[Bone mineral measurement using beam scanner with a single source of 241Am]

The feasibility of a bone mineral analyzer equipped with a single source of 241Am but with a specially designed water bath (Beam Scanner, Aloca Co. Ltd.) was evaluated both experimentally and clinically. The attenuation rate of 241Am gamma-ray showed an exponential decrease with the increase of the thickness of the plaster plate containing CaSO4. Measurements of the test tubes filled with Ca(OH)2 demonstrated the measured mineral values to be in good correlation with the amount of Ca(OH)2. The coefficient of variation (C.V.) of bone mineral values obtained by measuring the phantom 20 times was 4.06%. Reproducibility tests performed in 10 normal persons after an interval of 8 months revealed a C.V. of 2.0%. Bone mineral values seemed to reach their peak in the 4th decade and thereafter gradually decreased with aging in normal persons. A marked decrease of the bone mineral value was observed in 5 cases of osteoporosis. We conclude that the bone mineral measurement using the above described method is practical and reliable.