In preparation for a CT scan, patients are always asked to avoid food, especially when contrast material have to be injected. Contrast material may be injected intravenously, or administered by mouth. In some occasions used by enema in order to increase the distinction between various organs or areas of the body. Fluid or food may be restricted for several hours prior to the CT scan. If the patient has a history of allergy to contrast material , the requesting physician and radiology staff should be notified. All metallic materials and certain clothing around th body are removed because they can interfere with the clarity of images. Patients are placed on a movable table and the table is slipped into the center of a large dount-shaped machine, which takes the X-ray images around the body. The procedure can take from half an hour to an hour. If specific tests, biopsies, or interventions are performed by the radiologist during scanning. Additional time and monitoring might be required in some cases. It is important that during the scan process the patient should minimize any body movements by remaining as still as possible. This significantly increases clarity of the images. The CT scan technologist should tell the patient when to breath of hold breath during scans of chest and abdomen. If any problems are experienced during the scan, the technologist should be informed immediately. The technologist directly watches the patient through the observation window during the procedure. There should be an intercom system in the room for added patient safety. CT scan has vastly improved the ability of doctors to diagnosis many diseases earlier in their course and with much less risk than previous methods. Further refinements in this technology continues to evolve which promises even better quality and patient safety. High resolution CT scanners {HRCT] are used to accurately access the lungs for inflammation and scaring CT angiography is a newer technique that allows non invasive imaging of coronary arteries.
