by John R. Fischer
, Senior Reporter | March 18, 2022
Researchers at the Technical University of Munich have devised a new method for improving micro-computed tomography.
In micro-CT, scanners generate 3D images of the internal structure of samples with small dimensions. This provides information on the structure and characteristics of tissue as well as material samples for making diagnoses and other analyses.
The technique specifically applies to micro-CT with phase contrast using high-brilliance X-ray radiation, and combines a new microstructured optical grating with analytical algorithms. The result is higher contrast, resolution and sensitivity which give users the ability to assess microstructures in greater detail and investigate a broader range of samples such as soft tissues.
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The researchers developed the necessary technology based on the design of the Talbot Array Illuminator, a newly developed optical grating that is easy to produce, is reliant on X-ray radiation and can be used with different energies. This provides the prerequisites for high contrast and optimizes radiation dose compared to conventional modulators such as sandpaper, and reduces scan time. It also makes quantitative analysis possible, which allows researchers to compare absolute measurements of the electron density of tissues without having to make estimated assumptions about them.
“The new technology is more sensitive than comparable methods in this field. At very high resolutions, it depicts soft tissue with higher contrast than previously. High sensitivity is particularly important, for example, in order to detect fine differences within soft tissue," said professor Julia Herzen, professor of Biomedical Imaging Physics at the Technical University of Munich (TUM), in a statement.
X-ray imaging with phase contrast uses optical components to modulate X-rays as they travel to the detector, and results in a diffraction pattern. Comparing the pattern with and without the soft tissue provides information about its characteristics. By using the refraction of the X-rays created by the tissue's structures, the method shows the contrast of these structures and eliminates the need for inefficient structures such as sandpaper and absorption masks.
"The function of the new optical gratings resembles that of small lenses," said Herzen. "The gratings focus the x-rays to form tiny points. This renders the differences in intensity with and without the sample much clearer and makes it possible to visualize even minute differences in the tissue in greater detail.”
Collaborators in the study included the research centers, the Helmholtz-Zentrum Hereon and the Deutsches Elektronen-Synchrotron (DESY); the University of Trieste in Italy; and the University of Sheffield in the U.K.
Funding was provided by the European Research Council under the European Union Horizon 2020 research and innovation program, the British Heart Foundation and the Deutsche Forschungsgemeinschaft (DFG).