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Degree

Doctor of Philosophy in Medical Sciences (Ph.D.), University of Toledo Health Science Campus, Graduate School, 2004.

Abstract

Digital tomosynthesis is an imaging technique to produce a tomographic image from a series of angular digital images in a manner similar to conventional focal plane tomography. Unlike film focal plane tomography, the acquisition of the data in a C–arm geometry causes the image receptor to be positioned at various angles to the reconstruction tomogram. The digital nature of the data, however, allows for input images to be combined or mapped into the desired plane with the flexibility of generating tomograms of many separate planes and of generating oblique planes from a single set of input data. Angular data sets were obtained of phantoms utilizing a Lorad stereotactic biopsy unit with a coupled source and digital detector in a C-arm configuration. Tomographic images were reconstructed using iterative subtraction techniques with removal of out-of-focus planes, and an iterative reconstruction technique similar to Algebraic Reconstruction (ART). These were compared with standard single view digital radiographs. Tested indicators of quality are the line spread function, Modulation Transfer Function (MTF), Signal to Noise Ratio (SNR), Contrast to Noise Ratio (CNR), Signal to Background Ratio (SBR). The method's effectiveness at removing the blurred images of out-of-plane structures from the target plane was quantified in terms of the SNR, CNR and SBR. Imaging and reconstruction was also performed on a cadaver breast specimen. The technology proved effective at partially removing out of focus structures and enhancing SNR, CNR and SBR. However, spatial resolution was slightly degraded. The metrics SNR, CNR and SBR all improved as the number of projections was increased. The ART technique created images with greater clarity, and less blur, than did the iterative subtraction technique.

Subject Headings

Health Sciences, Radiology

Keywords

Mammography; Tomography; Imaging

Advisor

Michael Dennis

Pages

146p.

Document number: mco1095875968
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=mco1095875968

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