tomography, uses x-rays to create cross-sections of a 3D-object that later can be used to recreate a virtual model without destroying the original model.The term "micro" is used to indicate that the pixel sizes of the cross-sections are in the micrometer range. This also means that the machine is much smaller in design compared to the human version and is used to model smaller objects.
These scanners are typically used for small animals (
in-vivoscanners), biomedical samples, foods, microfossils, and other studies for which minute detail is desired.
The first X-ray microtomography system was conceived and built by Jim Elliott in the early 1980s. The first published X-ray microtomographic images were reconstructed slices of a small tropical snail, with pixel size about 50 micrometers. (JC Elliott and SD Dover. X-ray microtomography. J. Microscopy 126, 211-213, 1982.)
In 2005, [http://www.skyscan.be Skyscan] , a company that produces scientific instruments, introduced a nano-ct scanner, introducing the concept of
Nanotomography. Other companies producing such scanners include [http://www.xviewct.com North Star Imaging] and [http://xradia.com Xradia] for materials and semiconductor applications and [http://www.scanco.ch Scanco Medical AG ] for medical applications.
* Imaging system:
Fan beam reconstruction:The fan-beam system is based on a 1-dimensional x-raydetector and an electronic x-ray source, creating 2-dimensional cross-sectionsof the object. Typically used in human Computed tomographysystems.: Cone beam reconstruction:The cone-beam system is based on a 2-dimensional x-ray detector ( camera) and an electronic x-ray source, creating projection imagesthat later will be used to reconstruct the image cross-sections.
* Sample holder system:The sample stays still, and the camera and electronic x-ray source rotates.:This is best used for in-vivo animal scans, and other situations where the sample should remain unmoving, but is more expensive.:E.g.
SkyScan-1076or SkyScan-1078or Scanco VivaCT 40scanners for sample details. :The sample rotates, and the camera and electronic x-ray source stays still.:Much cheaper to build, since moving the sample requires fewer components than moving the camera and the electronic x-ray source.
* Open/Closed systems:Open x-ray system :In an open system, x-rays may escape or leak out, thus the operator must stay behind a shield, have special protective clothing, or operate the scanner from a distance or a different room. Typical examples of these scanners are the human versions, or designed for big objects.:E.g. Scanco medical XtremeCT scanner or [http://www.xviewct.com/products North Star Imaging M-Series] systems.:Closed x-ray system :In a closed system, x-ray shielding is put around the scanner so the operator can put the scanner on his desk or special table. Although the scanner is shielded, care must be taken and the operator usually carries a dose meter, since x-rays have a tendency to be absorbed by metal and then re-emitted like an antenna. Although a typical scanner will produce a relatively harmless volume of x-rays, repeated scannings in a short timeframe could pose a danger. :Closed systems tend to become very heavy because lead is used to shield the x-rays. Therefore, the smaller scanners only have a small space for samples.:E.g.
SkyScan-1076or SkyScan-1078or Scanco mCT 40or Scanco mCT 80scanners or [http://www.xviewct.com/products/imagix-computed-tomography-system North Star Imaging ImagiX] .
Biomedical:*Both dead and alive ( in vivo) rat and mouse scanning.:*Human skin samples, small tumors, mice bonefor osteoporosisresearch. :See in vivo microCTscanners for scanning examples.
Electronics:Small electronic components. E.g. DRAMIC in plastic case.
Microdevices:E.g. spray nozzle
Composite materialsand metallic foams:E.g. composite material with glass fibers 10 to 12 micrometres in diameter
Polymers, plastics:E.g. plastic foam
Diamonds:E.g. detecting defects in a diamondand finding the best way to cut it.
Foodand seeds:* E.g. piece of chocolate cake, cookies:* 3-D Imaging of Foods Using X-Ray Microtomography [http://www.cb.uu.se/~cris/Documents/GIT2003.pdf]
Woodand paper:E.g. piece of wood to visualize year periodicity and cell structure
Building materials:E.g. concreteafter loading.
Microfossils:E.g. bentonic foraminifers
Space: E.g. Locating Stardust-like particles in aerogelusing x-ray techniques [http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1228.pdf]
Stereo images:Visualizing with blue and green or blue filters to see depth
* [http://www.ecmjournal.org/journal/supplements/vol009supp01/pdf/v009supp01a24.pdf Synchrotron and non synchrotron X-ray microtomography threedimensional representation of bone ingrowth in calcium phosphate biomaterials]
* [http://www.ndt.net/article/wcndt00/papers/idn399/idn399.htm Microfocus X-ray Computer Tomography in Materials Research]
* [http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1228.pdf Locating Stardust-like particles in aerogel using x-ray techniques]
* [http://www.cb.uu.se/~cris/Documents/GIT2003.pdf 3-D Imaging of Foods Using X-Ray Microtomography]
* [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=544194 Use of micro CT to study kidney stones]
* [http://www.xviewct.com/ NSI Computed Tomography & Micro Computed Tomography systems, laboratory and service in the USA]
* [http://www.ugct.ugent.be Ghent University Centre for Tomography]
* [http://www.xraylab.com XRaylab.com Microtomography Reconstruction Software]
* [http://xct.anu.edu.au/ Australian National University micro-CT laboratory]
* [http://www.ctlab.geo.utexas.edu/ University of Texas micro-CT laboratory]
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