Hitachi

Customer FAQ

Frequently asked questions - computed tomography (CT)

How is CT scanning performed?

CT scanning itself is painless. However, sometimes a contrast fluid needs to be injected to help to define blood vessels, or to highlight the difference between normal and abnormal tissue in organs like the liver, kidneys and spleen.

Although the patient will be alone in the room during the scan, the technologist can see, hear and speak to him or her, at all times.

A CT examination usually takes five to ten minutes. When the examination is over, the patient may be asked to wait until the images are examined to determine whether more images are needed.

What are the benefits?

  • Unlike other imaging methods, CT scanning provides detailed views of many types of tissue, including the lungs, bones, soft tissues and blood vessels.
  • CT scanning is painless, non-invasive and accurate.
  • CT examinations are fast and simple, eg in trauma cases, they can reveal internal injuries and bleeding quickly enough to help to save a life.
  • Diagnosis made with the assistance of CT can eliminate the need for invasive exploratory surgery and surgical biopsy.
  • CT scanning can identify normal and abnormal structures, making it a useful tool to guide radiotherapy, needle biopsies and other minimally invasive procedures.

What are the risks?

  • CT images are generated using a special X-ray technique. Therefore, there is a certain level of radiation involved. For a routine CT scan, the level of radiation to the patient is about four times higher than the normal annual radiation dose from natural sources to which the patient is exposed (sun, soil, food and water). The level of radiation can be adjusted based on the size of the patient's body, so that only the minimal amount of radiation necessary for getting an accurate image is used.
  • Women should always inform their doctor or X-ray technologist, if there is any possibility that they are pregnant.
  • The risk of serious allergic reaction to iodine-containing contrast material is rare.

Can a person with a pacemaker have a CT scan?

CT scanners use X-rays to generate images, so a person with a pacemaker can have a CT scan, without any difficulty.

What is CT scanning?

CT (computed tomography) uses special X-ray equipment to obtain image data from different angles around the body and then uses computer-processing to show a cross-section and 3D display of body tissues and organs.

The examination table advances at a constant rate through the scanner gantry, while the X-ray tube rotates around the patient, tracing a spiral path through the body. This spiral path gathers continuous data, so there are no gaps between images.

The latest CT scanners use detector technology that supports faster, higher-quality image acquisition, with less radiation exposure. Current multislice CTs provide faster scanning or higher-resolution images. A spiral scan can usually be obtained during a single breath hold. This allows scanning of the chest or abdomen in ten seconds or under. Such speed is beneficial to all, especially elderly, paediatric or critically ill patients, for whom long scanning times could be problematic. Multislice CT also allows applications like CT angiography to be more successful.