The exposure indicator has as many different names as there are vendors in the market. The indicator is a vendor-specific value that provides the radiographer with an indication of the accuracy of their exposure settings for a specific image (ASRT, 2010). An over- or under-exposed image will deliver an incorrect exposure indicator whereas a correct exposure will provide a corresponding exposure indicator. On digital imaging systems, an exposure indicator provides useful feedback to the radiographer about exposures delivered to the image receptor (ASRT, 2010). Read the related blog on Diagnostic Reference Levels.
#Overexposed x ray how to
That’s why it’s so important for the radiographer to understand how to read and utilize the exposure indicators. The reason for this increased risk is that we’ve lost the visual connection between the exposure and an image’s appearance. The potential for gross overexposure is one issue we encounter when a radiology department or clinic changes to a digital image receptor. So how does a radiographer know if a digital image is over- or under-exposed? Digital systems produce images with consistent density and contrast regardless of the exposure factors (See figure 2). However, with digital imaging devices, brightness and contrast are no longer linked to exposure factors. The density and contrast of the image on film is controlled by the kV, mAs and other exposure factors. You take your image, hold it up to the viewbox and say: “This image is too light” “This image is too dark” or, “This image is just right!” If you underexpose your image, it will be too light, and if you overexpose the image, it will be too dark (See figure 1). Imaging in a radiology film environment is much like playing Goldilocks and the Three Bears. Reading Time: 5 minutes read Knowing how number is used is key to controlling exposure.
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