Why is CNR preferred over SNR in imaging quality assessment?

CNR, or Contrast-to-Noise Ratio, is preferred over SNR, or Signal-to-Noise Ratio, in imaging quality assessment because it specifically emphasizes the visibility of structures within an image against the background noise, which is crucial for interpreting diagnostic images effectively. CNR takes into account how well the contrast between different structures stands out relative to the noise present, making it a more relevant measure for assessing the actual quality of images in a clinical context.

By focusing on contrast, CNR helps radiologists and technicians evaluate the ability to differentiate between various types of tissues or abnormalities. Higher CNR values typically indicate that the differences in density or composition between structures and their surroundings are more pronounced, enhancing the diagnostic capability of the images. This aspect is particularly important in fluoroscopy, where the primary goal is often to visualize and assess specific features or defects accurately.

In contrast, while SNR provides valuable information about the overall quality of a signal in the presence of noise, it does not specifically address how well different structures can be distinguished from each other based solely on their contrast levels. Thus, while it has its uses, SNR may not fully capture the nuanced information needed for assessing image quality in clinical practices. The focus on contrast in CNR therefore leads to