By Marilyn Marchione, AP Medical Writer Marilynn Marchione, Ap Medical Writer – Mon Jun 14, 10:59 am ET We fret about airport scanners, power lines, cell phones and even microwaves. It's true that we get too much radiation. But it's not from those sources — it's from too many medical tests. Too much radiation raises the risk of cancer. That risk is growing because people in everyday situations are getting imaging tests far too often. Of the many ways people are overtested and overtreated, imaging is one of the most common and insidious. CT scans — "super X-rays" that give fast, extremely detailed images — have soared in use over the last decade, often replacing tests that don't require radiation, such as ultrasound and MRI, or magnetic resonance imaging. Radiation is a hidden danger — you don't feel it when you get it, and any damage usually doesn't show up for years. Taken individually, tests that use radiation pose little risk. Over time...