Surface and build-up region dose analysis for clinical radiotherapy photon beams

Appl Radiat Isot. 2008 Oct;66(10):1438-42. doi: 10.1016/j.apradiso.2008.02.089. Epub 2008 Mar 4.

Abstract

The standard clinical approach of dose measurement using a Farmer type fixed plane parallel cylindrical ionization chamber produces erroneous results in the build-up region. We studied dose distribution in this region using a Monte Carlo simulation technique and compared our results with data measured using extrapolation, parallel plate, and cylindrical farmer type ionization chambers for 6 and 10 MV photon beams from two different accelerators. The extrapolation chamber data agreed favorably with the Monte Carlo results, suggesting that dose at the skin surface and a few mm beneath is significantly lower than conventionally accepted values.

MeSH terms

  • Computer Simulation
  • Models, Statistical*
  • Monte Carlo Method
  • Photons / therapeutic use*
  • Radiation Dosage
  • Radiometry / methods*
  • Radiotherapy Planning, Computer-Assisted / methods*
  • Radiotherapy, Conformal / methods*
  • Reproducibility of Results
  • Sensitivity and Specificity