Index matching computerized tomography

TL;DR

This paper presents a safe, inexpensive, and educational model CT scanner using visible light and index matching to simulate X-ray CT physics, enabling quick and effective imaging for teaching purposes.

Contribution

Development of a novel visible light-based CT apparatus that mimics X-ray physics, facilitating hands-on learning with quick data collection and simple reconstruction.

Findings

Reliable imaging within 15 minutes

Uses index matching to prevent transmitted light loss

Employs simple back-projection for 2D imaging

Abstract

Computerized tomography (CT) has been used for decades by medical professionals to detect and diagnose injuries and ailments. CT scanners are based on interesting physics, but due to their bulk, cost, and safety, hands on experience with a medical CT scanner is unrealistic for undergraduate students. Therefore, operationally similar, yet small, safe, and inexpensive CT scanners are desirable teaching tools. This project details the development of a novel model CT scanning apparatus. The experimental setup presented utilizes visible light, has short data acquisition time, and operates on the same physics as its X-ray counterpart. The apparatus employs a laser and a photodiode to image a transparent material, while avoiding loss of transmitted intensity through index of refraction matching. A simple back-projection algorithm results in a 2D cross section of the scan object. We found we could collect data and reliably image samples in 15 min.