What is a CT Scan?
A CT scan, also called a CAT Scan, is a noninvasive medical test that uses detailed imaging to help diagnose and treat medical conditions throughout the body.
CT is an abbreviation for Computed Tomography. Tomography refers to two-dimensional image "slices" of a three-dimensional object. CT scanning uses special X-ray equipment in combination with sophisticated computers to produce multiple images of the inside of the body. These images can be examined and manipulated on a computer monitor to be studied in greater detail.
CT scans produce images of the internal organs, bone, soft tissue, and blood vessels, which provide greater clarity and reveal more details than regular X-rays.
How to prepare
- Wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure.
- Metal objects can affect CT images. Jewelry, eyeglasses, dentures, and hairpins will need to be removed before the exam, and you may also be asked to remove hearing aids and removable dental work.
- Depending on the type of CT Scan, you may be asked to refrain from eating or drinking for several hours before your exam.
- Be sure your doctor is aware of any recent illnesses or other medical conditions; if you have a history of heart disease, asthma, diabetes, kidney disease or thyroid problems; or if there is a possibility that you may be pregnant.
What to expect
Depending on the type of exam, a special dye may be used to make certain internal organs or systems of the body show up more clearly in the pictures. It will be swallowed, injected through an intravenous line (IV), or administered by enema. You may experience a warm sensation in the body when the dye is administered, and possibly a metallic taste in the mouth which should go away after a few minutes.
When the scan begins, you will be lying on a narrow CT examination table. The technologist will help position you, and straps and pillows may be used to help you maintain the correct position throughout the exam.
You will need to remain very still during the exam, as any movement can lead to blurring of the images, similar to the effect you see when taking a photograph of a moving object. You may be asked to hold your breath for short periods of time during the exam.
The table will move quickly through a doughnut-shaped opening in the machine as it determines where to begin the scan. Then, once the table is in the proper starting position, it will move slowly through as the scanning takes place. The scanning process is generally completed in 30 minutes.
After your CT Scan
When the scanning is complete, the technologist will review the images to verify that they are of high enough quality for accurate interpretation. The images will then be reviewed by a doctor, and you will hear back about the results within several days.
Generally, no recovery time is needed after a CT scan and you will be able to drive yourself home, or even back to work immediately after your appointment.
Risks or side effects
CT scans have been used since the 1970s. They are considered very safe, with the diagnostic benefits outweighing the possible risks in the majority of cases. They do utilize a small amount of radiation; however great care is taken to use the lowest dose of radiation possible while producing high-quality images.
If your CT scan calls for use of a contrast dye, there is a small risk of allergic reaction or inflammation caused by the dye.
Watch a video of Dr. Anthony Filly describing the lower dosage of radiation treatment you can expect at CHOMP.