CT (Computerized Tomography)

Radiology & Imaging

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Radiology & Imaging

CT (Computerized Tomography)

A computerized axial tomography scan is more commonly known by its abbreviated name, CAT scan or CT scan. It is an x-ray procedure which combines many x-ray images with the aid of a computer to generate cross-sectional views and, if needed, three-dimensional images of the internal organs and structures of the body.

HealthEast offers state-of-the-art high resolution CT scanning. This new frontier in imaging allows for superb sub-millimeter isotropic resolution that facilitates the imaging of small structures including small tortuous vessels, fine bony structures and coronary arteries, in addition to the full spectrum of CT scanning services.

There are many benefits of high resolution CT scanning:

  • Automated dose reduction for patients
  • Shortened breath-holds due to quicker scanning
  • Obtain thicker or thinner slices without rescanning the patient resulting in less radiation
  • Fast, accurate scan times means faster patient exams
  • Higher speed scanning means clearer, sharper images with fewer artifacts caused by patient movement
  • Full body CT angiography coverage

A CT scan is used to define normal and abnormal structures in the body and/or assist in procedures by helping to accurately guide the placement of instruments or treatments. A large donut-shaped x-ray machine takes x-ray images at many different angles around the body.

These images are processed by a computer to produce cross-sectional pictures of the body. In each of these pictures, the body is seen as an x-ray "slice" of the body, which is recorded on a film. This recorded image is called a tomogram. "Computerized axial tomography" refers to the recorded tomogram "sections" at different levels of the body.

Imagine the body as a loaf of bread and you are looking at one end of the loaf. As you remove each slice of bread, you can see the entire surface of that slice from the crust to the center. The body is seen on CT scan slices in a similar fashion from the skin to the central part of the body being examined. When these levels are further "added" together, a three-dimensional picture of an organ or abnormal body structure can be obtained.

CT scans are performed to analyze the internal structures of various parts of the body. This includes the head, where traumatic injuries (like blood clots or skull fractures), tumors, and infections can be identified. In the spine, the bony structure of the vertebrae can be accurately defined, as can the anatomy of the intervertebral discs and spinal cord. In fact, CT scan methods can be used to accurately measure the density of bone in evaluating osteoporosis. Occasionally, contrast material (an x-ray dye) is placed into the spinal fluid to further enhance the scan and the various structural relationships of the spine, the spinal cord, and its nerves. CT scans are also used in the chest to identify tumors, cysts or infections that may be suspected on a chest X-ray.

CT scans of the abdomen are extremely helpful in defining body organ anatomy, including visualizing the liver, gallbladder, pancreas, spleen, aorta, kidneys, uterus and ovaries. CT scans in this area are used to verify the presence or absence of tumors, infection, abnormal anatomy, or changes of the body from trauma.

Source: MedicineNet.com

Questions about CT scans and safety?

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Contact Radiology & Imaging

Call 651-232-5500 to make a radiology appointment at St. John's Hospital, St. Joseph's Hospital or Woodwinds Health Campus. This appointment line is open between 7 am and 6 pm.

Frequently asked questions about CT scans


Q: How should I prepare?

A: Preparation for your CT will depend on the type of exam; you will be given preparation instructions when your exam is scheduled.

  • Notify HealthEast if you are nursing or if there is a chance you could be pregnant
  • Please bring previous imaging study results (x-ray, MRI, CT, ultrasound ) such as reports, films or CD-roms if available
  • Please arrive 30 minutes early to verify your registration

Q: What should I expect during the exam?

A: You will lie on a cushioned table, and once comfortably positioned, the tabletop will move through a gantry (shaped like a big donut), which houses the x-ray tube and a set of detectors.

  • Using the lowest dose possible, multiple x-rays are passed through the body at different angles. Images are acquired by detectors that measure the x-rays that pass through your body.
  • The computer processes this information to form an image that the radiologist will review and interpret.
  • Some CT studies require a contrast material to enhance the visibility of certain tissues or blood vessels. In this instance, you are given an IV in your hand or arm. Once the contrast is injected, you may feel a warm, flushed sensation, and experience a metallic taste in your mouth that lasts for about two minutes.
  • You will receive special instructions if your exam requires you to consume an oral contrast agent (barium sulphate) in advance.
  • Depending on the type of exam, your CT scan requires that you relax and lie still for 5 to 30 minutes.

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Q: What should I expect after the exam?

A: A radiologist who specializes in a specific area of the body will review your images, and will prepare a diagnostic report to share with your doctor. Your doctor will consider this information in context of your overall care, and talk with you about the results.

Q: What should I wear?

A: Wear clothing that is comfortable (for example, sweat pants, t-shirt, shorts). It may be necessary for you to change into a patient gown depending on the area being scanned.

Q: Are there any special preparations/restrictions?

A: If your exam requires a contrast dye to be used, please do not eat anything for three hours prior to the exam.

Q: May I have a CT scan when I am breastfeeding?

A: If you have contrast as part of your exam, please suspend nursing for 24 hours after the scan.

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Q: Are barium sulphate studies painful?

A: No, but the volume of the barium can distend your abdomen and create a tight or cramping sensation. We conduct procedures rapidly so that patients can evacuate the barium as quickly as possible to eliminate the discomfort.

Q: How will I feel after the exam?

A: In most cases, you may resume normal activity immediately.

Q: Can I take my prescribed medication?

A: Yes, for any CT exam, you may continue taking your prescribed medication(s), with the exception of diabetic medication.

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Q: Why does HealthEast need to know a patient's creatinine level when scheduled for an exam requiring IV contrast?

A: The creatinine level shows whether the kidneys are functioning properly, thus protecting against renal failure.

Q: The patient is pregnant. Can she have a CT exam?

A: Generally, any ionizing radiation exam is contraindicated for pregnant women. Under circumstances where the benefits outweigh the risks, CT scans of certain body parts may be allowed.

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