Neutron Production in The Scattering S250 Mevion Proton-Therapy System

Abstract: Secondary radiation in a radiation therapy environment is considered a cause for post-treatment side effects including secondary carcinogenesis. In a proton-therapy setup, neutrons deliver a considerable extra dose to the patient. Various measurements and calculations of neutron dose suggest a wide range of values for this quantity. This paper provides a comparison between the previously published values and analyzes the Monte Carlo calculated neutron dose from the present work using the neutron cross-section data. The purpose is to provide a range for the convergence of several neutron-absorbed dose data points (e.g. 3.94 mSv/Gy in a Bonner sphere measurement and 0.4 mSv/Gy in a SWENDI measurement) in previous works of other authors.