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CNR: Alamanacco della Scienza


N. 11 - 20 giu 2012
ISSN 2037-4801

International info   a cura di Cecilia Migali


New high resolution computed tomography 

Scientists have developed an X-ray imaging method that could drastically improve the contrast of computed tomography (Ct) scans whilst reducing the radiation dose deposited during the scan. The new method is based on the combination of the high contrast obtained by an X-ray technique known as grating interferometry with the three-dimensional capabilities of Ct. It is also compatible with clinical Ct apparatus, where an X-ray source and detector rotate continuously around the patient during the scan. The results of their research are published in Pnas.

The main author of the paper is Irene Zanette from the European Synchrotron Radiation Facility Esrf (Grenoble, Fance) and Technical University of Munich Tum (Germany), and the team also comprises scientists from the Paul Scherrer Institute Psi (Villigen, Switzerland), the Karlsruhe Institute of Technology Kit (Germany) and Synchrotron Soleil (Gif-sur-Yvette, France).

In the past years, a lot of effort has therefore been put into the development of new X-ray imaging techniques that do not rely solely on absorption but increase the contrast through the observation of other types of interaction between X-rays and matter. Of these new methods, a very promising one is the so-called 'X-ray grating interferometry', in which microstructures, gratings developed at Psi and Kit, serve as optical elements for X-rays. The team of scientists has now made an important step towards clinical implementation of this technique - a new measurement protocol called 'sliding window' technique. "We wanted to shorten the gap between the potential offered by this extremely powerful technique and its application in the biomedical field. Our sliding window method reduces the dose and acquisition time and makes grating interferometry compatible with the continuous rotation of the gantry used in clinical Ct", says Timm Weitkamp from Synchrotron Soleil.

To demonstrate the exceptional resolution of the new technique, various soft tissue body parts of a small mammalian specimen, a rat, were imaged. Within the tests, rendered in 3D, minute details are visible such as the individual seminiferous tubules, tiny tubes in which sperm cells are formed. "These structures are simply invisible in standard Ct, even in high-resolution setups - not only because of their tiny size, but even more so because they hardly give any contrast", explains Zanette, who was recently presented the Esrf Young Scientist Award for her work.

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