OPERATION OF MEDICAL ACCELERATOR PATROAT HYOGO ION BEAM MEDICAL CENTER
A. Itano, T. Akagi, A. Higashi, Hyogo Ion Beam Medical Center, Shingucho, Hyogo, 679, Japan
S. Fukushima, A. Fujita, Mitsubishi Electric Corp., Wadamisaki, Kobe, 652-8555, JapanY. Honda, H. Isa, K. Nishikigouri, Accelerator Engineering Corp., Shingucho, Hyogo, 679, Japan
Abstract
PATRO (Particle Accelerator for Therapy, Radiologyand Oncology) is a medical accelerator facility forhadrontherapy of cancer at Hyogo Ion Beam MedicalCenter (HIBMC). Beam particles are proton (230 MeV)
and carbon (320 MeV/u). After the beam commissioning
and the tuning of irradiation system in 2000, we
performed the clinical trials with proton and carbon
beams from May 2001 until July 2002. We operated theaccelerator for about 11,000 hours since the beginning of
the beam tuning until the end of the clinical trials and forabout 5,000 hours during the clinical trials. No serious
troubles happened during the clinical trials. The stability
and the reproducibility of the beams were well proved.

1 INTRODUCTION
Hyogo prefecture government had started aconstruction of the medical accelerator facility PATRO(Particle Accelerator for Therapy, Radiology andOncology) for hadrontherapy with proton and carbon
beams since 1995 in Harima Science Garden City, which
is about 75km northwest of Kobe city. Figure 1 shows abird’s eye view of Hyogo Ion Beam Medical Center(HIBMC). An accelerator building for PATRO and ahospital with an inpatient ward (50 beds) are shown. Afterthe beam commissioning and the tuning of irradiation
system in 2000, clinical trials (with 30+30 patients) were
performed in 2001 with proton and in 2002 with carbon.
The Ministry of Health, Labour and Welfare approved a
medical use of the facility with proton in October 2002.
Proton radiotherapy will start in April 2003. Carbon
radiotherapy will start after the approval of medical use
with carbon beam, perhaps in 2004.

accelerates H2+, helium (Q/A=1/2) and carbon (Q/A=1/3)
up to 5 MeV/u. A stripper located downstream of Alvarez
linac makes proton and fully stripped carbon ion.
Operation rf frequency of the linacs is 200 MHz.
Debuncher then reduces a momentum spread of the beam.
Synchrotron ring is of a separated function type with astrong FODO focusing structure and its super periodicity
is 6. Maximum rigidity of the ring is 5.58 Tm (B=1.38T).
rf accelerating frequency range is 0.993 – 6.417 MHz
with harmonic number 3. The maximum rf voltage is 5.2
kV. The beam is extracted by the third-order resonancescheme at tune 11/3.
The accelerator control system [1] consists of:1) VME (Versa Module Europa) computers and Pattern
Memories for synchrotron pattern and timing control.
2) PLC (Programmable Logic Controller) for control ofDC power supplies, vacuum and monitors.

Figure 1: A view of Hyogo Ion Beam Medical Center.

2 SPECIFICATIONS OF THE 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 protonand helium, and 70 - 320 MeV/u (17 – 200 mm range) for
carbon. The beam intensities are required to satisfy thedose rate of 5 GyE/min. for treatment volumes of 15 cm
field size in diameter and of fully extended spread out
Bragg peak (SOBP) over the maximum beam range. Thefacility consists of injector, synchrotron wit 93.6 mcircumference, high-energy beam transport lines andpatient irradiation system. Figure 2 shows a layout of thePATRO. 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 linac system
Figure 2: Layout of the medical accelerator PATRO.

