Effective exposure level and diagnostic performance in endodontic radiography.
Image quality is limited by the information capacity of the image-forming system and can be computed from three parameters: contrast, resolution, and noise. These parameters can be combined to yield a single measure which determines the maximum amount of information obtainable from any x-ray system and is called the noise-equivalent number of quanta (NEQ) per unit area. The effects of image quality, expressed as noise-equivalent number of quanta (NEQ) per unit area, on the radiographic performance by dentists reading the position of an endodontic file in a root canal were studied. Three different speed films were used in conjunction with a fixed screen. NEQ values ranged between 0.64 x 10(4) and 14.3 x 10(4) per square millimeter. Components of variance associated with the position of the tooth apex and the tip of an endodontic file in a root canal were compared for the effect of different NEQs and observers. Results show that the standard deviation in locating a file tip and tooth apex may be a linear function of log NEQ. The estimated standard deviation associated with changes in NEQ was found to be relatively small compared to that observed among dentists. These findings indicate that a significant reduction in exposure would have a relatively small effect on the precision of endodontic distance measurements.
D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D006801:Humans; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement; D012390:Root Canal Therapy; D014076:Tooth Diseases / Q000000981:diagnostic imaging*; D014962:X-Ray Film; D014963:X-Ray Intensifying Screens