TY - GEN
T1 - Assessment of the activity distribution of metal radionuclides in plastic phantoms using μSPECT imaging and gamma counting
AU - Park, M.
AU - Mahmood, A.
AU - Zimmerman, R. E.
AU - Limpa-Amara, N.
AU - Makrigiorgos, G. M.
AU - Moore, S. C.
PY - 2006
Y1 - 2006
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=38549139540&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=38549139540&partnerID=8YFLogxK
U2 - 10.1109/NSSMIC.2006.356540
DO - 10.1109/NSSMIC.2006.356540
M3 - Conference contribution
AN - SCOPUS:38549139540
SN - 1424405610
SN - 9781424405619
T3 - IEEE Nuclear Science Symposium Conference Record
SP - 3139
EP - 3141
BT - 2006 IEEE Nuclear Science Symposium - Conference Record
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 2006 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
Y2 - 29 October 2006 through 4 November 2006
ER -