<title>Image Reconstruction Of Multiplane Gamma-Ray Sources With A Fresnel Zone Plate Aperture</title>

Abstract

A process is described for digitally reconstructing images of gamma-ray emitting organs recorded through an off-axis Fresnel zone plate aperture. This technique produces image cross sections for given depths which contain both quantitative and qualitative information about the source. The practicality of digital decoding is demonstrated experimentally by comparing the digital and optical reconstructions of images of a multi-plane gamma-ray source. Specifically, the multiplane source consists of numerals one, two and three located in three distinct planes at successive depths from the detector. The digital method of reconstruction has the following advantages over a method employing optical reconstruction. A quasi-real time system capable of recording and producing images can be assembled using components currently available. Quantitative data such as the source size and depth are readily determined. Digital image processing can be easily implemented to reduce the effect of artifacts and noise. Unlike the case using optical re-construction, the image depth dimension is not distorted in comparison with the source depth. Nonlinearity and film noise associated with the photographic process of obtaining a reduced transparency are avoided.