14 November 2018, by MIN-Dekanat
Artistic representation of human cells with gold nanoparticles.
A high-precision X-ray technique could catch cancer at an earlier stage and facilitate the development and control of pharmaceutical drugs. A test at DESY’s synchrotron radiation source PETRA III, which used so-called X-ray fluorescence for that purpose, has proved very promising, as is now being reported in the journal Scientific Reports by a research team headed by Florian Grüner from the University of Hamburg. The technique is said to offer the prospect of carrying out such X-ray studies not only with higher precision than existing methods but also with less of a dose impact. However, before the method can be used in a clinical setting, it still has to undergo numerous stages of development.
The idea behind the procedure is simple: tiny nanoparticles of gold having a diameter of twelve nanometres (millionths of a millimetre) are functionalised with antibodies using biochemical methods. “A solution containing such nanoparticles is injected into the patient,” explains Grüner, a professor of physics at the Centre for Free-Electron Laser Science (CFEL), a cooperative venture between DESY, the University of Hamburg and the Max Planck Society. “The particles migrate through the body, where the antibodies can latch onto a tumour that may be present.” When the corresponding parts of the patient’s body are scanned using a pencil X-ray beam, the gold particles emit characteristic X-ray fluorescence signals, which are recorded by a special detector. The hope is that this will permit the detection of tiny tumours that cannot be found using current methods.
Although the ideas of X-ray fluorescence imaging has been around for over 30 years, it has not been possible until now to implement it in human beings. This is because X-rays are repeatedly scattered inside the body. The result is a vast background from which it is very difficult to extract the actual signal. “My team delved into this issue, and we have now become the first group in the world to show experimentally how this problem can be solved,” says Grüner. They accomplished this using a computer algorithm that determines precisely those detector elements within the full solid angle of the measured X-ray spectra whose signals contain particularly little of the background noise.
For a first experimental test, the scientists sent the beam from PETRA III through a 30-centimetre thick cylinder made of polymethyl methacrylate (PMMA), which can be used to simulate the conditions in human tissue. These measurements of the background signal provided good confirmation of the preceding simulations.
„For a clinical application, the possibilities of using gold nanoparticles in diagnostics must be further researched and the development of suitable X-ray light sources, which also fit into a laboratory, must be promoted“ says Prof. Grüner.
Scientists from the University of Hamburg, the University Medical Centre Hamburg-Eppendorf, the Otto von Guericke University of Magdeburg, the Sloan Kettering Institute in New York City, Cornell University in the US state of New York, the Helmholtz Centre Munich, the University of Arizona in Tucson and from DESY were involved in the study that has now been published.
Text: DESY, Red.