Computed tomography scan (CT or CAT scan) is a non-invasive diagnostic imaging procedure that uses a combination of special X-ray equipment and sophisticated computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. These cross-sectional images of the area being studied can then be examined on a computer monitor or printed. 

CT scans are more detailed than general X-rays, showing detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans of internal organs, bone, soft tissue and blood vessels provide greater clarity and reveal more details than regular X-ray exams. CT scans also minimize exposure to radiation. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly.

In standard X-rays, a beam of energy is aimed at the body part being studied. A plate behind the body part captures the variations of the energy beam after it passes through skin, bone, muscle, and other tissue. While much information can be obtained from a standard X-ray, a lot of detail about internal organs and other structures is not available.

In computed tomography, the X-ray beam moves in a circle around the body. This allows many different views of the same organ or structure. The X-ray information is sent to a computer that interprets the X-ray data and displays it in a two-dimensional (2D) form on a monitor.

Using specialized equipment and expertise to create and interpret CT scans of the body, radiologists can more easily diagnose problems such as cancers, cardiovascular disease, infectious disease, trauma and musculoskeletal disorders.

CT scans of the chest can provide more detailed information about organs and structures inside the chest than standard X-rays of the chest, thus providing more information related to injuries and/or diseases of the chest (thoracic) organs.

Chest CT scans may also be used to visualize placement of needles during biopsies of thoracic organs or tumors, or during aspiration (withdrawal) of fluid from the chest. This is useful in monitoring tumors and other conditions of the chest before and after treatment.

CT scans may be done with or without "contrast." Contrast refers to a substance taken by mouth or injected into an intravenous (IV) line that causes the particular organ or tissue under study to be seen more clearly. Contrast examinations may require you to fast for a certain period of time before the procedure. Your physician will notify you of this prior to the procedure.

Care agreement:

You have the right to help plan your care. To help with this plan, you must learn about your health condition and how it may be treated. You can then discuss treatment options with your caregivers. Work with them to decide what care may be used to treat you. You always have the right to refuse treatment.

Related procedures

Other related procedures that may be used to assess the heart include:

• Resting or exercise electrocardiogram (ECG or EKG)
• Holter monitor
  
• Signal-averaged ECG
  
• Cardiac catheterization
  
• Chest X-ray
  
• Echocardiogram
  
• Electrophysiological studies
  
• Magnetic resonance imaging (MRI) of the heart
  
• Myocardial perfusion scans
  
• Radionuclide angiography
  
• Ultrafast CT scan