Computed Tomography (CT)

What is Computed Tomography?

Computed Tomography or "CT" scanning is a diagnostic imaging tool that produces detailed "slices" of anatomy that when assembled create important three-dimensional organ studies.

The scans are produced by an x-ray beam that rotates around the patient. As the x-rays pass through the body they are detected by special sensors, and information from the sensors is processed by the computer into an image on a video screen. Contrast agents can also be used.

Because of its ability to precisely image internal portions of organs and separate overlapping structures, the CT scan has become the diagnostic tool used most often to diagnose a variety of problems. The CT scan may also be used rather than exploratory surgery and other painful radiological exams.

Preparing for a CT Scan

Following are some general guidelines that may apply to many of the various CT examinations. The results of your exam will be provided promptly to your physician.

If an oral or intravenous contrast agent is being used during the exam (for example in an abdominal CT scan), you may be asked to avoid food and fluids two to four hours prior to your appointment. Contrast agents given by mouth or injection help your physician see the organs inside your body and are a standard part of many exams.

Because our schedules are often tight and emergency exams cannot be predicted, you may want to bring something with you to occupy your time while you wait for your test to be given.

Be sure you tell the CT technologist if you are allergic to any medication.

What to Expect During a CT of the Brain

Although the exact procedure you will follow may be different than the information provided here, this is a general description of the exam.

A CT technologist will position you on the exam table and place your head in a specially designed holder that is fitted with velcro straps. This helps you hold your head still during the exam and should not cause any discomfort.

The exam table then moves into position and your exam begins. During the scan, you will hear a "whirring" sound as the x-ray tube rotates around you. You will also feel the exam table move in small increments as the pictures are taken.

Usually two sets of pictures are done. After the first set, the CT technologist may need to inject an iodine contrast agent into a vein on the arm or hand. If this is necessary, the procedure will be explained to you in more detail.

Typically, the CT examination takes 10 to 20 minutes to perform.

What to Expect During a CT of the Chest

The exact procedure you will follow may be different than the information below, but this is a general description of the exam.

A CT technologist will position you on the exam table. For most exams, a needle will be placed in a vein of the arm or hand to allow iodine contrast to be injected during the scan. This allows your doctor to better see the arteries and veins in your chest and lungs.

As the exam begins, you will be asked to take several deep breaths and to then hold your breath for a short period of time while the scan is made. You will feel the exam table move as the scan progresses. During the scan you will hear a "whirring" sound as the x-ray tube rotates around you. If an iodine contrast is used, you will feel a warm sensation during the injection. This is a normal response to the contrast injection.

Typically, the CT examination takes 15 to 20 minutes to perform.

What to Expect During a CT of the Abdomen

The exact procedure you will follow may be different than the information below, but this is a general description of the exam.

You will not be able to eat or drink anything two hours prior to your exam. Shortly before your exam, you will be asked to drink a liquid contrast material. You must wait 30 minutes to one hour for the contrast to enter your bowels prior to having your scan. If you prefer, you can pick up your oral contrast material from the radiology department the day prior to your exam. Be sure to get specific instructions from CT personnel.

As the exam begins, you will be asked to take several deep breaths and to then hold your breath for a short period of time while the scan is made. You will feel the exam table move as the scan progresses. During the scan, you will hear a "whirring" sound as the x-ray tube rotates around you. If iodine contrast is used, you will feel a warm sensation during the injection. This is a normal response to the contrast injection.

Typically, the exam will take 15 to 30 minutes.

When Your Child Needs a CT Scan

If your doctor has scheduled your child for a CT scan, here are some helpful tips that can make this experience less stressful and help us better serve you and your child.

Your child may need to be sedated for the procedure. Although most of the procedures are not painful, they do require the child to remain still for 10 to 30 minutes. If your child is to be sedated, do not feed him or her any liquids or solid foods for six hours before your appointment. If your child is a baby that is still nursing or taking a bottle, you may fed him or her four hours before the exam.
You and your child will be in a room specifically designed and furnished to facilitate the sedation process. The sedation we administer is carefully monitored to allow the child to be still during his or her examination. This sedation process sometimes takes longer than we anticipate, so please plan several hours for the entire sedation process, scanning and post sedation observation. It is not a bad idea to bring some reading material or some other quiet, soothing activities.
Many exams require intravenous contrast to be injected into a small vein in the hand or arm. In most instances, your doctor, or whoever scheduled your examination, can let you know if this will be necessary for your child's exam. The IV contrast contains iodine and helps your doctors examine the vessels and organs in your child's body. If desired, your doctor can prescribe a topical cream to help ease the pain of the needle stick that occurs prior to the injection of the contrast. Your doctor's nurse or one of the radiology nurses can instruct you in the proper use of the cream. If your child has an infusion port, the topical cream can also be used before the port is accessed. Infusion ports can be accessed by your doctor's office or by the Radiology nurses.
Oral contrast is sometimes used with CT scanning. Oral contrast is a liquid that your child can drink and is used to outline the gastrointestinal tract during CT scans of the abdomen and/or pelvis. We have several ways of flavoring the contrast, or you may bring a favorite drink, such as juice, to mix with our contrast (No carbonated beverages please). It is also helpful if you bring along you child's favorite cup or bottle.
The Radiology Department at Saint Francis is very fortunate to have nurses who work closely with the radiologists to make the examination as comfortable as possible for you and your child. They are available to answer questions before, during and after the examination.