An adjustable mounting assembly, includes a load distributing plate configured for resting on, and being supported by, a top surface of a patient table a first clamp assembly adjustably coupled to a first side of the load distributing plate and configured for removable attachment to a first side rail of the patient table a second clamp assembly coupled to a second side of the load distributing plate and configured for removable attachment to a second side rail of the patient table and an adapter rail fixed to the second side of the load distributing plate and configured to detachably couple to a support assembly interface, such that an adjustable support assembly may be coupled to the load distributing plate to thereby allow for an off-center load attached to the support assembly to be moved relative to the patient table while the load remains substantially supported by the table surface.
