The 13th Symposium on Accelerator Science and Technology, Suita, Osaka, Japan, October 2001

Accelerator Facility PATRO for Hadrontherapy at Hyogo Ion Beam Medical Center
Akifumi ITANO
Hyogo Ion Beam Medical Center
1-chome 2-1, Kouto, Shingu-cho, Tho-gun, Hyogo, 679-5162, Japan
Abstract

Hyogo prefecture government has started a design andconstruction of accelerator facility PATRO(ParticleAccelerator for Therapy, Radiology and Oncology) for
hadrontherapy (Particle therapy) in 1995. The facility
consists of two 10 GHz ECR ion sources, 1 MeV/u RFQ
linac, 5 MeV/u Alvarez linac, synchrotron, high-energy
beam transport system and patient irradiation system. Beamparticles for therapy are proton (230 MeV) and carbon (320MeV/u). We have 5 treatment rooms including two
isocentric proton gantry ports. Beam test finished last year
and we have now a full intensity beam which enables a dose
rate of about 5 GyE/min. Transverse dose uniformity isobtained by the wobbling method. Ridge filter is used toobtain a spread-out Bragg peak (SOBP). Clinical trial byproton has successfully started this May. Clinical trial bycarbon is expected to start after completion of the proton
trial.
1. Introduction

Hyogo prefecture government had started a constructionof the accelerator facility PATRO (Particle Accelerator forTherapy, Radiology and Oncology) for hadrontherapy since1995 in Harima Science Garden City, which has about 2000
ha surface and is located about 75 km north-west of Kobecity. It is the major accelerator facility in the city together
with a synchrotron radiation accelerator facility SPring-8 asshown in Fig. 1. It is also a first hadrontherapy facility inJapan that is constructed by a non-national but a prefecture
government level [1-4].

diameter and of fully extended spread out Bragg peak
(SOBP) over the maximum beam range. The facility
consists of injector, synchrotron wit 93.6 m circumference,high-energy beam transport lines and patient irradiation
system. Fig. 2 shows a schematic bird's eye view of theaccelerator facility with photographs of its components ineach system. The injector has two 10 GHz ECR ion sources
with 35 keV/u output energy, 1 MeV/u RFQ linac, 5 MeV/u
Alvarez linac and debuncher. The Alvarez linac accelerates
H2+, helium (Q/A=l/2) and carbon (Q/A=l/3) up to 5
MeV/u. A stripper located downstream of it makes protonand fully stripped carbon ion. Operation rf frequency of thelinacs is 200 MHz. Debuncher then reduces a momentum
spread of the beam. Synchrotron ring is of a separatedfunction type with a strong FODO focusing structure and its
super periodicity is 6. Maximum rigidity of the ring is 5.58
Tm. The beam is extracted by the third-order resonancescheme. rf knockout extraction is also available to gate theextracting beam by patient's breezing. We have 5 treatment
rooms: with Oblique (45-deg) port A, Horizontal andVertical ports B, Horizontal port with patient seated position
C (A-C for carbon and proton) and two isocentric proton
gantry ports G 1 and G2. Ports in A and B has a large
irradiation field (15cmx15cm). Another horizontal port inC
has a small irradiation field (IOcm<j> ). Gantry ports Gl andG2 have an irradiation field with 15cm<!>. A wobbler beam

2. Specifications ofthe Facility

Beam particles of the accelerator facility include proton,helium and carbon. Beam energy ranges are 70-230 MeV/u(40- 300 mm range in human tissue) for proton and helium,
and 70- 320 MeV/u (17- 200 mm range) for carbon. Thebeam intensities are required to satisfy the dose rate of 5GyE/min. for treatment volumes of 15 em field size inFig. 1 Hyogo Ion Beam Medical Center and SPring-8
in Harima Science Garden City, Hyogo.

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;;l"'t;:;s..

~Rotating gantry

Oblique beam port

Vertical high energy beam transport line Horizontal high energy beam transport line~&~c;sas;~

Fig. 2......
......

