A new form of radiotherapy treatment, using 3D beams that curve around a cancerous tumour avoiding healthy tissue, has been developed by British scientists.

The technique, which halts the spread of cancer and reduces side-effects, will initially be used to curb the spread of prostate cancer. But if trials are successful it could be used on other cancers. Experts say it will be much more effective than conventional radiotherapy because a larger dose of radiation can be given, and it should reduce side-effects by up to 75 per cent.

Intensity modulated radiotherapy (IMRT) was unveiled yesterday at the Institute of Cancer Research in central London, where trials are to begin on 90 patients treated there and at the Royal Marsden Hospital in Sutton, south London, who have prostate cancer that has spread to the pelvis.

The development allows doctors to shape treatment precisely to the irregular and complex shape of tumours, which wrap themselves around healthy tissue in the body.

Standard radiotherapy treatment involves geometrical beams forming a "box" around a tumour before destroying it, but that approach can damage healthy tissue and leave permanent side-effects. It also delivers single beams withthe same dose of radiotherapy to every part of the tumour. With IMRT an image of the patient's body is taken using a CT scan and the information fed into a computer to find where irradiation is most and least needed, which allows it to calculate tailor-made treatment.

The radiation beams are delivered through special robotic "leaves" which move around during treatment, allowing various doses to be given to different areas of the tumour. The technique, used successfully in localised prostate cancer, allows doctors to deliver a total dose of radiotherapy 33 per cent higher than possible with conventional treatment, and is now used in 15 centres across the country.

Scientists at the Institute of Cancer Research are now trying to refine the technique to treat prostate cancer that has spread to the pelvis. Side-effects of conventional radiotherapy, such as diarrhoea, bleeding and bowel incontinence are severe, preventing doctors from giving effective treatment.

Dr David Dearnaley, senior lecturer at the institute, said: "This is a very exciting time for us. We finally have the technology to tailor radiotherapy treatment to complex 3D tumour shapes."

Meanwhile, a treatment for the bone disease osteoporosis, which involves injecting the spine with a "liquid cement", has been developed by researchers at the University of Maryland in the United States. The liquid cement is injected into the fractured vertebrae of the spine, in a procedure called percutaneous vertebroplasty.

The cement permanently fills and hardens in the tiny holes created by the disease and strengthens the collapsed vertebrae, relieving pain andpressure on the spine. Results of a study, presented to the annual meeting of the Society of Cardiovascular and Interventional Radiology in San Diego, showed 29 out of 30 patients treated with the cement reported significant pain relief.