Signal-to-noise ratio: Computed Dental Radiography versus Sens-A-Ray

Abstract

The signal-to-noise ratio (SNR) describes the ability of a detector to differentiate a signal from random fluctuations in signal intensity or noise in an image. The dose-response curves and the SNRs were measured and compared between Computed Dental Radiography (CDR) and Sens-A-Ray. The dose-response curves at 60, 70 and 80 kVp of both systems indicated that the pixel values increased in proportion to the radiation exposure. The pixel value gradient was slightly steeper for the CDR than for the Sens-A-Ray. Sensitivity increased slightly at the higher kVp setting with the CDR only. All SNRs increased with increased exposure for both systems. The SNR for the CDR was superior to that for the Sens-A-Ray, even with low exposures. The SNR for CDR increased steeply as exposure and average pixel values increased. On the other hand, the SNR for the Sens-A-Ray showed only a relatively slight increase with exposure. In conclusion, due to the high SNR in the lower exposure range, the CDR has the capability of substantially reducing the level of exposure in comparison with the Sens-A-Ray.