Novel X-ray machine is unveiled


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May 19, 2010
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Scientists have demonstrated a refined X-ray technique which can distinguish tiny variations in bone structures.

The technique uses X-rays delivered by powerful light sources and complex computer algorithms to resolve structural variations as small as 100 nanometres across.

Using the technique, the researchers have mapped in detail a bone fragment narrower than a human hair.

Hospital X-ray machines work by passing an X-ray pulse through a body onto radiographic film.

The X-rays pass through softer tissue but are mostly absorbed by hard bone - leaving an image in which the skeleton and tissue are clearly distinguishable.

In recent years, scientists have been scaling up the power of the X-ray, using massive particle accelerators or synchrotrons to deliver much larger radiation doses.

While these cannot be used on humans for obvious reasons, they can be used in research work to reveal details in materials which are too thick for use in electron microscopes.

But X-ray imaging has its own problems, with X-rays difficult to focus or manipulate even with corrective lenses.

What Martin Dierolf and a team of scientists based in Germany and Switzerland have done is to refine these X-ray techniques.

Instead of relying on how X-rays are absorbed by different materials, they have instead focused on how they are diverted or refracted as they pass through different substances. This "phase contrast" signal gives much clearer and detailed results.

They also abandoned using any corrective lenses, firing the X-ray pulse through a pinhole and then collecting the diffracted rays after they pass through the sample.

They then used a powerful computer programme to rebuild a 3D image of the object scanned by rewinding the passage of the X-rays.

"It's like reconstructing a broken cup by playing the movie backwards and by doing that you bring all the X-rays into the sample to see how they've reacted," says Professor Henry Chapman of the University if Hamburg, who reviewed the study.

BBC News - Novel X-ray machine is unveiled