Enhanced imaging using structured glass-ceramic scintillators

The National Institute of Biomedical Imaging and Bioengineering awarded the University of Tennessee, operating as the Space Institute, $157,000 on April 1, 2026, under the Discovery and Applied Research for Technological Innovations to Improve Human Health program (CFDA 93.286).

The recipient will develop novel structured glass-ceramic scintillator conversion screens to improve image quality and reduce dose in X-ray imaging applications using indirect flat panel detectors at megavoltage energies. The work includes fabricating conversion screens using unique processing methods, incorporating them into a custom flat panel detector with scanning and data acquisition electronics removed from the X-ray beam path, and evaluating performance in megavoltage portal imaging and megavoltage cone-beam computed tomography applications. Testing will measure detective quantum efficiency, modulation transfer function, noise power spectrum, temporal response including afterglow and lag, X-ray emission spectrum, X-ray absorption coefficient, and radiation hardness using phantoms and a 6 MV linear accelerator treatment beam. The conversion screens are designed to enable improved soft tissue contrast and real-time motion tracking capabilities while enhancing low-dose performance of megavoltage cone-beam computed tomography systems.

Performance occurs in Tullahoma, Tennessee, with a period of performance from April 1, 2026, through March 31, 2028. The award is a project grant, an assistance type for research funding.

Abstract

The investigators' goal is to improve image quality and reduce dose for x-RAY imaging applications employing indirect flat panel detectors (i-fpds) at high energies. The objective of this project is to develop novel structured, glass-based conversion screens that will detect x-rays with megavoltage (MV) energies more efficiently, resulting in large improvements in detective quantum efficiency (DQE). These conversion screens will be produced by unique processing methods and then evaluated for use in MV portal imaging applications and megavoltage cone-beam computed tomography (MV-cbct). The conversion screens will be incorporated into a custom flat panel detector, where the scanning and data acquisition electronics have been removed from the path of the x-RAY beam. The prototype imaging system will be exposed to a 6 MV treatment beam from a linear accelerator (linac). Measurements of modulation transfer function (MTF) and noise power spectrum (NPS) will be made, allowing calculation of the DQE. Phantoms, including a LAS vegas phantom for contrast-detail and parts of an alderson rando phantom for anatomy, will be imaged; these phantoms will reveal potential artifacts and non- uniformities that would not be evident from resolution and noise measurements. The temporal response will be measured, including afterglow in the glass scintillation pulses and lag in the prototype imaging system. Other relevant characteristics will be determined including x-RAY emission spectrum, x-RAY absorption coefficient, and radiation hardness. These novel conversion screens will enable increased performance in MV portal imaging, including improved soft tissue contrast and the enhancement of "beam's-eye-view" applications such as real- time motion tracking. The proposed research could also significantly improve the low-dose performance of MV-cbct systems. Furthermore, future refinements could lead to improvements in imaging applications using x-rays at KV energies and neutrons.