What is referred to as noise on a CT image?

Noise on a CT image generally refers to the random fluctuations in pixel values that compromise the quality of the image, leading to a grainy or unclear appearance. In this context, an artifact is a specific kind of disturbance in the image that is not representative of the actual anatomy or pathology, and can be caused by various factors including electronic interference, equipment malfunctions, or adjustments in processing algorithms. Such artifacts include streaks or bands that can obscure or distort the underlying anatomical structures, contributing to the overall impression of noise.

While radiation scatter, motion blur, and image interference can also degrade image quality, they are distinguished from the broader definition of noise. Radiation scatter refers to the phenomenon where X-ray photons deviate from their original path after interacting with matter, which can reduce image clarity and contrast. Motion blur occurs due to patient movement during the scan, leading to indistinct or smeared areas in the image. Image interference can arise from various sources affecting the imaging process, such as electronic noise from the detector systems.

In summary, while all these factors contribute to the degradation of CT images, artifacts specifically represent what is commonly referred to as noise, making the identification of this term particularly relevant in the context of CT image analysis and quality assurance.