Investigation of the radiological properties of various phantoms for their application in low energy X-rays dosimetry

It has been previously proven that the radiological properties of materials are strongly dependent on the incident radiation energy. Hence, the present study aimed to evaluate the radiological properties and soft tissue equivalency of conventional phantoms at the 1-50 keV photon energy as well as the feasibility study of using a more appropriate material instead of water. The equivalence of water and a number of conventional phantoms with breast and muscle were evaluated in terms of mass density (rho), effective electron density (N-eff), effective atomic number (Z(eff)), photon mass energy-absorption coefficient (mu(en)/rho), photon mass attenuation coefficient (mu/rho), total stopping power of electrons (S/rho)(tot) and the absorbed depth dose by using the Auto-Z(eff) software and XCOM, ESTAR database and Monte Carlo simulation method. The differences of rho, N-eff, Z(eff) and (S/rho)(tot) between investigated materials and breast were 0.5-17%, 0.2-9%, 0.7-26%, and 2-11%, respectively. Additionally, the differences of mu(en)/rho, mu/rho, and the absorbed depth dose between the investigated phantom materials and breast tissue were 18-56%, 16-53%, and 5-79% respectively. Also, the differences of rho, N-eff, Z(eff), mu(en)/rho, mu/rho, (S/rho)(tot), and the absorbed depth dose between the investigated phantom materials and muscle were 1-14%, 2-9%, 1-33%, 4-67%, 6-63%, 1-15% and 3-93%, respectively. Water cannot be considered as breast tissue equivalent phantom in the energy range of 1-50 keV. Moreover, the results of depth dose investigation showed that the GENIPIN gel is the most suitable breast tissue substitute in intraoperative radiotherapy method.