Effects of characteristic x-rays on assay of I-123 by dose calibrator.


Journal Article

Large differences in dose-calibrator readings are obtained if "high-purity" I-123 is assayed in different containers. Large correction factors are necessary for assaying another isotope of iodine, I-125, in a dose calibrator, because of absorption of the low-energy (28.4-keV, weighted mean) emissions. We found that up to 70% of the dose-calibrator response to I-123 can be due to characteristic x-rays with energies exactly the same as those emitted by I-125, and that dose-calibrator response to I-123 is also strongly affected by the absorption properties of the vial. An appropriate method to define I-123 activity uses a gamma camera with a medium-energy collimator to establish correction factors for dose-calibrator assay of I-123 in different containers. Correction factors for a plastic syringe and a thick-wall glass vial, were determined using this method. Measurement of I-123 activity in a copper absorber will eliminate the response to x-rays, and the gamma camera is useful in establishing the necessary correction factors.

Full Text

Duke Authors

Cited Authors

  • Harris, CC; Jaszczak, RJ; Greer, KL; Briner, WH; Coleman, RE

Published Date

  • December 1984

Published In

Volume / Issue

  • 25 / 12

Start / End Page

  • 1367 - 1370

PubMed ID

  • 6502258

Pubmed Central ID

  • 6502258

International Standard Serial Number (ISSN)

  • 0161-5505


  • eng

Conference Location

  • United States