Under observation

A team led by Dr John Lees, senior research fellow at the Bioimaging Unit of

Space Research Centre, has developed a small handheld gamma camera, based on technology used on NASA’s Chandra X-ray Observatory.

The device, based on charged coupled devices (CCDs), is designed to complement large gamma cameras used in hospitals. These are around 1m wide, expensive and not very portable. They also have a resolution of 10mm, making them ideal for imaging the whole body but not so accurate for providing images of small tumours.

The handheld camera has a resolution of 1mm and can be used to monitor the effects of treatment, such as examining the lymph nodes in breast cancer patients. By viewing the node closest to the tumour, doctors can see if the cancer has spread and so determine how aggressive further treatment should be. The camera has other potential applications such as non-destructive testing of pipes.

Lees presented the technology at a forum on cancer-fighting technologies hosted by the Particle Physics and Astronomy Research Council (PPARC).

Also introduced at the forum was a new particle accelerator technology, developed by researchers at the Rutherford Appleton Laboratory.

More than one in three people are diagnosed with cancer during their lifetime. Destroying cancer cells using X-rays and gamma rays during radiotherapy can stop cancer spreading, but may have serious side-effects for the patient owing to damage to surrounding tissues.

Proton and ion therapy minimises damage to tissues around the tumour, for example so that areas such as the back of the eye can be treated without damaging the eyesight or the need to remove the eye. However, these treatments are expensive.

Dr Rob Edgecock, Neutrino Factory group leader at RAL, has designed a circular particle accelerator that could make the tech-nology more affordable, allowing the health service to extend its use.

The device is a form of Fixed Field Alternating Gradient (FFAG) particle accelerator, a technology first used in the 1950s. Researchers in Japan have recently been developing FFAG devices, but these ‘scaling’ systems use large complex magnets. Edgecock’s ‘non-scaling’ FFAG design produces the same performance at a reduced cost.

In a standard accelerator the magnets in the machine consist of three coils. The two on the outside of the arrangement focus the particle beam vertically but de-focus it horizontally. The middle beam has the opposite effect, focusing the beam horizontally but de-focusing it vertically.

‘In our arrangement we do the opposite,’ said Dr Edgecock. ‘We can therefore compress the orbits of the particles by a factor of 10. There is only a small movement outwards by the particles.’ This allows the magnets to be smaller, making the design cheaper and easy to build.

The team is now creating an industrial-scale device that can be used in medicine or for industrial irradiation and sterilising items.