Overview

Special Features > Microdosimetric Function
Calculation of the probability density of deposition energies in microscopic sites, called as lineal energy y or specific energy z, is of great importance in estimation of relative biological effectiveness (RBE) of charged particles. However, such microscopic probability densities cannot be directly calculated by PHITS simulation using [T-Deposit] or [T-Heat] tallies, since PHITS is designed to simulate particle motions in macroscopic scale, and employs a continuous-slowing-down approximation (CSDA) for calculating the energy loss of charged particles. We therefore introduced a special tally named [T-SED] for calculating the microscopic probability densities using a mathematical function that can instantaneously calculate quantities around trajectories of charged particles. The function was developed on the basis of track structure simulation, considering productions of -rays and Auger electrons. Note that the name of "SED" derives from "Specific Energy Distribution". Using this function coupled with a microdosimetric kinetic model, you can directly calculate the biological dose for charged particle therapy. Details of the calculation procedure are given in Refs. [1,2]. References: [1] T. Sato et al. Radiat. Prot. Dosim. 122, 41 (2006) [2] T. Sato et al. Radiat. Res. 171, 107 (2009) (Open-access PDF). Example of physical and biological doses for charged-particle therapy calculated using the microdosimetric function coupled with a microdosimetric kinetic model.

Special Features > Microdosimetric Function

Calculation of the probability density of deposition energies in microscopic sites, called as lineal energy y or specific energy z, is of great importance in estimation of relative biological effectiveness (RBE) of charged particles. However, such microscopic probability densities cannot be directly calculated by PHITS simulation using [T-Deposit] or [T-Heat] tallies, since PHITS is designed to simulate particle motions in macroscopic scale, and employs a continuous-slowing-down approximation (CSDA) for calculating the energy loss of charged particles. We therefore introduced a special tally named [T-SED] for calculating the microscopic probability densities using a mathematical function that can instantaneously calculate quantities around trajectories of charged particles. The function was developed on the basis of track structure simulation, considering productions of -rays and Auger electrons. Note that the name of "SED" derives from "Specific Energy Distribution". Using this function coupled with a microdosimetric kinetic model, you can directly calculate the biological dose for charged particle therapy. Details of the calculation procedure are given in Refs. [1,2].

References:
[1] T. Sato et al. Radiat. Prot. Dosim. 122, 41 (2006)
[2] T. Sato et al. Radiat. Res. 171, 107 (2009) (Open-access PDF).

Example of physical and biological doses for charged-particle therapy calculated using the microdosimetric function coupled with a microdosimetric kinetic model.