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CT (Computed Tomography) Scan

What is a CT scan (computed tomography)?

In conventional 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 regular X-ray, specific detail about internal organs and other structures is not available.

With computed tomography scan (also called CT or CAT scan), the X-ray beam moves in a circle around the body. This allows for many different views of the same organ or structure, and provides much greater detail. The X-ray information is sent to a computer which interprets the X-ray data and displays it in two-dimensional form on a monitor.

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 being studied to be seen more clearly.

Before the procedure

  • If your procedure involves the use of contrast dye, you will be asked to sign a consent form that gives permission to do the procedure. Read the form carefully and ask questions if something is not clear.
  • Notify the technologist if you have ever had a reaction to any contrast dye, or if you are allergic to iodine.
  • Generally, there is no fasting requirement prior to a CT scan, unless a contrast dye is to be used. Your doctor will give you special instructions ahead of time if contrast is to be used and if you will need to withhold food and drink.
  • Notify the technologist if you are pregnant or suspect you may be pregnant.
  • Notify the technologist if you have any body piercing on your chest and/or abdomen.
  • Based on your medical condition, your doctor may request other specific preparation.

During the procedure

CT scans may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your doctor's practices.

Generally, a CT scan of the bones, joints, and soft tissue follows this process:

  1. You will be asked to remove any clothing, jewelry, or other objects that may interfere with the procedure.
  2. If you are asked to remove clothing, you will be given a gown to wear.
  3. If you are to have a procedure done with contrast, an intravenous (IV) line will be started in the hand or arm for injection of the contrast dye. For oral contrast, you will be given medication to swallow.
  4. You will lie on a scan table that slides into a large, circular opening of the scanning machine. Pillows and straps may be used to prevent movement during the procedure.
  5. The technologist will be in another room where the scanner controls are located. However, you will be in constant sight of the technologist through a window. Speakers inside the scanner will enable the technologist to communicate with and hear you. You will have a call button so that you can let the technologist know if you have any problems during the procedure. The technologist will be watching you at all times and will be in constant communication.
  6. The scanner will begin to rotate around you and X-rays will pass through the body for short amounts of time. You will hear clicking sounds, which are normal.
  7. The X-rays absorbed by the body's tissues will be detected by the scanner and transmitted to the computer. The computer will transform the information into an image to be interpreted by the radiologist.
  8. It will be important for you to remain very still during the procedure. You may be asked to hold your breath at various times during the procedure.
  9. If contrast dye is used for your procedure, you will be removed from the scanner after the first set of scans has been completed. A second set of scans will be taken after the contrast dye has been administered.
  10. If contrast dye is used for your procedure, you may feel some effects when the dye is injected into the IV line. These effects include a flushing sensation, a salty or metallic taste in the mouth, a brief headache, or nausea and/or vomiting. These effects usually last for a few moments.
  11. You should notify the technologist if you feel any breathing difficulties, sweating, numbness, or heart palpitations.
  12. When the procedure has been completed, you will be removed from the scanner.
  13. If an IV line was inserted for contrast administration, the line will be removed.
  14. You may be asked to wait for a short period of time while the radiologist examines the scans to make sure they are clear.

While the CT procedure itself causes no pain, having to lie still for the length of the procedure might cause some discomfort or pain, particularly in the case of a recent injury or invasive procedure such as surgery. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain.

After the procedure

If contrast dye was used during your procedure, you may be monitored for a period of time for any side effects or reactions to the contrast dye, such as itching, swelling, rash, or difficulty breathing.

If you notice any pain, redness, and/or swelling at the IV site after you return home following your procedure, you should notify your doctor as this could indicate an infection or other type of reaction.

Otherwise, there is no special type of care required after a CT scan of the bones. You may resume your usual diet and activities unless your doctor advises you differently.

Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.

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