An 80-year-old Brighton man died after he was struck by a truck at St. Elizabeth’s Medical Center in Brighton Monday afternoon, police said. The pedestrian was hit and killed on the grounds of the hospital, at the corner of Nevins and Warren streets, at around 1:30 p.m., police said. Officer Neva Coakley, a Boston police spokeswoman, said the driver has not been charged. She did not know whether the driver stayed at the scene. Police would not release the victim’s name until the family could be notified, she said.