How Does a Multislice CT Scanner Work?

Doctors all over the world are using computerized tomography (CT) to help confirm their diagnoses. A CT scan is a medical-imaging tool that gives a three-dimensional view of the human body. There are two major phases to a CT scan. First is the acquisition of the image, which is then followed by computer software reconstruction. A multislice CT scanner takes multiple frames, called slices, along the axis of a desired body part to make the resulting image.

Instructions

• 1

  Patients lie on a CT scanner while a transmitter and receiver spins around the patient taking multiple images in a circular motion. Images are taken with X-rays, highly energized photons that pass through soft tissue. Photons are common to us as visible light, but can become highly energized to become X-rays. The scanner will take images in small segments in a successive manner along the desired axis until the scan is complete.

• 2

  It may be necessary to use a contrast dye to allow for better images of a certain region. Some dyes can contain metals (barium) or an iodine-based dye. Contrast dye can be taken either orally, through intravenous lines or injected in another part of the body (such as rectum or joints). X-rays will not pass through dense particles such as bone and metal because the contrast dye contains small particles that coat soft tissues. This allows the doctor to look at body cavities (colon), vital organs and other important aspects of the human body.

• 3

  After images are taken from the CT scanner, they are sent to a dedicated computer to be reconstructed. Technicians can change settings through the computer to allow for a clear image to be interpreted by the radiologist. The computer arranges the slices in order from the series of images given from the scan. When slices are arranged together, a three-dimensional image is produced and can be manipulated for the best view. Looking at slices in a sequential manner gives an image that "jumps" from point to point. Using more slices gives more detail to the final image.