What is known is to belong in doctors’ everyday vocabulary can be incomprehensible technical jargon to the layman. What does the abbreviation 'CT' actually mean? This much is clear: it describes a diagnostic procedure that is worth closer consideration, even by non-medical practitioners, because it has become a cornerstone of modern medical investigation methods.
Diagnostic methods with perspective - Computer Tomography (CT)
Further development of the X-ray
Anyone to whom 'CT' doesn’t mean much at least can get an idea of what is meant from the term 'computer tomography', what is meant. Developed in the seventies of the 20th century, the scientists Cormack and Hounsfield, who discovered it, received the Nobel Prize for medicine. Since its introduction, CT has undergone continuous improvement, especially in terms of image quality and examination time (eg spiral CT ). It is no more than a computerised form of X-ray examination.
How CT works
Normal X-ray examination and CT are among the 'imaging processes' seen in medical technology which produce an image of the interior of the body. Various structures (eg, fat, bone, muscle, etc.) have different permeabilities to X-rays due to their densities. These differences can be recorded and displayed on a film in an suitable black and white image. In CT this is done with the aid of a computer.
The patient, lying on a table, is pushed through the opening of a X-ray tube, which in modern spiral CT continuously rotates around the patient in a spiral path. The point to be examined is scanned several times in a short space of time with a fine, usually fan-shaped beam. Probes measure the energy passing through the body, the light weakened in varying degrees by the various structures, and transmit this information as electrical impulses to a computer. This creates layer images of the body accurate to the millimeter. This gives cross-sections which are followed by longitudinal and oblique sectional images ( tomography), which can be joined together to ultimately form a multi-dimensional image in various contrasting shades of grey that is displayed on a monitor.
Advantages and disadvantages of CT examination
By contrast to normal X-ray examinations, CT is an easy, painless method which ensures the imaging of even minimal density differences, e.g., in or between organs. Therefore, amongst other things, it helps to locate minor and major changes in the tissue - specifically in the brain and the thoracic, abdominal and pelvic regions. CT is also used to effect in the areas of progression charting and follow-up diagnosis of cancer. Often it is the first sophisticated method for the diagnosis of acute internal diseases, such as haemorrhages. The reliability of the investigation is improved by additionally administered contrast agents, usually containing iodine and generally well tolerated. Based on studies, the radiation exposure is estimated to carry an extremely low health risk. Nevertheless, there are groups of patients, such as those who suffer from allergies, who should seek accurate information about risks. In addition, the instructions given by the doctor should be observed (eg no alcohol before colon CT , breathing during recording, etc.).
CT has not replaced conventional X-rays, although unlike X-rays it can depict organs multidimensionally and without superimposition. In some examinations though it is more appropriate, for example when taking tissue samples, because here they can provide the puncture needle with precise images of the place to be punctured. For fractures the ordinary X-ray continues to be the preferred method since it provides a more accurate picture of the bone due to a better spatial resolution.