What are the effects of radiation therapy?
The main type of radiation used in radiation therapy, or indeed, any other treatment involving radioactive sources, is gamma radiation, as alpha and beta radiation are difficult or impossible to detect through the skin once they have entered the body.
Many people who get radiation therapy have skin changes and some fatigue. Other side effects depend on the part of your body being treated. Skin changes may include dryness, itching, peeling, or blistering. These changes occur because radiation therapy damages healthy skin cells in the treatment area.
People who receive radiation therapy are often confined to hospital until the radioactivity has worn off, otherwise they run the risk of making other biological substances radioactive, particularly other human beings.
Sources for middle paragraph: http://www.cancer.gov/cancertopics/coping/radiation-therapy-and-you/page6