IT IS THE stuff of science fiction: gamma-ray technology used to treat patients surgically without any blood being spilt or any sign of a wound. Yet the future has already arrived in the form of a remarkable high-tech radiosurgical device called the Gamma knife, which can perform pinpoint-accurate brain surgery with none of the side-effects created by opening up the skull.

The “knife” uses gamma rays — a more energetic version of the ones applied in everyday X-rays — to knock out tumours or destroy damaged areas of the brain. Unlike traditional brain surgery, it is non-invasive; and unlike radiotherapy, it can target the area of a tumour with an accuracy to 0.1mm.

The knife is actually a combination of several technologies — the most striking of these is the helmet, which looks like an industrial-strength colander and which is held in place on the patient’s head with a “stereotactic frame”. The helmet has to be positioned precisely because each of the 201 holes in it allows a low-key intensity stream of cobalt-60 radiation to be beamed into the patient’s brain. Individually, each beam is harmless, but the key is to ensure that they all arrive at the same spot, a task carried out by sophisticated computer software.

The knife has now become standard treatment for acoustic neuroma — a benign tumour on nerves near the inner ear. If allowed to grow, the tumour can cause deafness, dizziness, facial paralysis and even death. According to Phil Blackburn, the neurosurgeon at the London Radiosurgical Centre (LRC), which has the Gamma knife technology, the operation to remove this growth “is very tricky — it is almost impossible to cut it out without damaging the nerves. Previously you might save a patient’s life, but at the cost of total deafness and a loss of control of one side of the face”.

A US study published last month comparing the results for surgery with Gamma knife treatment for acoustic neuroma found that postoperative complications were 47 per cent for surgery, against 4.6 per cent; the average hospital stay was two to 16 days for surgery, compared with one to two for the knife. The Gamma knife was also better at “hearing preservation”.

Such accuracy makes the Gamma knife valuable in treating other neurological conditions such as arteriovenous malformation (AVM), which involves a tangle of blood vessels. It may also prove a useful way of treating secondary cancers that have spread to the brain. The usual treatment is with radiation, but that is a far more broad-brush approach, and while surgery can deal only with a single tumour site at a time, the Gamma knife can target several. The three latest published studies on its use with tumours all describe it as “safe and effective”.

And soon the knife may also have a much larger role in some cases of epilepsy and Parkinson’s. “These conditions are mainly treated with pills at the moment,” says Peter Hamlyn, a consultant neurologist at the Royal London Hospital, “but there are growing worries about sideeffects. The Gamma knife offers surgical treatments that are too traumatic to do in the conventional way. It could be a real boon.”

The Parkinson’s Disease Society is more cautious. “There is a resurgence of interest in surgery,” says a spokesman, “but the risks of the Gamma knife are not yet known.” And certainly the process even of fitting the frame so that it is positioned accurately is agreed to be “uncomfortable”. Auxiliary nurse Jolene Keen, then 23, was in “awful pain” during her fitting, says her mother Sheila. “She was screaming and yelling that she wanted to go home.”

But a year later she’s “very happy” with the results of the treatment (for damaged blood vessels following a brain haemorrhage ) and is planning to go back to work.

Not everybody has a bad experience, stresses Phil Blackburn. “People do get sedated if they need it, but it takes only about ten minutes, and others breeze through it.”

According to Colin Melhuish, general manager of the LRC, there are up to 2,500 patients in the UK who could benefit from Gamma knife treatment (in the past six months the LRC has treated about 50 patients). If so, why has there not been greater use of the knife? “We are not quite sure,” he says. “It is partly to do with the way the NHS counts its costs. The Gamma knife destroys brain tissue with precisely targeted X-rays, so a patient can have the equivalent of major brain surgery and be back home in the evening. Apart from the benefit to the patent, this avoids all the costs of an operating theatre and a week or more in a hospital bed. But initially, treatment here shows up on the books as more expensive.”

The limited use of the Gamma knife reflects a general failure to fund neurosurgery properly in the UK, says Hamlyn. “It’s an absolutely proven standard treatment, used all over the world, but its introduction to the UK has been extraordinarily slow.”

The UK has just three Gamma knife centres in total, while the US has 65 and Japan 34. “I’ve had to fight to get my patients treated with it,” Hamlyn adds. “I’d estimate there are hundreds who could benefit from it, but don’t because of this blind spot over funding.”

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