Microscopy and Imaging Facility: Micro CT Scanner
SkyScan-1072 High-resolution desk-top micro-CT system
RECOMMENDED SAMPLE SIZE : 1.5cm diameter x maximum height of 3cm. RESOLUTION: 4 microns (this can be reached if sample has diameter of < 5mm). MAGNIFICATION: max 120x
Any conventional optical or electron microscope provides visualisation of 2-dimensional images of a specimen surface or thin section. In most cases a final conclusion about the original 3-dimensional object structures cannot be made on the basis of 2-dimensional information.
3-dimensional information of an object's structures can be obtained by cutting them into thin slices, which can then be visualised in the microscope (light or electron). After storing the images a 3-dimensional structure model can be reconstructed from the 2-dimensional information. This method is not only cumbersome but it is unreliable since the object structure can be altered by the preparation technique and the distance between the slices is usually too coarse to avoid loss of 3D information.
An x-ray (radiography) system produces 2-dimensional shadow images of the complete internal 3-dimensional structures, but in a single 2-dimensional shadow projection the depth information is completely mixed. Only an x-ray tomography system allows us to visualise and measure complete 3-dimensional object structures without sample preparation or chemical fixation.
How does it work?
A Micro-focused X-ray source illuminates the object of interest, which is positioned on a precision manipulator. The x-ray Shadow Images are acquired by a sensitive X-ray Camera. During the Image Acquisition the sample is rotated step at a time through 180 degrees. Images are recorded at each rotation. Using complex software 2 dimensional images (or slices) based on x-ray density can be recalculated from the x-ray Shadow Images.
One or more of these 2D images can be stored in the computer and then using another software package a stack of these images can be added together to form a 3D model of the sample. From this model it is possible to make virtual cuts or slices of the object in any direction. The software allows for numerical data to be calculated from the morphology of the samples structure.
For more information on instrument capabilities and examples of applications go to the manufacturers website at http://www.skyscan.be