Osaka Heavy Ion Therapy Center

Introduction of treatment equipment

Accelerator system

Accelerator room(Synchrotron) Accelerator room(Synchrotron)

Accelerator is a system that applies high voltage to charged particles and create high-energy charged particles in uniform velocity and direction (=particle beam). For heavy ion therapy, charged particles need to be accelerated to the energy that reaches the tumor. The main accelerator at this facility is a synchrotron (approx. 17 meters in diameter, approx. 57 meters in circumference). This is the most compact heavy ion medical accelerator in the world.

The synchrotron accelerates charged particles to the energy necessary for treatment by using a radio frequency electric field, and these charged particles circulate a few millions of times on the circular orbit (about 57 meters) per second. The maximum velocity of the accelerated particles is about 70% of light speed.


Principle and composition of injector

The injector is a device that accelerates the heavy ion beam up to the energy required to enter the synchrotron and consists of an ion source and a linear accelerator.

The ion source creates carbon ion from methane gas. The linear accelerator consists of an RFQ linac and APF IH-DTL, which accelerate carbon ion from methane gas to about 9% of the speed of light by applying high frequency voltage.

Composition of injector
Composition of injector

ECR* ion source

ECR ion source
Method Permanent magnet ECR ion source
Ion source C4+
Introduction gas CH4
Energy 10keV/u

*Electron Cyclotron Resonance

RFQ* Linac

RFQ Linac
Accelerated ions C4+
Energy 600keV/u
Frequency 200MHz

*Radio Frequency Quadrupole


Accelerated ions C4+
Energy 4.0MeV/u
Frequency 200MHz

*Alternating-Phase-Focused Interdigital H-mode Drift-Tube-Linac

Electromagnet power supply

About electromagnet power supply

Treatment requires high beam-position accuracy in submillimeter order. In the synchrotron, the accelerated beam is controlled by bending electromagnets that bend a beam along a circular trajectory, quadrupole electromagnets that have a lens role for focusing a beam and steering electromagnets that perform trajectory correction. The electromagnet power supply excites these electromagnets and plays an important role in controlling the beam position accuracy.

Features of the system and bending electromagnet power supply

This facility, characterized by the compact synchrotron and capability of scanning irradiation as important features, required a stable power supply which can reduce the noise as much as possible, in order to achieve that.

Under the guidance of Prof. Hiroshi Toki, the emeritus professor of Nuclear Physics Research Center at Osaka University, we developed a bending electromagnet power supply that adopts the Sato-Toki symmetrical three-line scheme, which was proposed as the definitive version of noise suppression. The current ripple that represents “fluctuation” shows the lowest value in the world, achieving high beam-position accuracy.

Bending electromagnet power supply specification

Output current 3800A
Output voltage ±1200V
Rise 755ms
Fall 435ms
Output average power 1.8MW
Output power 4.6MWp
Received capacity 2.4MVA(6.0MVAp), power factor 1, measures against harmonic suppression
Cooling method water cooling
Electromagnet 10mH, 8.0mΩ×12series connection
Current ripple 2×10-6p-p(Flat Top)

Treatment system

Treatment room Treatment room

There are 3 treatment rooms in this facility, and the patient position is verified by using the X-ray or the CT simulator before irradiation every time. Treatment room 1 has horizontal and oblique (45 degree) beam ports, and treatment rooms 2 and 3 have horizontal and vertical ports. In addition, treatment rooms 1 and 2 have the Real-time image Gating system, and treatment room 2 has the in-room CT simulator.

Control room Control room

Treatment room configuration

Treatment room 1 Radiation direction (Horizontal / 45 degree) + Real-time image Gating system
Treatment room 2 Radiation direction (Horizontal / Vertical) + Real-time image Gating system + In-room CT
Treatment room 3 Radiation direction (Horizontal / Vertical)
Treatment room configuration

X-ray imaging system

Configuration during X-ray imaging Configuration during X-ray imaging

It consists of an X-ray tube and a Flat Panel Detector (FPD) and takes 2 pairs of X-ray images to determine the treatment lesion. It is stored when not used.

