Medical Image Visual Noise

Mind Map

Learning  Guide

Learning Activities

Visuals for
Class Discussion



Objectives and Learning Activities

  • Describe the general appearance of visual noise in clinical images.

  • When looking at clinical images recognize visual noise.

  • Give at least two alternate names for visual noise in clinical images.

  • Briefly describe the two major sources of visual noise in radiographic images.

  • Describe and illustrate the general random nature of x-ray photons.

  • Explain how the random distribution of x-ray photons produces image noise.

  • Draw a simple graph showing the distribution of x-ray photons and explained the concept of standard deviation.

  • Describe the relationship of standard deviation to the mean or average number of photons.

  • Describe the relationship of quantum noise to x-ray receptor exposure.

  • Briefly describe the concept of the quantum sink.

  • Describe the disadvantage of using radiographic receptors with very high sensitivity or speeds.

  • Explain why quantum noise might be more of a problem with digital radiography than  with film screen radiography.

  • Describe the general relationship of image noise to image detail.

  • Explain in general terms how blurring reduces image noise.

  • Describe the relationship between digital image pixel size and noise.

  • Briefly describe how digital image processing can be used to reduce image noise and where it is used clinically.

  • Briefly describe how the process of averaging a series of images can be used to reduce noise and where it is used clinically.

  • Explain why  image display contrast has an effect on the visibility of noise.

  • Observe the effect of changing digital display window width on the visibility of noise in both digital radiography and CT.