A computed tomography, or CT, scan of the chest is a noninvasive test that uses ionizing radiation to create slices, which are images of the internal chest structure, notes the National Heart, Lung and Blood Institute. Unlike standard X-rays, it creates pictures with more details.
A chest CT scan is useful when a doctor wants to determine the exact size, shape and location of internal chest structures, including the lungs. It is also used when tracing the underlying cause of pulmonary symptoms such as chest pain and breath shortness, notes the National Heart, Lung and Blood Institute. The doctor may utilize this test to diagnose lung conditions such as a tumor, tuberculosis, pneumonia, pulmonary embolism and emphysema.
To perform the chest CT scan, a doctor instructs a patient to lie on a narrow table. The table moves through a hole in a scanner as an X-ray tube rotates around the patient's body to create slices. The machine controller sees and talks to the patient from a different room, explains the National Heart, Lung and Blood Institute. To avoid blurred pictures, the controller advises the patient to remain still during the procedure. He may also inject the patient with contrast dye to improve image clarity. If the patient is nervous about the procedure, the doctor may administer a sedative to relax the patient.
Though effective, a chest CT scan may cause cancer due to radiation exposure, states the National Heart, Lung and Blood Institute. It may also result in an allergy, including trouble breathing.