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Proceedings Paper

Investigation of noise and contrast sensitivity of an electron multiplying charge-coupled device (EMCCD) based cone beam micro-CT system
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Paper Abstract

A small animal micro-CT system was built using an EMCCD detectors having complex pre-digitization amplification technology, high-resolution, high-sensitivity and low-noise. Noise in CBCT reconstructed images when using predigitization amplification behaves differently than commonly used detectors and warrants a detailed investigation. In this study, noise power and contrast sensitivity were estimated for the newly built system. Noise analysis was performed by scanning a water phantom. Tube voltage was lowered to minimum delivered by the tube (20 kVp and 0.5 mA) and detector gain was varied. Contrast sensitivity was analyzed by using a phantom containing different iodine contrast solutions (20% to 70%) filled in six different tubes. First, we scanned the phantom using various x-ray exposures at 40 kVp while changing the gain to maintain the background air value of the projection images constant. Next, the exposure was varied while the detector gain was maintained constant. Radial NPS plots show that noise power level increases as gain increases. Contrast sensitivity was analyzed by calculating ratio of signal-to-noise ratios (SNR) for increased gain with those of low constant gain at each exposure. The SNR value at low constant gain was always lower than SNR of high detector gain at all x-ray settings and iodine contrast. The largest increase of SNR approached 1.3 for low contrast feature for an iodine concentration of 20%. Despite an increase in noise level as gain increases, the SNR improvement shows that signal level also increases because of the unique on-chip gain of the detector.

Paper Details

Date Published: 25 March 2016
PDF: 9 pages
Proc. SPIE 9783, Medical Imaging 2016: Physics of Medical Imaging, 97831W (25 March 2016); doi: 10.1117/12.2216794
Show Author Affiliations
Sumukh Bysani Krishnakumar, Univ. at Buffalo (United States)
Toshiba Stroke and Vascular Research Ctr. (United States)
Alexander R. Podgorsak, Univ. at Buffalo (United States)
Toshiba Stroke and Vascular Research Ctr. (United States)
S. V. Setlur Nagesh, Toshiba Stroke and Vascular Research Ctr. (United States)
Amit Jain, Toshiba Stroke and Vascular Research Ctr. (United States)
Stephen Rudin, Univ. at Buffalo (United States)
Toshiba Stroke and Vascular Research Ctr. (United States)
Daniel R. Bednarek, Toshiba Stroke and Vascular Research Ctr. (United States)
Ciprian N. Ionita, Univ. at Buffalo (United States)
Toshiba Stroke and Vascular Research Ctr. (United States)


Published in SPIE Proceedings Vol. 9783:
Medical Imaging 2016: Physics of Medical Imaging
Despina Kontos; Thomas G. Flohr, Editor(s)

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