Researchers have developed a groundbreaking X-ray imaging technique that allows for micron-resolution imaging of living organisms over extended periods of time. This breakthrough method significantly reduces the X-ray dose required for imaging, making it possible to study small or sensitive samples at high resolution without causing radiation damage. By relying on phase contrast imaging, which captures phase changes in X-rays as they pass through a specimen, the researchers were able to overcome the limitations of previous high-resolution imaging techniques.
The team, led by researchers from the Karlsruhe Institute of Technology in Germany, used dedicated highly-efficient X-ray optics and single-photon-counting detectors in their new imaging system. The combination of these technologies improved the dose efficiency for full-field imaging at micrometer resolution. The researchers demonstrated the capability of their method by capturing detailed images of tiny parasitoid wasps as they emerged from their host eggs for more than 30 minutes.
Previously, the radiation damage caused by high-resolution imaging limited observations to just a few seconds or minutes, explained Rebecca Spiecker, a member of the research team. Our method overcomes this limitation by reducing the necessary X-ray dose, enabling longer and more detailed studies of dynamic processes in living organisms.
X-ray imaging is a powerful tool for studying living organisms, as it allows researchers to visualize hidden structures and processes. However, the high doses of radiation involved in conventional X-ray imaging can be harmful and limit the duration of observations. Additionally, the detection efficiency of commonly used high-resolution detectors decreases as resolution increases, necessitating even higher X-ray doses for high-resolution imaging.
To address these challenges, the researchers employed a phase contrast imaging approach that directly magnifies the X-ray image, rather than converting it into visible light and then magnifying it. This allowed them to use highly efficient large-area detectors while maintaining a high spatial resolution of up to 1.3 microns.
The new imaging system utilizes a single-photon-counting imaging detector with a pixel size of 55 microns, along with a Bragg magnifier, which magnifies the X-ray image behind the sample using crystal optics. By optimizing these components for an X-ray energy of 30 keV, the researchers achieved a dose efficiency of over 90%. This means that the system provides better image quality while significantly reducing the X-ray dose required for imaging.
The researchers conducted a pilot study using their new system to observe living parasitoid wasps, which are commonly used for biological pest control. With minimal radiation exposure, they were able to track the development and emergence of the tiny wasps from their host eggs for a duration of 30 minutes.
In addition to studying small organisms, the researchers believe that their method could be valuable for biomedical applications such as gentle tomographic examinations of biopsy samples. However, the use of a Bragg magnifier requires a monochromatic, coherent, and collimated X-ray beam, which is currently only available at X-ray synchrotron facilities. The researchers are also working on improving the system to achieve a larger field of view and increased mechanical stability for even longer measurement times.
The development of this X-ray imaging technique opens up new possibilities for studying dynamic processes in living organisms with unprecedented detail and over prolonged periods of time. The reduced X-ray dose required for imaging allows for a range of applications, from understanding the behavior of small model organisms to examining biomedical samples. With further advancements, this method could lead to groundbreaking discoveries in various fields of research.
