Researchers working in Australia, France, Switzerland, and Germany have developed two new techniques that may expand the capabilities of X-ray imaging in clinical and pre-clinical applications. One of the new technologies is designed to reduce the radiation dose delivered during mammographies and other X-ray imaging procedures, while the other technique can provide 3D X-ray scans of fragile biological samples using only one exposure.
3D reconstruction of a gold nanostructure shows the acquired image (yellow) compared to a simulated phantom of the object (semi-transparent red). Scale bar: 200 nanometers. Credit: Pablo Villanueva-Perez, Deutsches Elektronen-Synchrotron
The first technique was tried at the Deutsches Elektronen-Synchrotron (DESY) in Germany, where a high-brilliance X-ray source was used to generate a 3D image of a target in a single exposure. Normally, multiple biological samples have to be imaged using such high-power X-ray sources, since the radiation invariably kills them. The new approach manages to create an image before actually killing the object, so it should be possible to look at the activities going on inside of viruses, bacteria, and larger things such as insects.
The second technique, called “Ghost Imaging” results in 3D X-ray images of the insides of objects that visible light can’t penetrate. The doses are much lower than doing multiple scans from different angles and may therefore lead to the potential for more frequent screenings of various diseases. Two X-ray beams, correlated with each other, are produced by a special device. One of the beams passes through the object being imaged, while the other beam flickers in a random pattern. As The Optical Society Explains:
The researchers created random X-ray patterns by shining a bright beam of X-ray light through a metal foam, which is like a sponge made of metal. They took a 2D image of this random beam, and then passed a very weak copy of it through the sample. A large-area single-pixel detector captured X-rays that passed through the sample. The process was repeated for multiple illuminating patterns and sample-object orientations to construct a 3D tomographic image of the object’s internal structure.
As a proof-of-concept experiment, the researchers carried out ghost X-ray tomography on an aluminum cylinder with a diameter of 5.6 millimeters and containing two holes of less than 2.0 millimeters diameter. They were able to produce 3D images with 1.4 million “voxels”–a term for 3D pixels–with a resolution, or voxel side-length, of 48 millionths of a meter.
All of this work is still confined to the depths of high-tech laboratories, but perhaps one day these technologies will translate into clinical practice.
Related papers in journal Optica: Ghost tomography and Hard x-ray multi-projection imaging for single-shot approaches…
Via: The Optical Society…
