Mammography Contrast Characteristics


Outline and Learning Guide

  • Introduction and Overview

  • Image Quality Requirements for Mammography
    High Contrast Sensitivity
    High Detail (Low Blurring)
    Low Visual Noise
    Minimal Artifacts
    Spatial Characteristics (Appropriate Projections and Field of View)

    Testing Image Quality
    The Phantom
    Specks (Calcifications)
    Visibility Requirements
    Specks (Calcifications)

    Factors Affecting Contrast Sensitivity
    Anatomical Environment
    X-ray Beam Spectrum
    Scattered Radiation
    Receptor and Image Display Contrast Characteristics

    The Anatomical Environment
    Breast Size and Thickness
    Breast Density

    Breast Compression
    Reduce and Equalize Variations in Breast Thickness
    Reduce Overlying Structures
    Reduce Motion Blurring

    Factors Affecting The X-ray Beam Spectrum
    Anode Material
    Filter Material

    Optimizing the X-Ray Spectrum
    Effect of Spectrum on Contrast and Dose
    Optimum Photon Energy
    Characteristic X-Radiation (Molybdenum and Rhodium)
    Filters (Molybdenum and Rhodium)
    KV Selection
    Automatic Spectrum Selection
    Contrast Mode
    "Dose" Mode

    Scattered Radiation
    Effect on Contrast
    Air Gap (With Magnification)

    Factors that Affect Film/Screen Contrast Characteristics
    Film Design
    Film Exposure Level
    Film Processing Level
    Viewing Conditions

    Factors that Affect Digital Mammography Contrast Characteristics
    Digital Image Processing
    Digital image Windowing
    Characteristics of Image Display

    Factors that Affect Film Exposure Level
    Automatic Exposure Density Value Setting
    Density Control Setting
    AEC Sensor Location
    Variations in Receptor Sensitivity

    Factors that Produce Variations in Receptor Sensitivity
    Variations in Film Sensitivity (Speed) from Manufacturer's Batch to Batch
    Variations in Screens Within the Clinic
    Quality Assurance Requirements
    AEC Tracking Error (Reciprocity Law Failure)
    Quality Assurance Requirements
    Variation in Film Processing Level
    Quality Assurance Requirements

    Factors that Produce Variations in Film Processing Level
    Type of Chemistry and Matching to Film
    Mixing and Dilution of Chemistry
    Replenishment Rates

    Development Time
    Development Temperature
    Quality Assurance Requirements

  • Film Viewing Conditions
    Viewbox Brightness
    Masking and Glare Control
    Room Illumination





Learning Objectives

1.      Explain why mammography requires a high contrast sensitivity compared to most other radiographic procedures.

2.      Explain why mammography requires the highest visibility of detail (lowest blurring) of all radiographic procedures.

3.      Describe, and demonstrate if possible, how the different image quality characteristics of a mammography imaging procedure can be evaluated using a standard test phantom.

4.    Describe the general anatomical conditions associated with a breast that can have an effect on contrast sensitivity.

5.      Describe how breast compression improves image quality.

6.      Describe the general relationship between x-ray beam photon energy and dose to the breast.

7.      Describe the general relationship between x-ray beam photon energy and contrast sensitivity in soft tissue.

8.      Identify the general range of x-ray beam photon energies is generally optimum for mammography.

9.      Describe and sketch the general spectral characteristics of an x-ray beam used for mammography as produced with a molybdenum anode.

10.  Explain and illustrate the function of filters (molybdenum and rhodium) that as used in mammography.

11.  Identify the clinical conditions when it is most appropriate to use a rhodium filter.

12.  Identify  appropriate KV values that are appropriate to use for the arrange of breast thicknesses.

13.  Explain the control factors that an operator must select when using automatic spectral selection in mammography.

14.  Briefly described the contrast characteristics of film used for mammography in comparison to other radiographic procedures.

15.  Describe the significant of level of exposure (density) that must be considered during mammography procedures with respect to film contrast.

16.  Identify conditions that can result in film exposure errors in mammography.

17.  Explain why the level of development is  important  when processing mammography films.

18.  Identify several conditions that can result in under development of mammography films.

19.  Explain why it is necessary to have consistent processing of mammography films.

20.  Describe the special viewing conditions required for observing  mammography films.







Mind Map