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Image quality in photon-counting CT images as a function of energy threshold
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Paper Abstract

In this study, we examined image quality in photon-counting CT images due to variation in energy thresholds. Images of an ACR quality control phantom were acquired using a prototype photon-counting CT scanner with two variable energy thresholds. The lower threshold, which varied between 20 to 50 keV, and the higher threshold, which varied between 50 to 90 keV, were used to separate the data into two energy bins. This produced a total of four images: threshold 1, containing signal between the lower threshold and the maximal value, threshold 2, containing signal between the higher threshold and the maximal value, bin 1, containing signal between the lower and higher threshold, and bin 2, containing signal between the higher threshold and maximal value. Thirteen pairs of energy thresholds were evaluated spanning the entire energy threshold space. An automated program was used to analyze images for standard quality control metrics including noise measurement, resolution, low contrast detectability, and contrast-to-noise ratio (CNR). Metrics were compared between image types and across energy thresholds. Threshold 1 images showed the least variation despite change in thresholds. Increasing the higher threshold degraded image quality in threshold 2 and bin 2 images, but improved performance in bin 1 images. Increasing the lower threshold decreased performance for bin 1 images. Resolution was largely unaffected by change in energy threshold.

Paper Details

Date Published: 1 March 2019
PDF: 8 pages
Proc. SPIE 10948, Medical Imaging 2019: Physics of Medical Imaging, 109484M (1 March 2019); doi: 10.1117/12.2512957
Show Author Affiliations
Jayasai R. Rajagopal, Duke Univ. Medical Ctr. (United States)
NIH Clinical Ctr. (United States)
Elizabeth C. Jones M.D., NIH Clinical Ctr. (United States)
Ehsan Samei, Duke Univ. Medical Ctr. (United States)


Published in SPIE Proceedings Vol. 10948:
Medical Imaging 2019: Physics of Medical Imaging
Taly Gilat Schmidt; Guang-Hong Chen; Hilde Bosmans, Editor(s)

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