RELATIONS BETWEEN THE EFFECTIVE DOSE AND THE INDICATIONS OF AN INDIVIDUAL DOSIMETER IN ANISOTROPIC PHOTON FIELDS

摘要

The effective dose, the personal dose equivalent, and the indications of an individual dosimeter are calculated, using the ROBOT computer program (Monte Carlo method), for the conditions of irradiation of an anthropomorphic heterogeneous ICRP phantom with wide beams of 40 keV-11 MeV photons for all solid angles. In anisotropic photon fields, the dosimeter indications satisfactorily estimate the personal dose equivalent. The dependence of the ratio of the effective dose to the indications of an individual dosimeter on the irradiation conditions is analyzed. It is noted that the individual dosimeter indications are not conservative when the phantom is irradiated from the back half-space. It is shown that for wide photon beams the ratio of the effective dose to the dosimeter indications determined neglecting the scattering of radiation inside the working room is an upper limit of the indicated ratio calculated taking scattering into account.