FILE - This Wednesday, Sept. 19, 2102 file photo shows a linear accelerator used to treat cancer at a hospital in Johnstown, Pa. Women treated with radiation for breast cancer are more likely to develop heart problems later, even with the lower doses used today, troubling new research suggests. The risk comes from any amount of radiation, starts five years after treatment and lasts for decades, doctors found. Patients shouldn't panic - radiation has improved cancer survival and that is the top p