Swaby, A. (ECE) – Improving X-ray Medical Imaging using Amorphous Selenium as a Photoconductive Layer

The presence of coronary artery calcification is a strong predictor for future cardiovascular events where cardiac risk categories are quantified depending on calcification size. Dual-energy chest X-rays provide high contrast visualization to improve opportunistic screening for quantifying coronary artery calcifications, determining bone mineral density (i.e., osteoporosis) and characterizing lung lesions. As a dual-energy imaging modality, multilayer flat panel detectors acquire low- and high-energy X-ray images as a polyenergetic, single-exposure. Combining two detectors into a dual-layer configuration, weighted subtraction techniques in the resulting images allow for differentiation of soft tissue from the projection of the bone structures and other high attenuating materials. To improve detection of calcifications < 1 mm in size, the performance of a dual-layer X-ray detector is investigated as a means of providing the necessary μm-resolution and spectral separation for enhanced contrast between low- and high-energy X-ray images. A cascaded linear systems model is used to simulate the modulation transfer function, detective quantum efficiency, and noise power spectrum of an amorphous selenium direct conversion top detector and a cesium iodide-based indirect conversion bottom detector. As the framework for system design and optimization, a generalized task-based analysis is used to analyze how the signal projections, noise contributions, task function, and weighting factors contribute to the detectability index of the dual-layer imaging system.

Event Host: Akyl Swaby, PhD Candidate, Electrical & Computer Engineering

Advisor: Dr. Shiva Abbaszadeh