A drive system for an imaging device having a curved arm. The drive system includes a carrier that engages the curved arm such that the arm can be moved along the carrier. The drive system includes a belt extending through the carrier and a motor, a drive shaft rotatably driven by the motor, and a drive pulley coupleable to the drive shaft through a clutch mechanism. The pulley engages the belt to move the curved arm relative to the carrier. The clutch mechanism is movable between an engaged position, at which the drive shaft is coupled to the drive pulley such that the motor moves the drive pulley, and a disengaged position, at which the drive shaft is uncoupled from the drive pulley so that the curved arm can be manually moved relative to the carrier. A clutch release mechanism moves the clutch between its engaged and disengaged positions.