Details

Autor(en) / Beteiligte

• Fountos, George
• Yasumura, Seiichi
• Glaros, Dimitris

Titel

The skeletal calcium/phosphorus ratio: A new in vivo method of determination

Ist Teil von

• Medical physics (Lancaster), 1997-08, Vol.24 (8), p.1303-1310

Ort / Verlag

United States: American Association of Physicists in Medicine

Erscheinungsjahr

1997

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• 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.