Computed tomography

Computed tomography (CT), was known as "EMI scan" as it was developed as an exclusive research branch of EMI, a company best known at present for its music and recording business. It is a medical imaging method utilizing tomography where digital geometry processing is employed to produce a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation. The word "tomography" is derived from the Greek tomos (slice) and graphein (to write). CT gives a volume of data which can be manipulated, through a step known as windowing, in order to demonstrate different structures based on their inherent property to block the X-ray beam. Although historically the images created were in the axial or transverse plane, modern scanners allow this volume of data to be reformatted in various planes or even as volumetric (3D) representations of structures. Now CT scan become most common in healthcare, and is also used in other fields, for example nondestructive materials testing. Another example is the DigiMorph project at the University of Texas at Austin which uses a CT scanner to study biological and paleontological specimens.Since its introduction in the 1970s, CT has become an exclusive tool in medical imaging to support X-rays and medical ultrasonography. But it is somewhat expensive. nowadays it is the gold standard in the diagnosis of different diseases. Recently CT scan also using for preventive medicine or screening for disease, for example CT colonography for patients with a high risk of colon cancer. Even if a number of institutions now offer full-body scans for the general population, this practice remains controversial due to its lack of proven benefit, cost, radiation exposure, and the risk of finding 'incidental' abnormalities that may trigger additional investigations..