Photon scattering in biomedically important elements.

A survey of recently published work on the biomedical and other applications of the ratios of coherent to incoherent scattering of gamma radiation off low Z elements has revealed that the functional dependence of any individual process is, for the most part, misrepresented. It is shown, by analysis of the available tabulated coherent and incoherent scattering functions, that an explicit power dependence of Z may not be easily expressed. Furthermore, Rayleigh scattering is much better represented by the modified form factor rather than the usual form factor approach. The quantities of interest in using the coherent to incoherent scattering intensity ratio have been identified and various parametrical procedures have been developed within the range of atomic number and momentum transfers of biomedical interest. Applications to bone mineral measurements are discussed and future investigations based upon recent, more accurate theoretical predictions of scattering cross-sections are suggested.