The earliest CT scanners acquired images one slice at a time by sequentially moving the X-ray source and detectors across the body, then moving the body incrementally a small amount to acquire the next slice. Multiple X-ray projections are used to reconstruct tissue structures based on complex mathematical algorithms. The final image is generated using data relating to the differential passage of the X-rays through different tissues. As the X-ray tube and detectors make a 360° rotation numerous profiles of the attenuated beams are recorded. The beams are collimated using lead shutters to a thickness of 1–10 mm. The emerging beam is recorded by a ring of detectors on the opposite side of the rotating gantry. A fan of X-ray beams is created and each beam passes through the tissues of interest. The X-ray tube is rotated around the patient for 360°. Today, computers are used to digitally encode density and spatial information about portions of the object.Ĭomputed tomography (CT) is a method of medical imaging that utilizes X-rays, or photons, to generate cross-sectional, two-dimensional images of the body. Traditionally, this energy was used to ionize a photographic plate for creation of an image. When an object is irradiated with photons generated in an X-ray tube they traverse the material and, depending on the intensity of the photon beam and the nature of the material imaged, some of the energy is lost (or attenuated) so that less energy emerges from the other side. Medical imaging based on this technology developed rapidly, and the basic concept has not changed in a major way since that time, although the technology has. He was awarded the first Nobel Prize in physics in 1901 for this discovery. In 1895 the German physicist Wilhem Konrad Röntgen discovered X-rays.
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