ELECTRON-BEAM DOSIMETRY FOR A MULTILAYER ABSORBER

Depth dose distributions were measured in a multilayer absorber of Ti-air-cellulose triacetate (CTA)-backing material (Pb, Sn, Fe, Al and CTA) irradiated with 300 and 800-keV electrons. The results are compared with the calculated value using computational code for multilayer absorbers (EDMULT) developed by Tabata et al. (1989, 1990). The absorbed dose in CTA exceeds the calculated value near the surface, while it is smaller than the calculated dose as the penetration depth becomes closer to the range of incident electrons. The measurements and computations show better agreement for the high-energy (800-keV) electrons than for the 300-keV electrons, probably because of the greater obiqueness of incidence at lower energies, which is not taken into account by the computation code.