In vivo analysis of bone calcium by local neutron activation of the hand: results in normal and osteoporotic subjects.

Mineral loss from bone can be measured accurately and reproducibly by neutron activation of the hand bones using a 5-min irradiation (10(6) n/cm2-sec) with two 200-microgram sources of Cf-252. The hand dose is 7.5 rad equivalent and the dose to the rest of body is 1.5 mrem. Controls (132) and osteoporotic patients (45) were compared. Between ages 20 and 60 the control group showed a bone calcium concentration of 0.177 +/- 0.025 g/cm3, independent of age. Between 60 and 70 the content remained unchanged in men but declined in women to 0.15 +/- 0.2 g/cm3. In all age groups osteoporotic patients in general showed lower calcium content. Comparison of our findings ("Ca") with estimates of bone mineral content obtained by photon absorptiometry ("BMC") yields 0.07 Ca + 0.262 (r = 0.87). Activation analysis of hand bone appears more precise than BMC for the monitoring of bone-mineral loss in each individual and as a measure of treatment efficacy.