A review of the discrepancy between the in-air and in-water calibration of cobalt-60 machines.
Causes for the discrepancy noted by Grant et al. between the in-water and in-air calibration of 60Co are discussed. Data are presented from measurements with a set of ionization chambers with thimbles of 0.5, 1.0, and 1.5 cm outside radii. These data include measurements of percentage depth dose, backscatter factors, and displacement factors. The results show that the discrepancy noted by Grant et al. is caused by a combination of small errors both in depth dose data and in the displacement factor incorporated into C lambda.
D000390:Air Ionization; D003037:Cobalt Radioisotopes / Q000032:analysis*; D006801:Humans; D011879:Radiotherapy Dosage; D012542:Scattering, Radiation; D014867:Water
D003037:Cobalt Radioisotopes; D014867:Water