Warangkana Weerawanich1,2, Mayumi Shimizu3, Yohei Takeshita4, Kazutoshi Okamura5, Shoko Yoshida6, Gainer R Jasa7, Kazunori Yoshiura5. 1. Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. yui@rad.dent.kyushu-u.ac.jp. 2. Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Mahidol University, Bangkok, Thailand. yui@rad.dent.kyushu-u.ac.jp. 3. Department of Oral and Maxillofacial Radiology, Kyushu University Hospital, Fukuoka, Japan. 4. Department of Oral and Maxillofacial Radiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan. 5. Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. 6. Section of Image Diagnostics, Department of Diagnostics and General Care, Fukuoka Dental College, Fukuoka, Japan. 7. Oral Radiology Division, Faculty of Odontology, University of the Republic, Montevideo, Uruguay.
Abstract
OBJECTIVES: (1) We sought to assess correlation among four representative parameters from a cluster signal-to-noise curve (true-positive rate [TPR] corresponding to background noise, accuracy corresponding to background noise, maximum TPR, and maximum accuracy) and the diagnostic accuracy of the identification of the mandibular canal using data from observers in a previous study, under the same exposure conditions. (2) We sought to clarify the relationship between the hole depths of a phantom and diagnostic accuracy. METHODS: CBCT images of a Teflon plate phantom with holes of decreasing depths from 0.7 to 0.1 mm were analyzed using the FindFoci plugin of ImageJ. Subsequently, we constructed cluster signal-to-noise curves by plotting TPRs against false-positive rates. The four parameters were assessed by comparing with the diagnostic accuracy calculated from the observers. To analyze image contrast ranges related to detection of mandibular canals, we determined five ranges of hole depths, to represent different contrast ranges-0.1-0.7, 0.1-0.5, 0.2-0.6, 0.2-0.7 and 0.3-0.7 mm-and compared them with observers' diagnostic accuracy. RESULTS: Among the four representative parameters, accuracy corresponding to background noise had the highest correlation with the observers' diagnostic accuracy. Hole depths of 0.3-0.7 and 0.1-0.7 mm had the highest correlation with observers' diagnostic accuracy in mandibles with distinct and indistinct mandibular canals, respectively. CONCLUSIONS: The accuracy corresponding to background noise obtained from the cluster signal-to-noise curve can be used to evaluate the effects of exposure conditions on diagnostic accuracy.
OBJECTIVES: (1) We sought to assess correlation among four representative parameters from a cluster signal-to-noise curve (true-positive rate [TPR] corresponding to background noise, accuracy corresponding to background noise, maximum TPR, and maximum accuracy) and the diagnostic accuracy of the identification of the mandibular canal using data from observers in a previous study, under the same exposure conditions. (2) We sought to clarify the relationship between the hole depths of a phantom and diagnostic accuracy. METHODS: CBCT images of a Teflon plate phantom with holes of decreasing depths from 0.7 to 0.1 mm were analyzed using the FindFoci plugin of ImageJ. Subsequently, we constructed cluster signal-to-noise curves by plotting TPRs against false-positive rates. The four parameters were assessed by comparing with the diagnostic accuracy calculated from the observers. To analyze image contrast ranges related to detection of mandibular canals, we determined five ranges of hole depths, to represent different contrast ranges-0.1-0.7, 0.1-0.5, 0.2-0.6, 0.2-0.7 and 0.3-0.7 mm-and compared them with observers' diagnostic accuracy. RESULTS: Among the four representative parameters, accuracy corresponding to background noise had the highest correlation with the observers' diagnostic accuracy. Hole depths of 0.3-0.7 and 0.1-0.7 mm had the highest correlation with observers' diagnostic accuracy in mandibles with distinct and indistinct mandibular canals, respectively. CONCLUSIONS: The accuracy corresponding to background noise obtained from the cluster signal-to-noise curve can be used to evaluate the effects of exposure conditions on diagnostic accuracy.
Authors: K Yoshiura; K Okamura; K Tokumori; E Nakayama; T Chikui; T K Goto; M Shimizu; T Kawazu Journal: Dentomaxillofac Radiol Date: 2005-11 Impact factor: 2.419