Comparative investigation of subjective image quality of digital intraoral radiographs processed with 3...

To evaluate the subjective diagnostic image quality of clinical digital intraoral radiographs processed with 3 different image-processing algorithms.

One hundred digital intraoral radiographs were collected and subsequently processed in 3 sets. In the first set the radiographs were processed for correction for attenuation and visual response. In the second set the radiographs were processed with the same algorithms but with an additional shift in gray levels so that the average brightness of a region of interest was displayed with the mean brightness of the computer monitor. In the third, the radiographs were processed with the default gamma-correction in the Dimaxis program (Planmeca Oy, Helsinki, Finland). The 3 radiographs that were differently processed from the same original were displayed simultaneously on the computer monitor. Ten observers evaluated subjectively all the radiographs according to the portrayal of normal structures under the same viewing conditions. Five of them performed repeated evaluations of 20 of the 100 radiographs 2 months later.

The best subjective diagnostic quality was found for the radiographs processed with the new algorithms plus an additional shift in gray levels. Radiographs processed with the new algorithms were preferred when compared with those processed with the default gamma-correction. The differences between the 3 types of radiographs were significant (P <.0001). No significant intraobserver differences were found (P=.5487).

Radiographs processed for correction for attenuation and visual response might be beneficial in clinical work. Clinical radiographs processed with the new algorithms plus an additional shift in gray levels further improve the subjective impression of normal structures.