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Flat-Panel Digital Mammography System: Contrast-Detail Comparison between Screen-Film Radiographs and Hard-Copy Images¹

¹ From the Departments of Radiology (S.S., A.K., S.V., C.J.D.) and Information Services (S.P.B.), University of Massachusetts Medical School, Worcester, Mass; and Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, Mass (H.V.). Received October 24, 2001; revision requested January 4, 2002; revision received March 20; accepted May 13. Supported by National Institutes of Health, National Cancer Institute grant RO1-CA88792. Address correspondence to A.K., Department of Radiology, Emory University School of Medicine, 1364 Clifton Rd NE, Rm A133A, Atlanta, GA 30322 (e-mail: akarell@emory.edu).

View larger version (115K): [in a new window]   Figure 1. Radiograph of the phantom acquired with the full-field digital mammography system illustrates the structured patterns in the phantom. The portion of the phantom that was used in this study was restricted to the area to the right of (below) the thick white line when the images were reviewed. This line does not exist physically in the phantom and is shown here to illustrate the region of interest.

View larger version (24K): [in a new window]   Figure 2. Line graph shows the detection characteristics for one observer with the digital system and three disk diameters. The horizontal line represents a 50% threshold level. The projection of the vertical dotted lines on the x axis gives disk depths that correspond to different disk diameters. Detection characteristics were obtained for all disk diameters and were used to generate the CD characteristics. A similar procedure was adopted to obtain the CD characteristics generated by all the observers with both SF and digital systems at threshold levels of both 50% and 62.5%.

View larger version (18K): [in a new window]   Figure 3. Schematic shows the theoretic model used to model the signal and noise transfer processes that occur when an observer perceives spatial information (Appendix).

View larger version (33K): [in a new window]   Figure 4a. Line graph shows the percentage correct detection characteristics for all observers with 0.80-mm disk diameter for (a) digital and (b) SF mammography. Markers represent experimental data points for each observer, while the smooth lines represent estimated detection characteristics.

View larger version (32K): [in a new window]   Figure 4b. Line graph shows the percentage correct detection characteristics for all observers with 0.80-mm disk diameter for (a) digital and (b) SF mammography. Markers represent experimental data points for each observer, while the smooth lines represent estimated detection characteristics.

View larger version (34K): [in a new window]   Figure 5a. Line graph shows the percentage correct detection characteristics for all observers with 0.40-mm disk diameter for (a) digital and (b) SF mammography. Markers represent experimental data points for each observer, while the smooth lines represent estimated detection characteristics.

View larger version (33K): [in a new window]   Figure 5b. Line graph shows the percentage correct detection characteristics for all observers with 0.40-mm disk diameter for (a) digital and (b) SF mammography. Markers represent experimental data points for each observer, while the smooth lines represent estimated detection characteristics.

View larger version (25K): [in a new window]   Figure 6a. Line graph shows the percentage correct detection characteristics for one observer with disk diameters of (a) 0.80 and (b) 0.40 mm for both digital and SF mammography. The observer achieved better detection characteristics with the digital system.

View larger version (26K): [in a new window]   Figure 6b. Line graph shows the percentage correct detection characteristics for one observer with disk diameters of (a) 0.80 and (b) 0.40 mm for both digital and SF mammography. The observer achieved better detection characteristics with the digital system.

View larger version (25K): [in a new window]   Figure 7. Line graph shows the mean CD characteristics obtained at the 50% threshold level for both SF and digital systems. On average, the digital system exhibits threshold contrast characteristics that are lower (better) than those for the SF system, which indicates higher fidelity for the digital images. The smooth lines indicate model-predicted CD diagrams for the SF and digital systems. The error bars indicate SD; depth = thickness.

View larger version (26K): [in a new window]   Figure 8. Line graph shows mean CD characteristics obtained at the 62.5% threshold level for both SF and digital systems. On average, the digital system exhibits threshold contrast characteristics that are lower (better) than those for the SF system, which indicates higher fidelity for the digital images. The smooth lines indicate model-predicted CD diagrams for the SF and digital systems. The error bars indicate SD; depth = thickness.