Computed tomography is an imaging test that uses X-rays and a computer to make detailed images of the body. A CT scan shows details of the bones, muscles, fat, and organs. CT scans are more detailed than standard X-rays.
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 your healthcare provider can get much information from a standard X-ray, it does not give a lot of detail about internal organs and other structures.
In a CT scan, an 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.
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 show up more clearly on the scan.
CT scans of the bones can give more detailed information about the bone tissue and bone structure than standard X-rays of the bone. CT scans can give healthcare providers more information related to injuries and/or diseases of the bone.
A CT scan of the bones may be used to assess bones; soft tissues, such as cartilage, muscles, and tendons; and joints for damage, lesions, fractures, or other problems. A CT scan may be done when another type of exam, such as an X-ray or physical exam, does not give enough information.
There may be other reasons for your healthcare provider to recommend a CT scan of the bones, joints, or soft tissues.
You may want to ask your healthcare provider about the amount of radiation used during the CT procedure and the risks related to your particular situation. Radiation from CT scans varies, but may be up to 100 times greater than a normal chest X-ray. It is a good idea to keep a record of your radiation exposure, such as previous CT scans and other types of X-rays, so that you can inform your healthcare provider. Risks linked to radiation exposure may be related to the cumulative number of X-ray exams and/or treatments over a long period.
If you are pregnant or think that you may be, tell your healthcare provider. Radiation exposure during pregnancy may lead to birth defects. If it’s necessary for you to have a CT of the bones, special precautions will be taken to reduce the radiation exposure to the fetus.
Nursing mothers should discuss with their provider whether to delay breastfeeding after receiving contrast. There are conflicting recommendations currently on this topic.
If contrast dye is used, there is a risk for allergic reaction to the dye. If you are allergic to or sensitive to medicines, contrast, or iodine, tell your healthcare provider. Studies show that most people will not have an adverse reaction from contrast; however, you will need to let your healthcare provider know if you have ever had a reaction to any contrast dye, and/or any kidney problems. A seafood allergy is not a contraindication for contrast.
Tell your healthcare provider if you have kidney problems. In some cases, the contrast dye can cause kidney failure. People with kidney disease are more prone to kidney damage after contrast exposure.
Alert your healthcare provider before having IV contrast if you take the diabetes medicine metformin. It may cause a rare condition called metabolic acidosis. If you take metformin, you will be asked to stop taking it for 48 hours after your CT scan. A blood test may be needed before you can start taking metformin again.
There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your healthcare provider before the procedure.
CT scans may be done on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your healthcare provider's practices.
Generally, a CT scan of the bones, joints, and soft tissue follows this process:
While the CT procedure itself causes no pain, having to lie still for the length of the procedure might be uncomfortable, particularly if you’ve recently been injured or had surgery. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to reduce any discomfort or pain.
If contrast dye was used, you may be watched for a time for any side effects or reactions to the contrast dye, such as itching, swelling, rash, or difficulty breathing. Tell the radiologist or your healthcare provider right away if you notice any of these symptoms.
If you notice any pain, redness, and/or swelling at the IV site after you go home, tell your healthcare provider. This could be a sign of infection or other type of reaction.
Otherwise, there is no special type of care needed after a CT scan of the bones. You may go back to your usual diet and activities unless your healthcare provider tells you differently.
Your healthcare provider may give you other instructions after the procedure, depending on your particular situation.
Before you agree to the test or the procedure make sure you know: