Figure 2: An X-ray image of a chest.
Credit: Mikael Häggström, CC0, via Wikimedia Commons.
Figure 3: An X-ray image of a backpack.
Credit: The original uploader was IDuke at English Wikipedia., CC BY 2.5, via Wikimedia Commons.
A large number X-ray images are taken every day all over the world. Imaging techniques are probably the most common X-ray techniques. The images map and show bones, tumors, organs etc. as in figure 2. X-ray imaging techniques can also see into non-biological subjects as seen in airports. In figure 3 one can, with X-rays, see the contents of a backpack containing among other things, batteries, bottles, and a camera.
With simple X-ray imaging techniques, only a flat image can be acquired. Radiologists and scientists can create a 3D-image of their subject by rotating it while the X-ray images are taken. To make it even smarter subjects are scanned in their lengths while they are rotating. This technique is called a CT-scan – which makes cross section images with X-rays. CT-scans have helped the health sector with looking into patients in 3D. The technique can very precisely find the placement, size, and appearance of a tumor.
In figure 4 below we see how a CT-scan can give high resolution imaging of the brain from the top of the skull down to the bottom near the jawbone. The images are taken on a new section every time and the, more than 30, images can together form a 3D image of the brain. Any potential tumors or blood clots can be accurately pinpointed and dealt with.
Figure 4: CT-scan of a brain, lower right corner is the start of the scan from the top of the cranium. Top left corner is the end of the scan at the bottom of the cranium near the jawbone.
Figure 5: Core drill samples from soil near oil fields to aid in in the examination of faults and cracks in oil field minerals..
Credit: Joshua Doubek, CC BY-SA 3.0, via Wikimedia Commons.
The strength of CT can also be utilized in geology when geologists for example want to drill for crude oil. Geologists use CT to pinpoint where and how they wish to proceed with drilling. CT also makes it possible to be on target with high precision.
In figure 5 above, one can see drill samples from oil fields. These are used to determine faults and cracks in minerals. Geologists can hereafter lay a plan for the most efficient drilling.
Figure 6: Sketch of diffraction.
Credit: U. Vainio, Public domain, via Wikimedia Commons.
Figure 7: Example of diffraction from a single crystal.
Credit: Del45, Public domain, via Wikimedia Commons.
X-ray diffraction is used to find the build and atomic constituents of a crystalline material. And what does that mean? Elements as for example metals prefer to align themselves to an ordered lattice. A lattice in a crystal can reflect-rays when certain conditions are met.
In figure 6 a sketch of diffraction from a large single crystal is seen. In figure 7 an example of a result of a diffraction experiment is shown. Diffraction from different layers of the ordered lattice can interfere with each other and give systematic dots as seen in figure 7.
Figure 8: Chocolate.
Modern chocolate is improved with the help of X-ray diffraction. The cacao in chocolate is crystallized – i.e. it is set in an ordered lattice. Chocolate producers exploit this fact about cacao to tune their recipes. Producers add or remove cacao and sugar to ensure the best crystal in the chocolate – which gives the snap in the chocolate and can determine the shimmer of the chocolate.
Figure 9: Computer chips.
Computer chips are in almost all kind of modern technology the smart phone is for example run by a computer chip. Computer chips are made of a crystalline material, namely the semiconductor, which can open and close for the electricity in the chip. Researchers and chip-producers use X-ray diffraction techniques to determine how to tune semi-conductor technology. The better the crystal the more powerful computers and smartphones we get.
Small angle scattering of neutrons and X-rays
To analyze ordinary crystals with a lattice structure scientists use X-ray diffraction. With unordered systems that are not in a lattice structure scientists cannot use diffraction. Instead scientists use solve this issue with small angle scattering.
Small angle scattering can use neutrons, that are elementary particles found in atoms, as well as light namely X-rays. A particle or light is shot or shone onto a subject in a small angle between 0 and 5 degrees. Some subjects scatter light or particles while other subjects are invisible to the shot. Looking at the biological subject in figure 10, scientists can use small angle scattering to get an idea of the size of the subject, its shape, how its outer surface looks in relation to its inner surface and the general relationship between the volumes and sizes of the respective surfaces.
When scientists use particles like neutrons for small angle scattering on a subject, they usually must know something about the subject’s atoms. Neutrons usually have the advantage of being most sensitive to atomic nuclei or their magnetic properties.
Figure 10: Biological samples eligible for small angle scattering experiments.
Credit: LadyofHats, Public domain, via Wikimedia Commons