EFFECT OF COMPTON SCATTERED PHOTONS ON EMISSION COMPUTERIZED TRANSAXIAL TOMOGRAPHY

Scattered photons generated by point sources in a cylindrical medium are simulated using Klein Nishina cross sections. These scattered photons are selectively projected in parallel paths to a collimated line detector. Transaxial reconstruction from these projections by standard means are generated to examine point spread functions of the scattered photons. This study is limited to single scatter because of the simplicity of its geometrical formulation and its proximity to the primary photons. Studies with point sources on and off the detector plane provide an understanding of artifacts in reconstructions due to scattering. For example, a reconstruction in the vicinity of a source point is similar (comparable isotropicity and FWHM) to a reconstruction of the source itself from its primary radiation. This central scatter image causes negligible degradation through its incorporation into the reconstructions. The problems arise from spread function tails and off-plane scatter which are broadly distributed. © 1979 IEEE.