Colonography, Computed Tomographic
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Colonography, Computed Tomographic
Virtual colonoscopy (VC, also called CT colonography or CT pneumocolon) is the use of CT scanning or magnetic resonance imaging (MRI) to produce two- and three-dimensional images of the colon (large intestine), from the lowest part, the rectum, to the lower end of the small intestine, and to display the images on an electronic display device. The procedure is used to screen for colon cancer and polyps, and may detect diverticulosis. A virtual colonoscopy can provide 3D reconstructed endoluminal views of the bowel. VC provides a secondary benefit of revealing diseases or abnormalities outside the colon. Procedure While preparations for VC vary, the patient will usually be asked to take laxatives or other oral agents at home the day before the procedure to clear stool from the colon. A suppository is also used to cleanse the rectum of any remaining fecal matter. The patient may also be given a solution designed to coat any residual faeces which may not have been cleared by t ...
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Volume Rendering
In scientific visualization and computer graphics, volume rendering is a set of techniques used to display a 2D projection of a 3D discretely sampled data set, typically a 3D scalar field. A typical 3D data set is a group of 2D slice images acquired by a CT, MRI, or MicroCT scanner. Usually these are acquired in a regular pattern (e.g., one slice for each millimeter of depth) and usually have a regular number of image pixels in a regular pattern. This is an example of a regular volumetric grid, with each volume element, or voxel represented by a single value that is obtained by sampling the immediate area surrounding the voxel. To render a 2D projection of the 3D data set, one first needs to define a camera in space relative to the volume. Also, one needs to define the opacity and color of every voxel. This is usually defined using an RGBA (for red, green, blue, alpha) transfer function that defines the RGBA value for every possible voxel value. For example, a volume ma ...
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Supine Position
The supine position ( or ) means lying horizontally with the face and torso facing up, as opposed to the prone position, which is face down. When used in surgical procedures, it grants access to the peritoneal, thoracic and pericardial regions; as well as the head, neck and extremities. Using anatomical terms of location, the dorsal side is down, and the ventral side is up, when supine. Semi-supine In scientific literature "semi-supine" commonly refers to positions where the upper body is tilted (at 45° or variations) and not completely horizontal. Relation to sudden infant death syndrome The decline in death due to sudden infant death syndrome (SIDS) is said to be attributable to having babies sleep in the supine position. The realization that infants sleeping face down, or in a prone position, had an increased mortality rate re-emerged into medical awareness at the end of the 1980s when two researchers, Susan Beal in Australia and Gus De Jonge in the Netherlands, indep ...
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Digestive System Imaging
Digestive may refer to: Biology *Digestion, biological process of metabolism Food and drink * Digestif, small beverage at the end of a meal *Digestive biscuit A digestive biscuit, sometimes described as a sweet-meal biscuit, is a semi-sweet biscuit that originated in Scotland. The digestive was first developed in 1839 by two Scottish doctors to aid digestion. The term ''digestive'' is derived from th ...
, a British semi-sweet biscuit {{disambig ...
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Gold Standard (test)
In medicine and statistics, a gold standard test is usually the diagnostic test or benchmark that is the best available under reasonable conditions. In other words, a gold standard is the most accurate test possible without restrictions. Both meanings are different because for example, in medicine, dealing with conditions that would require an autopsy to have a perfect diagnosis, the gold standard test would be the best one that keeps the patient alive instead of the autopsy. In medicine "Gold standard" can refer to the criteria by which scientific evidence is evaluated. For example, in resuscitation research, the "gold standard" test of a medication or procedure is whether or not it leads to an increase in the number of neurologically intact survivors that walk out of the hospital.''ACLS: Principles and Practice''. p. 62. Dallas: American Heart Association, 2003. . Other types of medical research might regard a significant decrease in 30-day mortality as the gold standard. The ...
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Gray (unit)
The gray (symbol: Gy) is the unit of ionizing radiation dose in the International System of Units (SI), defined as the absorption of one joule of radiation energy per kilogram of matter. It is used as a unit of the radiation quantity absorbed dose that measures the energy deposited by ionizing radiation in a unit mass of matter being irradiated, and is used for measuring the delivered dose in radiotherapy, food irradiation and radiation sterilization. It is important in predicting likely acute health effects, such as acute radiation syndrome and is used to calculate equivalent dose using the sievert, which is a measure of the stochastic health effect on the human body. The gray is also used in radiation metrology as a unit of the radiation quantity kerma; defined as the sum of the initial kinetic energies of all the charged particles liberated by uncharged ionizing radiation in a sample of matter per unit mass. The gray is an important unit in ionising radiation measuremen ...
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Ionizing Radiation
Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel up to 99% of the speed of light, and the electromagnetic waves are on the high-energy portion of the electromagnetic spectrum. Gamma rays, X-rays, and the higher energy ultraviolet part of the electromagnetic spectrum are ionizing radiation, whereas the lower energy ultraviolet, visible light, nearly all types of laser light, infrared, microwaves, and radio waves are non-ionizing radiation. The boundary between ionizing and non-ionizing radiation in the ultraviolet area is not sharply defined, as different molecules and atoms ionize at different energies. The energy of ionizing radiation starts between 10 electronvolts (eV) and 33 eV. Typical ionizing subatomic particles include alpha particles, beta particles, and neutrons. ...
