Design and construction of a quality control phantom for evaluation of the clinical imaging performance of electronic portal imaging devices

This study presents the design and construction of a quality control phantom for evaluating the clinical imaging performance of electronic portal imaging devices (EPIDs) used in radiation therapy. The phantom, incorporating lead sheets of varying thicknesses and a plexiglass scaling component, enables the assessment of key image quality parameters, including Noise, Uniformity, Contrast-to-Noise Ratio (CNR), Signal-to-Noise Ratio (SNR), Contrast, and pixel-to-millimeter scaling. A dedicated software application, developed using LabVIEW, facilitates automated and standardized analysis of EPID images. The phantom was tested across two radiotherapy centers, revealing differences in EPID performance, with Center A demonstrating lower Noise (۰.۵ vs. ۱.۶), better Uniformity (۱.۹ vs. ۹.۳), and higher CNR (۶۹.۳ vs. ۴۵.۶) and SNR values compared to Center B. The phantom's design, inspired by established models like the Las Vegas and PTW phantoms, supports both qualitative and quantitative evaluations, meeting TG۱۴۲ standards for spatial resolution (>۲ mm). This work highlights the efficacy of tailored quality assurance tools in enhancing EPID performance, ensuring precise radiation therapy delivery and improved patient outcomes.

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Keywords: EPID QC phantom ، image quality parameters ، radiotherapy ، Verification