With the ChromaXRM-500, Sigray introduces a CT system specifically designed for the requirements to be met in life sciences and the demands posed by polymer materials. The samples to be measured in these areas typically have very low contrast in the X-ray region, thus presenting a real challenge. The ChromaXRM-500 achieves a resolution in the submicron range (<300 nm voxel size) and can be fitted with up to five different detectors.
The X-ray tube installed in the ChromaXRM-500 is unique. It can be equipped with five different target materials to cover a wide energy range and to specifically use the target that provides the highest possible contrast for the sample to be measured. This "tailor-made" choice can increase throughput and contrast by a factor of up to 10x. For an example, look at Fig. 1: It shows images of the same sample taken with three different target materials. The image on the left was taken with a chromium target and shows high contrast, but low penetration of the sample. The image in the middle shows the same sample taken with a copper target. The comparison shows that here, both contrast and penetration are optimal. The picture on the right shows the sample with a tungsten target. Penetration is very good in this case, but the contrast is significantly lower.
Especially in the field of life sciences, X-ray microscopes belong to the more unsuitable systems when compared, e.g., to optical microscopes. X-rays are considered to be too powerful to examine tissue samples/soft tissue. However, with the ChromaXRM-500, high-quality images of unstained tissue samples can be taken by using a chromium target. As an example, Fig. 2 shows an image of liver cells.
Another example of materials that are difficult to examine are so-called low-Z materials, i.e. materials with a small atomic number such as carbon fibres or polymers. Here, it is also possible to achieve a significantly higher contrast in comparison with the contrast achieved with a standard radiation source based on a tungsten target.