Effects of small angle discrepancies on interpretations of subtraction images.
The present study examines interpretations of subtraction images of pairs of radiographs taken at 0 degrees, 1 degree, or 2 degrees of angle discrepancy. The radiographs were taken at each of 48 alveolar crestal sites on 15 dried human skulls. Computer-simulated lesions were induced at the sites on three fourths of the radiographs. Ten instructed dentists were asked to interpret the subtraction images as to the presence or absence of crestal change. A 2-degree angle discrepancy between radiographs resulted in a significant difference in sensitivity from that of radiographic pairs with a 0-degree discrepancy. However, we found no significant difference in sensitivity between 1-degree and 0-degree pairs of radiographs. In conclusion, a 1-degree geometric difference between pairs of radiographs does not significantly contribute to errors in interpretation of subsequent subtraction images.
Bates College, Lewiston, Maine.
M
M
Davis
K M
KM
Allen
E
E
Hausmann
D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging*; D006801:Humans; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000592:standards*; D011861:Radiography, Dental / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique / Q000379:methods*