What is a CT scan? 

A "CT" or "CAT" scan is the term used to describe a radiologic test known as "computerized tomography" (or computed axial tomography). The CT scanner is a doughnut-shaped machine that uses advanced x-ray technology to take pictures of cross-sections of your body, called "slices."

CT can see inside the brain and other parts of the body, into areas that cannot be seen on regular x-ray examinations. CT makes it possible to diagnose certain diseases earlier and more accurately than with other imaging tools. Because most diseases are better treated when found early, CT scans can help save lives. 

Is it Safe?

The test itself is completely painless. You will be asked to lie quietly on the CT scanner's "patient table" during the study. Depending on the type of study being done, you may be injected with, or be asked to drink, contrast material. This part of the procedure may be uncomfortable.

Many contrast agents contain iodine, which causes an allergic reaction in some individuals. Be sure to tell the technologist, nurse or radiologist if you have had an allergic reaction to iodine or a contrast agent in the past, or if you have any other allergies. You may have been given contrast material earlier as part of a CT scan, a kidney x-ray (also called an IVP), or a heart or blood vessel catheterization (also called an angiogram). See further discussion of contrast below.

CT scanners use x-rays. For your safety, the amount of radiation is kept to an absolute minimum and our equipment is kept in top shape. Because x-rays can harm a developing fetus, however, be sure to tell your doctor if you are, or think you may be, pregnant before preparing for the CT exam. Even if you haven't told your doctor, be certain to tell the CT scan technologist who prepares you for the study.

What can I do to prepare myself for the test? 

On the day of your CT scan, please do not eat solid food for four hours prior to your CT appointment. You may, however, have clear liquids (black coffee/tea, broth, clear soups, or juice) during this time in moderate amounts. Restricting solid foods in order to avoid stomach distress is a common safety precaution before many medical procedures. Specific preparation instructions will be given to you regarding your exam.

At the center

Plan to arrive at the CT scan suite at least 15 minutes before your scheduled appointment. This will allow the necessary time to prepare your paperwork. You will be asked to fill out a brief questionnaire about your medical history, medications and allergies, and insurance.

Depending on your study you may be asked to pick up oral contrast at least 4 hours prior to the exam. Specific instructions will be given to you at the time you at the time you pick up your contrast.

A CT technologist will introduce herself/himself to you, explain the test you are having, and answer your questions. Depending on the part of your body being scanned, you may be asked to remove any metal objects, such as jewelry, and change into a hospital gown.

What happens during the scan? 

The technologist will bring you into the CT scan room where you will lie down on the patient table (usually on your back). You should get comfortable because it is very important that you not move during the test. CT examinations differ depending on your medical problem and the part of your body being studied.

For example, if your abdomen is being studied, a series of pictures will be taken from your lower chest down to the upper pelvis. During such a study, you will be asked to hold your breath so that the pictures will not be blurred. The machine will make some noise, and the table may move slightly after each picture. Also, you may receive signals from the technologists (or from the machine) about your breathing. As part of your test, before or during the study, you may be given an injection (by a nurse, technologist or doctor) of a contrast agent. This allows the technologist to obtain clearer images of your organs. Should you have any discomfort during the test or after the injection, tell the technologist. All the CT personnel are trained and certified and know how to help you.

How long does a CT scan take? 

Each examination is tailored to individual requirements, so don't be alarmed if your exam is different from one you've had before, or if some additional pictures are taken after the first series is completed. From start to finish, the test usually lasts only 15 to 30 minutes. 

What happens after the scan? 

Once the CT staff are sure that enough information has been collected, you may leave and go about your normal activities without restriction. 

When do I get the results? 

Your exam will be reviewed by Silicon Valley radiologists who specialize in this type of imaging. Results are then available to your doctor through our online system or via fax. A formal written report will also be sent to the requesting doctor. Contact your doctor if you want to know about the results.