0>I~

A schematic bird's eye view of the§"@accelerator facility with photographs of its~

components in each system..

~s.

5

Accelerator building and inpatient clinic (right).

C"~~~--~~~~§· E,(:":;R 1on source

riFQ".ilna~

Alvarez Jinac

Synclirotron

The 13th Symposium on Accelerator Science and Technology, Suita, Osaka, Japan, October 2001

delivery system is used to produce transverse dose field
uniformity. Ridge filter is used to obtain a spread out Braggpeak (SOBP). One beam port for physical and/or biological

gauss change of reference magnet field, a B-clock pulse isgenerated to change an output frequency of digitalsynthesizer, which controls the accelerating cavity.

experiments is also constructed. Table 1 summarizes theclinical requirement and physical specifications of thecharged particle beams.
Medical center has an inpatient clinic with 50 beds. In
Fig. 2, an accelerator building and the clinic of the center

Amplification gain of the electronic circuit to measure themagnetic field was determined using an accelerating beam.
If the gain is not well adjusted, the accelerating beam isdeviated from central orbit and is finally lost. This wasactually observed by COD (Closed orbit distortion) monitor.
The amplification gain was changed so as to reduce thisare shown.
Table 1

deviation of the orbit and finally the beam was accelerated
up to the flat top (230 MeV/u). Slow beam extraction was

CLINICAL REQUIREMENT and PHYSICAL
SPECIFICATIONS of CHARGED PARTICLE BEAM

performed with slightly decreasing the current at flattop offocusing quadrupole magnet of the synchrotron ring.

Particles
Energy Range

Proton, Helium and Carbon
70- 230 MeV/u for p, He
70- 320 MeV/u for Carbon

Beam Intensity

Dose Rate
Beam Range

7.3x1o10

pps for p

1.8xl01 0

pps for He

1.2x109
pps for Carbon
5 GyE/min
40 - 300 mm for p and He
13 - 200 mm for Carbon±2% (over treatment field)
15cmxl5cm for ports A, B
1Ocm!j> for port C
15cm4> for gantry ports± 2mm (from isocenter)
400ms
0. 5 Hz for He and Carbon
1 Hz for proton

Extraction efficiency larger than 80% was obtained. Beamintensity was enough to treat patient with dose rate of2Gy/min. This was a maximum intensity officiallypermitted by radiation safety at that moment. Meanwhilebeams were successfully transported to the entrance of eachtreatment room. These results were obtained in about one
month from the start of synchrotron beam test, including aperiod of about 1 week for control software debugging, etc.

In February 2000, full intensity beams of the linacs wereThe OPF (Operation parameter file) thus obtained by He
beam tuning was used without modification to accelerate
and extract carbon beam. The beam could be observed atbeam transport line although the intensity was about 3
orders of magnitude less than that ofHe beam (thus about 2
orders of magnitude less than the required intensity forcarbon).
Then we started a beam test with proton beam. In one
day, beam was extracted with 10% of the required intensity.
Soon the full intensity beam was extracted with extraction
efficiency about 90%.
Finally we started a beam test with carbon (320MeV/u)
in May. In the beginning of June, all beams (p, He and C)
were extracted successfully with required intensity(although a limit of 2 GyE/min dose rate was stillmaintained) and with extraction efficiency 80 - 94%.
Meanwhile the beams were introduced into the treatment
rooms. Apparatus of irradiation system, including monitors

obtained [5,6]. Synchrotron beam test started from end ofMarch. We first started the beam test with He. 1-tum

for dosimetry, were tested using beams. Further details of
the synchrotron and its beam commissioning is describedinjection,

multi-tum injection and rf capture weresuccessively performed. Measurement of rotation frequencyof the beam in the ring by a real time spectrum analyzer wasvery effective to determine the frequency for rf capture.

elsewhere [7].
After the completion of official examination on radiation
safety in September, intensive test on irradiation system toform a uniform irradiation fields started. Meanwhile, toIn acceleration, rf frequency of acceleration cavity iscontrolled by magnetic field of dipole magnets. At about 0.2

inve~tigate the biological dose distribution and the relative
biological effectiveness (RBE) of proton and carbon beams,

Field homogeneity
Field size

Displacement of beam axis
Spill length
Maximum Repetition rate

3. Beam Test

Installation of the apparatus started in March 1999. Beamacceleration test of injector linacs started in December 1999.

