Define "quantum mottle" in the context of digital imaging.

Quantum mottle refers specifically to the noise in a digital image that occurs due to the statistical fluctuation in the number of X-ray photons that reach the detector. This situation typically arises when there are not enough photons hitting the detector, leading to a grainy or speckled appearance in the image. The fewer the X-ray photons, the greater the variability in the signal received by the detector, which manifests as a lack of uniformity in the brightness levels across the image.

This phenomenon is particularly evident in low-dose imaging scenarios where the detected signal is weak. It highlights the importance of adequate exposure to ensure image quality, as insufficient X-ray exposure can compromise diagnostic accuracy. Quantum mottle can be mitigated by optimizing the exposure parameters or using detectors with higher sensitivity, which increase the number of detected photons and improve overall image quality.