Energy-spectral Compton scatter imaging. II. Experiments

In Part I (see ibid., vol. 42, p. 2155 (1995)) of this two-part paper, the theoretical and mathematical aspects of the inverse problem of a Compton scatter imaging system that utilizes energy-spectral measurements were addressed. Image reconstruction algorithms, based on a single-scatter model, were devised and tested using Monte Carlo simulated point-detector responses. This part of the paper deals with the experimental problems associated with the physical size of the detector and the intrinsic distortions in its response function. The detector response to a point scatterer is measured and incorporated into a response function. This function is employed in a least squares detector unfolding method that also provides an estimate of the contribution, to the detector response, of multiple scattering in the imaged target. Reconstructions of the electron-density images for several test objects from experimentally measured detector responses are presented to demonstrate the viability of the detector unfolding and image reconstruction methods