Evaluating backscatter factor variations in diagnostic radiology using different phantom materials

The selection and characterization of tissue-equivalent materials are pivotal in medical physics for enhancing diagnostic radiology dosimetry and quality assurance. This study evaluates the dosimetric performance of epoxy and polyester resin phantoms in comparison to polymethyl methacrylate (PMMA). Four phantoms,two square and two cylindrical, were fabricated from epoxy, polyester, and PMMA materials. Their physical properties, including atomic composition, effective atomic number, electron density, and mass density, were analyzed. Dosimetric measurements such as entrance surface dose (ESD) and backscatter factors (BSF) were performed using a digital X-ray radiography system. Results indicate that polyester resin closely approximates PMMA in atomic composition and dosimetry at low intensities, while epoxy resin is more aligned with PMMA at higher intensities. BSF analysis revealed that both epoxy and polyester exhibit scattering behavior comparable to PMMA, with geometry significantly influencing BSF values. These findings support the viability of polyester and epoxy as cost-effective and efficient alternatives to PMMA for radiation dosimetry in clinical radiology, offering tailored solutions for specific diagnostic energy ranges and phantom geometries.