CT Scanners
Physics: AQA A Level, topic 10.5.4
CT Scanners
CT stands for computed tomography.
Basic principles
- The patient lies in a void between X-ray tube and detector.
- X-ray tube rotates around subject in a plane, detectors may rotate on opposite side or be an array of multiple fixed detectors.
- Highly collimated (narrow), monochromatic beam of X-rays used.
Basic principles cont.
- Slice of subject scanned and computer processes results to form image of the slice.
- X-ray tube and detectors are 'translated' or moved to produce an image of next 'slice'.
- Images of multiple slices are produced which are combined by computer into a 3-D image which can be rotated and viewed from any angle.
Advantages
- Full cross-sectional image
- Better resolution than ultrasound
- Non-invasive
- Better than conventional X-ray for imaging brain, abdomen, bone fractures
Disadvantages
- Highly ionizing, so needs to be used with care to keep the dose low
- Expensive
- Patients may have to hold their breath
- Contrast may be limited
Test yourself on CT Scanners
What does CT stand for?
CT Scanners