Document Detail

Calibration and evaluation of a 252Cf-based neutron activation analysis instrument for the determination of nitrogen in vivo.
MedLine Citation:
PMID:  2813511     Owner:  NLM     Status:  MEDLINE    
A novel clinical instrument for multi-element in vivo neutron activation analysis has been recently constructed in Swansea. The instrument is intended primarily for prompt gamma measurement of total and partial body calcium, total body nitrogen and partial body cadmium. For the measurement of nitrogen the subject is scanned both prone and supine across a vertical collimated neutron beam from a 4 GBq 252Cf source. Two shielded Nal(TI) detectors, each of volume 2760 cm3, are placed above the subject on the opposite side to that irradiated. The prompt gamma ray spectrum contains prominent peaks from hydrogen, nitrogen, chlorine and carbon. The optimisation, calibration and evaluation of the instrument for the measurement of nitrogen, by the reaction 14N(n, gamma)15N, is described. The calibration corrects the ratio of nitrogen-to-hydrogen counts measured from the subject for background gamma rays and the effects of body habitus. Body hydrogen is use as as internal standard. Repeated measurements of a homogeneous anthropomorphic phantom indicate that the ratio of nitrogen-to-hydrogen counts may be determined by a coefficient of variation of 1.6% for a neutron dose equivalent incident on the phantom of 0.45 mSv (QF = 10). The accuracy of the calibration was assessed by measuring three anthropomorphic phantoms (weight range: 41.4-110 kg) containing simulated skeletons and the major organs of the body. For these phantoms the mean discrepancy of the measured to the known nitrogen content was +4.9%. The simultaneous measurement of chlorine and carbon is discussed.
S J Ryde; W D Morgan; C J Evans; A Sivyer; J Dutton
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Physics in medicine and biology     Volume:  34     ISSN:  0031-9155     ISO Abbreviation:  Phys Med Biol     Publication Date:  1989 Oct 
Date Detail:
Created Date:  1989-11-29     Completed Date:  1989-11-29     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0401220     Medline TA:  Phys Med Biol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  1429-41     Citation Subset:  IM    
Swansea In Vivo Analysis Research Group, Department of Medical Physics and Clinical Engineering, Singleton Hospital, UK.
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MeSH Terms
Activation Analysis
Carbon / analysis
Chlorine / analysis
Gamma Rays
Hydrogen / analysis
Models, Structural
Neutron Activation Analysis / instrumentation*
Nitrogen / analysis*
Reproducibility of Results
Reg. No./Substance:
1333-74-0/Hydrogen; 7440-44-0/Carbon; 7440-71-3/Californium; 7727-37-9/Nitrogen; 7782-50-5/Chlorine

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