Reproducibility of and file format effect on digital subtraction radiography of simulated external root resorptions.Dentomaxillofac Radiol. 2006 Jan; 35(1):10-3.DR
To evaluate, in simulated external root resorptions (ERR), two factors that may affect results of digital subtraction radiography (DSR): (1) intraobserver and interobserver reproducibility and (2) effects of digital file formats (TIFF, BMP and JPEG) on the estimation of mineral loss.
Eleven incisors were radiographed three times (NR, no resorption; SR, small--#1/4 round bur; and LR, large--#2 round bur) on standardized projections. The resulting images were reproduced and saved as TIFF, JPEG and BMP file formats. The pairs of TIFF images (NR x SR and NR x LR) were subtracted three times at 1 week intervals by three observers. One observer subtracted pairs of images (NR x SR and NR x LR) for all file formats. For each subtraction the resorption area was selected and mean pixel density values were calculated.
Analysis of variance (ANOVA) (P = 0.05) showed no statistical differences for intraobserver and interobserver values. Mean pixel density values were: observer A, 121.60 +/- 2.56 (NR x SR) and 111.84 +/- 4.04 (NR x LR); observer B, 121.86 +/- 2.50 (NR x SR) and 110.92 +/- 3.36 (NR x LR); and observer C, 121.70 +/- 2.39 (NR x SR) and 111.10 +/- 2.67 (NR x LR). Also, no statistical differences were found between file formats for LR (TIFF, 110.88 +/- 2.79; JPEG, 111.35 +/- 3.35; BMP, 111.00 +/- 2.70) and for SR between TIFF (121.30 +/- 2.34) and JPEG (120.46 +/- 1.51) or BMP (121.67 +/- 2.18) file formats. Differences were found between the JPEG and BMP groups.
DSR is reproducible in simulated ERR, and JPEG or BMP file formats do not affect results.