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Noda, Shusaku; Hashimoto, Shintaro; Sato, Tatsuhiko; Fukahori, Tokio; Chiba, Satoshi*; Niita, Koji*
no journal, ,
Medical linac is commonly used in photonthereapy. High energy photons can induce the photonuclear reaction generating proton and neutrons. Improvement of the PHITS code is needed to accurately estimate the dose rate for the human body. In this study, we developed the PHITS code to applicable to the incident photon energy of 140 MeV; (1) adopted the evaluated photonuclear data file (JENDL/PD-2004), (2) improved the evaporation model for the light nuclei excited by photon, (3) developed the quasideuteron process in the JAERI Quantumn Molecular Dynamics (JQMD) model. Owing to these improvements, PHITS can handle the photonuclear reaction against the incident photon energy below 140 MeV. As an example, the photon-induced proton/neutron-emission cross sections are well reproduced using improved PHITS.
Ogawa, Tatsuhiko; Hashimoto, Shintaro; Sato, Tatsuhiko; Niita, Koji*
no journal, ,
Development of EBITEM is discussed.
Endo, Akira; Sato, Tatsuhiko
no journal, ,
Absorbed doses, linear energy transfers (LETs), and quality factors of secondary charged particles in organs and tissues, generated via the interactions of the spontaneous fission neutrons from Cf-252 and Pu-244 within the human body, were studied using the Particle and Heavy Ion Transport Code System (PHITS) coupled with the ICRP Reference Phantom. Both the absorbed doses and the quality factors in target organs decrease with increasing distance from the source organ. The analysis of LET distributions of secondary charged particles led to the identification of the relationship between LET spectra and target-source organ locations. A comparison between human-body-averaged mean quality factors and fluence-averaged radiation weighting factors showed that the current numerical conventions for the radiation weighting factors of neutrons, updated in ICRP103, and the quality factors for internal exposure are valid.