Abstract: A method and apparatus for prone position radiation therapy of breast tissue wherein a patient is placed in a prone position upon a platform positioned upon a radiation accelerator table of a radiation therapy accelerator machine to effectively isolate the breast tissue to be irradiated from the rest of the body. A top surface of the platform includes an aperture and/or adjustable opening through which the breast to be irradiated is inserted to hang freely and pendulously through the platform in an open space treatment field over the top of the accelerator table. The breast so positioned is free of contact with the platform and table and can be irradiated from all accessible angles of the accelerator head of the accelerator machine relative to the accelerator table without interference or obstruction by the platform and without any radiation incident upon untargeted portions of the patient's body.