Identification of oxygen-19 during in vivo neutron activation analysis of water phantoms

Hand bone equivalent phantoms (250 ml) carrying selenium in various amounts were irradiated and counted for in vivo neutron activation analysis (IVNAA) by employing a 4π NaI(TI) based detection system. During the analysis of counting data, a feature at a higher energy than the gamma ray peak from 77...

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Bibliographic Details
Published in:Physiological measurement 2015-12, Vol.36 (12), p.N127-N134
Main Authors: Tahir, Syed N A, Chettle, David R
Format: Article
Language:English
Subjects:
Gamma Rays
IVNAA
NaI(TI) detection system
Neutron Activation Analysis - instrumentation
Oxygen Radioisotopes - analysis
Oxygen Radioisotopes - chemistry
Phantoms, Imaging
Selenium - chemistry
Tandetron accelerator
Water - chemistry
water phantom
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Summary:Hand bone equivalent phantoms (250 ml) carrying selenium in various amounts were irradiated and counted for in vivo neutron activation analysis (IVNAA) by employing a 4π NaI(TI) based detection system. During the analysis of counting data, a feature at a higher energy than the gamma ray peak from 77mSe (0.162 MeV) was observed at 0.197 MeV. Further investigations were made by preparing water phantoms containing only de-ionized water in 250 ml and 1034 ml quantities. Neutrons were produced by the 7Li(p,n)7Be reaction using the high beam current Tandetron accelerator. Phantoms were irradiated at a fixed proton energy of 2.3 MeV and proton currents of 400 μA and 550 μA for 30 s and 22 s respectively. The counting data saved using the 4π NaI(TI) detection system for 10 s intervals in anticoincidence, coincidence and singles modes of detection were analyzed. Areas under gamma peaks at energies 0.197 MeV and 1.357 MeV were computed and half-lives from the number of counts for the two peaks were established. It was concluded that during neutron activation of water phantoms, oxygen-18 is activated, producing short-lived radioactive 19O having T1/2  =  26.9 s. Induced activity from 19O may contribute spectral interference in the gamma ray spectrum. This effect may need to be taken into account by researchers while carrying out IVNAA of biological subjects.
ISSN:0967-3334
1361-6579
DOI:10.1088/0967-3334/36/12/N127