Hi there, Cyberknife and other machines like rapidarc, linacs etc are various machines/ techniques to give radiation only. They may vary in their capacity to accurately deliver in millimeters precision but they all can only be used where radiation has some proven efficacy. In Papillary thyroid carcinomas radiotherapy by external beam has limited data and your oncologists and clinicians have to deliberate if there is a role for external beam radiotherapy and if yes then in your case there may be a role of cyberknife. Though how much cost versus benefit would be hard to tell. I hope this information helps, Regards