The next time your doctor says he can look right through you, he may be speaking literally and not just figuratively, especially if your doctor is George Stetten, a biomedical engineer at the University of Pittsburgh. Although doctors sometimes use ultrasound for looking inside patients, current technology requires that the doctors look away from the patient at an ultrasound display. Stetten says the result is a displaced sense of hand-eye coordination. "The difficulty is developing a natural way to visually merge ultrasound images with the real world," says Stetten. His "sonic flashlight" uses a process called tomographic reflection. By strategically positioning an ultrasound scanner and the ultrasound display on opposite sides of a half-silvered translucent mirror, he simultaneously sees the patient and the ultrasound image in perfect alignment with the body. Stetten says that he merges the virtual image in three dimensions with the interior of the patient. This simultaneous viewing makes the ultrasound image appear to occupy the same physical space as the body being imaged. The effect relies on precise geometric relationships between the ultrasound slice scanned, the monitor displaying the slice, and the mirror. "The reflected image is optically indistinguishable from the corresponding space within the patient," explains Stetten. For more information, call (412) 624-7762.