All ETDs from UAB

Advisory Committee Chair

John B Fiveash

Advisory Committee Members

Michael C Dobelbower

Matthew C Larrison

Richard A Popple

Timothy M Wick

Christopher D Willey

Document Type

Dissertation

Date of Award

2014

Degree Name by School

Doctor of Philosophy (PhD) School of Engineering

Abstract

High quality computed tomography (CT) scans are integral to the successful cancer radiation therapy treatment plan. Metal streak artifact in the CT image originates when a high density medical implant (dental, orthopedic, etc.) disproportionally attenuates the imaging beam and corrupts the imaging data. This impairs the physician's task of identifying important boundaries between tumor and healthy issue. The ability of treatment planning software to accurately compute vital radiation dosimetry metrics is also compromised. Many methods have been explored to mitigate the complications of streak artifact; however, none have been found effective and efficient for routine clinical use. This work explores the hypothesis that dual energy computed tomography (DECT) with an accompanying Metal Artifact Reduction Algorithm (MARS) is a convenient solution that can effectively address the major radiation treatment planning related complications caused by metal streak artifact. This work is based on three principal specific aims: (1) verify that streak artifact is a meaningful problem for patients with high-Z implants to both delineation and dosimetric accuracy; (2) demonstrate that DECT reduces the deleterious effects of metal streak artifact in a phantom; and (3) demonstrate that DECT is a viable solution to metal streak artifact for a human patient with an implanted high-z material causing streak artifact. Institutional IRB approval was obtained for the work. Several phantom designs were utilized and patients being treated in the University of Alabama at Birmingham (UAB) Department of Radiation Oncology were recruited for the study. A variety of metrics were used to assess the extent of streak artifact in the imaging data, as well as how successfully the artifact was allayed. The detriment of streak artifact to structure delineation and dosimetric accuracy were demonstrated in both phantom and patient imaging. DECT with MARS was successful in mitigating the effects of streak artifact to treatment planning in both phantom and patient imaging data. Dual energy CT with metal artifact reduction is useful in remedying the problems associated metal streak artifact in patients with high-z implanted devices, including both structure delineation and dosimetric inaccuracy. At present dual energy scans are being solely used clinically for diagnostic imaging; however, their potential value to radiation oncology is unmistakable.

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