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Biopsy
A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a disease. The tissue is then fixed, dehydrated, embedded, sectioned, stained and mounted before it is generally examined under a microscope by a pathologist; it may also be analyzed chemically. When an entire lump or suspicious area is removed, the procedure is called an excisional biopsy. An incisional biopsy or core biopsy samples a portion of the abnormal tissue without attempting to remove the entire lesion or tumor. When a sample of tissue or fluid is removed with a needle in such a way that cells are removed without preserving the histological architecture of the tissue cells, the procedure is called a needle aspiration biopsy. Biopsies are most commonly performed for insight into possible cancerous or inflammatory conditions. History T ...
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Renal Cell Carcinoma
Renal cell carcinoma (RCC) is a kidney cancer that originates in the lining of the proximal convoluted tubule, a part of the very small tubes in the kidney that transport primary urine. RCC is the most common type of kidney cancer in adults, responsible for approximately 90–95% of cases. RCC occurrence shows a male predominance over women with a ratio of 1.5:1. RCC most commonly occurs between 6th and 7th decade of life. Initial treatment is most commonly either partial or complete removal of the affected kidney(s). Where the cancer has not metastasised (spread to other organs) or burrowed deeper into the tissues of the kidney, the five-year survival rate is 65–90%, but this is lowered considerably when the cancer has spread. The body is remarkably good at hiding the symptoms and as a result people with RCC often have advanced disease by the time it is discovered. The initial symptoms of RCC often include blood in the urine (occurring in 40% of affected persons at the time th ...
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Mayo Clinic
The Mayo Clinic () is a nonprofit American academic medical center focused on integrated health care, education, and research. It employs over 4,500 physicians and scientists, along with another 58,400 administrative and allied health staff, across three major campuses: Rochester, Minnesota; Jacksonville, Florida; and Phoenix/Scottsdale, Arizona. The practice specializes in treating difficult cases through tertiary care and destination medicine. It is home to the top-15 ranked Mayo Clinic Alix School of Medicine in addition to many of the highest regarded residency education programs in the United States. It spends over $660 million a year on research and has more than 3,000 full-time research personnel. William Worrall Mayo settled his family in Rochester in 1864 and opened a sole proprietorship medical practice that evolved under his sons, Will and Charlie Mayo, along with practice partners Stinchfield, Graham, Plummer, Millet, Judd, and Balfour, into Mayo Clinic. Toda ...
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Barium Enema
A lower gastrointestinal series is a medical procedure used to examine and diagnose problems with the human colon of the large intestine. Radiographs (X-ray pictures) are taken while barium sulfate, a radiocontrast agent, fills the colon via an enema through the rectum. The term barium enema usually refers to a lower gastrointestinal series, although enteroclysis (an upper gastrointestinal series) is often called a small bowel barium enema. Purpose For any suspected large bowel disease, colonoscopy is the investigation of choice because tissue sample can be taken for investigation. Virtual colonoscopy (also known as CT colonography) is another preferred investigation, provided that facilities and expertise are available. Virtual colonoscopy also avoids the risk of total blockage of any stricture in the large bowel due to barium impaction. Some conditions are absolutely contraindicated for barium enema namely: toxic megacolon, pseudomembranous colitis, and recent history rigid en ...
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Colonoscopy
Colonoscopy () or coloscopy () is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It can provide a visual diagnosis (''e.g.,'' ulceration, polyps) and grants the opportunity for biopsy or removal of suspected colorectal cancer lesions. Colonoscopy can remove polyps smaller than one millimeter. Once polyps are removed, they can be studied with the aid of a microscope to determine if they are precancerous or not. Colonoscopy is similar to sigmoidoscopy—the difference being related to which parts of the colon each can examine. A colonoscopy allows an examination of the entire colon (1,200–1,500mm in length). A sigmoidoscopy allows an examination of the distal portion (about 600mm) of the colon, which may be sufficient because benefits to cancer survival of colonoscopy have been limited to the detection of lesions in the distal portion of the colon.
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Prone Position
Prone position () is a body position in which the person lies flat with the chest down and the back up. In anatomical terms of location, the dorsal side is up, and the ventral side is down. The supine position is the 180° contrast. Etymology The word ''prone'', meaning "naturally inclined to something, apt, liable," has been recorded in English since 1382; the meaning "lying face-down" was first recorded in 1578, but is also referred to as "lying down" or "going prone." ''Prone'' derives from the Latin ', meaning "bent forward, inclined to," from the adverbial form of the prefix ''pro-'' "forward." Both the original, literal, and the derived figurative sense were used in Latin, but the figurative is older in English. Anatomy In anatomy, the prone position is a position of the body lying face down. It is opposed to the supine position which is face up. Using the terms defined in the anatomical position, the ventral side is down, and the dorsal side is up. Concerning the ...
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