Americans love high-tech medical imaging machines. Computed tomography and other complex scanning techniques promise to spot cancer or heart disease early without the need for invasive procedures. And often they do. But as many as 4 million Americans each year may be exposed to relatively high radiation doses from various medical imaging machines that could slightly increase their risk of cancer, a New England Journal of Medicine study finds. The results are worrisome because the use of medical imaging is exploding despite a lack of proof in many cases that the new scans really improve patients’ health. An unanswered question: How many of these scans are truly necessary? By one estimate as many as one-third of CT scans may not really be needed. ‘It is concerning. We are exposing people to significant amounts of radiation and on the other hand we do not have evidence that [the scans lead to] improvement of health,’ says National Heart Lung and Blood Institute cardiologist Michael Lauer, director of the division of prevention and population sciences. Scanning is big business for numerous companies like General Electric, Siemens and Royal Philips Electronics that make the machines, as well as the doctors […]