In one embodiment, a braking system for a positioner unit in a medical imaging apparatus includes a first brake coupled to a drive unit that is configured to drive the positioner unit along an axis susceptible to influence of gravity. A second brake is coupled to the positioner unit, and configured for operating independently of the first brake. Examples of positioner unit include a patient cradle in a patient support table, and a C-arm and a pivot in a vascular gantry.