Computed Tomography (CT) imaging uses x-rays to produce cross-sectional images (or slices) of the brain. As x-rays pass through the body, they are absorbed or attenuated differently. These varying attenuation values give information on normal and abnormal structures in the brain and spine,  producing an image.

In helical CT imaging the x-ray tube which produces the x-rays is housed within a big ring-like structure opposite a detector. A fan beam of x-ray is created as the rotating frame spins the x-ray tube and the detector around the patient. The information from the detectors is then transferred to a computer, which will reconstruct a cross-sectional image.

When is CT performed?

The helical CT scanner is the workhorse of neuroimaging, and is the imaging method of choice for trauma and intracranial haemorrhage. The speed and real-time review capability of CT allows a quick overview in life threatening situations, with added advantage of ease of repeat studies. CT also plays a critical role in the early screening and diagnosis of many brain diseases, in spine imaging and in orbital-facial disease.