Abstract: A planar support assembly for use with a patient body support, an extension support assembly, and a plurality of interchangeable head supports is provided. The extension support assembly is releasably mounted on a portion of the patient body support such that the extension support assembly extends outwardly from the patient body support. The planar support assembly includes a generally planar support configured to releasably attach to an end of the extension support assembly opposite the patient body support. The planar support is configured to receive and support one of a plurality of interchangeable head supports, and the planar support is adjustable with respect to the patient body support in two or more dimensions.