Optimization of measurement distance of 109Cd K XRF system for obese subjects

The precision of results obtained from the 109Cd K XRF in vivo measurement system of bone lead for obese subjects with high BMI (body mass index) was poor. The main factor affecting the precision was the distance between tibia and detector. Compared with the standard phantom, a large phantom was used to simulate the obese subject in the measurements at different distances to the detector. The counts of Compton scattering increased highly because of the tissue overlying and surrounding tibia of the obese subject. When the distance between leg and detector was too small, the instrument would produce the distorted X-ray spectra, so that the obtained data were inaccurate. In order to ensure good measurement precision and accuracy, the distance between leg and detector should be maintained at 25 mm during the counting period. Meanwhile, the dead time displayed instantly on the instrument should be controlled to around 30%.

作 者： HUANG Shi-Bin McNEILL F E CHETTLE D R   作者單位： HUANG Shi-Bin(Shanghai Medical College,Fudan University,Shanghai 200032,China)

McNEILL F E,CHETTLE D R(Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4K1 Canada) 

刊 名： 核技術(英文版)  SCI 英文刊名： NUCLEAR SCIENCE AND TECHNIQUES  年，卷(期)： 2003 14(1)  分類號： X838 TL817+.1 R135.1+1  關鍵詞： Measurement distance   X-ray fluorescence   Bone lead   Obese subjects