Radiotherapy is used for a number of different medical purposes including:
● to cure an illness, for example by destroying a tumour (abnormal tissue),
● to control symptoms, such as relieving pain,
● before surgery, to shrink a tumour so that it is easier to remove, and
● after surgery, to destroy small amounts of tumour that may be left.
Radiotherapy is sometimes used in a process called total body irradiation (TBI). In severe cases of leukaemia (cancer of the bone marrow and white blood cells) or lymphoma (cancer of the lymphatic system), the whole body is given radiation to destroy the bone marrow cells.
After TBI, new bone marrow is transplanted. The new bone marrow is taken from a donor or from the patient before TBI.