Coherent scattering and the assessment of mineral concentration in trabecular bone

The number of 103.2 keV (153Sm) gamma-rays scattered coherently and incoherently from the os calcis of three cadaver feet has been measured using a high purity Ge detector. The ratio of the intensities of coherent to incoherent scattered photons is dependent on elemental composition while the number scattered incoherently is dependent on density. The results indicate that techniques for the assessment of mineral status in the skeleton may be based on either of these measurements and each will exhibit a similar sensitivity to a given biological change. It is shown that a method based entirely on the detection of coherently scattered photons will be more sensitive to changes in mineral composition than either of the above. Such a system is proposed and optimised with respect to incident beam energy and scattering angle. For a dose of 4 mSV, coherent intensity measurements with a precision of 3% are anticipated.