CAMRT Radiography Practice Exam

An MRT has selected an mAs value that is too high for the part being imaged. What will be the result?

1. Increase in automatic rescaling

2. Decrease of image brightness

3. Decrease in image contrast

4. Increase in quantum mottle

The correct answer is: Increase in automatic rescaling

When an MRT selects an mAs value that is too high for the part being imaged, the result is an increase in automatic rescaling. Automatic rescaling is a function of digital imaging systems that adjusts the brightness and contrast of the image based on the exposure values that were captured. If the mAs is excessively high, the system compensates by rescaling the image to maintain appropriate brightness levels, ensuring that the final output meets clinical requirements. While high mAs can lead to darker images initially, the automatic rescaling process effectively redistributes pixel values, which leads to a more uniform brightness level in the displayed image. This process helps to optimize the image for diagnostic purposes and ensures the visibility of anatomical structures, despite the overexposure. Understanding this concept is crucial as it highlights the sophisticated nature of digital imaging technology that allows for adjustments post-acquisition while reinforcing the importance of selecting appropriate exposure settings to minimize the need for rescaling.