Whole-body computed tomography (CT) screening has become popular despite the typical $1,000 price tag for the comprehensive X-ray scan. There can also be a hidden cost for each scan, of between $1,100 and $3,500, borne by the U.S. health care system, according to a new study. The extra expense results from the high number of harmless anomalies, or false positives, that scans turn up and that doctors must then check out (SN: 9/20/03, p.