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300 Longwood Avenue
Boston, MA 02115
(617) 355-6000
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My Child Has:
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Computed Tomography (CT Scan or CAT Scan)
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CT, or computed tomography, is a procedure that uses x-ray equipment to take detailed, cross-sectional images of your child's body. The information obtained is processed in a computer that displays a cross-section of body tissues and organs that are interpreted by a radiologist. CT is particularly useful because it can show many different types of tissue with great clarity and images can be obtained quickly.
The CT scanner itself is a large machine with a hole in the center, which has the appearance of a large donut. The child lies still on a table that slides into and out of the center of the hole and the machine takes pictures of small sections of the body that require investigation. You can assure your child that although the machine is large and makes "funny noises", it will not touch them during the scan.
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These pictures are obtained when an x-ray tube on a rotating gantry within the donut emits controlled amounts of x-ray radiation, which pass through the body and get picked up by an array of detectors on the opposite side of the gantry. (The gantry rotates around the patient in a helical or spiral motion.) Numerous pictures are obtained, producing thin two-dimensional "slices" of the area being studied. The slices are assembled by a dedicated computer, which compiles them into a detailed 3-dimensional picture that can be studied at all angles.
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CT provides detailed views of many types of tissues, including the brain, airway, lungs, bones, soft tissues and blood vessels. This makes it an excellent choice for evaluating the chest and abdomen. It is often used to diagnose appendicitis, investigate headaches, chest pain, fractures and evaluate a child's airway.
Your child's physician may request a CT scan to obtain specific diagnostic information that is not provided by other imaging technologies such as ultrasound, nuclear medicine, and magnetic resonance imaging. CT may be required to rule out disease or to facilitate medical, surgical, and other treatments for conditions of the central nervous system; eye, ear, nose, and throat; bones, joints, and muscles; heart and blood vessels; chest and lungs; abdominal organs and gastrointestinal tract, kidneys, urinary tract, and pelvic organs. Such conditions may include congenital and developmental disorders, genetic and metabolic diseases, infections and inflammatory conditions, traumatic and other types of injury, vascular and blood diseases, and childhood cancers.
Since it provides detailed information in a short period of time, it is often the imaging modality of choice in emergency situations. For instance, in trauma cases, CT can reveal internal injuries and bleeding quickly, providing important data that the medical care team may need to save a life. It is often used to evaluate whether a patient's appendix is about to perforate or why a child has a headache or trouble breathing.
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A CT scan is generally a very short procedure. Some types of CT scans can be obtained in a matter of seconds, while others take 10 minutes or longer. Regardless, actual imaging times are frequently less than 30 seconds. This typically depends on what area of the body is being studied. Children's Hospital's Department of Radiology has recently obtained a fast, multi-detector scanner that has further cut down on scanning time, while improving the quality of the scan. This in turn has decreased the need for sedation. However, because CT scans require your child to remain perfectly still and since some scans do require more time, sedation is frequently required for babies, young children, and developmentally delayed children. The decision to sedate your child typically depends on his or her age and the area of the body being studied. Some types of scans are more forgiving of slight movements, while others require your child to be entirely motionless for a greater length of time. It is up to your child's doctor and our radiologists to determine whether sedation is appropriate for your child. Often older children do not require sedation, but if your child has special needs, please be sure to let the referring physician know, so that we can determine in advance whether sedation is appropriate for your child.
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- If your child will be sedated, a nurse practitioner will call you in advance to obtain a detailed medical history. On the day of the procedure, the nurse or anesthesiologist will examine your child to be sure that sedation is a safe option.
- If sedation is necessary, or if the CT examination requires injection or ingestion of a contrast agent for image enhancement, specific dietary restrictions and other instructions will be provided by your physician in advance. For sedation, you must not give your child any solid food for 4 hours prior to the test. For infants this includes formula. Breast milk or clear fluids, including apple juice and other clear juice drinks, oral electrolyte solutions or popsicles may be give up to 2 hours before the examination time. These guidelines are important to your child's safety. If your child has food or liquid in his or her stomach while sedated, he or she can vomit and aspirate fluid into the lungs, which can be a serious problem. If eating and drinking guidelines are not followed, the CT exam must be rescheduled. In some special cases, general anesthesia must be used. If your child will be having anesthesia, talk to your doctor about specific instructions.
- It is also important to notify the CT staff of any active illness (cold, cough, fever, diarrhea, vomiting) or allergy. We may need to reschedule the test. Let us know of any previous drug reaction that may prohibit your child from undergoing the examination safely.
