A quality assurance for respiratory gated proton irradiation with range modulation wheel.

A quality assurance for respiratory gated proton irradiation with range modulation wheel. J Appl Clin Med Phys. 2018 Dec 30;: Authors: Yasui K, Shimomura A, Toshito T, Tanaka K, Ueki K, Muramatsu R, Katsurada M, Hayashi N, Ogino H Abstract The purpose of this study was to provide periodic quality assurance (QA) methods for respiratory-gated proton beam with a range modulation wheel (RMW) and to clarify the characteristics and long-term stability of the respiratory-gated proton beam. A two-dimensional detector array and a solid water phantom were used to measure absolute dose, spread-out Bragg peak (SOBP) width and proton range for monthly QA. SOBP width and proton range were measured using an oblique incidence beam to the lateral side of a solid water phantom and compared between with and without a gating proton beam. To measure the delay time of beam-on/off for annual QA, we collected the beam-on/off signals and the dose monitor-detected pulse. We analyzed the results of monthly QA over a 15-month period and investigated the delay time by machine signal analysis. The dose deviations at proximal, SOBP center and distal points were -0.083 ± 0.25%, 0.026 ± 0.20%, and -0.083 ± 0.35%, respectively. The maximum dose deviation between with and without respiratory gating was -0.95% at the distal point and other deviations were within ±0.5%. Proximal and SOBP center doses showed the same trend over a 15-month period. Delay times of...
Source: Journal of Applied Clinical Medical Physics - Category: Physics Authors: Tags: J Appl Clin Med Phys Source Type: research