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The influence of accurate attenuation correction on quantitative gamma camera imaging

Blundell, Helen Louise 2012. The influence of accurate attenuation correction on quantitative gamma camera imaging. PhD Thesis, Cardiff University.
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Abstract

Gamma camera systems are used in a variety of diagnostic applications to image and in some cases measure, the physiological uptake of a radioactive tracer within the body. A number of factors, particularly attenuation and scatter of photons within the body tissues can cause degradation of image quality and inaccuracies in the measurement of tracer uptake. Single photon emission tomography (SPECT) systems which incorporate an xray computed tomography (CT) facility have enabled accurate transmission images of the patient to be obtained. These ‘attenuation maps’ can be used to correct the SPECT images for the effects of attenuation. The aim of this project was to investigate the use of an x-ray CT based attenuation correction (AC) system in SPECT gamma camera imaging. The use of AC with other physical parameters of the imaging process including scatter was firstly examined in order to determine the optimum imaging parameters required to maximise image quality. The influence of attenuation, scatter and other imaging parameters on the accuracy of absolute and relative quantitative measurements was then investigated. The methodology involved using the GE Millenium Hawkeye gamma camera system to obtain images of a range of phantoms filled with various concentrations of radioactivity; from simple point sources to phantoms which simulate organs of the body. An attempt was made to establish SPECT sensitivity values that would allow accurate determination of activity in a region of interest. These sensitivity values were applied to all subsequent measurements and a measure made of quantitative accuracy. The results showed that the sensitivity value used for quantitative SPECT measurements must reflect the reconstruction method and corrections used in the acquisition. Attenuation correction proved to be more significant than scatter correction in quantitative accuracy, with activity results being within 30% of expected values in all cases where AC was used.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Engineering
Subjects: R Medicine > R Medicine (General)
T Technology > T Technology (General)
Uncontrolled Keywords: gamma camera imaging ; SPECT/CT ; attenuation correction ; scatter correction and quantitative accuracy
Date of First Compliant Deposit: 30 March 2016
Last Modified: 09 Jan 2018 21:29
URI: http://orca.cf.ac.uk/id/eprint/46469

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