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FFDM Quality Assurance Guidelines for Mammography Facilities

This chapter outlines FFDM testing protocols under MQSA regulations, addressing components such as signal-to-noise ratio, modulation transfer function, and uniformity testing. Each manufacturer has unique testing schedules and equipment requirements. The importance of calibration, artifact detection, and image consistency is emphasized. Phantom imaging, compression force evaluation, and physicist surveys are integral to maintaining quality standards.

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FFDM Quality Assurance Guidelines for Mammography Facilities

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  1. CHAPTER 17 Quality Assurance for Full Field Digital Mammography

  2. MAMMOGRAPHY QUALITY STANDARDS ACT (MQSA) • Designed as guide during reign of film/screen mammography • Basic requirements remain unchanged for FFDM • No set standards for FFDM • FDA cedes standard testing must comply with the manufacturers’ recommendations for each unit • Each manufacturer has set testing protocols and schedules for their own equipment • Still need to conform to MQSA regulations

  3. TEST SCHEDULES

  4. TEST SCHEDULES

  5. FFDM TESTING • Secondary erasure of imaging plates (computed radiography only) • Image converted to electronic signal, then image erased

  6. FFDM TESTING • Signal-to-noise ratio • Ratio of signal power to noise power corrupting the signal • Can affect image quality • The higher the signal compared to noise, the better the image

  7. FFDM TESTING • Modulation Transfer Function • Also known as spatial frequency response • Measure of transfer of contrast from subject to image • High spatial frequencies correspond to fine image detail • Only performed on units that use indirect conversion digital detectors

  8. FFDM TESTING • Automatic Optimization of Parameters Mode • Checks system to be sure unit chooses correct technique for each setting • Test using 3 thicknesses of acrylic block using predetermined compression force for each exposure • Each manufacturer has different settings; provide same results • Not all manufacturers require testing by technologist

  9. FFDM TESTING • Uniformity/Artifacts/Flat Field/Interplate Consistency • Images must be uniform in intensity and free of artifacts • Uniformity testing reveals and maps areas of detector no longer operating optimally • Artifacts have many sources • Recommended thickness of block varies between manufacturers

  10. FFDM TESTING

  11. FFDM TESTING

  12. FFDM TESTING • Dead pixels • Consistent black or white spot seen on all images • Calibration procedures for location and removing usually performed by manufacturers’ service; can be performed remotely

  13. FFDM TESTING

  14. FFDM TESTING

  15. FFDM TESTING • Ghosting • Outlines of previous mammogram images • Often seen on flat-field test • Recommend testing by physicist if suspected

  16. FFDM TESTING

  17. FFDM TESTING • Calibration • More a housekeeping chore • Keep images consistent • Weekly program • Unit resets self • Important to perform at correct temperature

  18. FFDM TESTING • Softcopy display: monitors and workstations • Monitors must remain consistent and provide adequate brightness and contrast • Each manufacturer has proprietary workstations • Some facilities prefer workstations from different vendor (ie, PACS vendor) • Acceptable as long as meet FDA requirements and FFDM and PACS are compatible • Use SMPTE test pattern

  19. FFDM TESTING

  20. FFDM TESTING • Compression thickness

  21. FFDM TESTING • Laser printers • Printer uniformity • DICOM Printer Quality Control: SMPTE (Hologic)

  22. TESTS COMMON TO BOTH F/S AND FFDM • All testing required by MQSA • Process of testing will vary by manufacturer • Standards set by manufacturer may be more stringent than MQSA requirement

  23. TESTS COMMON TO BOTH F/S AND FFDM • Phantom Imaging • Compression Force • Repeat/Reject Analysis • Visual Check • Viewbox and Viewing Conditions • Physicist Survey

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