Tomography is imaging by sections or sectioning. A device used in tomography is called a tomograph, while the image produced is a tomogram. The method is used in medicine, archaeology, biology, geophysics, oceanography, materials science, astrophysics and other sciences. Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the Archaeology, archeology, or archæology (from Greek grc ἀρχαιολογία archaiologia – grc ἀρχαῖος archaīos Foundations of modern biology There are five unifying principles Geophysics, a major discipline of Earth sciences, is the study of the Earth by quantitative physical methods especially by seismic, electromagnetic Oceanography (from the greek words Ωκεανός meaning Ocean and γράφω meaning to write also called oceanology or Materials Science or Materials Engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of Science and Astrophysics is the branch of Astronomy that deals with the Physics of the Universe, including the physical properties ( Luminosity, In most cases it is based on the mathematical procedure called tomographic reconstruction. The mathematical basis for tomographic imaging was laid down by Johann Radon. The word was derived from the Greek word tomos which means "a section" or "a cutting". Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly A tomography of several sections of the body is known as a polytomography.
For example, in conventional medical X-ray tomography, clinical staff make a sectional image through a body by moving an X-ray source and the film in opposite directions during the exposure. X-radiation (composed of X-rays) is a form of Electromagnetic radiation. Consequently, structures in the focal plane appear sharper, while structures in other planes appear blurred. By modifying the direction and extent of the movement, operators can select different focal planes which contain the structures of interest. Before the advent of more modern computer-assisted techniques, this technique, ideated in the 30's by the radiologist Alessandro Vallebona, proved useful in reducing the problem of superimposition of structures in projectional (shadow) radiography. For medical radiography see Radiology Radiography is the use of X-rays to view unseen or hard-to-image objects
More modern variations of tomography involve gathering projection data from multiple directions and feeding the data into a tomographic reconstruction software algorithm processed by a computer. The mathematical basis for tomographic imaging was laid down by Johann Radon. In Mathematics, Computing, Linguistics and related subjects an algorithm is a sequence of finite instructions often used for Calculation Different types of signal acquisition can be used in similar calculation algorithms in order to create a tomographic image. With current 2005 technology, tomograms are derived using several different physical phenomena listed in the following table.
|Physical phenomenon||Type of tomograph|
|nuclear magnetic resonance||MRI|
Some recent advances rely on using simultaneously integrated physical phenomena, e. X-radiation (composed of X-rays) is a form of Electromagnetic radiation. Computed tomography (CT is a Medical imaging method employing Tomography. Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions Single photon emission computed tomography (SPECT or less commonly SPET is a Nuclear medicine tomographic imaging technique using Gamma rays. Electron-positron annihilation occurs when an Electron and a Positron (the electron's anti-particle) collide Positron emission tomography ( PET) is a Nuclear medicine imaging technique which produces a three-dimensional image or map of functional processes in the Not to be confused with Supersonic. Ultrasound is cyclic Sound pressure with a Frequency greater than the upper The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The atom probe is an atomic-resolution Microscope used in Materials science that was invented in 1967 by Erwin Müller, J g. X-rays for both CT and angiography, combined CT/MRI and combined CT/PET. Computed tomography (CT is a Medical imaging method employing Tomography. Angiography or arteriography is a Medical imaging technique in which an X-ray image is taken to visualize the inside or lumen, of blood vessels Computed tomography (CT is a Medical imaging method employing Tomography. Computed tomography (CT is a Medical imaging method employing Tomography. Positron emission tomography ( PET) is a Nuclear medicine imaging technique which produces a three-dimensional image or map of functional processes in the
The term volume imaging might subsume these technologies more accurately than the term tomography. However, in the majority of cases in clinical routine, staff request output from these procedures as 2-D slice images. As more and more clinical decisions come to depend on more advanced volume visualization techniques, the terms tomography/tomogram may go out of fashion.
Many different reconstruction algorithms exist. In Tomography, a variety of practical reconstruction algorithms have been developed to implement the process of reconstruction of a 3-dimensional object from its projections Most algorithms fall into one of two categories: filtered back projection (FBP) and iterative reconstruction (IR). In Mathematics, the Radon transform in two dimensions named after the Austrian mathmematician Johann Radon, is the Integral transform consisting of the Iterative reconstruction is a method or group of Algorithms used to reconstruct 2D and 3D images from the projections of an object These procedures give inexact results: they represent a compromise between accuracy and computation time required. FBP demands fewer computational resources, while IR generally produces fewer artifacts (errors in the reconstruction) at a higher computing cost.
Recently a new technique called synchrotron X-ray tomographic microscopy (SRXTM) allows for detailed three dimensional scanning of fossils. Computed tomography (CT is a Medical imaging method employing Tomography.