Final answer:
Teletherapy is an external radiation therapy technique that aims to selectively kill cancer cells while minimizing damage to healthy tissue. Multiple beams are used to concentrate the radiation dose in the tumor, while spreading it out over a larger volume of normal tissue.
Step-by-step explanation:
Teletherapy is an external radiation therapy technique used in the treatment of cancer. It involves delivering high-energy beams of radiation to the precise location of a patient's tumor, with the goal of killing cancer cells while minimizing damage to surrounding healthy tissue. This is achieved by carefully planning the therapy and using multiple beams of radiation that intersect at the tumor site, concentrating the dose in the tumor while spreading it out over a larger volume of normal tissue.