Biological test2.
1992 Clinical trials
3.

Some special terminology in the above schedule aredefined as follows:Technical components: Accelerator and beam
1.
delivery.
Building structure: Standard elements of the2.
building.
Convention a1 components: Building components
3.
directly related to the accelerator only, e.g.,shielding (except stractural walls), cooling tower
special power requirements, cranes.
Commissioning: Bringing the installed components
4.
into a full and reliable operating status;operator training.
From our preliminary investigation on the NIRS
heavy particle accelerator for medical use, one of thetypical plan view of a conceptual facility layout which
will be satisfy the accelerator requirements, is shownin Fig.2. The principal elements of this machine are:a strong focusing synchrotron as a main acclerator; apre-accelerator, consisting of a Penning ion source, an
RFQ and Alvarez linacs; a beam delivery system; and a
The specification ofcomprehensive control system.
these elements will be put into concrete shape in thestage of design studies.
This accelerator facility is unique and expensive
Therefore, we are fully expecting that theresource.
new facilities will also be focus to a variety of
external users who will conduct their own experimental
research or collaboration on our programs with ourstaff.

411