New ray of hope for health checks

A different range in the electromagnetic spectrum could replace X-rays and detect engine pollution

A new imaging technology looks set to offer a less harmful alternative to X-rays. It will also have non-medical applications, such as allowing scientists to gain a better understanding of how fuel burns in an engine.

Terahertz imaging, which is being developed by a team of UK engineers, will be used to detect abnormalities on the surface of the skin, such as melanomas, to diagnose blood disorders and to monitor tooth decay.

But the technology is also likely to benefit sectors such as the aerospace, food and chemicals industries, said Dr Robert Miles, deputy director of the Institute of Microwaves and Photonics at Leeds University.

Health checks

The joint project, involving engineers at Leeds and Cambridge Universities and UMIST, has been funded by a £3m grant from the government’s new basic technology research programme, which is designed to support developments with a high impact and wide-reaching benefits.

Terahertz waves use a much lower frequency range of the electromagnetic spectrum than X-rays, between microwaves and infrared. These have been difficult to generate in the past as the frequency is too high for use in ordinary transistors, but too low for lasers.

Unlike X-rays, terahertz waves are claimed not to be harmful to health, although they cannot penetrate the body in the same way, due to its high water content. But for parts where this is not a problem, such as teeth, the new technology is likely to replace X-rays, said Miles.

Researchers are also planning to develop a terahertz endoscope to detect disorders of the internal organs, he said. ‘It is a very new technology – we are literally looking at things with a new light. It is a part of the electromagnetic spectrum from which we have not looked at the world before.’

Engine pollution

The engineering researchers at UMIST believes that terahertz imaging will help to reduce the environmental impact of aerospace engines.

Dr William Truscott, senior lecturer in electrical and electronic engineering at UMIST, said a lot of research has been done into the complex nature of combustion, but until now it has been impossible to study the heart of high-pressure flames as soot particles turn the area yellow, meaning even laser beams cannot penetrate.

‘Terahertz waves should be able to see through these soot molecules, as they have a longer wavelength,’ he said. ‘We are now hoping to look at the chemical processes of a flame to see what is going on inside.’

This new understanding should help Rolls-Royce to produce low-polluting jet engines, he claimed. Reducing levels of pollutants such as nitrogen oxide in exhaust gases requires a lean fuel mixture for combustion. But using lean mixtures makes the combustion process unstable, rapidly destroying the combustion chamber. Being able to see what is going on inside the combustion process should help engineers to solve the problem, said Truscott.

Textiles, food and books

The Leeds University researchers are looking at the use of terahertz waves in analysing wear and tear on fibres, and how textiles change when coated in chemicals, particularly within the process industry.

In addition, the imaging technology can be used to study what happens to food during processing, said Dr Miles. ‘It is very sensitive to the presence of water in food, so it could give us a greater understanding of freeze drying, or simply as a method of monitoring food on the production line.’

Terahertz waves are also sensitive enough to allow experts to read fragile historical books without even opening the cover. Whereas X-rays simply penetrate straight through books, terahertz waves should be at just the right length to take images of the words on each individual page, said Miles.