The North Carolina Department of Correction is readying a new medical complex at Central Prison to replace buildings that are too cramped and outdated to adequately treat a growing and aging prison population. The new $155 million hospital and mental health facility just west of downtown will begin accepting patients next month. Demolition of the old hospital starts Nov. 28. Corrections officials say the expanded medical treatment offered in the facility will cut the cost of treatment in outside hospitals by a third. And the expansion comes at a time when community hospitals are pushing the prison system to take care of more of its own patients.Security also was a factor, as prisoners require constant supervision during the hospital visits.