What Is a Thoracic CT Scan?

A thoracic CT scan, or computer tomography scan, provides a series of x-rays of organs and structures in the chest and upper abdominal region. Detecting internal bleeding or fluid filled areas, evaluating a chest injury, or assessing the position and size of organs are some of the reasons for having a CT scan. The entire thoracic CT scan procedure generally lasts less than half an hour and causes no adverse reactions.

The CT scan requires the patient to lie perfectly still on a narrow table that slides in and out of a cylindrical opening in the main scanning device, which resembles a large washing machine. Once inside the scanner, patients may talk to the technician when needed, as the machine contains a microphone and speakers for two-way communication. During the imaging study, an x-ray tube and a sensor detector, located opposite from each other within the device, rotate around the patient, emitting x-rays from all directions.

The x-rays pass through the patient and travel to the sensor, which records the returning signals. When the rays of the thoracic CT scan contact structures within the body, they weaken in signal strength. The sensor receives the signals, software interprets the data and converts the signals into images. The machine produces hundreds of images for each rotation of the scanner. Physicians review the images individually or the software can stack the images on top of each other to create a three-dimensional view of the thorax.

After the software records the images, physicians view the findings on a computer screen, on film, or on a compact disc. Depending on the structures the physician desires to examine, the thoracic scan may take 15 to 30 minutes before completion. Patients occasionally require a dose of intravenous contrast dye if physicians need to view vascular structures or specific organs. The dye makes these areas more visible and shows abnormalities or blockages. Instructions usually advise patients not to eat or drink for at least four hours before a scan if they will require contrast injections.

Having a thoracic CT scan presents the risk of exposure to x-rays, but beyond having possible difficulty lying on the table for an extended length of time, there are no side effects from thoracic CT scans.The contrast dye used during the procedure may contain iodine, and individuals with allergies to the substance should notify staff prior to the procedure. Patients may experience burning at the start of the infusion, along with a warm flushed feeling and a metallic taste. The symptoms associated with contrast usually only last a few minutes. After the procedure, staff generally advise the patient to drink plenty of fluids, which helps to flush the substance from the body.