MONTE-CARLO SIMULATION USING PHITS OF SECONDARY NEUTRONS PRODUCED IN-PATIENT DURING 16O ION THERAPY.

In hadrontherapy, oxygen ions 16O can be currently considered as an alternative to carbon ions 12C designed specifically for the treatment of deep and radioresistant tumors. Secondary particles, particularly neutrons constitute a serious problem of undesirable additional irradiation to surrounding healthy tissue. The objective of this study is to evaluate, by Monte-Carlo simulation [code Particle and Heavy Ion Transport code System (PHITS)], the contribution in terms of dose of secondary neutrons produced during interaction 16O ion of 300 MeV u-1 in a soft tissue phantom. The dose of 16O ion, secondary particles and neutrons is evaluated, as well as the particle fluence and energy spectra of neutrons. The contribution to the total dose of secondary neutrons in a soft tissue phantom represents 0.1%. This dose, although apparently insignificant, is essential to conduct even more in-depth studies to understand the long-term effects of these secondary neutrons on the patient's body especially in pediatric case.