Successful Development of a Next-Generation Proton Therapy System ─ Enables Irradiation of Mobile Organs in a Shorter Time ─

June 22, 2022

Sumitomo Heavy Industries, Ltd. (hereinafter referred to as “SHI”, Head Office: Shinagawa-ku, Tokyo; President: Shinji Shimomura) has implemented beam testing at its Saijo Plant (Ehime Prefecture) of a next-generation proton therapy system(*1) that is currently under development, and confirmed attainment of the specified irradiation performance. This system will shorten proton beam irradiation time, reduce building volume needed for equipment launching , and simplify patient positioning.

[Concept of ultra-high-speed scanning of lungs]
[Single-room system layout]

[Three objectives of proton therapy]
1. Irradiation of organs subject to respiratory movement
Carcinomas which move due to respiration account for more than 20% of cancer cases worldwide, and that percentage is increasing. (*2) Due to amendment of the medical payment system in fiscal 2022, the range of application of proton therapy has been broadened to large liver cell carcinomas , intrahepatic bile duct carcinomas, locally-advanced pancreatic carcinomas , and cases involving local recurrence after colon cancer surgery (Treatment is limited to unresectable cancers in all cases ). (*3) With existing proton therapy, it was challenging to achieve accurate therapy of organs which move due to respiration such as the lungs, liver, and pancreas. To realize high-accuracy therapy of a mobile organ, proton beam irradiation must be achieved in a shorter time, while reducing movement of the organ due to respiration.

2. Launching of proton therapy systems requires a large building volume, and this hinders installation in hospitals.

3. Proton therapy requires high-accuracy patient positioning. This task takes time , and limits the number of patients who can be treated in one day.

[Three features of our next-generation proton therapy system]
1. Proton beam irradiation time can be shortened to 1/3 by using a superconducting cyclotron (*4) and ultra-high-speed scanning (*5) technology. Rapid irradiation is achieved by combining a 1000-nA proton beam from a superconducting cyclotron, 0.1-second energy switching thanks to ultra-high-speed scanning technology, and a maximum scan speed of 100 m/s. Rapid irradiation is expected to finish while a person is holding a single breath , thus enabling accurate therapy of mobile organs.

2. A reduction of ca. 30% in building volume can be achieved by using a system design optimal for a single room. This approach shows promise for reducing building construction expenses , and starting therapy sooner due to the shortened construction period.

3. Use of a 360° gantry and large field-of-view cone beam CT (*6) simplifies patient positioning with high accuracy. This helps to shorten therapy time.

[Beam testing]
Beam testing was implemented at the Accelerator Application Center, a newly established facility at SHI’s Saijo Plant . Key aspects of irradiation performance were tested, including energy switching time, scan speed, and beam position accuracy, and the specified performance was confirmed. Comprehensive irradiation testing, simulating actual targets, was implemented and shortening of irradiation time was verified.

Going forward , SHI will continue working to develop products in the cancer therapy area with the aim of realizing a society where people can live long, healthy lives.

(*1) This next-generation proton therapy system is an unapproved medical system .
(*2) Source: “Global Cancer Observatory – IARC”
(*3) Source: “Individual Amendment — Ministry of Health, Labour and Welfare”
(*4) A cyclotron is a proton accelerator characterized by high intensity and a continuous beam.
(*5) Scanning irradiation is an irradiation method which minimizes damage to normal tissues and organs surrounding a carcinoma by scanning with a narrow proton beam according to the cancer shape.
(*6) Cone-beam CT is an imaging method which captures 3D images through X-ray photography while rotating a gantry.