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The skeletal calcium/phosphorus ratio: A new in vivo method of determination
Author(s) -
Fountos George,
Yasumura Seiichi,
Glaros Dimitris
Publication year - 1997
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.598152
Subject(s) - in vivo , coefficient of variation , nuclear medicine , materials science , germanium , gadolinium , chemistry , biomedical engineering , nuclear magnetic resonance , optics , physics , medicine , chromatography , microbiology and biotechnology , silicon , metallurgy , biology
We describe a new method for assessing the Ca/P ratio of bone in vivo using γ‐ray photon absorptiometry. The theoretical approach of the method and the estimation of the variance are presented. Two radiation sources, Gd‐153 (100 keV), and I‐125 (27.5 keV), and a germanium detector were used to determine this ratio. Measurements were made on bone phantoms with different Ca/P ratios; also, the ratio was measured on lamb and sheep tibias, rabbit tibias, and human fingers. Since the accuracy of the method is affected by the amount of fat and collagen in the measurement field, the effect of collagen and fat on the measurements also was investigated. In all cases, the precision of the method, expressed as the coefficient of variation (CV): 100 × standard deviation/mean , was near to the theoretical one, ranging from 1.8% to 3.2%. For human fingers, the CV was 3.2%, a value near to the theoretical 2.9% with a dose to the skin ranging from 0.044 to 0.066 mGy, depending on the width of the finger.