Standardization of Radioactive Iodine
- 6 May 1949
- journal article
- research article
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 109 (2836) , 456-461
- https://doi.org/10.1126/science.109.2836.456
Abstract
Results of standardization of samples of radioiodine with equal I131 content performed by 70 laboratories in this country show a standard deviation of 30% and range from 43 to 180 units. Differences developing between laboratories making absolute standardizations by coincidence measurement and gamma ionization methods are probably related to errors in our conception of the disintegration scheme of I131. Standardizations against long-lived radioactive standards face the difficulty that energy spectra of the standard and I131 differ. Difficulties arise in laboratories performing standardizations with instruments calibrated against a known I131 sample due to variations in prepn. and handling of samples, losses in drying, and fluctuations in the efficiency of Geiger-Muller counter tubes with temp., atmospheric pressure, ageing, etc. Use of ionization chambers which are less sensitive but more rugged and reliable, and give more reproducible values than G-M tubes in standardizing will decrease the errors. Two suitable icnization chambers are discussed.Keywords
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