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Contamination of ionization chambers by talcum powder
Author(s) -
Hanson William F.,
Arnold Donald J.,
Shalek Robert J.,
Humphries Leroy J.
Publication year - 1988
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 - 10.1118/1.596194
Subject(s) - contamination , dosimetry , ionization chamber , ionization , calibration , materials science , environmental science , radiochemistry , nuclear engineering , nuclear medicine , chemistry , physics , medicine , engineering , ion , ecology , quantum mechanics , biology , organic chemistry
This is a word of caution to anyone using ionization chambers protected by thin rubber sheaths in water. Four Farmer‐type ionization chambers contaminated with talcum powder were received for calibration by the Accredited Dosimetry Calibration Laboratory at the University of Texas M. D. Anderson Cancer Center. The chambers show a marked energy dependence (5% to 20%) to soft orthovoltage x rays. The response of the contaminated chambers is compared with the chambers’ response before contamination and after cleaning. Techniques for identifying contaminated chambers and suggestions for cleaning them are presented.