This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Radiation treatment planning, Subject name: Radiology
[{'content': 'For the treatment of deep seated tumors, the following rays are used. \nSelect and explain. \nA. X- rays and Gamma- rays, B. Alpha rays and Beta -rays, C. Electrons and positrons, D. High power laser beams', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. is \'a\' i.e. X-rays and Gamma-rays X-rays and gamma rays are electromagnetic waves with highest penetrating power.For deep seated tumours rays with maximum penetrating power is required so x-rays and gamma rays are used.Harrison 141h/e states - "Megavoltage X-rays are used to irradiate internal deep seated lesions since high energy penetrating beams deliver a less intense superficial dose and spares the skin".', 'role': 'assistant'}]