Surface and build-up region dose analysis for clinical radiotherapy photon beams.
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.
Ishmael Parsai
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E
Department of Radiation Oncology, University of Toledo Health Science Campus, 3000 Arlington Avenue, Toledo, OH 43614, USA. e.parsai@utoledo.edu
Shvydka
Diana
D
Pearson
David
D
Gopalakrishnan
M
M
Feldmeier
John J
JJ
D003198:Computer Simulation; D015233:Models, Statistical; D009010:Monte Carlo Method; D017785:Photons / Q000627:therapeutic use*; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity