PHOTON BACKSCATTERING TISSUE CHARACTERIZATION BY ENERGY-DISPERSIVE SPECTROSCOPY EVALUATIONS

Techniques for in vivo tissue characterization based on scattered phot ons have usually been confined to evaluating coherent and Compton peak s. However, information can also be obtained from the energy analysis of the Compton scattered distribution. This paper looks at the extensi on of a technique validated by the authors for characterizing tissues composed of low-atomic-number elements. To this end, an EDXRS (energy dispersive x-ray spectrometry) computer simulation procedure was perfo rmed and applied to test the validity of a figure of merit able to cha racterize binary compounds. This figure of merit is based on the photo n fluence values in a restricted energy interval of the measured distr ibution of incoherently scattered photons. After careful experimental tests with 59.54 keV incident photons at scattering angles down to 60 degrees, the simulation procedure was applied to quasi-monochromatic a nd polychromatic high-radiance sources. The results show that the char acterization by the figure of merit, which operates satisfactorily wit h monochromatic sources, is unsatisfactory in the latter cases, which seem to favour a different parameter for compound characterization.