Computed Tomography (CT)

Computed tomography (CT) (also called Computerized Axial Tomography or CAT scan) is a diagnostic procedure that uses special x-ray equipment to obtain cross-sectional, three-dimensional pictures of the body. A CT scanner rotates around the body and produces image “slices” of the body, while the patient lies on the table. A computer then compiles the images to give a series of detailed cross-sectional pictures of the inside of the body. Unlike an x-ray image, which shows only bone, CT images have the unique ability to show soft tissue, bone, and blood vessels.

Uses of CT in pancreatic cancer

• To detect the presence of a tumor.

• To provide information, in the form of pictures, about the size and location of a tumor and whether the tumor has spread (metastasized).

• To guide a biopsy (removal of cells or tissue from the tumor for examination).

• To help plan for surgery or radiation therapy.

• To determine whether the tumor is responding to treatment.

Types of CT

• Conventional CT: An x-ray beam is directed at several different angles and levels in the abdomen. Contrast dye, administered orally or intravenously may be given to help make the organs visible on film. A computer processes the images into approximately 1⁄2-inch
cross-sectional slices of the abdomen.

• Spiral (helical) CT: The x-ray bean remains on continuously, unlike the conventional CT. In a spiral CT, the x-ray beam rotates around the patient, in a spiral pattern, as the patient lies on a slowly moving table. The spiral CT is more efficient and produces three-dimensional images that are more detailed than conventional CT images.

What to expect during a CT procedure

In preparation for a CT procedure, the patient is positioned on the table by the technician. The patient may be given a contrast dye, by mouth or by IV, before or during the CT procedure, which will help make the organs visible on the resultant images. The patient is then positioned inside the CT scanner. The technician controls the CT examination from a control room next to the CT room. The technician may instruct the patient through an intercom, to remain still and possibly to hold his/her breath for a few seconds

The table is slowly passed through the CT scanner, while the x-ray beam rotates around the patient. Depending on the model of CT scanner, there may be some noise associated with the rotating x-ray beam.

CT scans typically last from 15 to 60 minutes. When the CT procedure is complete, the technologist will assist the patient from the table. It may take several days to learn the results from a CT scan.

Risks associated with CT

CT scans are not painful and have very few associated risks. Patients undergoing CT scans will be exposed to a very small amount of radiation. The amount of radiation exposure from a CT scan can be slightly higher than from a regular x-ray. In rare instances, some people experience an allergic reaction to the contrast dye used during a CT scan. Symptoms of a mild allergic reaction include itching and small bumps on the skin (hives). A more serious allergic reaction may include shortness of breath and swelling of the throat or other parts of the body. The patient should notify the technician immediately if he/she experiences any of these symptoms during or after the CT procedure.

Combined Positron Emission Tomography (PET)/Computed Tomography (CT)

PET/CT scanning combines two imaging tests into one procedure. The PET scan produces images by detecting tissues that are using more fuel (glucose). Since cancer cells use glucose at a faster rate than normal cells, tumors appear different on PET images. By combining the PET and CT scans, a more complete picture of the tumor may be obtained than by either exam alone. The combined PET/CT scan may provide doctors with more information about the location of the tumor and whether it has grown or spread. This new technology is available only at a few facilities in the United States and may not be covered by insurance. Private insurance companies handle coverage for PET scans on a case-by-case basis.

For more information about CT scans, contact a Patient and Liaison Services (PALS) Associate by phone at 877-272-6226 or by email at pals@pancan.org.

Additional resources:

American College of Radiology

http://www.acr.org

Radiology Info - The radiology information resource for patients

http://www.radiologyinfo.org