Physics of Medical Imaging

Impact of number of repeated scans on model observer performance for a low-contrast detection task in computed tomography

[+] Author Affiliations
Chi Ma, Lifeng Yu, Baiyu Chen, Christopher Favazza, Shuai Leng, Cynthia McCollough

Mayo Clinic, Department of Radiology, 200 First Street SW, Rochester, Minnesota 55905, United States

J. Med. Imag. 3(2), 023504 (May 26, 2016). doi:10.1117/1.JMI.3.2.023504
History: Received December 22, 2015; Accepted April 26, 2016
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Abstract.  Channelized Hotelling observer (CHO) models have been shown to correlate well with human observers for several phantom-based detection/classification tasks in clinical computed tomography (CT). A large number of repeated scans were used to achieve an accurate estimate of the model’s template. The purpose of this study is to investigate how the experimental and CHO model parameters affect the minimum required number of repeated scans. A phantom containing 21 low-contrast objects was scanned on a 128-slice CT scanner at three dose levels. Each scan was repeated 100 times. For each experimental configuration, the low-contrast detectability, quantified as the area under receiver operating characteristic curve, Az, was calculated using a previously validated CHO with randomly selected subsets of scans, ranging from 10 to 100. Using Az from the 100 scans as the reference, the accuracy from a smaller number of scans was determined. Our results demonstrated that the minimum number of repeated scans increased when the radiation dose level decreased, object size and contrast level decreased, and the number of channels increased. As a general trend, it increased as the low-contrast detectability decreased. This study provides a basis for the experimental design of task-based image quality assessment in clinical CT using CHO.

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© 2016 Society of Photo-Optical Instrumentation Engineers

Citation

Chi Ma ; Lifeng Yu ; Baiyu Chen ; Christopher Favazza ; Shuai Leng, et al.
"Impact of number of repeated scans on model observer performance for a low-contrast detection task in computed tomography", J. Med. Imag. 3(2), 023504 (May 26, 2016). ; http://dx.doi.org/10.1117/1.JMI.3.2.023504


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