The limitations and pitfalls in clinical implications of Bragg's peak: A theoretical SRIM – TRIM model of human breast tumor

Abstract

Proton beam therapy is unique because it allows for minimal scattering as particulate beam pass through tissue and deposing ionizing energy at precise depth i.e. Bragg peak. This study is aimed to investigate the limitations and pitfalls in clinical application of Bragg peak in theoretical model of human breast tumor. The Microsoft; "The Stopping and Range of Ions in Matter (SRIM)" version 1998, and 2003 was used. A model of breast tumor was designed and the projection of irradiated ions (hydrogen or carbon) crossed multi-layers including skin, adipose tissue, normal and abnormal breast tissues of different densities. The results showed that the stopping power of carbon ions was higher than corresponding hydrogen ions and proportionally increased with tissue density. The longitudinal range was directly correlated with acceleration potential energy for both hydrogen and carbon ions. The straggling of the hydrogen ions and to lesser extent the carbon ions tended to be declined, for each accelerated potential, with increment in density of breast tissue. The energy loss was higher with carbon ions compared with hydrogen ions. Irradiation with hydrogen or carbon ions resulted in breast tissue damage which was proportionally related to the accelerated potentials and inversely with target density. The damaging effect of carbon ions was inferior to that of hydrogen ions. It concludes that typical Bragg's peak can be achieved when the density of irradiated tissue , the localization of abnormal tissue , the type of ions radiation and the acceleration potentials are taken collectively in consideration.