Document Detail


A study of thyroid radioiodine monitoring by Monte Carlo simulations: implications for equipment design.
MedLine Citation:
PMID:  9394405     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Monte Carlo simulations have been performed to evaluate the design of collimated detectors used to measure 125I or 131I in the thyroid gland. Two detector sizes were simulated for each radioisotope: (i) for 125I monitoring 2.54 cm diameter and 7.62 cm diameter and 0.2 cm thickness and (ii) for 131I monitoring 2.54 cm diameter, 3.2 cm thickness and 7.62 cm diameter, 6.4 cm thickness. The virtual thyroid gland was 20 g. Activity was placed in both the gland and the remainder of the body in varying amounts to assess the efficacy of collimation. The results show that the detector should be sufficiently large so that its solid angle of acceptance when placed 15 cm anterior to the skin surface will include the whole of a moderately enlarged thyroid gland. Heavy collimation to reduce the contribution of extrathyroidal radioiodine within the subject's body is not normally required. It may be of more value as a positioning device and spacer ensuring an appropriate and constant neck to detector distance than in cutting down counts from extrathyroidal activity. In specifying a sensitive detector system for monitoring intrathyroidal radioiodine, a wide angle of acceptance and sufficient detector crystal thickness take precedence over collimation and shielding.
Authors:
G H Kramer; M J Chamberlain; S Yiu
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Physics in medicine and biology     Volume:  42     ISSN:  0031-9155     ISO Abbreviation:  Phys Med Biol     Publication Date:  1997 Nov 
Date Detail:
Created Date:  1998-01-15     Completed Date:  1998-01-15     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0401220     Medline TA:  Phys Med Biol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  2175-82     Citation Subset:  IM    
Affiliation:
Human Monitoring Laboratory, Radiation Protection Bureau, Ottawa, Ontario, Canada.
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MeSH Terms
Descriptor/Qualifier:
Computer Simulation
Equipment Design
Humans
Iodine Radioisotopes / metabolism*,  pharmacokinetics
Monte Carlo Method*
Radiation Dosage
Radiation Monitoring / instrumentation,  methods*
Radiotherapy, Computer-Assisted / instrumentation,  methods
Thyroid Gland / metabolism*,  radiation effects
Chemical
Reg. No./Substance:
0/Iodine Radioisotopes

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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