Biophysical simulations for estimating biological effects after exposure to ionizing radiation; Current state and future prospects

Matsuya, Yusuke  ; Saga, Ryo*

Monte Carlo radiation transport simulations and biophysical models are powerful tools to evaluate the biological effects after ionizing radiation in radiation protection and radiation therapy. When exposing human body to radiation, DNA lesions as an early biological response are induced by deposition energy, leading to cell death with a certain probability. To precisely evaluate such effects, it is needed to perform translational studies among radiation physics, chemistry, and biology. Here, we introduce two simulation tools for predicting biological effects, i.e., Particle and Heavy-Ion Transport code System (PHITS) and integrated microdosimetric-kinetic model (IMKM). First, PHITS track-structure calculation at DNA scale enables to estimate the DNA damage yields by electrons and protons. Meanwhile, the IMKM considering various biological factors such as DSB repair kinetics and cancer stem-liken cells can successfully reproduce in vitro cell survival and clinical outcome. This review shows the development history and future prospect of the PHITS and the IMKM, which can expect to be further applied to the research fields of radiation research and quantum life science.