What is Proton Therapy?
Proton therapy is one of the promising therapeutic methods against cancer. A proton beam is obtained by accelerating the proton, the atomic nucleus of hydrogen, to high energy level. One of the features of proton therapy is the optimal dose distribution in the human body. Proton beam’s Bragg Peak makes this radiation very effective for the targeted irradiation of the tumor with lower side effects to surrounding healthy tissues. Unlike surgical procedures, this is a gentle and noninvasive treatment that allows patients to be treated as outpatients and the quality of life (QOL) can be kept. For this reason, proton therapy is attracting attention around the world.
Proton therapy is reported to be adopted for the treatment of cancer in head/neck, lung, liver, esophagus, pancreas, pediatric, prostate, etc. from existing facilities in the world.
Comparison of dose distributions between X-ray therapy (left) and proton therapy (right)
Bragg Peak
Features
Reliable accelerator technology for medical applications
The SHI Group developed cyclotrons for proton beam therapy by utilizing the accelerator technology that it has been developing since the early 1970s. In 1997, the SHI Group delivered the first proton beam therapy cancer treatment system to the National Cancer Center Hospital East. In 1998, the SHI Group commenced operations as Japan’s first proton beam therapy cancer treatment facility to be installed in the hospital (and the second in the world). The system continues to offer stable operation to this day.
Configuration of proton beam therapy systems
Proton beam therapy systems are comprised of an accelerator (cyclotron), an energy selection system, a beam transport system, and rotating gantry irradiation equipment (gantry, irradiation nozzle, and patient positioning equipment). (This system has been approved as medical equipment by the Ministry of Health, Labor and Welfare.)
Compact and flexible layout
Placing the cyclotron and the compact gantry top and bottom helps to reduce the required building space significantly, and enables the development of an installation plan in locations where space is limited (in the case of the top-and-bottom layout type).
A cyclotron to continuously supply high-intensity proton beams
This feature helps to shorten the beam irradiation time, leading to a reduction of the load on the patient, and it is highly adaptable for the irradiation of respiratory organs (such as the lungs or liver, etc.) and high-precision scanning methods.
Top and bottom installation layout
Cyclotron (Aizawa Hospital Proton Therapy Center)
Line Scanning
Pencil beam scanning (PBS) delivers narrow proton beams to the targeted cancer tissue conforming to the shape of tumor and enables complex tumors to be irradiated precisely, while concentrating high dose and minimizing side effects for surrounding healthy tissues. In comparison with the conventional broad beam irradiation, preparation prior to treatment is easier and the consumable cost for patient’s specific compensators and collimators can be decreased by PBS. Line scanning technology (“Line Scanning”), which is one of the PBS technologies and SHI’s original one, irradiates proton beams continuously in stable beam current for each layer with change of scanning speed. Irradiation time by Line Scanning is shorter than that by spot scanning irradiation which irradiates proton beams intermittently.
The world’s first patient treatment with Line Scanning was started in National Cancer Center Hospital East (Kashiwa, Japan) in October, 2015. Then, number of Line Scanning treatment in our facilities in Japan, Taiwan and Korea have been increasing rapidly and IMPT (Intensity Modulated Proton Therapy) has been utilized in those facilities.
Image Guide Technologies for Precise Treatment
Accurate patient positioning is carried out by 6-axis robotic couch and orthogonal X-ray DR System which is high range of movement and high accurate locating before irradiation. . Cone Beam CT image can be acquired with X-ray DR system by rotating gantry. In addition, we can provide the patient positioning system from 3D image by setting up the On-rail CT device and sharing bed for diagnosis and treatment. (Option)
Proton Therapy System
This system consists of the accelerator (cyclotron), energy selection system, beam transport system, rotating gantry, irradiation nozzle, patient positioning system, etc.
(Picture: Aizawa Hospital in Matsumoto, Japan)
