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Proceedings Paper

Effects of frequency on image quality in terahertz-pulsed images
Author(s): Anthony J. Fitzgerald; Emmanuel Dzontoh; Torsten Loeffler; Karsten Siebert; Elizabeth Berry; Nick N. Zinov'ev; Robert E. Miles; Michael A. Smith; J. Martyn Chamberlain
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Paper Abstract

Terahertz imaging is an emerging modality, with potential for medical applications, using broadband sub-picosecond electromagnetic pulses in the range of frequencies between 100 GHz and 100 terahertz (THz). Images can be formed using parameters derived from the time domain, or at the range of frequencies in the Fourier domain. The choice of frequency at which to image may be an important factor for clinical applications. Image quality as a function of frequency was assessed for a terahertz pulsed imaging system by means of; (i) image noise measurements on a specially designed step wedge, and (ii) modulation transfer functions (MTF) derived from a range of spatial frequency square wave patterns. It was found that frequencies with larger signal magnitude gave lower image noise, measured using relative standard deviation (standard deviation divided by mean) for uniform regions of interest of the step wedge image. MTF results were as expected, with higher THz frequency signals demonstrating a consistently higher MTF and higher spatial frequency limiting resolution than the lower THz frequencies. There is a trade-off between image noise and spatial resolution with image frequency. Higher frequencies exhibit better spatial resolution than lower frequencies, however the decrease in signal power results in a degradation of the image.

Paper Details

Date Published: 3 May 2002
PDF: 10 pages
Proc. SPIE 4682, Medical Imaging 2002: Physics of Medical Imaging, (3 May 2002); doi: 10.1117/12.465548
Show Author Affiliations
Anthony J. Fitzgerald, Univ. of Leeds (United Kingdom)
Emmanuel Dzontoh, Univ. of Leeds (United Kingdom)
Torsten Loeffler, J.W. Goethe-Univ. (Germany)
Karsten Siebert, J.W. Goethe-Univ. (Germany)
Elizabeth Berry, Univ. of Leeds (United Kingdom)
Nick N. Zinov'ev, Univ. of Leeds (United Kingdom)
Robert E. Miles, Univ. of Leeds (United Kingdom)
Michael A. Smith, Univ. of Leeds (United Kingdom)
J. Martyn Chamberlain, Univ. of Leeds (United Kingdom)

Published in SPIE Proceedings Vol. 4682:
Medical Imaging 2002: Physics of Medical Imaging
Larry E. Antonuk; Martin Joel Yaffe, Editor(s)

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