Pixelated columnar CSI:Tl scintillator for high resolution radiography and cone-beam CT

Stuart R. Miller, Bipin Singh, Matthew S.J. Marshall, Conner Brown, Niral Sheth, Gengxin Shi, Jeffrey H. Siewerdsen, Wojciech Zbijewski, Vivek V. Nagarkar

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Microcolumnar CsI:Tl scintillator screens have been the gold standard in X-ray imaging for many years due to their high density, high atomic number, and scintillation efficiency. The structured screens provide an improvement in performance by channeling the light to the detector, improving detection efficiency and spatial resolution. We have taken this concept a step further by laser-machining the CsI:Tl scintillator to provide pixels that match the detector pixels. This allows for still thicker CsI:Tl layers up to 700 µm pixelated with pitch of 100 µm to match CMOS flat panel pixels, thus improving X-ray absorption and resolution. We are investigating the applications of CMOS detectors with pixelated scintillators for imaging of bone microarchitecture on diagnostic Cone Beam CT (CBCT) systems to provide improved quantitative metrics for diagnosis of osteoporosis and osteoarthritis. The scintillator design includes reflective coatings applied to the laser-cut grooves to improve optical isolation between pixels. Such coatings are created by atomic layer deposition (ALD), a unique approach, which permits formation of reflectors over inter-pixel grooves with aspect ratios as high as 140:1. Here we present initial results quantifying performance gains in CMOS detector resolution and their impact on the quality of bone microstructure segmentation. We demonstrate 77% gain in spatial resolution at 2 lp/mm and extension of the limiting resolution from 3 lp/mm to 4.5 lp/mm for the CMOS detector with a pixelated screen compared to a commercial sensor. In a bench-top CBCT study emulating diagnostic systems for orthopedic applications (extremity CBCT), we achieved >0.75 correlations in metrics of trabecular microarchitecture between pixelated CsI:Tl based CBCT and gold-standard micro-CT. The pixelated scintillator is expected to have significant impact for many other applications including mammography and digital radiography, where resolution and dose efficiency (DQE) of the detector are of critical importance.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2020
Subtitle of host publicationPhysics of Medical Imaging
EditorsGuang-Hong Chen, Hilde Bosmans
PublisherSPIE
ISBN (Electronic)9781510633919
DOIs
StatePublished - 2020
EventMedical Imaging 2020: Physics of Medical Imaging - Houston, United States
Duration: Feb 16 2020Feb 19 2020

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume11312
ISSN (Print)1605-7422

Conference

ConferenceMedical Imaging 2020: Physics of Medical Imaging
CountryUnited States
CityHouston
Period2/16/202/19/20

Keywords

  • CBCT
  • Computed tomography
  • Microcolumnar scintillator
  • Pixelated CsI scintillator

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

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