A contrast medium is a radiopaquesubstance used to facilitate roentgenvisualization of internal structures of the body such as the urogenital sinus. A physician might require a patient to ingest barium before an X-ray investigation of the intestines, with barium acting as a contrast medium to make the radiograph more clear. Radiopaque is matter that does not allow a certain amount of electromagnetism to pass through. ... Look up Substance in Wiktionary, the free dictionary Substance may refer to: Substance theory: in philosophy, substance is that element of an object without which it would not exist, or what exists only by itself (causa sui) Chemical substance: in chemistry, a substance is an element, compound with uniform composition. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Visualization can refer to: Graphic Visualization as in any technique for creating images, diagrams, or animations to communicate any message. ... With regard to living things, a body is the integral physical material of an individual, and contrasts with soul, personality and behavior. ... The urogenital sinus (also known as the persistent cloaca) is a part of the human body while it is an embryo. ... Physician examining a child A physician is a person who practices medicine. ... General Name, Symbol, Number barium, Ba, 56 Chemical series alkaline earth metals Group, Period, Block 2, 6, s Appearance silvery white Atomic mass 137. ... The intestine is the portion of the alimentary canal extending from the stomach to the anus and, in humans and mammals, consists of two segments, the small intestine and the large intestine. ... Radiography is the creation of images by exposing a photographic film or other image receptor to X-rays. ...
Medical imaging is the process by which physicians evaluate an area of the subjects body that is not normally visible. ... It has been suggested that medical imaging be merged into this article or section. ...
References
Dorland's Illustrated Medical Dictionary (Twenty-sixth Edition) (ISBN 0-7216-1645-3)
For arguments in phase contrast microscopy, the role of the specimen in altering the optical path length (in effect, the relative phase shift) of waves passing through is of paramount importance.
In contrast, when the refractive index of the surrounding medium exceeds that of the specimen, the wave is advanced in phase upon exiting the specimen.
Contrast is modulated by varying the properties of the phase plate, including the absorption of the metallic film (or anti-reflective coatings), the refractive index of the phase retarding material, and the thickness of the phase plate.
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