Date of Award

Spring 2025

Language

English

Embargo Period

4-27-2025

Document Type

Master's Thesis

Degree Name

Master of Science (MS)

College/School/Department

Department of Physics

Program

Physics

First Advisor

Carolyn MacDonald

Committee Members

Carolyn MacDonald, Vivek Jain, Alexander Khmaladze

Keywords

Beam Stop Array

Subject Categories

Medical Biophysics | Optics

Abstract

X-ray scatter in Cone Beam Computed Tomography (CBCT) considerably degrades image quality by introducing CT value shifts, low-contrast degradation, and distinctive artifacts, thereby limiting adoption in both clinical and industrial applications. This paper presents an innovative scatter correction method based on a Beam Stop Array (BSA) that combines optimized hardware design and advanced algorithmic interpolation techniques. By strategically positioning a BSA with periodically arranged lead columns between the X-ray source and the object, the approach selectively blocks the primary beam, allowing for pure scatter measurement. The resulting sparsely sampled scatter data are accurately interpolated using cubic spline and projection-domain techniques to reconstruct full-field scatter distributions while concurrently restoring missing primary beam information. An extensive experimental study, including phantom and pelvic model scans, demonstrates that the proposed method achieves HU accuracy, noise reduction (by approximately 10%), and artifact suppression comparable to or exceeding conventional anti-scatter grid (ASG) techniques. Furthermore, optimization strategies such as overexposure handling, secondary calibration, and exemplar-based inpainting for artifact repair further enhance image quality. These results highlight the potential of the proposed BSA-based scatter correction scheme to deliver low-dose, high-precision CBCT imaging and set the stage for future integration with deep learning algorithms for improved computational efficiency and artifact mitigation.

License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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