X-Rays in 3-D Show Nanosized Details

By Gwyneth Dickey, Science News

A new X-ray microscope technique gives a super-detailed look inside small samples, and does it in 3-D.

An international team of scientists used the method to look inside a tiny piece of mouse bone to reveal inner details as small as 100 nanometers, such as hidey-holes for bone cells and connecting channels between those pockets.

The new technique, published in the Sept. 23 Nature, rolls several new technologies into one. A powerful X-ray source sends a beam through a sample to a highly sensitive photon-counting detector without the need for an image-forming lens.

On their way through the object, X-rays are slightly scattered by variations in the density of the material. The detector measures the intensity of the scattered waves and a powerful computer program uses that information to reconstruct a two-dimensional image of the sample.

After an image is made at each degree in a 180-degree view of the material, a computer program puts all the images together to get a three-dimensional image, similar to the way a CT brain scan is put together. The 3-D reconstruction shows tiny inner variations in density never before measurable.

This type of imaging won’t work in living things, because the X-ray dose is too high and the technology too expensive, says study coauthor and X-ray physicist Pierre Thibault of the Technical University of Munich’s campus in Garching, Germany. 

But researchers can take biopsies to look at small samples, for example to see what happens during bone loss from osteoporosis, he says. The technique could also be useful in materials science to look at how metals mix together to create new alloys, or how a material develops tiny fractures.

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