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The effects of collimation on image formation in anger gamma cameras

Harrison, Nia Eleri; (1993) The effects of collimation on image formation in anger gamma cameras. Doctoral thesis (Ph.D.), University College London (United Kingdom). Green open access

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Abstract

This thesis investigates the effects that collimators have on gamma camera images in nuclear medicine studies using technetium-99m. A Monte Carlo simulation of photon transport through a multihole collimator was written to determine the average point source response function of collimators. The code is flexible, thus enabling the modelling of different dimensions, hole misalignments and alternative structures. Separate computer programs were written to produce images of source distributions using various collimator response functions. The effects on the response functions and images of photons which have passed through collimator walls are determined. Collimator hole angulations of up to 1° are simulated and images produced using collimator simulations with random angulations over the collimator. The effects of angulation on the spatial resolution and linearity are investigated. Laminated collimator structures are proposed as a means of producing more robust, lighter weight collimators. Response functions are obtained for several different layer thicknesses and are compared with those of a conventional lead collimator. It is shown that computer images obtained from a laminated collimator compare favourably with those from a conventional lead collimator. Alternative materials to lead are considered for use in collimators and depleted uranium is determined to be suitable. The improved absorption properties of uranium would enable a much reduced septal thickness to be used with no increase in photon penetration. Such a reduction would also produces an increase in collimator efficiency.

Type: Thesis (Doctoral)
Qualification: Ph.D.
Title: The effects of collimation on image formation in anger gamma cameras
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: (UMI)AAI10046189; Applied sciences; Anger gamma camera
URI: https://discovery.ucl.ac.uk/id/eprint/10099538
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