Coherent-Compton scattering for the assessment of bone mineral content using heavily filtered x-ray beams.

The feasibility of using heavily filtered x-ray beams to assess trabecular bone mineral content has been investigated by measuring the ratio of coherent to incoherent scattered x-rays with a high purity Ge detector. The technique uses the strong dependence of coherent scattering on the effective atomic number of the scattering medium. With an x-ray beam filtered with a high-atomic-number filter, a spectrum characterised by a sharp discontinuity at the K-absorption edge is produced. Analysis of the spectral shape after scattering allows the coherent to Compton scattering ratio to be obtained. Theoretical and experimental results from phantom studies are presented and a comparison made between the results obtained with x-ray beams and radionuclide sources respectively. The influence of overlying tissue thickness on the sensitivity of the measurements is demonstrated.