Sala Seminarios IFIC (Edf. Institutos de Investigación) Viernes, 10 de Febrero de 2006 a las 12:00 PM
Resumen
CT imaging evolves faster than ever. After the advent of spiral CT in the early nineties multislice
CT scanners were introduced in 1998. Today 64-slice scanners allow to cover a complete
anatomical region with in a few seconds with isotropic spatial resolution of below 0.5 mm. The
technology behind these devices is rather complex. CT detectors, based on ceramic scintillators,
must be able to read out large amounts of data within short times; up to 600 MB/s data transfer
rates are achieved. X-ray tubes must have the capability to withstand centrifugal forces of more
than 20 g since rotation times are in the order of 0.3 s.
An even more important key technology is image reconstruction. It is rather easy to perform reconstruction
for single or four-slice scanners but it becomes arbitrarily difficult for cone-beam
scanners since one runs into the so-called cone-beam problem. Today, clinical cone-beam scanners
are either equipped with Feldkamp-type or with advanced single-slice rebinning (ASSR)-
type algorithms. They must be capable of handling redundant data (arbitrary spiral pitch) to ensure
full dose utilization. Further these algorithms must be able to perform phase-correlated image
reconstruction for imaging the heart.
The increase in spatial resolution leads to a potential increase in patient dose. Important measures
to compensate that effect are dose modulation techniques, automatic exposure control and adaptive
filtering algorithms.
This lecture gives an overview of CT technology, CT image reconstruction algorithms and the
interdependence of CT image quality and dose. Important parameters are introduced and underlying
relations are discussed.
