Computed Tomography (CT) scans are increasingly valuable tests for a wide range of medical conditions, from trauma to cancer. To help diagnose and treat every patient more quickly and accurately, White-Wilson Medical Center was one of the first in the nation to install the SOMATOM® Definition AS 64 from Siemens Healthcare. The SOMATOM Definition AS 64 is the world's first CT scanner that adapts to virtually any patient, provides each person with complete dose protection and offers clinicians improved diagnostic information.
Computed Tomography (CT), also known as Computed Axial Tomography (CAT), is a painless, sophisticated X-ray procedure. Multiple images are taken during a CT or CAT scan, and a computer compiles them into complete, cross-sectional pictures ("slices") of soft tissue, bone, and blood vessels.
A CT scan obtains images of parts of the body that cannot be seen on a standard X-ray. Therefore, these scans often result in earlier diagnosis and more successful treatment of many diseases.
A CT scan is considered to be a safe examination. While CT imaging does involve X-rays, the diagnostic benefits generally outweigh the risks of X-ray (radiation) exposure.
CT scanning was developed during the mid-1970s. The original systems were dedicated to head imaging and were very slow and it took hours to acquire the images for each individual slice. The newest scanners collect as many as four slices of data in less than 350 microseconds.
This great improvement in the speed of CT scanning has been accompanied by increased patient comfort and higher resolution images. And, as scan times have become faster, the time of X-ray exposure has decreased, providing better image quality at lower X-ray doses.
In general, no special preparation is required for a CT scan. Comfortable, loose clothing should be worn, although in some cases a patient will be asked to change into a hospital gown for the examination. It is important to remove any metal prior to the exam: jewelry, dentures, eyeglasses, belt buckles, and metal zippers and buttons can interfere with the images.
A patient may be asked to limit eating and drinking to clear liquids, such as water, black coffee and tea, and broth for several hours prior to the appointment for a CT scan. This request will be dependent upon the facility and the type of examination.
For many CT examinations, a contrast agent (a liquid that enhances imaging of certain organs or blood vessels) will be administered. Depending on the type of examination, the contrast may be given orally, intravenously, or as an enema. If certain types of contrast will be used during an examination, the patient may be required to fast for several hours or use an enema to cleanse the colon prior to his/her appointment.
Q: Does CT hurt?
A: CT imaging itself is painless. The patient is required to remain motionless during the examination (which is difficult for some people), but the actual scan causes no bodily sensation.
Q: How long will the CT take?
A: The length of a complete CT examination varies, depending on the type of CT required. Procedures usually take between 5 and 15 minutes. Some of the more complicated CT examinations take longer.
Q: Do all CT scans require the administration of a contrast agent?
A: Not all CT examinations require the use of a contrast agent. When a contrast agent is required, it is because the radiologist and referring physician determine that it is necessary for diagnosis. Contrast agents are considered to be safe and side effects are uncommon. The benefits associated with the improved imaging of particular organs generally outweigh the low risk of allergic reaction.
Q: Is it all right to have a CT during pregnancy?
A: Pregnant women should not have a CT, or any other X-ray examination, while in the first trimester (the first three-month period) of the pregnancy. Other exams, such as ultrasound, are available to help diagnose a medical condition in such cases.
Q: What is the difference between CT and MRI?
A: CT and MRI differ in two basic ways. CT uses X-rays to detect and record the radiation absorbed by different tissues, and sends the data to a computer to transform into images. MRI does not use X-rays. Instead, MRI employs a powerful magnetic field to monitor the nuclei of hydrogen atoms in water, the most abundant element in the body. When subjected to the magnetic field of an MRI, the hydrogen protons are knocked out of alignment and emit a radiofrequency signal that is detected by the MRI machine, which then processes the signals into images. CT scans usually show little differentiation in soft tissues, but highlight solid structures, like calcium deposits or kidney stones. MRI scans emphasize detailed tissue structures due to differences in water content.
Click here for the instructions to prepare patients for a CT scan.
Fully Accredited By ACR White-Wilson Medical Center is fully accredited by the American College of Radiology.
