Reconstruction

Reconstruction is a mathematical procedure and a key part of computed tomography (CT). Two-dimensional individual images are transferred into a three-dimensional model of the object shown.

The term computed tomography is a combination of the words “computer” and “tomography,” where “tomography” means imaging different regions of the examined object by sections. A modern computer scanner can display sections of or an entire object in just a few minutes.

As with conventional X-rays, computed tomography is based on the attenuation of X-rays by different materials in the object. A CT scanner operates by rotating the object between the X-ray tube and the X-ray detector, whereby the part of the object being examined is scanned by a cone-shaped X-ray beam. The attached detector captures the more or less attenuated X-rays from the object and forwards them to a computer for fast reconstruction and processing. The computer then generates cross-sectional images, or “slices,” from the measured values. Systems with area detectors can record several layers simultaneously, which considerably speeds up the examination process. Whereas in the past only two-dimensional slices were computed, today’s systems usually generate three-dimensional volume datasets, which allow computations that go beyond the layer levels for a vivid three-dimensional representation of the object.