What category describes external beam radiation techniques used to treat cancer from outside the body?

• A. Brachytherapy
• B. Cobalt-60 Unit (Gamma Knife)
• C. External Beam
• D. Linear Accelerators

Answer: (C)

The main idea is radiotherapy delivery based on where the radiation source sits relative to the patient. Treatments that come from machines outside the body are called external beam radiotherapy. These use devices like linear accelerators to generate high-energy photons or electrons and aim the beams at the tumor from outside the body. TheGamma Knife setup, though it uses multiple cobalt-60 sources, also delivers beams from outside the patient and converges them on the target, so it falls under this umbrella rather than brachytherapy. Brachytherapy, by contrast, places radioactive sources inside or very close to the tumor. So the category described—radiation given from outside the body to treat cancer—fits External Beam.