A patient support system to be used in conjunction with a standard linear accelerator, and other sources, is described that allows access of the treatment beam to the breast from up to 360 degrees. This support system places the patient in a prone position with the breast going through an aperture. The prone position increases the separation of the breast from the chest wall and other critical organs and reduces motion of the target tissue due to breathing. This invention offers up to 360 degree radiation beam access to the breast. This helps in skin sparing, better dose conformity, and allows one to use modern treatment techniques such as IMRT and IGRT. It also includes a provision for an imaging system. This invention can also be used with CT and MR imaging modalities.