Frequently Asked Questions Regarding CT (CAT) Scan
What is a CT scan?
CT stands for Computed Tomography. It is a computerized X-ray machine that examines the body. The scanner is comprised of a table and a gantry. The gantry is the donut shape part that houses the X-ray source. The X-ray source rotates inside the gantry as the patient moves through. Data is obtained and processed by a computer to produce a two dimensional image.
What are contrast agents?
Contrast agents are used to image tissues and structures that are not normally seen, or not seen very well. Intravenous contrast agents are used to enhance organs and visualize blood vessels. Oral contrast agents are used to visualize the digestive tract.
How do CT scans differ from MRI scans?
CT and MRI images sometimes look very similar, but the equipment used to perform the scans is different. CT uses ionizing radiation just as with a routine X-ray, while MRI uses a magnetic field. Depending on the clinical indications, one may be preferred over the other, or both may be desirable. CT scanners are faster and as a result, claustrophobia and movement are not as problematic as with the MRI scanner.
What will I feel during the scan?
CT scanning causes no pain, just as a routine X-ray is painless. If intravenous contrast is used, you may feel warm and flush and get a metallic taste in your mouth. These sensations normally disappear after a few minutes.
Will I need to drink anything?
Most abdominal scans require the patient to drink a barium sulfate oral contrast mixture. This mixture is flavored and not at all unpleasant. Oral contrast highlights the stomach and upper intestine providing the radiologist with a detailed image for review. If you are scheduled for a CT scan requiring oral contrast, you will be asked to arrive one hour before the scan time.
How long will the scan take?
The scan itself takes seconds. The total visit time is much longer due to prep and positioning. If oral contrast is required, about 45 to 60 minutes is needed for the contrast to move through your digestive tract. If no oral contrast is required, the examination will take about 15 to 30 minutes, including the time for intravenous preparation and interview. In some cases additional scanning is required as scans are tailored to suit individual diagnostic needs.
Can my spouse/friend stay in the room with me?
No. CT scanners use ionizing radiation and only the patient requiring the scan is permitted in the room.
Should I have a CT scan if I am pregnant?
Pregnancy is not an absolute contraindication to CT. Most pregnant women should avoid getting CT, but some situations may require it. We are happy to speak with providers to help guide the best course of action, whether that be an alternative to CT, or proceeding with CT in special situations.
Why do some patients need contrast and others not?
Depending upon your condition and the images required to diagnose or rule out pathology, X-ray dye or intravenous contrast may or may not be needed. The radiologist reviews the information sent to us by your physician and decides what contrast is needed to provide the best images.
Are there any instructions I need to follow after the scan?
If no contrast was used, there are no instructions and you may continue with your normal activities. If intravenous contrast or oral contrast is used, you will be instructed to drink water for the rest of the day to help eliminate the contrast.
Will I have to hold my breath?
Depending upon the body part being scanned, you may be required to hold your breath several times during the scan. It is important that you not move during the scan. The technologist will instruct you on breathing prior to the start of the scan.
Can I breastfeed after an injection of intravenous contrast?
Does the radiation stay in my body?
No. CT uses a thin beam of radiation that is captured by detectors as it exits your body.