March 19, 2014 — Hokkaido University and Hitachi Ltd. completed construction of facilities incorporating the Probeat-RT Proton Beam Therapy System within the Hokkaido University Hospital. Hokkaido University and Hitachi had been jointly developing the Probeat–RT. The project was awarded a grant in 2010 under the Funding Program for World-Leading Innovative R&D on Science and Technology (the “FIRST Program”), a national project sponsored by the Japanese government. The University plans to begin treatments using the newly constructed facilities March 19, 2014.
The FIRST Program is a major research support structure established as part of a Japanese government initiative to promote science and technology. 30 out of 565 applicant "Core Researchers and Projects" were awarded grants based on their notable potential in the advancement of Japanese science and technology in March 2010. Hokkaido University's "Advanced Radiation Therapy Project Real-time Tumor-tracking with Molecular Imaging Technique" project was awarded a FIRST grant following an application by Hiroki Shirato, department of radiation medicine, Graduate School of Medicine. This was the only application accepted in the field of radiation therapy. The goal of “Advanced Radiation Therapy Project Real-time Tumor-tracking with Molecular Imaging Technique” is to develop a treatment system that can dramatically reduce the irradiation of normal tissue, in a compact, low-cost system that demonstrates international competitiveness. This goal is achieved by combining the Real-time Tumor –tracking Radiation Therapy developed by Hokkaido University through X-ray therapy with Hitachi’s spot scanning proton beam irradiation technology. In this way, Hokkaido University and Hitachi will offer a proton beam therapy system that can accurately irradiate a tumor that moves due to respiration, for example in the lung and liver.
At the recently completed facility, Hokkaido University will provide treatment using spot scanning irradiation technology from Hitachi and strive to quickly develop a treatment system that incorporates its own moving tumor tracking irradiation technology. Hitachi has already applied for approval for manufacture and sales of the treatment system combining spot scanning irradiation and Real-time Tumor-tracking Radiation Therapy. It hopes to receive approval and begin treatments in the first half of FY 2014.
By merging technologies and expertise, the system reduces the size of the gantry, the irradiation nozzle and the accelerator. In this approach, they have created a treatment system that is easy to use and more compact overall. In comparison to the Probeat-III Proton Beam Therapy System, which was released previously by Hitachi, the circumference of the accelerator has been reduced to 18 m from the original 23 m; the gantry, which had a maximum external length of 11 m and an internal diameter of 3.5 m, has been reduced in size to a maximum external length of 9 m and an internal diameter of 2.5 m. The installation area required for the system as a whole has been reduced by approximately 30 percent.
In “Real-time Tumor Tracking Radiation Therapy,” gold markers are inserted in the proximity of the tumor, and a computed tomography (CT) system is used to identify the marker positions in relation to the tumor core. Using an X-ray fluoroscopy system from two directions, this technology automatically pinpoints the gold markers positions on a fluoroscopy image using pattern recognition, and repeatedly calculates the spatial position at regular intervals. The treatment beam only irradiates the targeted tumor when the gold markers are located within a few millimeters of the planned positions. As this operation is performed at high speed, it is possible to irradiate tumors with a high degree of accuracy, even when they move within the body, for example due to the patient’s respiration. Compared to conventional methods that irradiate the entire area in which the tumor might migrate, this system reduces the irradiation volume by 50-75 percent, allowing a reduction in the irradiation of normal tissue.
Hitachi’s Spot scanning irradiation technology uses a constant, narrow beam, repeatedly turning this beam on and off at high speed as it progressively changes location. In this way, the beams can be targeted with high precision according to the shape of the tumors, even if those shapes are extremely complex, thus minimizing the impact on normal tissue.