TY - GEN
T1 - Image quality in photon-counting CT images as a function of energy threshold
AU - Rajagopal, Jayasai R.
AU - Jones, Elizabeth C.
AU - Samei, Ehsan
N1 - Publisher Copyright:
© SPIE. Downloading of the abstract is permitted for personal use only.
PY - 2019
Y1 - 2019
N2 - 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.
AB - 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.
KW - Computed tomography
KW - Energy threshold
KW - Image quality
KW - Photon-counting
UR - http://www.scopus.com/inward/record.url?scp=85068419267&partnerID=8YFLogxK
U2 - 10.1117/12.2512957
DO - 10.1117/12.2512957
M3 - Conference contribution
AN - SCOPUS:85068419267
T3 - Progress in Biomedical Optics and Imaging - Proceedings of SPIE
BT - Medical Imaging 2019
A2 - Schmidt, Taly Gilat
A2 - Chen, Guang-Hong
A2 - Bosmans, Hilde
PB - SPIE
T2 - Medical Imaging 2019: Physics of Medical Imaging
Y2 - 17 February 2019 through 20 February 2019
ER -