QST develop new prototype for heavy-ion radiotherapy using laser acceleration called the 'Quantum Scalpel'

Heavy-ion radiotherapy is known to exert low physical strain on patients and allow them to quickly bounce back post recovery, so it is referred for cancer patients from a quality-of-life standpoint. Currently, seven heavy-ion radiotherapy facilities are operational in Japan, and 20 more are under construction worldwide, 12 of which are made in Japan. To gain a competitive edge of Japan in this field, cost reduction and sophistication are considered essential. In particular, devices capable of accelerating carbon ions to approximately 73% of the speed of light are considered important.

Senior Principal Researcher Hironao Sakaki (Professor of the Interdisciplinary Graduate School of Engineering Science (IGSES) at Kyushu University) and Senior Researcher Sadaoki Kojima of the Kansai Institute for Photon Science at the Foundational Quantum Technology Research Directorate of the National Institutes for Quantum Science and Technology (QST) collaborated with Sumitomo Heavy Industries and Hitachi Zosen to develop the world's first prototype of a laser-driven ion injection device using laser/plasma acceleration. Following this development, the team undertook integration tests to realize a compact heavy particle cancer treatment device, called the 'Quantum Scalpel.' They aim to practically implement the fourth-generation type accelerator, with dimensions of approximately 46 x 34 square meters, that is, around one-sixth of the current accelerator size, by 2030, and using the developed laser, they plan to further reduce the accelerator dimensions to approximately 10 x 20 square meters in the fifth-generation type.

To construct the prototype, three components, a laser device, an ion acceleration section, and an ion transport section, had to be developed. To create the ion acceleration section, the team combined Hitachi Zosen's advanced film-forming processing technology, developed for continuously generating functional thin films, and QST's targeting technology, developed for generating high-purity carbon ions; they co-developed this technique to continuously produce stable target thin films. For the ion transport section, they co-developed an efficient ion transport system by combining Sumitomo Heavy Industries' advanced technology for conventional compact ion accelerators with QST's laser-driven carbon ion beam technology. In addition, the electromagnets from the linear accelerator part of SPring-8 were reused as electromagnets in the ion transport system.

By integrating these materials and methods, the laser-driven ion injection device prototype was developed. In future, the initiated integration tests are expected to collect the data essential for manufacturing the demonstration unit.

Sakaki stated, "Unexpectedly, laser acceleration has improved the beam quality. I would like to extend this research and explore domains other than quantum scalpels."