From what I understand, Cobalt 60 is a type of Gammaknife, which is really stereostatic radiosurgery, and is not really surgery, but a precise form of radiation with minimal effect on surrounding tissue, which was largely used on brain tumors. Gammaknife, Cyberknife are trademarked names.
Linear accelerators, most commonly used, are state of the art radiation machines, such as IMRT, IGRT, VMAT, IORT, Stereostatic Radiosurgery, that deliver customized high doses of x-rays to tumors in all areas, while sparing normal tissue.
http://oralcancerfoundation.org/facts/imrt-radiation/