To Scan or Not to Scan it has become popular for some people to have yearly whole-body scans (CT scans, formerly called CAT scans) using x rays, just to see if they detect anything suspicious. A number of medical people have recently questioned the advisability of such scans, due in part to the radiation they impart. "Typically, one such scan gives a dose of 12mSv, applied to the whole body. By contrast, a chest x ray typically administers 0.20mSv to only 5.0 kg of tissue. How many chest x rays would deliver the same total amount of energy to the body of 75-kg person as one whole-body scan?