Spiral computed tomography
|Spiral computed tomography|
Spiral computed tomography is a computed tomography technology involving movement in a helical pattern for the purpose of increasing resolution. Most modern hospitals currently use spiral CT scanners.
CT beam types have included parallel beams, fan-beams, and cone-beams.
SSCT and MSCT
Since its invention by Kalender in the 1980s, helical scan CT machines have steadily increased the number of rows of detectors (slices) they deploy. The prototype 16 multi-slice scanner was introduced in 2001 and in 2004, 64 multislice scanners are on the market. These can produce an image in less than a second and thus can obtain images of the heart and its blood vessels (coronary vessels) as if frozen in time.
The earliest devices, developed in 1989, were called "SSCT", for "single-slice spiral computed tomography". In 1998, "MSCT" or "multi-slice spiral computed tomography" was introduced.
Helical (or spiral) cone beam computed tomography
In cone-beam computed tomography (commonly abbreviated CBCT), the x-ray beam is conical.
Helical (or spiral) cone beam computed tomography is a type of three dimensional computed tomography (CT) in which the source (usually of x-rays) describes a helical trajectory relative to the object while a two dimensional array of detectors measures the transmitted radiation on part of a cone of rays emanating from the source.
In practical helical cone beam x-ray CT machines, the source and array of detectors are mounted on a rotating gantry while the patient is moved axially at a uniform rate. Earlier x-ray CT scanners imaged one slice at a time by rotating source and one dimensional array of detectors while the patient remained static. The helical scan method reduces the x-ray dose to the patient required for a given resolution while scanning more quickly. This is however at the cost of greater mathematical complexity in the reconstruction of the image from the measurements.
- Avinash C. Kak and Malcolm Slaney (2001). Principles of Computerized Tomographic Imaging. Society for Industrial and Applied Mathematics ISBN 978-0-89871-494-4 / ISBN 0-89871-494-X.
- Alan Conrad Bovik (2009). The essential guide to image processing. Academic Press. pp. 743–. ISBN 978-0-12-374457-9. Retrieved 4 June 2011.
- Kalender WA (1994). "Technical foundations of spiral CT" Semin Ultrasound CT MR 15: (2) 81-89.
- Kalender WA (1994). "Spiral or helical CT: right or wrong?" Radiology 193: (2) 583.
- Robert Cierniak (12 January 2011). X-Ray Computed Tomography in Biomedical Engineering. Springer. pp. 31–. ISBN 978-0-85729-026-7. Retrieved 4 June 2011.
- Helical Cone-Beam CT at the US National Library of Medicine Medical Subject Headings (MeSH)