3) RIO (Remote Input Output) local controllers with
optical fiber link distributed in DC power supply units.
4) Irradiation system I/F (interface) PLC.
5) PC (Personal Computer) with Windows NT for Man
Machine Interface (MMI).
6) Ethernet and PLC networks.
These configurations satisfy a response time of data
update cycle in MMI, change of power-supply current andpattern data loading. Interfacing with irradiation systemestablishes a QA (Quality Assurance) of the treatment.
Figure 3 shows the accelerator control room. Area of thecontrol room is 130 m2. There are 2 sets (left and right) ofconsole with 3 display screens, of which the central one isfor MMI with mouse and keyboard, and another console(center) with 1 display as an operation file server.
We have 5 treatment rooms: A with Oblique (45-deg)
port, B with Horizontal and Vertical ports, C with
Horizontal port with patient sitting position (A-C forcarbon and proton) and G1, G2 with isocentric proton
gantry ports. A wobbler beam delivery system is used toproduce transverse dose field uniformity. Ridge filter isused to obtain a spread out Bragg peak (SOBP). Table 1
summarizes the clinical requirement and physicalspecifications of the charged particle beams. Proton andcarbon beams are used for the treatment. Further detail ofthe accelerator is described elsewhere [2,3].

3 BEAM COMMISSIONING
Installation of the apparatus started in March 1999.
Beam acceleration test of injector linacs started inDecember 1999. In February 2000, full intensity beams of
the linacs were obtained [4,5]. Synchrotron beam test
started from end of March. We first started the beam testwith He. 1-turn injection, multi-turn injection, rf capture,acceleration and slow extraction at 230 MeV/u weresuccessively performed. Extraction efficiency larger than
80% was obtained. Beam intensity was enough to treat
patient with dose rate of 2Gy/min. This was a maximum
intensity officially permitted by radiation safety at that

Figure 3: Accelerator control room of PATRO.

moment. Meanwhile extracted beams were successfullytransported to the entrance of each treatment room. These
results were obtained in about one month from the start ofsynchrotron beam test, including a period of about 1 week
for control software debugging, etc. The operation
parameter file (OPF) of synchrotron thus obtained by He
beam tuning was used without modification to inject,accelerate and extract carbon beam at 230 MeV/u. The
beam could be observed at beam transport line, although
the intensity was about 3 orders of magnitude less thanthat of He beam.
Then we started a beam test with proton beam (230MeV). In one day, beam was extracted with 10% of therequired intensity. Soon the full intensity beam wasextracted with extraction efficiency about 90%.
Finally we started a beam test with carbon (320MeV/u)
in May after the increase of power demand of HIBMC up
to 2.8 MW. This amount of power demand is maintained
during the clinical trials and the proton radiotherapy thatstarts in April 2003. 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 wasstill maintained) and with extraction efficiency 80 - 94%.
Meanwhile the beams were introduced into the treatment
rooms. Apparatus of irradiation system, including
monitors for Dosimetry, were tested using beams. Further
details of the synchrotron and its beam commissioning isdescribed elsewhere [2].
After the completion of official examination onradiation safety in September, intensive test on irradiation
system to form a uniform irradiation fields started. FromDecember, a real simulation test of treatment with theparticipation of medical staffs started. Software of both
treatment control system and accelerator control system
was checked and revised.
In April 2001, an operation with full intensity beam,
which enables the treatment with dose rate of 5 GyE/min,
was permitted by official radiation safety office.
Table 1: Clinical requirements and physical specificationsof the charged particle beams.
Particles
Proton, Helium and Carbon
Energy Range
70 - 230 MeV/u for p, He70 - 320 MeV/u for Carbon
Beam Intensity
7.3x1010 pps for p
1.8x1010 pps for He
1.2x109
pps for Carbon
Dose Rate
5 GyE/minBeam Range
40 - 300 mm for p and He
13 - 200 mm for Carbon
Field homogeneity±2% (over treatment field)
Field size
15cmx15cm for ports A, B
10cmφ for port C
15cmφ for gantry ports G1, 2
Displacement of beam
± 2mm (from isocenter)
Spill length
400ms
Maximum repetition
0.5 Hz for He and Carbon
1 Hz for proton

