How does a CT scan work?

A CT scan, or computed tomography, is a type of imaging procedure that uses x-ray equipment to create detailed pictures of the inside of a body. It is also known as a computerized axial tomography (CT).

The images created during a CT scan record the body in 2-D “slices” which can be viewed on their own, or stacked together to create a 3-D image. Computer software is used to create both of these types of images. Modern CT machines build their photos in a continuous spiral (or helical) rather than traditional “slices.” This technique is faster, results in higher quality 3-D images, and can help locate small abnormalities more easily than a traditional CT machine can.

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What is a CT scan used for?

  • Circulatory diseases and conditions: a CT scan can be used to diagnose circulatory (blood) system diseases and conditions such as coronary artery disease (atherosclerosis), blood vessel aneurysms, and blood clots
  • Muscular and skeletal injuries: a CT is also useful for detecting and diagnosing spinal conditions, head injuries, skeletal injuries, and damage to internal organs
  • Other diseases and conditions: some types of cancer, inflammatory diseases such as sinusitis and inflammatory bowel disease, as well as common urinary issues such as kidney and bladder stones can be detected and diagnosed with a CT scan
  • Cognitive disorders and diseases: CT scans can be used to identify structural issues in the brain such as atrophy, strokes, hydrocephalus, and cognitive diseases such as Alzheimer’s disease 

MRI used in medical imaging