Radiographic contrast | Radiology Reference Article | changethru.info
Radiographic contrast is the degree of density difference between two areas on a radiograph. Contrast makes it easier to distinguish features of interest, such as. Milliampere-seconds more commonly known as mAs is a measure of It is due to this law that radiographers will have to take into consideration all other factors ( mA, focal spot, SID, kVp) to reduce time to avoid motion blur. Quiz questions. hangman, crossword, word scramble, games, matching, quizes, and tests. Describe the relationship between exposure time and density, Directly proportional mAs. What is the relationship between kVp and scatter? Directly proportional.
What is image receptor contrast? The range of densities the image receptor is capable of recording.
How does mAs affect radiographic contrast Under or over exposure How does focal spot size affect radiographic contrast No influence. How does the anode heel effect affect radiographic contrast? Little effect How does filtration affect contrast? How does beam restriction collimation affect contrast? How do grids affect contrast?
What are two types of motion? Give an example of involuntary motion. By a factor of 4 inversely. What are the seven types of radiologic tissue types. The overall blackness on the image.
Also described as the amount of black metallic silver on a film. Unwanted density on the film. Generally, as contrast sensitivity increases, the latitude of the radiograph decreases. Radiographic latitude refers to the range of material thickness that can be imaged This means that more areas of different thicknesses will be visible in the image.
Free Radiology Flashcards about Exposure Factors
Therefore, the goal is to balance radiographic contrast and latitude so that there is enough contrast to identify the features of interest but also to make sure the latitude is great enough so that all areas of interest can be inspected with one radiograph. In thick parts with a large range of thicknesses, multiple radiographs will likely be necessary to get the necessary density levels in all areas.
Film Contrast Film contrast refers to density differences that result due to the type of film used, how it was exposed, and how it was processed.
Since there are other detectors besides film, this could be called detector contrast, but the focus here will be on film. Exposing a film to produce higher film densities will generally increase the contrast in the radiograph. More information on film characteristic curves is presented later in this section. From the shape of the curves, it can be seen that when the film has not seen many photon interactions which will result in a low film density the slope of the curve is low.
In this region of the curve, it takes a large change in exposure to produce a small change in film density.
Milliampere-seconds (mAs) | Radiology Reference Article | changethru.info
Therefore, the sensitivity of the film is relatively low. It can be seen that changing the log of the relative exposure from 0. However, at film densities above 2. In this region of the curve, a relatively small change in exposure will result in a relatively large change in film density.
For example, changing the log of relative exposure from 2. Therefore, the sensitivity of the film is high in this region of the curve.