EFFECTS OF AMBIENT LIGHT AND VIEW BOX LUMINANCE ON THE DETECTION OF CALCIFICATIONS IN MAMMOGRAPHY

OBJECTIVE. Viewing conditions can affect diagnostic performance differ ently depending on background optical densities. We quantified detecti on accuracy when viewing calcifications in glandular tissue under reco mmended viewing conditions versus accuracy with lower view box luminan ce and higher ambient lighting. MATERIALS AND METHODS. A phantom with adipose, 50% adipose and 50% glandular, and glandular-simulating mater ial was imaged, and images were interpreted by five medical imagine ph ysicists using two lighting conditions: the recommended one, high view box luminance (4365 nits) with low ambient light (25 1x), and a subop timal one, low view box luminance(1763 nits) with moderate ambient lig hting (290 1x). Then, a dense (Breast Imaging Reporting and Data Syste m breast composition pattern type 4) unfixed cadaveric breast with num erous native calcifications was imaged 28 times. Nineteen of the films had added clusters of simulated calcifications. Three radiology fello ws, each with 11 months of training in mammography, identified the add ed calcification clusters in the images under the two lighting conditi ons. Changes in phantom analysis and accuracy of the clinical diagnosi s were compared for each lighting condition. RESULTS. On mammograms of the phantom, both speck and fibril identification were degraded by an average of 1.4 objects for the adipose-simulating section (with its d arker optical density), For medium optical densities, found in the sec tion with the simulation of 50% glandular and 50% adipose tissue, subo ptimal lighting conditions had little or no effect on speck and fibril identification. For sections of the phantom that simulated glandular tissue, an average of 0.6 specks or fibers were not seen when lighting was suboptimal. With the dense cadaveric breast, the fraction of adde d calcification clusters detected by the three observers improved by a n average of 17% when low luminance viewers and high ambient light wer e replaced with recommended viewing conditions: individual scores of t he observers improved significantly: p values ranged from .02 to .05. CONCLUSION. Luminance of the view box and ambient lighting significant ly affect detection of calcifications in dense breasts when images are interpreted by radiologists with about 1 year of training in mammogra phy. Detection of calcifications in phantoms is primarily degraded for adipose tissue with its darker optical density. However, when lightin g conditions are suboptimal, some observers also have trouble detectin g calcifications in glandular tissue with its low optical density.