A breakthrough at STFC's Rutherford Appleton Laboratory is set to revolutionise X-ray imaging. With potential applications ranging from novel medical imaging to security screening, physicists have found a way to produce a bright, high energy X-ray or gamma ray source, much more energetic than those commonly used in radiology. The special properties of these X-rays make them ideally suited to producing high resolution images in medical applications. Gamma rays are commonly observed in astronomy by satellites, and typically have energies above 100 KeV.
The results, published online at Nature Physics (Sunday 18 September 2011) could pave the way for systems that will reveal far greater detail than is possible at the moment.
The bright gamma-ray source was demonstrated on the internationally unique Gemini laser at STFC's Central Laser Facility by a team led by the University of Strathclyde.
The laser beam is focussed into a tube of plasma, which is formed by ionising hydrogen. Electrons are trapped in the ion-cavity formed behind the laser pulse and accelerated to high energies.
They pick up energy from the laser much in the way that a child picks up kinetic energy on a swing. This gives rise to an intense beam of gamma ray photons with energies of several 100's keV to several MeV.
Some of these gamma-rays are so intense that they can pass through 20 centimetres of lead and would take 1.5 metres of concrete to be completely absorbed. They are also strongly polarised (like a laser) and are emitted from a very small area which makes them ideal for use in high resolution medical imaging where structures such as hairline fractures are often invisible using conventional X-rays.
Until now, such high energy X-rays could only be produced at high cost using accelerators that are 100s of metres in size. This breakthrough opens the way for systems that could be much more compact and produced at reduced cost. Screening for disease and for illegal goods in transport are just two potential applications. This research is still in its early stages and more work needs to be carried out to develop the technique.
More details may be found in the University of Strathclyde's press release (link opens in a new window).