What is a CT scan?
CT is an abbreviation for computed tomography, which is a valuable diagnostic medical exam that combines X-ray and computers. Often called CAT scans, CT scans have been performed successfully for almost 30 years.
A CT scan gives the radiologist a non-invasive way to see inside your body. One advantage of CT is its ability to rapidly acquire two-dimensional pictures of your anatomy. Using a computer, these 2-D images can be presented as 3-D images for in-depth clinical evaluations.
Why do people need a CT scan?
CT exams are performed when people are ill or injured, or when a doctor suspects a medical problem that cannot be detected easily with a routine physical examination. CT is also used to rapidly obtain specific diagnostic information that hasn't been provided by other imaging technologies, such as ultrasound, traditional X-ray and magnetic resonance imaging (MRI).
If you have any questions concerning your exam, please ask your physician or the radiology technologist.
What should be expected?
A CT technologist will escort you into the scanning room, where you'll see a table and a large, doughnut-shaped device called a gantry. The technologist will have you lie down on the padded table and ensure sure you're comfortable. You'll be asked to lie very still during the scan and to hold your breath for a short time to minimize any body movement.
How long will the exam take?
The actual scan, in which the CT scanner acquires X-ray images of your body, takes only a few seconds. The rest of the CT exam, however, takes longer as the images are processed on the computer. The entire exam will take approximately 10 minutes, depending on the specific exam. You will only have to hold still for a few seconds during the X-ray portion of the exam.
Are IVs or shots involved?
Depending on the exam, a solution called "contrast" may be administered with an IV to help improve the accuracy of the examination. Because of this, it is very important to let your doctor know beforehand if you've ever had an allergic reaction to contrast, or if you have any other allergies, especially an allergy to iodine-based products or shellfish.
What happens after the CT examination?
The radiologist will carefully analyze your CT images, review the findings with your physician, and provide a report. Your physician will then discuss the results with you.
Safety of CT Scans
You can be assured that CT is a safe and effective diagnostic procedure. In fact, nearly 35 million CT exams are performed in the U.S. every year.
The technologist, or registered radiographic technologist (RT), who performs your CT scan is required by law to be certified by the American Registry of Radiology Technologists. This ensures that all people involved in your care are professionals who can safely operate the CT scanner, and obtain the best images to assist your doctor in making an accurate diagnosis. Board-certified radiologists interpret the results of the CT scan. The radiologist then forwards the information to your physician.
Preparing for a CT Exam
Unless directed by your physician, the following guidelines will ensure your CT scan is performed under optimal conditions:
- Arrive properly dressed in comfortable clothing containing no metal, sweat suits work best.
- Visit the restroom shortly before the scan.
- Take medication as usual, with minimal water. If you are taking pain medication, please do so 30 minutes before the scan to help you lie still.
- If you have had barium studies of your stomach or colon within the last 48 hours, please tell your physician beforehand or the CT technologist when you arrive.
For specific exams, follow these guidelines unless otherwise directed by your physician:
Head Scan: Remove hairpins, earring, etc. Do not eat or drink four hours before your scan time. The scan will last approximately 10 minutes.
Abdomen and Pelvis Scan: You will usually be required to drink a barium substance to outline the digestive system before the scan. Hospital or clinic personnel will provide you with the barium and instructions. Do not eat or drink anything else (except medications) for four hours before your scan time. You will be asked to place your arms comfortably over your head and will be asked to hold your breath for about five seconds several times during the scan.
Chest Scan: Do not eat or drink four hours before your scan time. Clothing containing metal should be removed. Women should remove their bra before the exam begins. You may be asked to swallow barium with the consistency of marshmallow cream to outline your esophagus. You will be asked to place your arms comfortably over your head and will be asked to hold your breath for about five seconds several times during the scan.
Spine Scan: It is not necessary to fast before your scan. You may be asked to place your arms comfortably over your head or on your chest.