Slides in this set
The X-ray source fires off narrow beam X-rays as it
rotates along the trajectory. The X-rays are
detected after they have passed through the body.
They are of varying strengths as the amount of X-
rays absorbed by the tissue depends on the tissue
Each full rotation takes a slice of the brain or area
The information from the two-dimensional
computer images can be reconstructed to produce
three-dimensional images by some modern CT
The advantages and disadvantages of CT scans
· Can show inflammation, bleeding, · Far more X-rays are involved in a CT scan than
in ordinary X-rays, thus they are more
damage to internal organs and dangerous.
abnormal structures, such as
tumours. · Carcinogenic: can cause cancer.
· Can produced a 3D image. · Teratogenic: can cause foetal anomalies.
· Patients must remain still.
· As a CT scan can detect abnormal
tissue it is a useful device for · Limited resolution even though it is more
planning areas for radiotherapy and detailed than normal X-rays.
· Still images and thus function of areas of the
brain is hard to be identified
· The structure of the brain will be
revealed. · Not as good as MRI for looking at the spinal