4 DAILY OPERATIONFOR THE CLINICAL TRIALS
During May – November 2001, clinical trials [6] with
proton beam were performed. Every weekday at 5 o'clockin the morning, two operators come to the control room.
They start a cooling water system and then patrol theequipments in accelerator room. In 20 to 30 minutes,
temperature of the cooling water for linac cavities becomestabilized. Then they set the power supplies of accelerator
on. In 15 minutes, all power supplies become working.
Then they start beam tuning by checking beam profiles
and intensity at ECR ion source, linacs, synchrotron andhigh-energy beam transport line (HEBT) successively. Inabout 5 minutes, they check beam profile and intensity infront of a neutron shutter at the entrance of one treatment
room. Then they introduce a beam into the treatment
room and check the beam profile at isocenter, where
tumor of patient will be located. They check beamprofiles and their central positions in all treatment rooms
and for several rotation angles of the gantries for three
proton energies every day, i.e., 15-18 beam courses
depending on the treatment request of the day (Differentrotation angle of gantry is counted as one course.) for 150,
190 and 230 MeV of proton beam. These three energies
cover the different beam range in human tissue requiredby the treatment. To change the beam course and checkthe beam profile it takes about 3 - 5 minutes. It takes
about 15 minutes to change the beam energy and thencheck the beam profile in front of one treatment room. Allparameter change of the (steering) magnet power supplies
after the beam tuning and the resulting beam profile justin front of the neutron shutter are stocked in the memoryof accelerator control computer for each beam course.
These parameters are set on the request of beam course by
medical staff for the treatment and the stocked profile iscompared with a beam profile measured at that moment.
At 8 o’clock, other operation staffs join the operation.
In the stage of clinical trial, we check the beam profile
in all treatment rooms to take statistical data on thereproducibility of the beam position at isocenter. For thefixed beam, it is ±0.5-1mm. For the gantry, it is ±1mm.
From 9 o'clock, we start patient treatments. Intensity ofproton beam supplied for the treatment is typically
7-8x1010 ppp with synchrotron pulse length T of 1.6 sec.
Maximum number of patients treated in a day was 15 andthe treatment was finished at about 5 o'clock in theevening. Patient Dosimetry is repeated every day for eachpatient. It is also measured even in the treatment roomwith no entry of the patient at that day to take statistical
data on stability and reproducibility.
With statistical evidence obtained in the clinical trials
on the stability, the amount of daily beam tuning in themorning and Dosimetry checking procedure will bereduced in routine operation for therapy.
During January – July 2002, clinical trials with carbon
beam were performed. Operators started a beam tuning at
7:00 am, as the number of the patients were limited tofive, no gantry port is applicable to carbon beam and theenergies used for the treatment were 250 and 320 MeV/u.
Carbon beam supplied for the treatment is typically
93.8x10 ppp with synchrotron pulse length T of 3.3 sec.

5 START OF PROTON RADIOTHERAPYAND OPERATION OF THE MACHINE
After the approval of PATRO as a medical facility bynational government on October 2002, the facility
PATRO was delivered from manufacturing company,Mitsubishi Electric Corporation, to Hyogo Ion Beam
Medical Center (HIBMC). HIBMC started the machine
operation with its own responsibility. One shift operationis performed from 8:45 – 17:45 on weekday with 6
operation staffs from Accelerator Engineering Corp
(AEC). 3 staffs works for accelerator operation andanother 3 staffs works for QA of treatment irradiation
system. Final tuning of accelerator and treatment
irradiation system is performed. Software debugging isalso performed. Ridge filters to form SOBP (Spread-OutBragg Peak) are fabricated and tested by beams.
From April 2003, the proton radiotherapy and 2-shiftoperation during 6:00 – 22:00 will start. With another one
staff for managing and operation, 13 operators of AEC
work for the operation of PATRO. Saturday is for weekly
maintenance. On Sunday and holidays, the machine isstopped. If some machine trouble happens on weekday,
the machine will be operated on Saturday to recover thetreatment.
Maintenances are scheduled two times in a year, one
for 3 weeks and another for 1 week. As an interruption oftreatment for more than four successive days means afailure of the treatment, the maintenance is strictly
preventive.

6 CONCLUDING REMARKS
During two years clinical trials, with operation time ofabout 5000 hours, there were no serious troubles thatinterrupted the treatment. The stability and thereproducibility of the beams were well proved. Many
debugging of the control programs were performed to
reply demands and claims from medical staffs. The
reliability of the facility was much increased.

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