Radiology - Technology Information Portal
Sunday, 24 November 2024
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Searchterm 'Image' found in 4 terms [
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Zooming
Zooming increases scale factors of images within a window. Zooming takes a selected region and extends it over the entire matrix of the displayed CT image. Usually, a zoom reconstruction increases the accuracy of the CT numbers by decreasing the overall size of the displayed image pixels, which decreases the possibility of many tissues occupying a single pixel (partial volume averaging).
Zooming or targeting is not the same as image magnification.

See also Banding.
Banding
Banding is a set of functions performed by placing and dragging the mouse pointer on an image. For example, the zooming of images by placing the mouse pointer on an image, pressing and holding the mouse button, dragging a box around the area of interest, and releasing the mouse button to zoom. Other banding operations include panning and zooming.
Brightness
The brightness is the balance of light and dark shades in a displayed image. High brightness (also called density or intensity) settings produce bright images and low settings produce dark images. The contrast determines how many gray levels are displayed and the density determines the intensity.
Digital Mammography
The digital mammography is an electronic imaging procedure of the breast. The number of breast imaging facilities equipped with digital mammography (also called computed radiography mammogram (CRM), CR mammogram) is growing due to a number of advantages.
Digital images can be stored directly in a picture archiving and communication system (PACS) and allows the printing, enhancement, magnification, or brightness and contrast manipulation for further evaluation. The sensitivity of digital mammography compared to film mammography is better in women with dense breasts, a population at higher risk for breast cancer, due to these post processing possibilities.
'The American College of Radiology's (ACR) Imaging Network found that digital mammography detected up to 28 percent more cancers than film-screen mammography in women age 50 and younger, premenopausal and perimenopausal women, and women with dense breasts, as reported in October 2005 in the New England Journal of Medicine.'

Advantages of digital mammography:
Faster image acquisition;
shorter examination time;
improved contrast between dense and non-dense breast tissue;
under or over x-ray exposure can be corrected without repeated mammograms;
post processing of breast images for more accurate detection of breast cancer;
Easy storage and transmission over phone lines or a network.

Existing mammography equipment can be converted to 'digital' operation, which allows cost savings compared to integrated digital mammography systems.

See also Breast MRI.
Filter Grid
Filter grids are used to reduce scattered noise and increase contrast in x-ray images. Primary radiation passing through an object gets scattered caused by the various density of different materials. Scatter radiation produces noise (radiographic fog) on the film or detector, which degrades the diagnostic quality. Anti-scatter grids act as filters between patient and film (or receiver) to remove scatter radiation. The use of a grid is recommended with body parts thicker than 10 cm and kVp values about 60 kV.
X-ray filter grids are available with focused or parallel strips. These two types are produced with linear or crossed grid configurations. The septa of filter grids consist of high radiation absorbing materials (e.g. lead) separated by permeable parts. During radiation exposure, movement of the grid blurs a projection of the septa.
If the image receptor and x-ray tube (with the focal spot) are in a fixed position relative to one another the grid is automatically aligned. In mobile radiography, the position of the focal spot and the image receptor is variable. Additionally cassettes incorporating anti-scatter grids are also available.
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 [last update: 2023-11-06 02:01:00]