You may feel a need to urinate. However, these are only side effects of the contrast injection, and they subside quickly. If you swallow oral contrast material, you may find the taste mildly unpleasant. However, most patients can easily tolerate it. If you receive an enema, you can expect to experience a sense of abdominal fullness.
You may also feel an increasing need to expel the liquid. If so, be patient; the mild discomfort will not last long. When you enter the CT scanner, you may see special light lines projected onto your body. These lines help ensure that you are in the correct position on the exam table. With modern CT scanners, you may hear slight buzzing, clicking and whirring sounds. These occur as the CT scanner's internal parts, not usually visible to you, revolve around you during the imaging process.
You will be alone in the exam room during the CT scan, unless there are special circumstances. For example, sometimes a parent wearing a lead shield may stay in the room with their child. However, the technologist will always be able to see, hear and speak with you through a built-in intercom system. With pediatric patients, a parent may be allowed in the room but may need to wear a lead apron to minimize radiation exposure.
After a CT exam, the technologist will remove your intravenous line. They will cover the tiny hole made by the needle with a small dressing. You can return to your normal activities immediately. A radiologist , a doctor specially trained to supervise and interpret radiology exams, will analyze the images. The radiologist will send an official report to the doctor who ordered the exam.
You may need a follow-up exam. If so, your doctor will explain why. Sometimes a follow-up exam further evaluates a potential issue with more views or a special imaging technique. It may also see if there has been any change in an issue over time. Follow-up exams are often the best way to see if treatment is working or if a problem needs attention. There is no conclusive evidence that radiation at small amounts delivered by a CT scan causes cancer.
Large population studies have shown a slight increase in cancer from much larger amounts of radiation, such as from radiation therapy. Thus, there is always concern that this risk may also apply to the lower amounts of radiation delivered by a CT exam. When a CT scan is recommended by your doctor, the expected benefit of this test outweighs the potential risk from radiation.
You are encouraged to discuss the risks versus the benefits of your CT scan with your doctor or radiologist, and to explore whether alternative imaging tests may be available to diagnose your condition. Soft-tissue details in areas such as the brain, gallbladder , internal pelvic organs, and joints such as knees and shoulders can often be better evaluated with magnetic resonance imaging MRI.
In pregnant women, while CT can be performed safely, other imaging exams not involving radiation, such as ultrasound or MRI, are preferred but only if they are likely to be as good as CT in diagnosing your condition. A person who is very large may not fit into the opening of a conventional CT scanner. Or, they may be over the weight limit—usually pounds—for the moving table. Please type your comment or suggestion into the text box below.
Note: we are unable to answer specific questions or offer individual medical advice or opinions. Some imaging tests and treatments have special pediatric considerations. The teddy bear denotes child-specific content. Please contact your physician with specific medical questions or for a referral to a radiologist or other physician. To locate a medical imaging or radiation oncology provider in your community, you can search the ACR-accredited facilities database.
This website does not provide cost information. The costs for specific medical imaging tests, treatments and procedures may vary by geographic region. Web page review process: This Web page is reviewed regularly by a physician with expertise in the medical area presented and is further reviewed by committees from the Radiological Society of North America RSNA and the American College of Radiology ACR , comprising physicians with expertise in several radiologic areas.
Outside links: For the convenience of our users, RadiologyInfo. Toggle navigation. What is CT Scanning of the Body? What are some common uses of the procedure? How should I prepare? What does the CT equipment look like? How does it work How is the procedure performed?
What will I experience during and after the procedure? Who interprets the results and how do I get them? What are the benefits vs. What are the limitations of CT Scanning of the Body? Which test, procedure or treatment is best for me? CT imaging is: one of the fastest and most accurate tools for examining the chest, abdomen and pelvis because it provides detailed, cross-sectional views of all types of tissue.
It's considered the best method since the image allows a physician to confirm the presence of a tumor, measure its size, identify its precise location and determine the extent of its involvement with other nearby tissue. CT is commonly used to assess for pulmonary embolism a blood clot in the lung vessels as well as for aortic aneurysms. In pediatric patients, CT imaging is often used to evaluate:. In some patients, contrast agents may cause allergic reactions, or in rare cases, temporary kidney failure.
