(Thursday, 7/18/2019) 10:00 AM - 12:00 PM
Room: 304ABC
Purpose: To improve phantom-based dosimetry precision for nuclear medicine applications by providing a free dose calculation tool using advanced anatomy models.
Methods: Twelve National Cancer Institute adult/pediatric phantoms developed from patient images were used to calculate photon and electron Specific Absorbed Fractions (SAFs) for 68 source and 55 target regions, using MCNPX Monte Carlo code. S values were then derived from the SAFs for 299 radionuclides commonly used in nuclear medicine. The graphical user interface-based computer program, named National Cancer Institute dosimetry system for Nuclear Medicine (NCINM) was finally developed to facilitate data input/output. A comprehensive comparison of our S values was conducted with those previously published by Lamart et al. for iodine-131– based on the ICRP reference adult computational phantoms, and OLINDA/EXM 1.0 – based on the ORNL stylized phantoms.
Results: The ratios of our iodine-131 S values to those from Lamart et al. were on average 0.99±0.04σ and 0.98±0.03σ, respectively, for adult male/female phantoms in case of self-absorption within 8 major organs, and 0.79±0.46σ and 0.93±0.51σ, respectively, for adult male/female phantoms in case of cross-irradiation between these same organs. The ratios of our S values for iodine-131, technetium-99m and gallium-68 to those from OLINDA/EXM 1.0 were on average 0.91±0.15σ, 0.87±0.14σ, and 0.88±0.15σ over eight adult/pediatric phantoms, in case of self-absorption, and 1.34± 0.62σ, 1.48±0.82σ, and 1.36±0.62σ in case of cross-irradiation between the same organs, respectively.
Conclusion: A good agreement was observed between iodine-131 S values calculated on realistic phantoms: the NCI phantom series vs. the ICRP 110 reference phantoms. Greater differences were, however, revealed in S values between NCINM and OLINDA/EXM 1.0, especially for cross-irradiation, which emphasizes the impact of realistic human anatomy models on S values. The program will be useful for epidemiologic studies of risk and patient dose monitoring in nuclear medicine procedures.
Keywords
Dosimetry, Phantoms, Nuclear Medicine
Taxonomy
IM- Nuclear Medicine General: Radiation dosimetry & risk
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