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Proceedings Paper

1D pixelated MV portal imager with structured privacy film: a feasibility study
Author(s): Pavlo Baturin; Daniel Shedlock; Marios Myronakis; Ross Berbeco; Josh Star-Lack
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Paper Abstract

Modern amorphous silicon flat panel-based electronic portal imaging devices that utilize thin gadolinium oxysulfide scintillators suffer from low quantum efficiencies (QEs). Thick two dimensionally (2D) pixelated scintillator arrays offer an effective but expensive option for increasing QE. To reduce costs, we have investigated the possibility of combining a thick one dimensional (1D) pixelated scintillator (PS) with an orthogonally placed 1D structured optical filter to provide for overall good 2D spatial resolution. In this work, we studied the potential for using a 1D video screen privacy film (PF) to serve as a directional optical attenuator and filter. A Geant4 model of the PF was built based on reflection and transmission measurements taken with a laser-based optical reflectometer. This information was incorporated into a Geant4-based x-ray detector simulator to generate modulation transfer functions (MTFs), noise power spectra (NPS), and detective quantum efficiencies (DQEs) for various 1D and 2D configurations. It was found that the 1D array with PF can provide the MTFs and DQEs of 2D arrays. Although the PF significantly reduced the amount of optical photons detected by the flat panel, we anticipate using a scintillator with an inherently high optical yield (e.g. cesium iodide) for MV imaging, where fluence rates are inherently high, will still provide adequate signal intensities for the imaging tasks associated with radiotherapy.

Paper Details

Date Published: 9 March 2017
PDF: 6 pages
Proc. SPIE 10132, Medical Imaging 2017: Physics of Medical Imaging, 1013240 (9 March 2017); doi: 10.1117/12.2254606
Show Author Affiliations
Pavlo Baturin, Varian Medical Systems, Inc. (United States)
Daniel Shedlock, Varian Medical Systems, Inc. (United States)
Marios Myronakis, Bringham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School (United States)
Ross Berbeco, Bringham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School (United States)
Josh Star-Lack, Varian Medical Systems, Inc. (United States)

Published in SPIE Proceedings Vol. 10132:
Medical Imaging 2017: Physics of Medical Imaging
Thomas G. Flohr; Joseph Y. Lo; Taly Gilat Schmidt, Editor(s)

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