Calculation of Dose Deposition
Gamma rays and X-rays interact with matter mainly by photoelectric
absorption, Compton scattering, or pair production. The dose deposited by
individual photons is a function of their energy. When the fluence (intensity
vs. energy distribution) of X-rays and gamma rays is known, dose deposition
can be estimated by looking up fluence-to-dose conversion factors, of by
calculating deposited dose from the local (attenuated) fluence in an absorber
and the (energy dependent) interaction coefficients of the local fluence.
Neutron and Gamma-ray Fluence-to-Dose Factors can be found in
ANS Standard ANS - 6.1.1 - 1991.
Dose deposition in multilayered absorbers is calculated accurately by the
PC program PHOTKOEF. This program calculates dose distributions in multilayered absorbers as functions of depth, and dose deposition functions for selected layers of multilayered absorbers as functions of energy. Energy transport across interfaces of dissimilar materials is considered by PHOTKOEF. Inputs to PHOTKOEF can be single photons or spectrally distributed photons.
www.nucleonics-online.com/623.html
Edited on 3 October 2002 - E-mail to the
Webmaster
