The conversion coefficients from Нр(10) to effective dose in the fields of photon radiation and their use in the development of occupational exposure models

The paper presents the values of the conversion coefficients from the operational quantity, HP(10)/ to the protection quantity, effective dose (E). The conversion coefficients were calculated in a number of points located at a depth of 10 mm under the surface of the torso of the computational model MIRD-5 of the body of an adult. The simulated irradiation conditions corresponded to both uniform and sharply non-uniform irradiation of the employee in the fields of photon radiation with the energy from 0.04 to 2 MeV. It was demonstrated that for the uniform radiation and the “typical” location of the individual dosimeter on the employee’s body, the E/HP(10) ratio is less than one in the entire range of radiation energies for the directions of its incidence in front and from the left side, i.e. Hp(10) is a conservative assessment of E. When the radiation falls on the back and for the “typical” location of an individual dosimeter on the employee’s body in the entire range of radiation energies, the ratio E/Hp(10) is significantly larger (for the energies <0.1 MeV) or close to one, i.e. Hp(10) is not a conservative assessment of E. In the spatial non-uniform fields of photon radiation with an increase in the degree of non-uniformity irradiation of the employee’s body, the values of the conversion coefficients decreased. When irradiation in front and from the left side an individual dosimeter placed in a “typical” position will be conservative estimate the value of an effective dose of the employee in the entire considered range of energies. When irradiation on the right side an individual dosimeter placed in a “typical” position will underestimate the value of an effective dose in the entire considered range of energy. It was demonstrated that the optimal location of the individual dosimeter on the surface of the employee’s body allows us to adequately assess according to his indications the value of an effective dose even with significantly changing geometry of its irradiation during a complete cycle of treatment with the source of ionizing radiation. 

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