Investigation of the convolution method for polyenergetic spectra

Nikos Papanikolaou, T. Rockwell Mackie, Carol Meger-Wells, Mark Gehring, Paul Reckwerdt

Research output: Contribution to journalArticlepeer-review

134 Scopus citations


The distribution of absolute dose per unit fluence from polyenergetic photon beams impinging upon a water phantom was calculated using two convolution approaches that properly account for beam hardening effects. Dose deposition kernels calculated previously using the EGS4 Monte Carlo code are convolved with the primary terma to give the dose for monoenergetic photon beams of energies ranging from 100 kev to 50 MeV. A polyenergetic dose distribution is composed of separately calculated monoenergetic components, which are appropriately weighted with the fluence spectrum to yield the polyenergetic dose distribution. Alternatively, a single convolution for the polyenergetic beam is considered, where a composite polyenergetic kernel is convolved with the respective polyenergetic terma. The effects of the polyenergetic kernel variance due to beam hardening as well as the effect of tilting the kernels for a diverging beam geometry were also examined. The depth dose data produced using the two proposed methods were compared with measured data and Monte Carlo simulations and showed good agreement.

Original languageEnglish (US)
Pages (from-to)1327-1336
Number of pages10
JournalMedical physics
Issue number5
StatePublished - Sep 1993
Externally publishedYes


  • Monte Carlo
  • Radiotherapy
  • beam spectrum
  • convolution
  • convolution kernel
  • homogeneous phantom
  • photon dosimetry

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging


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