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Plot [ 2.2 IT* (T- 0.7) IT,

preclinical biology experiments were performed using
human cell lines cultured in vitro as targets from October toDecember. Skin damage effect was also measured using
mice as targets in the same period.
From December, a real simulation test of treatment withthe participation of medical staffs started. Software of bothtreatment control system and accelerator control system was0.70Proton~ '-.,:I"'

0.5

checked and revised.
In April 2001, an operation with full intensity beam,
which enables patient treatment with dose rate of 5
GyEimin, was permitted by official radiation safety office.

1,5} ]{T,0.4'----..

432~-...........

5sec

Plot[ 4 IT * (T - 1.6 ) IT,

4. Gated Beam Extraction by Patient Breezing
Gated beam extraction by patient's breezing is now
indispensable in hadrontherapy to obtain a good dose
distribution on cancer target and to reduce a damage of
normal tissue [8]. rf knockout method was used for thegated beam extraction [9]. To keep effective beam intensity
in gated extraction, it is necessary to choose a cycle length
T (sec) of synchrotron pulse properly. If we assume thatpatient breezing motion is random relative to synchrotron
pulse, one can calculate a probability that the gate coincides
with flat top of synchrotron pulse as a ratio (T -A)IT, where
A is a sum of the times for flat base, acceleration anddeceleration. Then an effective beam intensity or effective
dose is proportional to 1/T*(T-A)IA. The effective doses areplotted as a function ofT in Fig. 3 for proton and carbon. It
has a maximum at T around 1. 6 sec for proton and at T

{T, 2,5} ]Carbon...---........

0.62
0.6/

n0.58
l.

~/I~

I

t0.56

IlI

0.54
0.52

0.5
2

2.5

3

3.5

4"'~

4.5

5sec

Fig. 3 Effective dose as a function of synchrotron pulse
length T (sec).

around 3.3 sec for carbon. Fig. 4 shows a proton beam spillof gated extraction. Circulating beam current increases
during acceleration and decreases by extraction. But whengate is off, the beam current keeps its intensity, as the beam
is no more extracted. Then it is decreased duringdeceleration. At about two third of the synchrotron pulses,
beam was extracted and irradiated on patient.

5. Daily Operation for the Clinical Trial
From May, clinical trials by proton beam started. Every
weekday at 5 o'clock in the morning, two operators come toFig. 4 Gated beam extraction. Magnet current, circulating
beam current and beam spill are shown.

the control room. They start a cooling water system andthen patrol the equipments in accelerator room. In 20 to 30
minutes, temperature of the cooling water for linac cavities
become stabilized. Then they set the power supplies ofprofiles and intensity at ECR ion source, linacs, synchrotron
and high-energy beam transport line (HEBT) successively.
In about 5 minutes, they check beam profile and intensity inaccelerator on. In 15 minutes, all power supplies becomeworking. Then they start beam tuning by checking beam

front of a neutron shutter at the entrance of one treatment
room. Then they introduce a beam into the treatment room-163-The .13th Symposium on Accelerator Science and Technology, Suita, Osaka, Japan, October 2001

and check the beam profile. They check beam profiles andtheir central positions in all treatment rooms and for several

