Gcse revision help, radioactive isotopes in medicine?

radio-isotopes are used both for diagnosis (not x-rays, but isotopes themselves, are used in diagnosis of cancer, thyroid and kidney diseases for example), as well as for the treatment of some diseases, mostly cancer. By injecting or inserting the radio-active substance in the body, we can target the diseased organ or tissue rather than the whole body, for example, radio-active iodine will be taken up by the thyroid, in some cases radio-therapy is used, by bombarding the cancer by radiation generated outside the body. The whole thing is known as nuclear medicine or radiotherapy (treatment by radiation) and is used mainly in hospitals that specialize in cancer treatment (oncology centers).