Radiotherapy: technical aspects

During the 100 years of its history, radiotherapy has evolved into a mainstay of cancer treatments received by at least 40% of patients with the diagnosis. Whereas palliative radiotherapy is given over 1–10 treatments, radical treatments can extend up to 7 weeks. Radiotherapy may be given using external beam machines or by inserting radioactive isotopes close to or into the cancer. Recent integration of spiral computed tomography (CT), magnetic resonance imaging and positron emission tomography scans into staging has transformed localization of tumours. CT simulation has permitted the design of highly conformal treatment plans. Modern computers and linear accelerator have facilitated the delivery of these plans with intensity modulated radiotherapy. Radiotherapy and drugs are increasingly being combined to improve the therapeutic ratio. Clinical trials are means whereby new treatment approaches are evaluated.