6. Summary

rotation angles of the gantries for three proton energies

Accelerator facility for hadrontherapy must supply very
stable beams for the patient treatment and with high degree

every day, i.e., I5-18 beam courses depending on thetreatment request of the day (Different rotation angle ofgantry is counted as one course.) for I 50, 190 and 230 MeVof proton beam. These three energies cover the different
beam range in human tissue required by the treatment.
Beam profile just upstream of the neutron shutter is stockedin the memory of accelerator control computer. To changeof reproducibility when beam course change and/or energychange are required. From the results of daily operations forthe clinical trials, it is proved that the accelerator facility atHyogo Ion Beam Medical Center stands for theserequirements. After the completion of clinical trial withproton, clinical trial with carbon is expected to start. Patient

the beam course and check the beam profile it takes about 3

treatment with commercial basis is also expected to start- 5 minutes. It takes about 15 minutes to change the beam

next year.

energy and then check the beam profile in front of one
treatment room. All parameter change of the (steering)magnet power supplies after the beam tuning and theresulting beam profile just in front of the neutron shutter are

I express my thanks to the colleagues of the hyogo ion

stocked in the memory of accelerator control computer for

beam medical center, guest scientists from institutes andeach beam course. These parameters are set on the request

universities, and engineers ofMitsubishi El. Corp. and otherof beam course by medical staff for the treatment and thecompanies for their participations to this hadrontherapy

stocked profile is compared with a beam profile measured atproject on the stages of design, construction, commissioningthat moment.

and daily operation. My special thanks are for the operation
crews of Mitsubishi El. Corp. and Accelerator Engineering

In the stage of clinical trial, we check the beam profile inall treatment rooms to take statistical data on thereproducibility of the beam position at isocenter. For thefixed beam, it is ±0.5-Imm. For the gantry, it is ±lmm.
Gantry beam position at isocenter seems to have some
hysteresis of about ±I mm depending on the direction of therotation to arrive at the position. So gantry isocenter isreproduced within ±2mm, as is required by specification.
We are now studying how to reduce number of OPF(Operation parameter file) to cover all rotation angles of thegantry. 4 OPF seem to suffice (45, 135, 225, 315 deg) tocover within about ±Imm. We will add 4 OPF (0,90, 180,270 deg). In total 8 OPF will cover all rotation angles ofgantry.
From 9 o'clock, we start patient treatments. Intensity ofproton beam supplied for the treatment is typically

7. Acknowledg ements

Corp.
References[I] A Itano et al., Proc. ofNIRS International Seminar on
the Application of Heavy Ion Accelerator to Radiation
Therapy of Cancer in connection with XXI PTCOG
Meeting, Chiba, Japan, NIRS-M-103 (1994) 88.
[2] A ltano et al., Proc. of the lOth Sympo. on Accel. Sci.
and Tech., Hitachinaka, Japan (1995) 398.
[3] A Itano et al., Advances in Hadrontherapy, The 2nd Int.
Sympo. on Hadrontherapy, PSI and CERN, 9-13 September
1996, Elsevier (1997) 193.
[4] T. Akagi et al., Proc. ofthe lith Sympo. on Accel. Sci.

7-8xl010 ppp with synchrotron pulse length T of 1.6 sec.
When there were I4 patients for the treatment in a day as

and Tech., Harima, SPring-8, Japan (1997) Il6.
[5] K. Sawada et al., Rev. Sci. Instrum. 71(2000)987.
[6) K. Sawada et al., Proc. of the 3rd Symp. on Accel. andwas the case in August, the treatment was finished at about

Related Technology for Appl., Tokyo, Japan (2000) 11.

5 o'clock in the evening. Patient Dosimetry is repeated[7] Y. Ishi et al., these proceedings.
[8) S. Minohara et al., Int. J. Radiation Oncology Bioi. Phy.,

every day for each patient. It is also measured even in thetreatment room with no entry of the patient at that day totake statistical data on stability and reproducibility.
With statistical evidence obtained in the clinical trials, the47 (2000) 1097.
[9] K. Noda et al., Nucl. Instrum. Methods Phy. Res., A374
(1996) 269.

amount of daily beam tuning in the morning and dosimetry
checking procedure will be reduced in future operation.

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