Treatment Planning System

Function of treatment planning system

The treatment planning system is to simulate and to evaluate the dose, irradiation area and direction of the heavy ion beam before irradiating to the treatment area. It consists of the planning and planning support softwares.

Planning support software(RayStation Doctor)

The RayStation Doctor, which is adopted as planning support software, is a software for contouring and evaluating treatment planning, and sets contour shapes of tumors on CT images taken in advance.

Configuration of treatment planning system

Configuration of treatment planning system

Planning software(VQA Plan)

The VQA Plan, which is adopted as planning software, is a software that performs irradiation planning and dose calculation. It simulates heavy ion beam dose distribution in the body and creates treatment planning data. The pencil beam method widely used for particle beam is adopted as dose calculation algorithm.

During the treatment period, changes in shape of the tumor can be seen according to the patient's body shape and treatment progress. As VQA has many correcting functions in consideration of patient positioning setup error and organ motion in actual treatment, it is possible to calculate daily dose distribution according to daily change and accumulate daily dose distribution during the treatment period, and doctors can compare the evaluations of the dose distribution with the initial treatment planning and daily dose distribution and the dose integration results by deforming the CT images. Furthermore, millimeter adaptation along with patient's treatment progression can be done quickly.

VQA Plan
RayStation Doctor

Patient Positioning System

The patient positioning system determines the patient’s position in order to irradiate heavy ion beams with high accuracy. It consists of a treatment couch, laser markers, X-ray imaging devices and a patient image analysis system (PIAS).

Robotic couch

The robotic couch aligns the patient position with high precision of within 1 mm by 6-axis movement.

Laser marker

Align the patient's body surface with a laser marker.

X-ray imaging system (for front and side / for real-time motion tracking)

X-ray imaging system consists of an X-ray tube and an FPD (flat panel detector). Front and side X-ray imaging systems are used to determine the patient irradiation position. For real-time image gating, the position of the gold markers are confirmed in real time by capturing periodic X-ray images.

Patient Image Analysis System

PIAS (Patient Image Analysis System) calculates the differences between the reference images by the treatment planning system and the current X-ray images of the day of treatment by superimposing the both corresponding images. According to the difference, PIAS also calculates the couch control data automatically which realizes high throughput treatment with minimum operation.

PIAS has three patient positioning methods - DRR*-DR* (2D/2D) mode, CT-DR (3D/2D) mode and CT-CT (3D/3D) mode.

*DRR Digitally Reconstructed Radiography
*DR Digital Radiography

PIAS Patient positioning images

*Region Of Interest

Outline of treatment facilities

Basic specifications of accelerator

Ion source Model Permanent magnet type ECR 1 unit
Frequency ~10GHz
Production ion C4+
Energy 10keV/u
Linear accelerator Equipment configuration RFQ linear accelerator, IH linear accelerator
Frequency 200MHz
Energy 600keV/u(RFQ), 4.0 MeV/u(DTL)
Synchrotron Accelerated ion C6+
Number of accelerated particles 5.7×109 ppp
Energy 140-430 MeV/u
Circumference 57m
Repetition frequency About 1/2 Hz (typical value)
RF 0.97-7.68MHz, 2.5 kV max.
Beam injection Multiple injection method (effectively 20 turns)
Beam extraction Slow extraction

Main specifications of equipment

Ion species Carbon ion
Depth in the body Up to 30 cm
Irradiation field size Up to 20 cm × 20 cm
Dose rate 5 Gy (RBE) / min (range 20 cm, irradiation volume 1 liter)
Beam delivery system 3 rooms 6 ports (horizontal 3, vertical 2, oblique 45 degrees 1)


2 units manufactured by Canon Medical Systems Co., Ltd.
(One has 80 rows and detectors. The other has a large bore with 16 rows and detectors.)


1 unit manufactured by Canon Medical Systems Co., Ltd.
(1.5 Tesla)

Electronic medical record

Hitachi, Ltd. Open-Karte AD