The study of the effectiveness of Particles in radiation therapy using GEANT4 simulation

This thesis describes a Monte-Carlo based simulation study in order to investigate
the impact of radiation quality especially linear energy transfer (LET) on the
damage of living cell induced by radiation. In this study, the simplified target is
used for determining the pattern of the energy deposition of charged particles at different
energies in macroscopic level by using Geant4 toolkit. This study highlights
the factor that may cause the erroneous LET calculation when using small target in
the model. It is shown that although LET is used as a universal term to describes
radiation quality, its stochastic nature causes uncertainty when incorporating with
biological outcome. In addition, the structural DNA model is used to quantify
a number of radiation-induced DNA damage in microscopic level by incorporating
with spatial distribution of energy deposition. It is important to note that the
number of DNA damage is significantly dependent on adjustable parameters in the
simulation including energy threshold for inducing the damage. Finally, the experimental
database, PIDE, of various cell types and particles allows investigating the
factors including type of cell and particle that influence biological effect.