Comparison of MatriXX evolution and MatriXX resolution dosimetry systems and their sensitivity to gantry angle variations in gamma index measurements

Abstract

Author(s): El Ghalmi Mohammed, El Mahjoub Chakir, Lakbir El Hamidi, Raoui Yasser*, Herrassi Yassine, Oustous Aziz, Jioudy Basma, Errouadi Morad, ELOuardy Khalid, Talsmat Khalid and Chouib Fatima Ezzahra

T This study investigates the dosimetric performance of two advanced dosimetry systems, MatriXX evolution and MatriXX resolution, using gamma index measurements under fixed and varying gantry angles. The study aims to elucidate the impact of system characteristics and gantry angulation on dosimetric accuracy in radiation therapy quality assurance. Accurate dose delivery in radiation therapy relies on robust quality assurance measures provided by dosimetry systems. MatriXX evolution and MatriXX resolution are widely recognized for their ability to capture dose distributions, with MatriXX resolution offering higher detector density and spatial resolution compared to MatriXX evolution. The gamma index, a metric commonly used for dosimetric evaluation, quantifies the agreement between calculated and measured dose distributions, crucial for ensuring treatment efficacy and patient safety. Measurements were performed using the Elekta Infinity LINAC operating at 6 MV and 6 FFF (Flattening Filter Free) modes. Dose distributions were calculated using the Monaco Monte Carlo treatment planning system, simulating clinical scenarios with both fixed gantry angle (0°) and varying gantry angles. Gamma index evaluations were conducted using criteria of 2%/2 mm and 3%/3 mm to assess dosimetric accuracy. Analysis of gamma index results revealed significant differences between MatriXX evolution and MatriXX resolution. MatriXX resolution consistently demonstrated superior gamma index values, particularly under strict criteria (2%/2 mm), attributable to its enhanced detector density and spatial resolution capabilities. Variations in gantry angle introduced notable changes in gamma index values for both dosimetry systems, highlighting the influence of beam orientation on dosimetric accuracy. In conclusion, this study underscores the critical role of dosimetry system characteristics and gantry angulation in radiation therapy quality assurance. MatriXX resolution's superior performance over matriXX evolution in detecting small dose discrepancies underscores its suitability for precise dosimetric evaluations. The findings emphasize the necessity of comprehensive QA protocols considering angular effects to ensure accurate radiation dose delivery in clinical practice.

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