Unobtrusively tracking eye gaze direction and pupil diameter of mammographers

Abstract

The visual process that radiologists use for diagnosis is incompletely understood. This study developed techniques to unobtrusively track direction and pupil diameter of radiologists reading a wide variety of films. We evaluated the eye gaze patterns of mammographic experts to gain knowledge that might improve the rate of early detection of breast cancer. A video camera with a near-infrared light filter is pointed at the mammographic expert who is reading mammograms. The video images are analyzed in real time on a personal computer to detect eye gaze direction and pupil diameter. Two separate trials were used: 1) to demonstrate the system's speed and ability to work with mammograms (a brief test with one mammographer was used) and 2) four mammographic experts evaluated 14 mammograms. In the first trial, the system successfully tracked the eye gaze of a mammographer who quickly recognized the patient case, with the pupil diameter briefly increasing 40%, and then the gaze direction dwelling in an area of microcalcifications. In the second trial, 66% of the false-positive results for films with masses were associated with long eye gaze dwells, whereas 33% of the prolonged dwells for films with microcalcifications were associated with true-positive diagnoses. This near-infrared light system successfully tracked the eye gaze direction and pupil diameter of mammographic experts evaluating films. The association of long eye gaze dwells with diagnostic accuracy varied with the type of object being viewed. In films with masses, false-positive diagnoses were associated with long dwells. In films with microcalcifications, true-positive diagnoses were associated with long dwells.