An analytical approach to organ equivalent dose estimation based on material composition photon attenuation coefficient

Abstract

Monte Carlo photon transport calculation is widely used with anthropomorphic phantoms to estimate equivalent doses for different photon energies and exposure geometries. Although a high precision probabilistic method, it is computationally expensive. The uncertainties in the physical input parameters and deviations in the particle simulation from the actual exposure also limit the accuracy of the dose conversion coefficients. This study presents an analytical method of calculating the organ equivalent dose of virtual adults from external gamma radiation based on elemental tissue composition energy transfer, energy-absorption coefficient, and photon interaction. The two methods developed are based on ICRU-four and nine elements in tissues. The methods are subsequently used to estimate the equivalent dose for various organs in virtual male and female adults exposed to external monoenergetic gamma rays. The equivalent dose results from the simulated geometries show the accuracy and adaptability of the proposed method. The result is also in agreement with the International Commission on Radiological Protection (ICRP) publication 116. Moreover, the result shows that the proposed method can accurately calculate organ equivalent dose from external photon irradiation without considering the complex photon transport computations used in existing photon transport codes. In addition, compared with four other conventional approaches, the evaluation result shows that the proposed analytical approach enhances computation efficiency without compromising dose calculation accuracy.