Feasibility study of utilizing XRV-124 scintillation detector for quality assurance of spot profile in pencil beam scanning proton therapy

Abstract

PurposeThe purpose of the current study is to (i) investigate the feasibility of utilizing the XRV-124 – a cone-shaped scintillation detector – to measure the spot size and spot position in pencil beam scanning proton therapy, and (ii) compare the spot sizes acquired by the XRV-124 with that of the widely used Lynx detector. MethodsSpot position was tested by delivering a map of 30 spots at different locations to the XRV-124. Spot position test included energies 70–210 MeV. Spot size measurements were performed at the isocenter using the XRV-124 and Lynx detectors for a total of 32 energies (70–225 MeV at an increment of 5 MeV) at four cardinal gantry angles. ResultsThe position (X, Y, and Z) of the radiation isocenter was within ±0.3 mm. For spots placed on the horizontal (X) and longitudinal (Y) axes of the spot map, both the X and Y locations of the spots were within ±0.5 mm. The spots placed diagonally in the map showed a higher deviation (±0.9 mm). In evaluating spot sizes acquired using the XRV-124 vs. Lynx, the results from the XRV were found to be slightly higher but within 0.2 mm for energies ≥130 MeV and within 0.4 mm for energies <130 MeV. ConclusionsIt is feasible to utilize the XRV-124 to perform the quality assurance of position and size of a pencil proton beam around the radiation isocenter but within the usable XRV-124 cone area.