Angular variation of scattering volume and its implications for Compton scattering tomography

If quantitative and qualitative precision is to be achieved in X-ly-rays Compton scattering densitometry and tomography, the volume of interaction within which a useful signal is collected must be well defined and accurately estimated. This work presents a numerical study of the variation of scattering angles and collimator sizes. The effect of choosing back-scattering angles for measurement in both the densitometry and tomographic modes of this technique is studied. A symmetry is observed between the volume at forward and back scattering angles. A symmetry exists, however, within the scattering angle range 90 +/- 30 degrees. It is proposed that the best volume/spatial resolution in Compton scattering densitometry/tomography is obtainable within the above mentioned scattering angle range. (C) 1999 Elsevier Science Ltd. All rights reserved.