Abraham Verghese, a professor at the Stanford University School of Medicine, tells the story of a woman brought into the E.R. for respiratory problems. In an earlier era, doctors would have performed a physical examination to make a diagnosis, but the woman was given a C.T. scan directly. The result? The scan showed tumors in her breasts and cancer throughout her body. Rather than praise the abilities of the C.T. machine, however, Verghese says its omnipresence has allowed doctors to become complacent—a thorough physical examination should have detected her tumors and other cancer-related symptoms long before.