N° 70–2001: Astronomy helps advance medical diagnosis techniques

Effective treatment of cancer relies on the early detection and removal of cancerous cells. Unfortunately, this is when they are hardest to spot. In the case of breast cancer, now the most prevalent form of cancer in the United Kingdom, cancer cells tend to congregate in the lymph nodes, from where they can rapidly spread throughout the rest of the body. Current medical equipment can give doctors only limited information on tissue health. A surgeon must then perform an exploratory operation to try to identify the diseased tissue. If that is possible, the diseased tissue will be removed. If identification is not possible, the doctor may be forced to take away the whole of the lymphatic system. Such drastic treatment can then cause side effects, such as excessive weight gain, because it throws the patient's hormones out of balance.

Now, members of the Science Payloads Technology Division of the Research and Science Support Department, at ESA's science, technology and engineering research centre (ESTEC) in the Netherlands, have developed a new X-ray camera that could make on-the-spot diagnoses and pinpoint cancerous areas to guide surgeons. Importantly, it would be a small device that could be used continuously during operations.

"There is no photography involved in the camera we envisage. It will be completely digital, so the surgeon will study the whole lymphatic system and the potentially cancerous parts on his monitor. He then decides which parts he removes," says Dr. Tone Peacock, Head of the Science Payloads Technology Division.

The ESA team were trying to find a way to make images using high-energy X-rays because some celestial objects give out large quantities of X-rays but little visible light. To see these, astronomers need to use X-ray cameras. Traditionally, this has been a bit of a blind spot for astronomers. ESA's current X-ray telescope, XMM-Newton, is in orbit now, observing low energy, so-called 'soft' X-rays. European scientists have always wanted to follow up XMM-Newton's success with a satellite called XEUS. It would be capable of taking images of the high-energy 'hard' X-rays but a reliable camera has eluded them - until now.

For the first time, the ESTEC researchers have produced a microchip, similar to that found in a household video camera but capable of detecting hard X-rays instead of visible light. The key is that, instead of silicon, the new chip is made from a chemical compound called epitaxial gallium arsenide. This new material was developed under the ESA leadership of Dr Marcos Bavdaz to the very demanding requirements of such hard X-ray sensors. The prototype sensor has now successfully completed its extensive tests at a German X-ray test facility (HASYLAB).

It may seem surprising that medical imaging is similar to observing high energy X-rays from space. However, hard X-rays are the only type that will pass through the human body.

Dr Alan Owens, who is closely involved in the research at ESA, explains: "For the lymphatic system a radioactive tracer which emits X-rays is injected into or near the breast tumour. The tracer focuses on those parts of the system which are cancerous. With a small camera it is therefore possible to image this cancerous tissue during surgery."

The ESA team were aware, from an early stage, that the work they were doing could lead to better medical equipment and sought expert advice. "We are talking to the people at Leiden University Medical Centre," explains Owens. "Also they can test and evaluate what we produce." A small lightweight X-ray camera would be a very important addition to the set of tools available to the surgeon.

Having made the basic camera sensor, the next stage in this work is to develop a system to send the images to television screens in real time. "We are developing that now with our industrial partners, such as Metorex, a research and development company in Finland," says Peacock.

Once ESA, which is a non-profit organisation, has developed the technology to make this X-ray camera work, its task is done. The industrial partners will take over, producing a camera for medical use. ESA will adapt its design to provide European astronomers with a new view of the Universe.

For further information please contact:

ESA - Communication Department

Media Relations Office

Tel: +33(0)1.53.69.7155

Fax: +33(0)1.53.69.7690

Dr Tone Peacock, ESA - ESTEC,

Noordwijk, The Netherlands

Tel: + 31 (0)71 565 3563

Anthony.Peacock@esa.int

Dr Marcos Bavdaz, ESA - ESTEC,

Noordwijk, The Netherlands

Tel: + 31 (0)71 565 4933

Marcos.Bavdaz@ea.int

Dr Alan Owens, AURORA c/o ESA - ESTEC,

Noordwijk, The Netherlands

Tel: + 31 (0)71 565 5326

Alan.Owens@esa.int

Professor E.K.J. Pauwels, Leiden University Medical Centre Nuclear Medicine, Leiden, The Netherlands Tel : +31 (0)71 526 3475

E.K.J.Pauwels@lumc.nl Dr J.A.K Blokland, Leiden University Medical Centre Nuclear Medicine, Leiden, The Netherlands Tel : +31 (0)71 526 3485 J.A.K.Blokland@lumc.nl For more information on the ESA Science Programme, visit the ESA Science website at: http://sci.esa.int

For further information:

Media Relations Office

Tel: +33(0)1.53.69.7155

Fax: +33(0)1.53.69.7690