MaineGeneral Health suffered a cyberattack on its computer network last month that compromised personal information belonging to patients, employees and prospective donors, the health system announced Tuesday. While investigation into the breach continues, patients referred to MaineGeneral Medical Center for radiology services, such as MRIs and CT scans, over the last several years appear to be at the highest risk. Data identified as potentially compromised by the Federal Bureau of Investigations include dates of birth and emergency contact names, addresses and telephone numbers for patients referred by treating physicians to the hospital for those services since June 2009.