This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, 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: Both X-rays and gamma rays have no mass; rather, they are packed of available energy ready to be released on collision with a substance. Because they have no mass, X-rays and gamma rays can penetrate more deeply into the tissue before releasing their energy. This process, which is commonly referred to as photon irradiation, is used to treat deep-seated tumors such as those located in the thoracic, abdominal, or pelvic areas.', 'role': 'assistant'}]