- Your child should not be wearing any metal, so dress your child in comfortable clothing with no metal snaps, belt buckles or zippers. If your child is having a head CT scan, he or she will be asked to remove any metal hair clips or jewelry.
- Explain to your child, in simple terms, why he or she needs to go to the hospital and have the test. You can explain to your child that although the CT test makes a funny noise, the machine never touches your child and the procedure doesn't hurt. Some CT tests do require IV (intravenous) administration of contrast material to enhance the image and tests of the abdomen require ingestion of an oral contrast solution 90 minutes in advance of the test.
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- Upon arrival at the radiology suite, check in at the front desk. The CT scheduling coordinator will confirm your appointment and registration.
- If your child is going to be sedated, you will first see the CT nurse, who will ask you some questions and perform a clinical screening examination. After you see the nurse, you will be greeted by the CT technologist who will explain the test to you in detail, answer any questions you may have.
- If your child is having an abdominal scan, you'll need to arrive 2 hours in advance of your examination time because your child will most likely have to drink oral contrast, a clear fluid that will show up on an abdominal scan to enhance detail. Depending on the type of test, some children will need IV-administered contrast. This is administered just before the test. Children who are having an abdominal exam sometimes require both types of contrast.
- We cannot administer IV contrast through a PICC (peripheral indwelling central venous cather), some central lines, or any portocaths or broviac lines. The contrast material is very thick and could potentially damage these lines.
- Although we try our very best to adhere the to the outpatient schedule, urgent cases involving acutely ill inpatient and emergency patients frequently arise, and this can result in delays. We try our best to accommodate these emergency add-on cases without disrupting our scheduled patients, but we cannot predict the timing of such emergencies. If there is a delay, the technologist will keep you informed. If you've been waiting for a half-hour or more with no update on the status of your child's study, please check with the front desk staff to update you and your child.
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First, the CT technologist positions and secures your child comfortably on the bed of the large donut-shaped gantry of the CT scanner. At this point, an intravenous line may be placed with a small needle into your child's hand or foot. The technologist then performs the CT examination as protocoled by the radiologist. The technologist is in direct contact with a radiologist at all times. All patients undergoing sedation or anesthesia and all critically ill or unstable patients receive continuous vital monitoring and support by a nurse or physician. Other emergency staff are immediately available as well.
During the procedure, your child will hear some noise and feel the bed move. It is particularly important for your child to remain still when this happens since the CT scanner is obtaining images at that time. Holding still during the exam helps shorten the total exam time and prevents delays. An entire CT examination may take from ten minutes to one hour depending on the type of information required by the radiologist and your physician. However, as noted previously, total imaging time is frequently less than 20-30 seconds.
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If an intravenous (IV) injection is required, your child may feel minor discomfort from the needle. The CT procedure itself is painless. The machine never touches your child, but the machinery may seem intimidating, particularly for very young children. Fortunately, our entire staff is very familiar with childhood behavior. Since we work exclusively with children, we have our own strategies to help a child feel comfortable. However, we still highly recommend that a parent or guardian stay with the child during the procedure. Having a loved one in the room can make a big difference in decreasing your child's anxiety level. However, if you are pregnant, for the safety of your unborn child, it is strict department policy that you must remain outside the room. Please plan on having an alternate or additional caregiver in this situation.
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Although CT studies require the use of ionizing radiation (x-rays), the amount of radiation used is minimized by advanced CT detectors and computer technology to achieve the best image quality at the lowest possible radiation dose. Also, protective shielding is applied routinely to prevent unnecessary radiation exposure to sensitive tissues. CT, like other imaging technologies in radiology, is FDA approved for its safety and effectiveness.
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After the images are obtained, the radiologist will check to make sure the images are adequate to evaluate your child's condition. Sometimes, additional pictures may need to be taken. Once it is confirmed that pictures are sufficient, the IV line will be removed and you and your child will be free to go. If your child was sedated, he or she will need to wake up in our recovery room, and be evaluated by an experienced pediatric nurse prior to discharge.
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After careful analysis of your CT images, the radiologist will review the findings with your physician and provide a report. You should review the results of the test with the physician who ordered the study, so that the imaging findings can be discussed with you in a context that is appropriate to your child's unique clinical condition.
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The information on this website should not be taken as medical advice,
which can only be given to you by your personal health care professional. |
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Copyright © Children's Hospital Boston. All rights reserved. |
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