Efficacy of a new software in eliminating the angulation errors in digital subtraction radiography

To evaluate the efficacy of a new software developed for digital subtraction radiography at tolerating the vertical and horizontal angulation changes between the X-ray source and object.

The right first molar of a preserved dry mandible was imaged with 0 degrees vertical and 0 degrees horizontal tube angulation. Then, the vertical angle was changed to +10 degrees, -10 degrees, +15 degrees and -15 degrees, and the same tooth was radiographed in each condition, accordingly. The same procedure was performed with 5 degrees horizontal angular modifications in both mesial and distal directions. All radiographs were automatically developed and were digitized with 600 dots per inch (dpi) spatial resolution. New software and Emago were used to subtract the images with angulation alterations from the original image, and a total of 20 subtracted images were obtained. Ten experienced specialists evaluated the images and rated the efficacy of the programs. Data were analysed statistically and alpha was accepted as 0.05.

The total score of the new software was 190 and that of Emago was 117 for vertical angular alterations, whereas the scores were 51 and 21, respectively, for horizontal angular alterations. The differences between the overall scores of the softwares were statistically significant (P<0.05). Overall evaluation revealed that the new software was rated with higher scores for subtracted images obtained with both vertical and horizontal angular alterations.

Both programs managed to tolerate vertical angulation alterations up to 10 degrees and horizontal angulation changes up to 5 degrees ; however, the new program performed better than Emago.