Film Contrast Characteristics

Learning Objectives

References and Resources

Mind Map Summary

Learning Objectives

• Using data from a film exposed with a sensitometer, sketch a  graph showing how film density increases with increasing exposure.  Give two names for the curve which you have just drawn.
• Identify and label three distinct segments of the curve.
• Identify the characteristic or feature of the curve that determines the amount of image contrast that will be produced.
• Define the parameter film contrast factor and show how it relates to the film characteristic curve.
• Define the two parameters gamma and average gradient and show how they are related to the film contrast factor.
• Describe the concept of film latitude and its significance.
• Describe the general relationship between latitude and maximum film contrast.
• Describe the basic difference between a latitude film and a contrast film.
• Explain which type of film is used for chest radiography and why.
• Sketch three characteristic curves which compare the following processing conditions
• optimum development
• under development
• over development
•  
• Describe two undesirable effects resulting from under processing of radiographic film.
• Describe two undesirable effects caused by over processing of radiographic film.
• Define film fog.
• Describe the general appearance of a fogged film.
• Identify four potential sources of fogging that can occur in a radiology facility.

References and Resources

1.  Chapter 16. The Physical Principles of Medical Imaging, 2^ndEd. Perry Sprawls.  Medical Physics Publishing.

Resources on the Web

Mind Map