IV contrast agents should not be administered to patients with abnormal kidney function since they may induce a further reduction of kidney function, which may sometimes become permanent. Children are more sensitive to ionizing radiation and have a longer life expectancy and, thus, a higher relative risk for developing cancer than adults.
Parents may want to ask the technologist or doctor if their machine settings have been adjusted for children. In this breast CT scanner, a woman lies prone in a specially designed large table with her breast suspended in a special opening in the scanning bed. The scanner rotates around the breast, without passing through the chest, thus reducing the radiation that would be delivered to the chest in a conventional CT scanner.
Listen to a podcast about the scanner. Five new projects are underway from this new funding opportunity, representing creative, innovative, interdisciplinary approaches that would not have been funded otherwise. You can read more about them below:.
Customized imaging Web Stayman, Johns Hopkins University The amount of radiation required for a CT scan depends on a number of variables, including the size of the patient, the part of the body being scanned, and the diagnostic task at hand. For example, smaller patients require less radiation than larger patients, and scanning a denser part of the body, such as soft tissue near the pelvis, requires more radiation than scanning the lungs.
In addition, diagnostic tasks that require high image clarity, such as locating a faint tumor, generally require more radiation. The goal of this project is to modify both the hardware and software of modern CT systems so that the device can adapt the shape, position, and intensity of the x-ray beam to the specific imaging scenario.
The research leverages patient-specific anatomical models and mathematical models of imaging performance to direct x-rays where they are needed and, consequently, to avoid or to limit x-ray exposure where it is not needed. This will help maximize imaging performance for specific diagnostic tasks while minimizing radiation exposures. Constructing tools for researchers Cynthia McCollough, Mayo Clinic The goal of this work is to develop resources that enable the research community to easily create and compare new approaches to reducing radiation dose of routine CT scans without compromising diagnostic accuracy.
Using these assets, researchers have demonstrated that there is considerable potential for radiation dose reduction in CT exams of the abdomen, which are among the highest dose CT exams in common clinical use. Faster processing Jeffrey Fessler, University of Michigan To reduce radiation yet still produce good quality CT images, more sophisticated methods are needed to process the raw data from the CT system. Those advanced methods, called image reconstruction algorithms, can require undesirably long computing times, so they can be used only for some patients currently.
The goal of this project is to develop algorithms that are fast enough to allow low-dose CT imaging to be used for every patient. An integrated approach Norbert Pelc, Stanford Medical School At every stage in the design of CT scanners, there are opportunities to make changes that reduce radiation dose. Because these changes are inter-related, the goal of this project is to take an integrated approach, exploring approaches such as modifying the photon counting detector the part of the CT scanner that detects x-rays , dynamic x-ray illumination adjusting the amount of radiation used throughout the duration of a scan , and image reconstruction methods.
The computer then combines several 2D slices to create a 3D image of the body, making it easier for a doctor to pinpoint where the patient's problem exists. The scan itself typically takes less than 15 minutes depending on the area of the body being imaged. To make it easier to identify abnormalities, the patient may be given a contrast material. Solutions containing contrast materials, such as iodine or barium , are introduced into the body orally, rectally or injected directly into the bloodstream, depending on the target tissue.
The materials in the solution work by temporarily altering how X-rays interact with certain body tissues, which makes those tissues appear different in the resulting image, according to the Radiological Society of North America.
The contrast helps doctors distinguish between normal and abnormal tissue. CT scan images help doctors diagnose and pinpoint infections, muscle disorders, bone fractures, cancer, tumors and other abnormalities. In emergency situations, CT scans are life-saving tools that allow doctors to quickly determine the extent of internal injuries or internal bleeding, according to the Radiological Society of North America.
CT scans are also vital in cancer diagnosis, treatment and research, according to the National Cancer Institute. While CT scans can be vital tools for assessing health, there are risks associated with the scan. X-rays are a source of ionizing radiation, which can damage sensitive tissues such as lymphoid organs and blood.
CT scans around the abdomen are not advised for pregnant women because of a chance the fetus would be exposed to harmful radiation. More time in the CT scanner may lead to higher-quality images but also a higher radiation dose, which is often unnecessary, said Dr.
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