1991 Volume 47 Issue 12 Pages 2002-2008
The data table of a 1cm dose equivalent per fluence to estimate the effective dose equivalents conservatively from external photon beams were given by ICRP. However these data were calculated with single energy photon beams; therefore, it must be careful when for applying the data to photon beams with spectral distributions. In this paper, we calculated the 1cm dose equivalent per unit exposure for spectral photon beams by means of a Monte Carlo simulation, and ascertained the suitability of the usual method which estimates dose equivalents by means of ICRP data corresponding to the effective energy of the spectral beam. Consequently, the 1cm dose equivalent per unit exposure calculated for primary X-ray beams and for scattered photon beams from an irradiated body were in good agreement with the ICRP data corresponding to the effective energies of each beam. However, those calculated for X-rays transmitted through a lead shield showed a considerably lower value than ICRP data corresponding to their effective energies.