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DOI: 10.1148/rg.252045185
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Technological and Psychophysical Considerations for Digital Mammographic Displays1

Ehsan Samei, PhD

1 From the Duke Advanced Imaging Laboratories, Departments of Radiology, Physics, and Biomedical Engineering, Duke University, DUMC Box 3302, Durham, NC 27710. From the AAPM/RSNA Physics Tutorial at the 2003 RSNA Scientific Assembly. Received October 4, 2004; revision requested November 3 and received December 6; accepted December 13. The author has no financial relationships to disclose.


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  		Figure 1.  Cross section of a medical CRT.

 


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  		Figure 2.  Stack diagram of a medical LCD. TFTs = thin-film transistors.

 


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  		Figure 3a.  Graphs show the contrast threshold of the human visual system in the state of variable adaptation (a) and the corresponding luminance response (b), which is used for calibrating mammographic displays. DICOM = Digital Imaging and Communications in Medicine, JND = just noticeable difference.

 


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  		Figure 3b.  Graphs show the contrast threshold of the human visual system in the state of variable adaptation (a) and the corresponding luminance response (b), which is used for calibrating mammographic displays. DICOM = Digital Imaging and Communications in Medicine, JND = just noticeable difference.

 


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  		Figure 4.  Graph shows the contrast threshold of the human visual system in the state of fixed adaptation for displays with different luminance ratios. The adaptation is assumed to occur at the average of log luminance, <L>, of the luminance range. JND = just noticeable difference.

 


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  		Figure 5.  Graph shows the contrast threshold of the human visual system at close inspection (30-cm) and normal viewing (60-cm) distances. The curves correspond to the logarithmic averages, <L>, of four typical luminance ranges shown in Figure 4. The curves are based on the theoretical fits of Barten (9) to the data of van Meeteren and Vos (10) with the angular size of the object limited to 1°, the solid angle subtended by the fovea.

 


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  		Figure 6a.  (a) Screen from a CRT displaying a uniform pattern shows the structured raster line noise and phosphor noise. (b) Screen from an LCD displaying the same uniform pattern shows the pixel structured noise.

 


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  		Figure 6b.  (a) Screen from a CRT displaying a uniform pattern shows the structured raster line noise and phosphor noise. (b) Screen from an LCD displaying the same uniform pattern shows the pixel structured noise.

 


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  		Figure 7.  Examples of the test patterns developed by Task Group 18 of the American Association of Physicists in Medicine. (The full set of patterns is downloadable from DAILabs.duhs.duke.edu/tg18.)

 




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