Beam Delivery Method for Carbon-ion Radiotherapy with the Heavy-ion Medical Accelerator in Chiba.

Koji Noda

doi:10.14338/ijpt-15-00041.1

Abstract

The heavy-ion medical accelerator in Chiba (HIMAC), Japan, has been using carbon-ion radiation therapy since 1994, and the number of patients treated with this technique has reached around 10,000. The HIMAC employs single beam wobbling as a beam-delivery method. Based on the broad-beam method, respiratory-gating and layer-stacking irradiation methods were subsequently developed, which have contributed to significantly increasing irradiation accuracy. During the study and research and development to downsize carbon-ion radiation therapy facilities, a spiral beam-wobbling method was developed, which has been employed in compact carbon-ion radiation therapy facilities constructed in Japan. Toward the further development of the HIMAC treatment, the National Institute of Radiological Sciences has developed new treatment technologies, such as phase-controlled rescanning, based on a fast 3-deminsional (3D) scanning method with a pencil beam toward adaptive cancer radiation therapy. A heavy-ion rotating gantry, combined with 3D-scanning, is currently under development. These technologies developed by the National Institute of Radiological Sciences will hopefully boost the use of heavy-ion radiation therapy worldwide.

Highlights

Heavy-ion beams are suitable for deeply seated cancer radiation therapy because of their high-dose localization and high biological effect in the Bragg-peak region
The National Institute of Radiological Sciences (NIRS), constructed the heavy-ion medical accelerator in Chiba (HIMAC), Japan [1], as the world’s first heavy-ion accelerator facility dedicated to medical applications
Because the HIMAC facility should carry out treatments for static targets and for moving ones, we developed a 3D scanning method with a new technique

Summary

Introduction

Heavy-ion beams are suitable for deeply seated cancer radiation therapy because of their high-dose localization and high biological effect in the Bragg-peak region. Particle radiation therapy requires a 3D biological-dose distribution within several percentage points of the uniformity on a tumor, with as low a dose as possible in the surrounding normal tissue For this purpose, various beam-delivery methods have been proposed and used [13]. Pencil-beam 3D scanning is an irradiation method that covers the dose distribution with a small beam and narrow Bragg peak, which allows full advantage of the heavy ions. The PCR method was proposed and developed for adaptive cancer radiation therapy for static and moving tumors In this method, schematically shown, rescanning completes irradiation on 1 isoenergy slice during 1 respiratory-gated period. The PCR method consists of 2 main technologies: (1) the intensity-modulation technique for constant irradiation time on each isoenergy slice with different cross-sections, shown in Figure 3, and (2) the fast scanning technique for completing multiple rescanning within a defined amount of time

Intensity modulation

Fast 3D scanning

Findings

Conclusion