Computed Tomography

Computed tomography (CT) is an integral component of the general radiography department. Unlike conventional radiography, in CT the patient lies on a couch that moves through into the imaging gantry housing the x-ray tube and an array of specially designed "detectors". 

Depending upon the system the gantry rotates for either one revolution around the patient or continuously in order for the detector array to record the intensity of the remnant x-ray beam. These recordings are then computer processed to produce images never before thought possible. The familiar radiograph lacks a third dimension; it can only show us a two-dimensional view of the human body. CT on the other hand reconstructs images in a variety of body planes the most usual being the axial or cross sectional plane. The image created displays CT numbers which mainly reflect the physical properties of the tissues being investigated. Because of the large range of the CT number scale and the fact that the image is digital, it is possible to manipulate the display to show the underlying soft tissues with enhanced contrast as well as the bony structures.

Technological innovation has been a continuous feature of CT since its invention in 1971. Scanners today are capable of gathering even more data about the body structure in a time span that is measured in seconds thereby enhancing its clinical usefulness. CT innovation has meant radiographers today need to be able to recognize and evaluate anatomical structures in a variety of body planes.

ref.: http://www.med.monash.edu.au/radiography