Copyright 2009
Computed tomography is an imaging technique whereby the attenuation of a beam of x-rays obtained at multiple projections of an object is used to produce an image of the internal structure of that object using a mathematical algorithm.
X-ray tubes provide the source of the X-ray beam which are detected by scintillation detectors.
Collimators are used to control scatter radiation and also to control slice thickness, that is, the voxel length. Collimators are positioned at the x-ray tube and also near the detector.
The X-ray tube rotates around the patient and on the opposite side of the tube a set of detectors rotates in synchrony. With multislice CT scanners, mutiple rows of detectors are present. The newest generation scanners have up to 16 rows of detectors. The width of the X-ray beam remains the same but the combination of detectors used can be varied. This results in improved resolution in the z-axis.