title: Graphite calorimeter in water phantom and calibration of ionization chambers in dose to water for 60Co gamma radiation.
abstract: A graphite calorimeter similar in size and shape to a Farmer type 0.6-cm3 ionization chamber was developed for direct measurement of absorbed dose at a specified depth in a water phantom irradiated by a beam of 60Co gamma radiation. The accuracy of the absorbed dose determined was estimated to be +/- 1.1% at a dose level of 4 rad/s (4 X 10(-2)Gys-1). The absorbed dose to water at the calibration depth of 5 cm was standardized for our 60Co gamma bean, for a 60-cm SSD and 10 X 10 cm2 field. Farmer type ionization chambers were calibrated against the standardized absorbed dose. The overall accuracy in calibrating the ionization chambers was +/- 1.2%.
mesh_terms: D002138:Calibration; D002151:Calorimetry / Q000295:instrumentation*; D003037:Cobalt Radioisotopes / Q000627:therapeutic use*; D004307:Dose-Response Relationship, Radiation; D006801:Humans
chemical_list: D003037:Cobalt Radioisotopes