Principles of the new CT scans

In comparison with previous devices, the new ones have benefited from two major advances:

• helical scanning: the X-Ray producing tube is moved around the patient at the same time as the row of detectors. All these devices turn around the table which is progressively moved at the centre of the cycle without stopping. The software allows a transformation from helical images to slice images.
• multislice devices (see the diagramm below): (also called volumic CT-scan), they benefit from multiple rows of detectors (here on the diagram 16) which receive X-Rays dispersed in a pyramidal way. Through sophisticated algorithms, the software reconstitute slices. A unique pass of the patient through the device gives many thin images. Through specific calculations, body reconstruction can be elaborated in the other planes: saggital view, frontal view, therefore allowing very precise anatomical studies. Due to the shot speed, motion (respiratory, cardiac) is negligible and vascular study is feasible.

Principle of multisclice computer tomography.

A few pictures allow an illustration of the potential power of these techniques (healthy subject).

(Click on the link and and on the crab to come back to this page)

Frontal view after software reconstitution,

Saggital view after software reconstitution,

Frontal view using various vascular times for vascular demonstration,

Reconstitution of coloured images.