This question and answer guide will help you understand the test you are having, and let you know what to expect before, during and after the procedure.
What is a CT scan?
A computerized axial tomography scan is more commonly known as a CT scan. The scanner is a doughnut-shaped machine approximately 2 feet long. It combines xray technology and computers to generate a cross section image of your body referred to as a “slice”. Imagine your body as a loaf of bread, and you are looking at it from one end. The entire slice of the bread is seen from the crust to the inside. A CT scan slices in a similar manner, looking at the body from the end, scanning a “slice”, and seeing your body from the skin to the inside organs. The CT scanner, using the computer software can put the slices back together to create a 3D image that can rotate for doctors to see the body from all angles.
The CT scanner can show several types of tissue- lung, bone, soft tissue, and blood vessels- with clarity.
What are some common reasons for a CT scan?
CT scans are used to evaluate most medical problems. Used for traumas, and diagnosing and evaluation of infections, bone problems, and cancers. It allows the radiologist to easily diagnose problems such as cancers, cardiovascular disease, infectious disease, traumas and musculoskeletal disorders. CT is used in hospitals and outpatient imaging centers. In the hospital, CT is also used for biopsies and for planning radiation treatments for tumors. Most recently, CT technology has advanced to allow imaging of the cardiac arteries.
Who performs the test?
Your personal physician requests the CT scan to be done. A Radiologic technologist, a highly trained licensed professional performs the actual scan, under the direction of the radiologist. The Radiologist is a medical doctor, specializing in reading the xray exam performed.
How do I prepare for the test?
You should wear comfortable, loose- fitting clothing for your exam. Metal objects, such as zippers, snaps, wires, pins, jewelry should try to be avoided. You may be asked to remove hearing aids, glasses, and any removable dental work that is in the area of interest being scanned.
You may be asked not to eat or drink for 4 hours before your test depending on what type of scan your doctor orders.
Since this is an xray, women should always inform their doctor or the radiologic technologist if there is any possibility they may be pregnant.
How long does a CT take?
Each exam is tailored to the individual’s requirements, so don’t be alarmed if your exam is different from one you’ve had before, or some addition pictures need to be taken. From the start of the actual scan to the finish, most CT scans last only 10-20 minutes. In cases where oral contrast is needed, there is an hour to “prep” by drinking the oral contrast before you are scanned. Some patients elect to pick up the oral contrast prior to there scan date, in which case, that patient will drink the contrast 2 hours before their appointment time. When they arrive will only have to drink 1 more cup and then can be scanned.
What happens during the test?
Unless your test requires an I.V. injection of contrast, a CT scan is not painful. The technologist will bring you in the room where you will lie down (most often on your back) on the CT table. It has a pad on it and we are able to put a cushion under your knees to help make you comfortable. You will need to hold still during the exam, as moving will create blurry images that the doctor will not be able to read. The table will slide you through the scanner and then back out. Depending on the part of the body being scanned, you may be asked to bring your arms over your head. You may also be asked to hold your breath. For instance in performing a CT of the chest, you will be lying on your back, with your arms over your head. You will hear instructions saying “Take in a breath and hold it.” When you hear that, you will need to take a deep breath in and hold it in until you hear the instructions to “Breathe”. Another example, for a head CT, you will be lying on your back, with your arms on your stomach. The table will slide you through the scanner, you need to hold your head still, but you can breathe normally.
The technologist will explain your exam to you, and let you know how long it should take, any the correct position and instructions you will need. You will also be told that at any time, we can hear and see you, should you have any problems.
A CT exam sometimes requires the use of “contrast materials” to enhance the visibility of the organs and vessels. There are 2 types of contrast. Oral contrast, a barium mixture, highlights the stomach and bowel in your body. This can be taken 2 hours before your appointment, or you can arrive approximately 1 hour before your appointment time to sit and drink at the center. And I.V. contrast, an injection, highlights the vessels, kidneys and bladder in your body.
What are the benefits vs. risks?
Before your test the nurse or technologist will ask your medical history. It is necessary to bring a list of medical conditions and medicines you are taking. Patients over the age of 60 will need recent (3-4 months) BUN and Creatinine blood work available. If you do not have any blood work available, contact your physician to order it for you. The results are needed before your scan. Certain conditions indicate a higher risk of reaction to the I.V. contrast or potential problems eliminating the material from your system after the exam. If you have a history of active asthma and are on daily medications/inhaler, then you will be advised to contact your physician for premedication and referred to the medical center for your scan. If you are allergic to the I.V. contrast, you will need to contact your physician to be pre medicated, and referred to the medical center for your scan. If you are on dialysis, you will need to schedule your appointment within approximately 24 hours before your next dialysis if I.V. contrast is required. Any patients with kidney problems, or certain heart conditions, may not be able to receive I.V. contrast. If you have any questions, ask the scheduling department to speak to a technologist or nurse, before you make your appointment.
Nursing mothers should wait 48 hours before resuming breast-feeding if I.V. contrast is used.
The most common problem in a CT scan is a reaction to the I.V. contrast. A mild adverse reaction to the I.V. contrast can be sneezing, itching, rash, or hives. The radiologist will come to evaluate you before you leave. In rare cases, other symptoms such as shortness of breath or swelling in the throat are a more serious reaction and are treated promptly by the radiologist.
The oral contrast (barium) comes in flavors and most patients tolerate it well. On occasion, some patients have a side effect of diarrhea after the barium. Keep in mind that if your problem is diarrhea to begin with, it continues no matter what you consume.
What will I feel during the test?
If you are receiving the I.V. injection you may feel a passing sensation of warmth, and a metallic taste in your mouth. These last only a few minutes.
What happens after the test?
Unless you have other tests scheduled, you are free to leave. Instructions will be given to resume normal meals and to drink plenty of fluids, to eliminate the contrast medium from your body. You can resume all normal activity.
When do I get the results?
The radiologist studies the exam and dictates a report. This report is faxed or sent to your physician. This generally takes 24 hours. Your physician should then let you know the results of the exam.
We hope this information helps you to understand what a CT scan is and what is done. If you have any questions about CT scans, please write them down, and discuss with your physician. If you need any other information when you call scheduling they will be able to help get those questions answered.
A CT scan is simple, and provides important information about your health.
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