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Build‐up region of megavoltage photon radiation sources
Author(s) -
Velkley D. E.,
Manson D. J.,
Purdy J. A.,
Oliver G. D.
Publication year - 1975
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.594158
Subject(s) - ionization chamber , radiation , photon , ionization , dosimetry , volume (thermodynamics) , percentage depth dose curve , nuclear medicine , optics , photon energy , materials science , physics , atomic physics , ion , medicine , quantum mechanics
Measurements of surface dose and build‐up have been measured for photon radiation sources with maximum energy from 1.2 to 25 MeV. A variable volume ionization chamber was used and the results extrapolated to what would be obtained with a zero volume chamber. The results are found to depend systematically on the plate separation of a parallel plate ionization chamber and an empirical method was derived for correcting measurements made with a fixed volume chamber. The relationship of dose build‐up curves with skin reactions in radiation therapy patients is discussed.