S1692
Physics - Detectors, dose measurement and phantoms
ESTRO 2026
with characteristic patterns across patients. These findings suggest that integrating spectroscopic data into the imaging framework of the proposed system could enhance proton range verification and tissue characterization. References: [1] H. Paganetti, "Range uncertainties in proton therapy and the role of Monte Carlo simulations," Physics in Medicine & Biology, vol. 57, no. 11, p. R99, 2012. Keywords: proton range verification, gamma ray spectroscopy
generated on Accuray Precision 3.5.0.1 treatment planning system and delivered with a Cyberknife S7 Accuray treatment machine. PSQA were measured three times: first applying LUT correction to myQA SRS; second with GAS+ correction, third with SRSMapCheck detector (SunNuclear). Gamma passing rate (using a global 3%/1mm criteria with a 5% threshold) from the three methods were compared. In addition, the LUT correction table provided by the vendor was compared to our measurements. Results: We found good agreements between vendor LUT and our (Figure1). MyQA PSQA resulted in good overall passing rates for all plans and methods. Results from SRSMapCheck were found equivalent in terms of passing rates although the number of considered measurement points for the evaluation were smaller (Figure2).
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Enhanced gantry angle sensor (GAS+) correction for Cyberknife patient specific QA with a CMOS solid state detector Nicolas Perichon 1 , Khazra Shahid 1 , Sabrina Décaillet 1 , Marie Fargier-Voiron 1 , Mireille Conrad 1 , Cédric De Marco 1 , Oscar Matzinger 1,2 , Maud Jaccard 1 1 Clinique Générale-Beaulieu and Clinique de Genolier,, Swiss Medical Network, Geneva, Switzerland. 2 Department of Health Sciences and Technology, ETH, Zürich, Switzerland Purpose/Objective: The myQA SRS solution (IBA), designed for machine and patient-specific quality assurance (PSQA), provides a spatial resolution of 0.4mm making it particularly suitable for SRS and SBRT quality assurance. Previous studies [1,2] showed an angular dependence of the array detector response affecting measurement accuracy. This study aims to evaluate the new angular dependence correction solution developed by IBA using the enhanced gantry angle sensor (GAS+) for Cyberknife PSQA. Material/Methods: MyQA SRS detector array is made of a CMOS solid state film-class resolution detector containing 105000 measurement points in an active measurement area of 12cmx14cm. Adapted to Cyberknife positioning tracking, a dedicated fiducial plate is fixed on the top surface of the array; and both inserted in a cylindrical phantom to perform measurements. Two solutions are proposed to correct angular dependence response: look up table (LUT)(extracts beam incidence angles from treatment plan) and enhanced GAS+. The GAS is an inclinometer fixed on the Cyberknife cover whose reference zero angle is set when Cyberknife is at perch position. When a beam is detected by the array, frames are recorded and angular information is processed by the software to apply a calculated correction to the acquisition.To assess the new developed correction (GAS+), five PSQA clinical treatment plans, intracranial and rachis, were
Conclusion: The enhanced gantry angle sensor (GAS+) solution developed for IBA myQASRS was tested and compared to the existing LUT approach. Good agreement was found on passing rate results between the two methods and the measurements performed with another device for five clinical treatment plans. Additional PSQA need to be performed to improve the robustness of this study. Others treatment localization (prostate) for which treatment beams angle are usually different are currently under investigation. References: [1] Padelli, F.; Aquino, D.; Fariselli, L.; De Martin, E. IBA myQA SRS Detector for CyberKnife Robotic Radiosurgery Quality Assurance. Appl. Sci. 2022, 12,
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