Final answer:
Gamma Knife, Cyberknife, Tomotherapy, and Truebeam are brand names for External Beam Therapy (EBT), a method of delivering a high energy beam of radiation to a tumor while minimizing harm to surrounding healthy cells.
Step-by-step explanation:
The terms Gamma Knife, Cyberknife, Tomotherapy, and Truebeam are brand names for External Beam Therapy (EBT), which is a method of delivering a high energy beam of radiation to the precise location of a patient's tumor. EBT can use either x-ray or gamma rays, and the beams are carefully planned to destroy cancer cells while minimizing harm to surrounding healthy cells. The radiation beam is usually generated with a linear accelerator.