What is a Computed Tomography (CT) Scan?
A computed tomography scan, commonly known as a CT scan, is an imaging technique which is used to obtain cross-sectional images of the hard and soft tissues of the body using a special rotating x-ray machine connected to a computer.
Indications for CT Scans
A CT scan may be indicated for:
- Identifying various muscle and bone disorders like tumours or fractures.
- Accurately locating infections, masses, or blood clots within the body.
- Guiding various medical procedures like radiation therapy, biopsy, or surgery.
- Identifying the presence of conditions like heart and lung disease, liver masses, or cancer and also monitoring these conditions.
- Analyzing the progress and effectiveness of various treatment methods.
- Detecting internal bleeding or injuries.
Preparation of CT Scans
- You will usually be asked to change from your regular clothing into a hospital gown.
- All metal and electronic accessories like a watch, jewellery, belt, dentures, etc. should be removed as metal in these objects might interfere with the CT scan.
- Generally, you will be advised to avoid eating or drinking anything a few hours before the CT scan.
- Inform you, doctor, if you are pregnant or think you may be pregnant.
Procedure for CT Scans
The procedure is generally conducted on an outpatient basis and involves the following steps:
- You will be asked to lie on the table connected to the scanner.
- Contrast dye, if needed, may be given to you orally or injected through an IV line connected to your arm. Your doctor or technician should immediately be alerted in case you develop any allergic reactions related to the dye like sneezing or itching.
- You will be able to communicate with the technician through the speakers attached to the CT scanner.
- CT scanners generally resemble a large doughnut with a motorized table that slides in and out of the scanner, with straps and pillows to comfortably prevent movements during the test.
- For head scans, you will be provided with a specially designed cradle attached to the table to hold your head in place during the scan.
- As the table moves into the scanner the detectors and x-ray tube revolve around you, forming several images of thin cross-sections or slices of your body during each revolution. There will be buzzing noises that indicate the scanner is doing its work.
- In some cases, you may be asked to hold your breath for a few seconds during the image capturing process.
- Once the procedure is completed, the IV line will be disconnected, and you will be allowed to go home.
- The results will be sent to the radiologist to read and report back to you.
Generally, you will be allowed to return to your regular activities once you are done with the test. You may receive specific instructions on food and drinks in case a contrast dye was used during the test procedure such as drinking plenty of fluids to flush out the dye from your body.
Risk and Side Effects of CT Scans
Side effects to CT scans are very rare and may include:
- Allergies related to the contrast dye. Your doctor should always be informed of your various allergies, especially in case of allergic reactions towards certain medications, food, or iodine.
- Kidney problems due to the contrast dye. Your doctor should be informed of any previous kidney disorders prior to the scans to avoid such complications.
- Risk of cancer from radiation is very small from one CT scan but increases with multiple scans.