Air kerma rate constants for gamma emitters used most often in practice

Abstract

It is often required to estimate the dose rate at a distance from radionuclides that are sources of X rays and gamma rays. Such calculations may be required for planning radiation protection measures in the vicinity of radioactive sources or patients containing radionuclides, calibrations of radiation instruments or for estimating the absorbed dose rate to patients receiving brachytherapy. The factor relating activity and air kerma rate is called air kerma rate constant-Gamma(delta). In this paper, the results of recalculation of this quantity for unfiltered point sources of radionuclides in practice used most often are given. The calculations included corrections for internal conversion of X rays and gamma rays and detailed accounting of the generation of the K and L series X rays from internal conversion and electron capture. Particular air kerma rate constants were calculated for each discrete line in the photon spectrum of radionuclide with a yield per decay event GT 0.01% and the energy GT 20 keV. Since the energy structure of the photon spectra and accessible discrete numerical values of the mass energy-transfer coefficient for air are not the same, the cubic spline interpolation was used to obtained the coefficient, where the photon spectrum data are available. In the calculation, the latest gamma ray spectral data for all radionuclides and latest data for the mass energy-transfer coefficient for air are used. Air kerma rate constants for the following 35 radionuclides are calculated: C-11, N-13, O-15, F-18, Na-24, K-42, K-43, Cr-51, Fe-52, Fe-59, Co-57, Co-58, Co-60, Ga-67, Ga-68, Se-75, Mo-99, Tc-99m, In-111, In-113m, I-123, I-125, I-131, Xe-127, (133)xe, Cs-137, Eu-152, Eu-154, Tm-170, Ta-182, Ir-192, Hg-197, (198)AU, Tl-201 and Am-241.