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Searchterm 'Film' found in 5 terms [
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Fluoroscopic System
When invented, a fluoroscopic system consisted of x-ray tube, fluorescent screen and x-ray table. In 1950's, the development of the image intensifier revolutionized fluoroscopes. The basic components are extended by a gantry, image intensifier, camera, film and monitor system. The x-ray tube is usually located under the patient table, in opposition to the image intensifier and film cassette or display unit. The patient table can be rotated to an upright position for certain examinations and can be lowered to horizontal position for other imaging procedures. In some instances, the unit can be operated from outside the room.
Today, the transition from conventional to digital fluoroscopy replaces the image intensifier. A flat-panel detector in combination with sensitive image sensors and digital image processing improves the diagnostic ability of a modern system.
Magnification
Usually, magnification is the enlargement of an area by interpolation after the reconstruction of an image. Magnification does not provide more information, but allows a better view of certain object details. A zoom reconstruction is based on the raw data of the scan. Magnification software enlarges an image by mapping one pixel onto an n x n array of screen pixels (pixel stretching).
Other types of magnification include electron-optical, geometric, the product of geometric and the electron-optical magnification and enlargement by imaging procedures.
Electron-optical magnification is the ratio of the dimension of the detector input image and the size of the image on the screen. This ratio is determined by all electronic and optical imaging processes of the image chain, provided that one camera pixel is mapped onto accurately one monitor pixel.
Geometric magnification occurs in x-ray images when the focal spot is theoretically assumed to be a point and not an area. For nanofocus and microfocus radiographic systems, the focus-to-detector (film) distance and the focus-to-object (film) distance defines the geometric magnification.
The total magnification is the product of the electron-optical and geometric magnification. Possible magnifications are up to a factor of 26,000.
Magnification procedures in medical imaging are usually produced by extended distance between the subject and the image receptor.
Mammogram
A mammogram is a low dose x-ray of the breast used to detect and diagnose breast disease, or to provide a baseline reference for later comparison. Multiple images are obtained by different positioning of the breast. The breast compression during mammography is an essential component to produce an optimal diagnostic mammogram. Film mammography units use film to both capture and display the image; digital mammography units use electronic equipment.
A spot compression reduces the thickness of the area of interest and improves contrast and separation of breast tissues.
Mammography
Mammography is a diagnostic imaging procedure of the breast to detect and evaluate breast disease. Mammography is widely used as a screening method and plays a key role in early breast cancer detection.
The screening mammography is used to detect breast changes in women who have no signs or symptoms or noticed breast abnormalities. The goal is to detect a breast tumor before any clinical signs are observable.
A diagnostic mammography is used to investigate suspicious breast changes, such as a breast lump, an unusual skin appearance, breast pain, nipple thickening or nipple discharge.
A breast screening or standard mammography requires two mammograms from different angles of each breast including craniocaudal view and mediolateral view. Additional images can be made from other angles or focus on microcalcifications or other suspicious areas.
A mammogram is created by special mammography equipment with long wavelength of the used x-rays. Film-screen mammography is still the most widely used technology, but the state of the art technique is digital mammography. Conventional x-ray equipment was used to produce mammograms until dedicated mammography equipment became available in the late 1960s. Film-screen mammography and xeromammography, introduced in the early 1970s, used lower radiation doses and produced sharper mammograms. The second generation of mammography systems has been introduced in the early 1980s. Chief disadvantages of analog mammography include the labor-intensive handling of the cassettes, relatively slow processing time, the lack of a direct interface to the x-ray system, and no post processing possibilities.
Mammograms of high quality should be done with the lowest radiation dose as possible. Adequate breast compression is important due to shortening of the exposure times, immobilization of the breast, reduction of motion and blurring and prevention of overpenetration by means of equalizing breast thickness.
Further breast imaging procedures include breast ultrasound and breast MRI.
Xeromammography
Xeromammography or xeroradiography is a breast imaging. Xeroradiography uses photoelectric records of x-ray images on a coated metal plate. Xeromammography as distinct from film-screen mammography uses low-energy photon beams, long exposure times and dry chemical developers.
Although xeromammography has sensitivity and specificity comparable with those of a film-screen mammogram, it is not recommended for screening or diagnostic mammography because of maintenance problems and the need for higher breast radiation doses compared with modern low dose mammography equipment.
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