Contrast-Detail comparison between unprocessed and processed CDMAM images

The purpose of this study is to compare Contrast Detail Curves (CDCs) of unprocessed and processed digital images. Images of a CDMAM (contrast detail for mammography) phantom had been acquired at 29 kV Tungsten-Rhodium anode-filter combination and 100 mAs; unprocessed images were subsequently processed using five clinically available image processing algorithms. Scoring of CDMAM images was then performed using human observers and automatic reading. Five observers conducted a four-alternative forced-choice experiment on a set of four images, for each processing condition. For the automatic analysis of CDMAM images the CDCOM software program was used. Contrast Detail Curves were then computed both for the human and automatic reading by fitting a psychometric curve, after applying a smoothing algorithm (Gaussian filter). For both types of readings the CDCs from processed and unprocessed images were compared. We verified the statistical significance of the difference Δ between contrast threshold measurements at 0.1 mm target size (Figure of Merit, FoM), for unprocessed and processed images and for each image processing algorithm separately. The non-parametric bootstrap method was used. No statistical significant difference is found between raw and processed images. This study shows that CDMAM images may not be appropriate in assessing image processing algorithms.