Physical and biological impacts of collimator-scattered protons in spot-scanning proton therapy.

ABSTRACT: To improve the penumbra of low-energy beams used in spot-scanning proton therapy, various collimation systems have been proposed and used in clinics. In this paper, focused on patient-specific brass collimators, the collimator-scattered protons' physical and biological effects were investigated. The Geant4 Monte Carlo code was used to model the collimators mounted on the scanning nozzle of the Hokkaido University Hospital. A systematic survey was performed in water phantom with various-sized rectangular targets; range (5-20 cm), spread-out Bragg peak (SOBP) (5-10 cm), and field size (2 × 2-16 × 16 cm² ). It revealed that both the range and SOBP dependences of the physical dose increase had similar trends to passive scattering methods, that is, it increased largely with the range

SUBMITTER: Ueno K 

PROVIDER: S-EPMC6612695 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature