title: Build-up region of megavoltage photon radiation sources.
abstract: 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.
mesh_terms: D003037:Cobalt Radioisotopes; D008433:Mathematics; D055585:Physical Phenomena; D010825:Physics; D011827:Radiation / Q000295:instrumentation*; D011829:Radiation Dosage; D011882:Radiotherapy, High-Energy
chemical_list: D003037:Cobalt Radioisotopes