Treatment for some tumours of the brain can now be carried out without opening the head as in conventional surgery. Radiotherapy treatments are given in a more concentrated way by means of stereotactic mapping, in which a frame is attached securely to the head (see photo) to make sure the radiation beams are very finely controlled. In one type (x-knife), this is achieved by arcing beams around the patient.

In the other method (gamma knife) individual beams of radiation aim at a single point within the head. Each beam on its own does no damage to any tissue but where the beams meet, at a point where position and size is very carefully controlled, the combined power of the radiation is sufficient to shrink the tumour. The concept has been nicknamed radiosurgery and the x- and gamma knife methods are very similar in the dose of radiation they give. Although this is a relatively new concept, the safety and effectiveness of radiosurgery have been well proven in a number of countries. A gamma knife unit has been operating for a number of years in the Royal Hallamshire Hospital, Sheffield, and a new one was launched at the Cromwell Hospital, London, in September 2008. X-knife units are currently in operation at Addenbrooke’s Hospital in Cambridge, and in London at St Bartholomew’s, the Royal Free and the Royal Marsden hospitals.

There are two main advantages of radiosurgery. It can successfully treat some deep-seated tumours that are out of reach of conventional surgery and tumours whose position renders them too dangerous for open surgery. Secondly, because of its non-invasive nature, there is less risk to the patient. Radiosurgery requires extreme accuracy, which at present can only be achieved for conditions within the head.