The automatic movement of the imager during gantry rotation to avoid collision. If collision avoidance detects that gantry rotation will cause a collision between the imager and the couch, collision avoidance will attempt to move the imager to avoid that collision. Avoidance may require reducing the gantry rotation speed while the imager is being moved. If the process also moves the imager, when possible the system will return the imager to its original position. If the imager cannot be returned to its starting position, the user will be notified. Because collision avoidance can affect the velocity of the gantry, it is disabled during CT scans.