Can a CT Scan Detect Cancer?
Mar 18, 2019
A CT scan is one of the most frequently utilized exams to detect cancer and to show things such as a tumor’s shape and size. CT scans are most often done as an outpatient procedure. The scan is painless and usually takes between 5 to 30 minutes.
What does a CT scan show?
CT scans show a cross-section of the body, commonly referred to as a slice. The image shows your bones, organs, and soft tissues more clearly than a standard x-ray. Although a CT scan is sometimes described as a “slice” or a “cross-section,” no cutting or incisions are involved.
CT scans can show a tumor’s shape, size, and location. They can even show the blood vessels that feed the tumor – all in a non-invasive setting. By comparing CT scans done over time, doctors can see how a tumor is responding to treatment or find out if the cancer has come back after treatment.
How do CT scans work?
CT scans are similar to a standard x-ray exam, which uses a broad beam of radiation from only one angle. A CT scan uses an ultra-thin beam to create a series of pictures taken from multiple angles. The information from each angle is fed into a computer, which then creates a black and white picture that shows a slice of a certain area of the body – much like looking at a single slice from a loaf of bread
Contrast materials are often used to get a clearer picture. These contrast materials can be swallowed as a liquid, injected into a vein through an IV or put into the intestines through the rectum as an enema.
By layering CT image slices on top of each other, the machine can create a 3-dimensional (3-D) view. The 3-D image can be rotated on a computer screen to look at different angles.
How do I prepare for a CT scan?
CT scans are most often done on an outpatient basis, so you don’t have to be in a hospital to get one.
Your doctor or the imaging facility will let you know if your exam will require contrast dye. Before getting the dye, be sure to let your health care team know if you’ve ever had a reaction to contrast dye, seafood, or iodine. This is important because reactions to these things may put you at risk for reacting to the contrast dye used in CT scans. If there’s a risk that you might have an allergic reaction, you may be given a test dose of the contrast dye first. People who have had a severe reaction in the past may need to take drugs (usually a steroid, like prednisone) to help prevent another reaction. Sometimes these drugs need to be started the day before the scan.
In some cases, you may be instructed to not to eat or drink overnight or for several hours before the test. Or you might need to use a laxative or an enema to clean out your bowel and remove material that could get in the way of seeing inside the belly and intestines.
What is it like having a CT scan?
The scanner is a large, doughnut-shaped machine. You will lie down on a thin, flat table that slides back and forth inside the hole in the middle of the scanner. As the table moves into the opening, an x-ray tube rotates within the scanner, sending out many tiny x-ray beams at precise angles. These beams quickly pass through your body and are detected on the other side of the scanner. You may hear buzzing and clicking as the scanner switches on and off.
You will be alone in the exam room during the CT scan, but the technologist will be able to see, hear, and talk to you at all times.
While a CT scan is painless but you may find it a bit uncomfortable to hold still in certain positions for minutes at a time. You may also be asked to hold your breath for a short time, since chest movement can affect the image.
How long does a CT scan take?
A CT scan can take anywhere from 5 to 30 minutes, depending on what part of the body is being scanned. Most scans take between 5 and 10 minutes, depending on how much of your body needs to be looked at and whether contrast dye is used. It often takes more time to get you into position and give the contrast dye than to take the pictures.
Click here to learn more about having a CT scan performed at Suburban Imaging.