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Graphite calorimeter in water phantom and calibration of ionization chambers in dose to water for 60 Co gamma radiation
Author(s) -
Rao I. S. Sundara,
Naik S. B.
Publication year - 1980
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 - 10.1118/1.594685
Subject(s) - ionization chamber , absorbed dose , dosimeter , calibration , imaging phantom , ionization , dosimetry , calorimeter (particle physics) , materials science , percentage depth dose curve , radiation , radiochemistry , irradiation , gamma ray , dose profile , nuclear medicine , physics , nuclear physics , optics , chemistry , ion , detector , medicine , quantum mechanics
A graphite calorimeter similar in size and shape to a Farmer type 0.6‐cm 3 ionization chamber was developed for direct measurement of absorbed dose at a specified depth in a water phantom irradiated by a beam of 60 Co gamma radiation. The accuracy of the absorbed dose determined was estimated to be ±1.1% at a dose level of 4 rad/s (4×10 −2 Gy s −1 ). The absorbed dose to water at the calibration depth of 5 cm was standardized for our 60 Co gamma beam, for a 60‐cm SSD and 10×10 cm 2 field. Farmer type ionization chambers were calibrated against the standardized absorbed dose. The overall accuracy in calibrating the ionization chambers was ± 1.2%.