Radiotherapy: technical aspects

Radiotherapy is an important cancer treatment: in patients who are cured of cancer, radiotherapy contributes to cure in around 40% of cases. Radiotherapy also has an important role in improving symptoms in individuals with incurable cancer. Whereas palliative radiotherapy is typically given over 1–10 treatments, radical treatments can extend over 4–8 weeks. Radiation is often delivered externally by machines called linear accelerators. It can also be delivered using brachytherapy, where radioactive implants are placed in or close to a tumour, or systemic isotopes, which are swallowed or injected and then locate and destroy cancer cells.