CR-39を用いた高エネルギー荷電粒子が人体内中に生成する短飛程二次粒子の線量寄与の研究

In addition to energy loss bay ionization process from therapeutic primary radiation of protons and carbon jons, they can undergo nuclear interactions with nuclei of Z>1, resulting in the production of high-LET(linear energy transfer) target fragment particles. One of the few methods to detect these short-range particles is by means of CR-39 plastic nuclear track detector analyzed with an atomic force microscope. The LET spectra of 160 MeV protons, 150 MeV/n helium ions and 290 MeV/n carbon ions induced secondary particles were experimentally measured with CR-39. As a pleliminary results, we found that the production cross section of secondary increases with the nuclear charge, whereas the dose contribution to the pri,ary ions decreases due to the low fluence for high LET particles