Assessment of the activity distribution of metal radionuclides in plastic phantoms using μSPECT imaging and gamma counting

M. Park, A. Mahmood, R. E. Zimmerman, N. Limpa-Amara, G. M. Makrigiorgos, S. C. Moore

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

At neutral pH, metal radionuclides, e.g., In-111 and Y-90, precipitate and adhere to container walls, yielding nonuniform activity distributions in compartments of plastic phantoms used for dosimetry validation. For various concentrations of a chelator, EDTA, we evaluated the uniformity of activity distributions in phantoms, as well as the accuracy of a fluorescent liquid dosimeter, coumarin-3-carboxylic acid (CCA). Solutions of In-111 and Y-90 with activity concentrations of 10-25μCi/cc containing increasing EDTA concentrations (0-25μM) were stored in polymethyl methacrylate (PMMA) phantoms for 24 h to accumulate dose. Activity in the solution was then measured in a gamma counter and/or by μSPECT imaging. Phantoms containing 0.1 mM CCA with EDTA were also irradiated either with a Cs-137 irradiator or with Y-90 to evaluate the effect of EDTA concentration on fluorescence intensity (FI). Activity measurements from images and gamma counting indicated that 40-50% of the activity of In-111 and Y-90 (25μCi/cc) accumulated on phantom walls for EDTA concentration <2.5μM, whereas no adherence was observed for EDTA concentration >2.5μM. For a fixed absorbed dose, fluorescence intensity decreased by <15% when using 2.5μM EDTA. For all EDTA concentrations, a linear dose-FI relationship was observed up to ∼15Gy. For phantom dose measurements using metal radionuclides, solutions should contain ∼1,000 EDTA molecules for each radiolabeled atom to obtain a uniform activity distribution.

Original languageEnglish (US)
Title of host publication2006 IEEE Nuclear Science Symposium - Conference Record
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages3139-3141
Number of pages3
ISBN (Print)1424405610, 9781424405619
DOIs
StatePublished - 2006
Externally publishedYes
Event2006 IEEE Nuclear Science Symposium, Medical Imaging Conference and 15th International Workshop on Room-Temperature Semiconductor X- and Gamma-Ray Detectors, Special Focus Workshops, NSS/MIC/RTSD - San Diego, CA, United States
Duration: Oct 29 2006Nov 4 2006

Publication series

NameIEEE Nuclear Science Symposium Conference Record
Volume5
ISSN (Print)1095-7863

Other

Other2006 IEEE Nuclear Science Symposium, Medical Imaging Conference and 15th International Workshop on Room-Temperature Semiconductor X- and Gamma-Ray Detectors, Special Focus Workshops, NSS/MIC/RTSD
CountryUnited States
CitySan Diego, CA
Period10/29/0611/4/06

ASJC Scopus subject areas

  • Radiation
  • Nuclear and High Energy Physics
  • Radiology Nuclear Medicine and imaging

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