@misc{oai:repo.qst.go.jp:00066896,
 author = {小平, 聡 and 小平 聡},
 month = {Sep},
 note = {The LET spectrum, absorbed dose and dose equivalent from secondary particles of LET_H2O ≥15 keV/µm deposited within the plateau of the Bragg curve in primary particle-induced nuclear target fragmentation reactions in tissue during proton and heavy ion radiotherapy were measured using CR-39 plastic nuclear track detectors and analyzed by means of atomic force microscopy. It was found that secondary target fragments contributed 20% to dose equivalent for primary protons (157 MeV), 13% for primary helium ions (145 MeV/n) and 4% for primary carbon ions (383 MeV/n), respectively. While this additional dose is currently not considered in any standard treatment planning software, such contributions to dose to healthy tissue are significant from the point of view of patient radiation safety. The smaller contribution measured for energetic carbon ion beams compared to proton beams can be considered an advantage of carbon ion radiotherapy over proton radiotherapy. This type of measurement is not only relevant to radiation protection in cancer therapy, but also in space radiation dosimetry and protection, since 99% of the space radiation environment consists of energetic protons and helium nuclei. Some verification of secondary particles with CR-39 were reported by measuring stopping particles in the detector. The type of ground-based experiment reported here are useful for investigating the dose contribution of secondary target fragmentation produced by space radiation to the absorbed dose and dose equivalent received by space crews., 23th WRMISS(Workshop on Radiation Monitoring for the International Space Station)における口頭発表},
 title = {Contribution to dose in healthy tissue from secondary target fragments in therapeutic proton, He and C beams measured with CR-39 plastic nuclear track detectors},
 year = {2018}
}