Analysis of photon beam exit dose using photon point kernels.

  • Milton K Woo
  • Published 1994 in Physics in medicine and biology


The Monte Carlo method is used to analyse the dose fall-off at the exit surface of a megavoltage photon beam. The convolution/superposition method of dose calculation using Monte-Carlo-generated homogeneous photon kernels is shown to be in error for exit dose calculation. Instead, photon kernels that incorporate modelling of the exit surface were generated, also using Monte Carlo, to analyse the problem, and the calculated dose fall-off using these kernels agrees well with measured data. In addition, the physics underlying the characteristics of the dose fall-off is analysed based on complete Monte Carlo modelling. Practical improvements to the convolution/superposition method are suggested.

Cite this paper

@article{Woo1994AnalysisOP, title={Analysis of photon beam exit dose using photon point kernels.}, author={Milton K Woo}, journal={Physics in medicine and biology}, year={1994}, volume={39 4}, pages={687-702} }