Yohei Takeshita1,2, Mayumi Shimizu3, Gainer R Jasa4, Warangkana Weerawanich2, Kazutoshi Okamura2, Shoko Yoshida5, Kenji Tokumori6, Junichi Asaumi1, Kazunori Yoshiura2. 1. 1 Department of Oral and Maxillofacial Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama , Japan. 2. 2 Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University , Fukuoka , Japan. 3. 3 Department of Oral and Maxillofacial Radiology, Kyushu University Hospital , Fukuoka , Japan. 4. 4 Division of Oral Radiology, Faculty of Dentistry, Republic University , Montevideo , Uruguay. 5. 5 Department of Diagnostics and General Care, Section of Image Diagnostics, Fukuoka Dental College , Fukuoka , Japan. 6. 6 Department of Radiological Technology, Faculty of Fukuoka Medical Technology, Teikyo University , Fukuoka , Japan.
Abstract
OBJECTIVES: To compare the results of a new quantitative image quality evaluation method that requires no observers with the results of receiver operating characteristic (ROC) analysis in detecting the mandibular canal (MC) in cone beam CT (CBCT) images. METHODS: A Teflon (polytetrafluoroethylene) plate phantom with holes of different depths was scanned with two CBCT systems. One CBCT system was equipped with an image intensifier (Experiment 1), and the other was equipped with a flat panel detector (Experiment 2). Holes that were above the threshold gray value (ΔG), calculated using just-noticeable difference (JND), were extracted. The number of extracted holes was used as the index of the image quality, and was compared with the Az values calculated by ROC analysis to detect the MC. RESULTS: The number of extracted holes reflected the influence of different scanning conditions, and showed a strong correlation with the Az values calculated by ROC analysis. Indices of the number of extracted holes corresponding to high Az values for detecting the MC were obtained in both experiments. CONCLUSIONS: Our image quality evaluation method applying JND to images of a standardized phantom is a quantitative method that could be useful for evaluating the detectability of the MC in CBCT images.
OBJECTIVES: To compare the results of a new quantitative image quality evaluation method that requires no observers with the results of receiver operating characteristic (ROC) analysis in detecting the mandibular canal (MC) in cone beam CT (CBCT) images. METHODS: A Teflon (polytetrafluoroethylene) plate phantom with holes of different depths was scanned with two CBCT systems. One CBCT system was equipped with an image intensifier (Experiment 1), and the other was equipped with a flat panel detector (Experiment 2). Holes that were above the threshold gray value (ΔG), calculated using just-noticeable difference (JND), were extracted. The number of extracted holes was used as the index of the image quality, and was compared with the Az values calculated by ROC analysis to detect the MC. RESULTS: The number of extracted holes reflected the influence of different scanning conditions, and showed a strong correlation with the Az values calculated by ROC analysis. Indices of the number of extracted holes corresponding to high Az values for detecting the MC were obtained in both experiments. CONCLUSIONS: Our image quality evaluation method applying JND to images of a standardized phantom is a quantitative method that could be useful for evaluating the detectability of the MC in CBCT images.
Authors: Laurence Gaalaas; Donald Tyndall; André Mol; Eric T Everett; Ananta Bangdiwala Journal: Dentomaxillofac Radiol Date: 2015-12-16 Impact factor: 2.419
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