Total body calcium (TBCa) was measured using a cyclotron for in vivo neutron activation analysis (IVNAA) in 20 healthy women, 15 women with vertebral compression fractures, and 8 women with wrist fractures. The precision of the technique, using phantoms, was 1.8% for a dose of 13 mSv. A formula for predicted TBCa (TBCap) was derived from the 20 normal women based on span and years postmenopause. The coefficient of variation of TBCa after normalization in the normal women was 6.6%. The mean TBCa values for the vertebral and wrist fracture groups were 69% and 84% of TBCap for women at the time of the menopause. The low TBCa in the wrist fracture group was attributable to post-menopausal bone loss. Of the low TBCa in the vertebral fracture group, about half the loss could be attributed to postmenopausal age and half to other factors.

Aged↗

PubMedDate not supplied

Comparisons between fat measurements by dual-energy X-ray absorptiometry, magnetic resonance imaging and underwater weighing.

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Absorptiometry, Photon↗

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Apparatus for the measurement of total body nitrogen using prompt neutron activation analysis with californium-252.

Details of clinical apparatus designed for the measurement of total body nitrogen (as an indicator of body protein), suitable for the critically ill, intensive-care patient are presented. Californium-252 radio-isotopic neutron sources are used, enabling a nitrogen measurement by prompt neutron activation analysis to be made in 40 min with a precision of +/- 3.2% for a whole body dose equivalent of 0.145 mSv. The advantages of Californium-252 over alternative neutron sources are discussed. A comparison between two irradiation/detection geometries is made, leading to an explanation of the geometry adopted for the apparatus. The choice of construction and shielding materials to reduce the count rate at the detectors and consequently to reduce the pile-up contribution to the nitrogen background is discussed. Salient features of the gamma ray spectroscopy system to reduce spectral distortion from pulse pile-up are presented.

Activation Analysis↗