- Definition
Computerized Tomography, or CT, is a type of imaging that builds structure through a collection of cross-sectional images. CT is different from an X-ray in that it allows us to visualize 3D structures.
- Discovery
Sir Godfrey Hounsfield discovered CT in the last 1960s. His years in the Electrical and Musical Industry (EMI) contributed to his thorough understanding of radar and computer systems, matched only by his passion for them. One of his final projects in EMI was to develop a computer software. The program will compile x-rays from multiple angles and organize them to a 3D object. This would eventually lead to the CT, which became a revolutionary go-to imaging modality for further investigations.
Sir Hounsfield received the Nobel Prize in Physiology in 1979!
- Mechanism
We have covered how a x-ray machine works. A CT contains that machine as well. A patient goes through a donut-shaped CT machine, which contains an x-ray tube and x-ray detector array around the rim. They rotate together around the patient, and a large number of x-ray are shot from multiple angles. The data from the detectors are then processed by a computer to reconstruct images. There are different types of CT as well:
- MSCT: multislice CT. There are multiple rows of detectors to obtain high amounts of data simultaneously. All modern CT scanners
- DSCT: dual-source CT. Two pairs of x-ray tubes and detectors, 90 degrees from each other. The acquisition speed is improved, and thus DSCT is used for coronary imaging (because heart is always moving, its imaging needs to be QUICK).
- DECT: dual-energy CT. One set of high-energy x-rays and another of low-energy x-rays. Then the images are combined to create new images that can suppress certain tissues.
- Indications
CT can be a great method for evaluating patients with diverse etiologies: infections, inflammations, trauma, neoplasms. Due to its wide application, CT is used as a way to further characterize findings from radiograph or ultrasound. CT is appropriate especially for the following systems:
- Respiratory
- Gastrointestinal
- Vasculature
- Musculoskeletal