A team of medical researchers from the Charité analyzed the damage caused by high-energy focused X-rays in fish and mammal bone samples at BESSY II. Using a combination of microscopy techniques, the scientists were able to document the destruction of collagen fibers induced by the electrons emitted by the mineral crystals. X-ray methods might have an impact on bone samples when measured for a long time, they conclude.
It has long been known that above a certain dose, x-rays damage living tissue, so there are clear medical indications for x-rays to minimize radiation exposure. In basic research on the properties and characteristics of mineralized tissue samples such as bone, researchers rely on increasingly powerful X-ray sources.
Fish and mammal bones
Until now, the motto was actually: more flux and more energy is better because you can get greater depth of field and higher resolution with more intense x-rays. »
Dr Paul Zaslansky de la Charité University Medicine
Zaslansky and his team have now analyzed fish and mammal bone samples on BESSY II’s MySpot beamline.
BESSY II generates a wide range of well-characterized X-rays, precisely focused in an intermediate energy range that allows a better understanding of the finest structures and even the chemical and physical processes of materials. “Thanks to sensitive detectors and rather mild irradiation conditions in BESSY II compared to harsher synchrotron X-ray sources, we were able to demonstrate on our various bone samples that collagen fibers are damaged by the absorption of irradiation in mineral nanocrystals,” summarizes Zaslansky. the results of the study.
Protein Fiber Imaging
“We examined the samples under second-generation harmonic laser scanning microscopy for protein fiber imaging,” says first author Katrein Sauer, who is doing her PhD on Zaslansky’s team. Together with HZB expert Dr. Ivo Zizak, she irradiated bone samples from pike, pigs, cattle and mice with precisely calibrated X-ray light.
trail of destruction
The beams left a trail of destruction clearly visible on confocal and electron microscopy images. “High-energy photons of X-ray light trigger a cascade of electronic excitations. The ionization of the calcium and phosphorus in the mineral then damages proteins like collagen in the bones,” Sauer explains. Collagen degradation increases with irradiation time, but also appears even with short high-flux irradiation.
Minimum doses for research on living materials
“X-ray methods are considered non-destructive in materials research, but at least for bone tissue research, that’s not true,” says Zaslansky. “We need to be more careful in basic medical research so that we don’t damage the very structures that we actually want to analyze. So, as everywhere in medicine, and even when there is no living tissue and DNA to damage, it is a question of using a minimum dose to obtain the information that reflects the material state without causing of damage.
