<prompt> For the treatment of deep-seated tumors, the following rays are usedX rays and Gamma raysAlpha rays and Beta raysElectrons and positronsHigh power laser beams  <response>: 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. 