A Study on the Visual System of the Digital Periapical Images.
- Author:
Eun Suk CHOI
1
;
Kwang Joon KOH
Author Information
1. Department of Oral and Maxillofacial Radiology, School of Dentistry, Chonbuk Natiional University, Korea.
- Publication Type:Original Article
- Keywords:
digital periapical image;
visual system
- MeSH:
Dental Caries;
Humans;
ROC Curve
- From:Journal of Korean Academy of Oral and Maxillofacial Radiology
1999;29(1):261-274
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
OBJECTIVES: The purpose of this study was to evaluate the optimal distance and angle of observers by modulation transfer functions(MTFs) and receiver operating characteristics(ROCs). MATERIALS AND METHODS: Digital periapical radiograms were taken from 43 patients who have dental diseases(19 patients : dental caries, 12 patients : periapical lesions, 12 patients : periodontal diseases). Segmental images(4x4cm) were evaluated by 4 MTFs and ROC analysis. RESULTS: The optimal distance(magnification) using MTF by Mannos & Sakrison was 12.97, and those by Nill, Ngan and Rao were 8.39, 4.78, 5.84 respectively. The optimal distance obtained from 4 radiologists by ROC analysis was 32cm(Az value : 0.89), and it was 40cm(Az value : 0.78) from 4 non-radiologists. There were significant differences of Az values between 4 radiologists and 4 non-radiologists at 24, 32 and 40cm (p<0.05). No significant differences of optimal distances were observed using 4 MTFs among +20, +10, 0, -10, -20 degrees(p>0.05). The optimal angle obtained from 4 radiologists by ROC analysis was +20 degrees (Az value : 0.91), and no significant differences of Az values were observed among +20, +10, 0, -10 and 20 degrees(p>0.05). The optimal angle obtained from 4 non-radiologists by ROC analysis was 0 degree(Az value : 0.81), and no significant differences of Az values were observed among +20, +10, 0, -10 and 20 degrees(p>0.05). And there was significant difference of Az value between 4 radiologists and 4 non-radiologists at +20 degree(p<0.05), but no significant differences of Az values were observed among +10, 0, -10 and -20 degrees(p>0.05).
