the table material or a radio frequency or magnetic contrasting matter something that the imaging system and detector of the radiation therapy system can detect so that when scanned with or without a patient or phantom on the table the precise location of the patient treatment table in the x y and z planes is known the radiographic indexing markers may also have the ability to be visually seen by the technician doctor physicist or other health care provider conducting the procedure this is important so that the table may be reconstructed alone or with a phantom on it by the radiation therapy system software providing a very good indication of where the table top is prior to treatment application_number US 57756704 A description referring now to the drawings fig1 illustrates a radiation therapy machine 10 suitable for use with the present invention the radiation therapy machine 10 preferably includes a radiotranslucent table 12 having a cantilevered top 14 the table top 14 is received within a bore 18 of an annular housing 20 of the radiation therapy machine 10 with movement of the table 12 along tracks 16 extending along a longitudinal axis such as the z axis of a cartesian coordinate system 22 the table 12 is preferably disposed along a translation axis and may slide along that axis through the bore 18 passing first the front surface and then the rear surface the table 12 is preferably supported along the guide tracks 16 and moved by a motorized drive such as is well known in the.