What is being measured when assessing noise in phantom images during daily QC tests?

When assessing noise in phantom images during daily quality control (QC) tests, the primary focus is on signal-to-noise ratios. Noise is an unwanted variation in the signal, which can obscure or distort the true image being captured by the PET scanner. The signal-to-noise ratio quantifies the level of the desired signal compared to the level of background noise. A higher signal-to-noise ratio indicates a clearer image with less interference from noise, which is crucial for accurate interpretation of PET images. This measurement helps technicians to verify that the system is functioning optimally and producing images that can be reliably used for diagnostic purposes.

In contrast, while aspects like contrast resolution, spatial resolution, and image uniformity are all important parameters in imaging quality, they specifically refer to different characteristics of the images. Contrast resolution pertains to the ability of the system to distinguish between different levels of signal, spatial resolution refers to the system's capacity to distinguish fine details in the image, and image uniformity assesses the consistency of the signal across the entire image field. However, when the concern is specifically about noise, the signal-to-noise ratio is the most relevant measurement.