A monitoring system for a radiation therapy system (100) having movable components (102, 104, 106, 110, 112, 114, 116), the radiation therapy system (100) operable to selectively deliver a radiation therapy beam along a beam axis (140), the monitoring system comprising a plurality of external measurement devices (124) arranged to obtain position measurements of components of the radiation therapy system (100) and a patient substantially fixed in position with respect to a movable patient support (116) so as to provide location information, a controller (202) operable to receive position information from the plurality of external measurement devices (124) and provide movement commands to the movable patient support (116) to automatically align the patient in a desired pose, and a control system operable to determine whether the actual orientation of at least one moveable component of the radiation therapy system meets predetermined criteria for correspondence with a desired orientation of the at least one component relative to a positioned patient.
