Comparing tissue-equivalent properties of polyester and epoxy resins with PMMA material using Gate/Geant4 simulation toolkit

Abstract

This study investigates the applicability of cost-effective and commercially available polyester and epoxy resins as alternative materials for polymethyl methacrylate (PMMA) in computed tomography (CT) dosimetry phantoms. The mass attenuation coefficients (μ/ρ) of the resin samples were determined using the GEANT4/GATE simulation framework and compared with those of PMMA material over a spectrum of diagnostic photon energies from 10 to 150 keV. A CT scanner was used to acquire the mean attenuation values (CT number) of the fabricated samples at 80,100,120 and 140 kVp CT tube energy. The study found that the resins have similar physical properties and dosimetry behavior to PMMA at all energies. Polyester has a negligible 1% deviational variance in mass attenuation from PMMA. Epoxy demonstrates substantially elevated mass attenuation coefficients compared to PMMA at inferior photon energies between 10 and 40 Kvp. However, with ascending photon energy, the mass attenuation coefficients of epoxy resin and PMMA become more homologous, ultimately converging indistinguishably at 100 Kvp. The CT number results showed that polyester has a 3% difference from PMMA. Moreover, the epoxy resin's CT numbers were within 18HU of PMMA material. These findings demonstrate the feasibility of using low-cost, readily available resin composites such as polyester and epoxy resins as a substitute material for CT dosimetry phantom in computed tomography.