Dose conversion coefficients for external photon irradiation
The algorithm for calculation of dose conversion coefficients based on Monte Carlo simulation of the photon radiation transport within the computational human phantoms presented. The algorithm was implemented as DosesMale and DosesFemale programs for organisms, starting from the reference male and female phantoms. In order to verify these programs, the «fluence-absorbed dose» and «fluence-effective dose» conversion coefficients were determined for situations of the reference phantoms exposure to a broad unidirectional energy-homogeneous beam of photon radiation in 4 projections: anterior-posterior, posterior-anterior, left lateral, and right lateral. The calculated conversion coefficients were compared with the reference values provided by the International Commission on Radiological Protection for external photon irradiation of the whole body. The «fluence-absorbed dose» conversion coefficients of the majority of critical organs and tissues were in a good agreement with the reference values (relative difference below 3-5 %). Only for some organs (mammary gland of the male phantom, esophagus and «remaining tissues» of the female phantom) significant discrepancies were observed (above 7 %). For the «fluence-effective dose» conversion coefficients, maximal relative differences between the calculated values and the reference values were not higher than 3.5 %. About 700 dose conversion coefficients were calculated with the help of DosesMale and DosesFemale programs for dental, lungs, intestinal, thoracic, lumbar, and lumbosacral radiography.