Self-absorption effects on electron absorbed fraction in the anterior nose

The electron absorbed fraction in the anterior nose is estimated in the International Commission on Radiological Protection Publication 66 using the EGS4 Code and a cylinder model. The electrons are assumed to come from point sources lining the inner surface of the nose. Although the radioactive source particles are carried in dust, self-absorption in the dust is ignored. Consequently, the absorbed fractions published in ICRP 66 cannot represent the correct energy deposition in the basal cell region. In this work we estimate the energy lost by the emitted electrons inside spherical dust particles, which vary in diameter from 1 micron to 100 microns. The absorbed fractions in the basal cell layer are then estimated using the modified electron energy spectrum. To illustrate these effects, modified absorbed fractions for a dust particle radius of 20 microns are compared to the absorbed fractions presented in ICRP 66. Significant differences are noted.