Date of Award

4-1999

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Engineering Physics

First Advisor

Jeffrey B. Martin, PhD

Abstract

Multiplexed Compton Scatter Tomography (MCST) is explored as a method of nondestructively generating cross-sectional images of a sample's electron density. MCST is viable when access is available to only one side of the sample because it registers scattered gamma radiation. Multiplexing in scattered photon energy and in detector position allows simultaneous interrogation of many voxels with comparatively wide collimation. Primary components include a radioisotope source, fan beam collimators, and energy-discriminating detectors. The application of MCST to inspecting aluminum airframes for corrosion is considered. This application requires source gammas near 100 keV where the scattered gamma energy is severely broadened by the momentum of electrons in the target. A deterministic system model is developed to map the sample's voxel densities to the instrument's measurements. The model incorporates advanced features to avoid using a detector response function. Two image reconstruction methods are developed and investigated: filtered backprojection and iterative reconstruction. A demonstration MCST system is assembled from components available commercially. It is used to image several aluminum phantoms and to validate the system model and iterative image reconstruction algorithm. A next-generation MCST system is modeled. Issues are considered such as efficiency, counting time, and contrast recovery in various samples.

AFIT Designator

AFIT-DS-ENP-99-1

DTIC Accession Number

ADA362461

Comments

The author's Vita page is removed.

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