Radiotherapy is a treatment involving the use of high-energy radiation. It's commonly used to treat cancer.
Almost half of all people with cancer have radiotherapy as part of their treatment plan.
Radiotherapy is also sometimes used to treat benign (non-cancerous) tumours and other conditions, such as thyroid disease and some blood disorders.
Radiotherapy can be used, alone or in combination with chemotherapy (chemoradiotherapy), to try to cure cancers.