Search results
Results from the WOW.Com Content Network
Contrast resolution or contrast-detail is an approach to describing the image quality in terms of both the image contrast and resolution. Contrast resolution is usually measured by generating a pattern from a test object that depicts how image contrast changes as the structures being imaged get smaller and closer together.
The maximum contrast of an image is termed the contrast ratio or dynamic range. In images where the contrast ratio approaches the maximum possible for the medium, there is a conservation of contrast. In such cases, increasing contrast in certain parts of the image will necessarily result in a decrease in contrast elsewhere.
Projectional radiography, also known as conventional radiography, [1] is a form of radiography and medical imaging that produces two-dimensional images by X-ray radiation. The image acquisition is generally performed by radiographers , and the images are often examined by radiologists .
Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object.Applications of radiography include medical ("diagnostic" radiography and "therapeutic radiography") and industrial radiography.
Iodinated contrast contains iodine.It is the main type of radiocontrast used for intravenous administration.Iodine has a particular advantage as a contrast agent for radiography because its innermost electron ("k-shell") binding energy is 33.2 keV, similar to the average energy of x-rays used in diagnostic radiography.
In order to image the body so that the maximum information will result, higher subject contrast areas require a higher kVp so as to result in a low radiographic contrast image, and vice versa. Although the product of tube current and exposure time, measured in milliampere-seconds (mA·s), is the primary controlling factor of radiographic ...
Contrast, also known as gamma, is the slope of the tone reproduction curve in a log-log space. High contrast usually involves loss of dynamic range — loss of detail, or clipping, in highlights or shadows. Color accuracy is an important but ambiguous image quality factor. Many viewers prefer enhanced color saturation; the most accurate color ...
The advantages of these methods compared to normal absorption-contrast X-ray imaging is higher contrast for low-absorbing materials (because phase shift is a different mechanism than absorption) and a contrast-to-noise relationship that increases with spatial frequency (because many phase-contrast techniques detect the first or second ...