The change in the radiation quality within a target volume is negligible in low-LET radiation therapy (X-ray therapy, proton-beam therapy), and the therapeutic effect has been predicted empirically based on the absorbed dose. On the other hand, in the case of carbon therapy, which is high-LET, the radiation quality changes markedly within the target volume, especially with the depth. Accompanying this change, the treatment effect (RBE) also changes greatly. Therefore, a new treatment model has been indispensable. We review the beginning of carbon therapy in Japan, and present an introduction to a scanning system, the development of advanced models incorporating the microdosimetry method, and developments concerning various detectors.
A carbon-ion clinical study began in June of 1994. In order to apply carbon beams to radiation therapy, we must modify the pristine carbon beam according to a real situation of clinical treatments. In this section, we describe how we had prepared for heavy ion therapy, especially how we developed the design of the Spread-Out Bragg Peak.
Carbon beams, used for cancer therapy, are characterized by rapidly changing radiation qualities as well as dose. This is significantly different from ordinary types of radiation. As a result, the biological effect and treatment efficacy change and actually increase around an end point. Therefore, a reliable biological model is indispensable for safe and efficient therapy. This article describes the development and character of the NIRS biological model, and compares it with the GSI biological model. Further development of various detectors for measuring the radiation qualities is outlined.
Recently, advanced treatment techniques such as respiratory gating, scanning irradiation, and intensity-modulated particle therapy have been developed and utilized worldwide. To make the best use of these techniques and increase the clinical effectiveness of charged-particle therapy, it is important to investigate the effects of repair and oxygen enhancement ratio (OER) on biological effectiveness of the therapy. If the effects are non-negligible, the effects should be considered in clinical RBE system. In this chapter, recent efforts to investigate these effects are briefly overviewed.
We have been conducting clinical research to establish carbon-ion radiotherapy (CIRT) as a standard treatment and to further improve clinical results. We established the Japan Carbon-ion Radiation Oncology Study Group（J-CROS）， conduct comparative research, and utilize the technology of National Institutes for Quantum and Radiological Science and Technology to develop treatment methods with higher therapeutic effects. We will introduce the Current status and Perspective of CIRT and the latest results by disease.
Exposure to space radiation will be a limiting factor in future missions beyond low Earth orbit, such as to Mars. Mission durations will range from many days to weeks and many months, all spent outside the geomagnetic field, exposed to chronic galactic cosmic rays (GCR) as well as periodic solar particle events (SPE). Experiments in space are difficult and expensive. While it is not feasible to replicate the full space radiation environment on the ground, some particle accelerators are capable of producing significant components of the GCR. From the late 1990s through the present day HIMAC has been one of the most important such facilities. In this section we review a number of experiments in which HIMAC has been used to further international research in space radiation physics and biology, including radiation shielding, detector development for crewed and robotic spacecraft, radiation effects on biological organisms and electronics.
Measurements of nuclear fragmentation cross sections and of particle production in thick targets are needed for the development of space radiation shielding. Cross sections are used as source terms for models of fragmentation and transport, and thick target measurements for model validation and to evaluate candidate shielding materials and concepts. Here we briefly review how HIMAC ion beams have been used to simulate elements of the space radiation field for cross section and thick target measurements.
The ICCHIBAN project was an international collaboration to intercalibrate and intercompare the response of the different detectors and instruments used for radiation dosimetry aboard manned spacecraft. The objectives of the ICCHIBAN project were: 1) to determine the response of space radiation instruments and dosimeters to heavy ions of charge and energy similar to that found in the galactic cosmic radiation (GCR) spectrum; 2) to compare the response and sensitivity of various space radiation monitoring instruments and aid in reconciling differences in measurements made by various radiation instruments during space flight; and 3) to establish and characterize a heavy ion “reference standard” against which space radiation instruments can be calibrated. ICCHIBAN experiments were carried out at a number of particle accelerator facilities, the vast majority, eight, using the HIMAC heavy ion accelerator at the National Institute for Radiological Sciences, Chiba, Japan. Benefits of the ICCHIBAN project included the identification and correction of problems in calibration and data interpretation of a number of active space radiation instruments, and the demonstration of the overall efficacy and reproducibility of passive radiation dosimeters, especially luminescence-based detectors such as TLD and OSLD used in conjunction with CR-39 PNTD.
Space radiation exposures are distinct from those in charged particle radiotherapy in that they are typically low dose, low dose rate and mixed field. It is not feasible to exactly replicate these conditions in ground-based facilities, but carefully designed experiments at HIMAC have provided insight into the biological effects of space radiation.
The mechanisms of Single Event Effects (SEEs) on Silicon Carbide (SiC) power devices are becoming clearer. However, to completely understand the mechanisms of SEEs on SiC power devices and to explore radiation hardened technologies for SiC power devices, it is necessary to study the radiation response of SiC power devices using high-energy heavy ions at accelerator facilities such as the Heavy Ion Medical Accelerator in Chiba (HIMAC). The radiation hardening test methodology using high energy heavy ions is reviewed and the application of HIMAC for SEE testing is introduced with recent results from tests of SiC power devices.
A variety of radiation detectors and instruments have been deployed to characterize the radiation environment in low and high Earth orbit, lunar orbit, Mars orbit and on the surface of Mars. Here we discuss the testing and calibration of these detectors using HIMAC ion beams.