Which parameter increases the risk of quantum noise in an image?

The risk of quantum noise in an image is particularly influenced by the amount of radiation exposure. Quantum noise arises due to the statistical nature of photon detection—essentially, when fewer photons are detected, there's a higher likelihood of randomness in the data collected, leading to noise in the resultant image.

When exposure is low, there are fewer photons that interact with the detector, which can result in increased quantum noise. The increased randomness of counting fewer photons can compromise the clarity and quality of the image. This directly correlates with the idea that a lower exposure means the system may not have enough signal (or photons) to drown out background noise, hence causing noise to become more pronounced in the final image.

High photon flux, increased kVp settings, and high matrix size do not inherently increase the risk of quantum noise in the same way that low radiation exposure does. High photon flux means more photons are available for detection, which generally reduces noise. Increased kVp can improve penetrability and contrast without necessarily increasing noise. High matrix size improves spatial resolution but can reduce the amount of signal per pixel if the total photon count is low, but this is not the primary driver of quantum noise compared to exposure levels.