Measurement of mass attenuation coefficient of polyvinyl alcohol (PVAL) as breast tissue equivalent material in the photon energy range of 16.61-25.26 keV

Abstract

Medical physics phantom is commonly designed to mimic physical properties of human tissue. Phantom is widely used to provide quantitative and qualitative information upon its interaction with ionizing radiation in medical imaging, radiation dosimetry and treatment planning procedures. This study was carried out to fabricate a potential medical physics phantom material for mammography using polyvinyl alcohol (PVAL). The mass attenuation coefficients (μ/ρ ) of the PVAL gel samples were calculated based on the measurement of attenuation coefficient studies with low photon energy. The gel samples were prepared at 4 concentrations (5, 10, 15 and 20 %) of PVAL solution. Single photon beam transmission in the energy range between 16.61 and 25.26 keV was used to determine the μ/ρ of the PVAL gel. The low photon energy was chosen as the effective energy used in mammography is in a range between 17.5 to 22.6 keV. This was achieved by using the X-ray fluorescent (XRF) configuration. The experimental μ/ρ were compared with theoretical values of water and breast tissue calculated by using the XCOM computer program. The measured value of μ/ρ of the PVAL gels agreed with the XCOM values of water and breast tissue. The 5% and 10% PVAL gel samples were the closest to water while the 20% PVAL was the closest to breast tissue.