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Design of a near-field coded aperture cameras for high-resolution medical and industrial gamma-ray imaging

Roberto Accorsi

DSpace@MIT (Massachusetts Institute of Technology), 2001

65 citations

Abstract

Coded Aperture Imaging is a technique originally developed for X-ray astronomy, where typical imaging problems are characterized by far-field geometry and an object made of point sources distributed over a mainly dark background. These conditions provide, respectively, the basis of artifact-free and high Signal-to-Noise Ratio (SNR) imaging. When the coded apertures successful in far-field problems are used in near-field geometry, images are affected by extensive artifacts. The classic remedy is to move away from the object until a far-field geometry is restored, but this is at the expense of counting efficiency and, thus, of the SNR of the images. It is shown in this thesis that the application to near-field of a technique originally developed to mitigate the effects of non-uniform background in far-field applications results in a considerable reduction of near-field artifacts. This result opens the way to the exploitation in near-field problems of the favorable SNR characteristics of coded apertures: images comparable to those provided by state-of-the-art imagers can be obtained in a shorter time or while administering a lower dose to patients.

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