Comprehensive characterization of proton pencil beam profiles using a novel couch-mounted 2D strip detector system

Proton therapy has gained prominence in recent years, with over 300,000 patients treated worldwide using advanced techniques like pencil beam scanning (PBS). Accurate measurement of proton beam characteristics is crucial for optimizing treatment plans and ensuring patient safety. This study introduces a novel two-dimensional strip detector system, CROSS, integrated with a programmable couch mount, designed to evaluate proton beam properties across various gantry angles. The CROSS detector's performance was validated through comparisons with a pinpoint chamber, Gafchromic EBT3 film, and the XRV-124 detector. Spot size measurements showed a slight increase compared to the pinpoint chamber, with average deviations of 11.3% in the Y-direction and 6.3% in the X-direction. Spot position accuracy tests demonstrated excellent agreement with EBT3 film, with an average positional deviation of 0.11 ± 0.06 mm, and all deviations remaining within 0.2 mm. The beam characteristics across different gantry angles showed maximum spot size variations of 0.17 mm in the Y-axis and 0.11 mm in the X-axis. Proton isocenter measurements with CROSS were largely consistent with XRV-124, with deviations under 0.2 mm in most cases, except for gantry angles of 90° and 315°, where deviations of 0.25 mm and 0.33 mm were observed. These findings highlight the CROSS detector's precision and versatility, making it a valuable tool for quality assurance in proton therapy.