In
microtomography X-ray
X-rays (or rarely, ''X-radiation'') are a form of high-energy electromagnetic radiation. In many languages, it is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it in 1895 and named it ' ...
scanners, cone beam reconstruction is one of two common scanning methods, the other being
Fan beam reconstruction.
Cone beam reconstruction uses a 2-dimensional approach for obtaining projection data. Instead of utilizing a single row of detectors, as fan beam methods do, a cone beam systems uses a standard
charge-coupled device
A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are ...
camera, focused on a
scintillator
A scintillator is a material that exhibits scintillation, the property of luminescence, when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate (i.e. re-emit the absorbe ...
material. The scintillator converts X-ray radiation to visible light, which is picked up by the camera and recorded. The method has enjoyed widespread implementation in
microtomography, and is also used in several larger-scale systems.
An X-ray source is positioned across from the detector, with the object being scanned in between. (This is essentially the same setup used for an ordinary X-ray
fluoroscope).
Projections from different angles are obtained in one of two ways. In one method, the object being scanned is rotated. This has the advantage of simplicity in implementation; a rotating stage results in little complexity. The second method involves rotating the X-ray source and camera around the object, as is done in ordinary CT scanning and
SPECT imaging. This adds complexity, size and cost to the system, but removes the need to rotate the object.
The method is referred to as cone-beam reconstruction because the X-rays are emitted from the source as a cone-shaped beam. In other words, it begins as a tight beam at the source, and expands as it moves away.
See also
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Computed tomography
A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...
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Industrial CT scanning
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Tomographic reconstruction
References
{{Medical imaging
Medical imaging
Medical physics
X-ray computed tomography