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Resident Physics Series

Resident Physics Series. ACR Mammography Protocols. Mammography Quality Standards Act (MQSA). “ to ensure the safety and reliability of mammography and help detect breast cancer in its earliest, most treatable stages ” Mammography practice under federal control (FDA). 1992. MQSA Requirements.

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Resident Physics Series

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  1. Resident Physics Series ACR Mammography Protocols

  2. Mammography Quality Standards Act (MQSA) • “to ensure the safety and reliability of mammography and help detect breast cancer in its earliest, most treatable stages” • Mammography practice under federal control (FDA) 1992

  3. MQSA Requirements • Yearly physics surveys • Yearly FDA inspections • Georgia x-ray regulators on contract with FDA • FY 2013 • No violations: 87%

  4. Facility Accreditation by “Accrediting Body” • American College of Radiology (ACR) • State of Arkansas • State of Iowa • State of Texas

  5. FDA Facility & Procedure Count

  6. Number of Accredited FFDM Units Nov 03 Jun 11

  7. Number of Accredited Units Nov 03 Jun 11

  8. % FFDM Units Dec 2003 Jun 2011

  9. FDA-Approved FFDM Units Last 5 Years

  10. Mammography QC Manual Revised Edition, 1999 • Radiologist • Clinical Image Quality • Radiologic Technologist • Medical Physicist Sections

  11. Quality Assurance (QA) • Every imaging procedure is necessary & appropriate to clinical problem at hand • images contain information critical to solution of that problem QA should ensure

  12. Quality Assurance (QA) • recorded information is • correctly interpreted • made available to patient’s physician in a timely fashion • consistent with image quality objectives, examination results in lowest possible • radiation exposure • cost • inconvenience to the patient

  13. Quality Control (QC) QC is integral part of QA • Acceptance Testing • detection of defects in equipment that is newly installed or has undergone major repair • Baselines • Establishment of baseline equipment performance • quantitative data when system operating properly

  14. Quality Control (QC) • Diagnosis • Diagnosis of changes in equipment performance before they become radiologically apparent • Verification • Verification of correction of causes of deterioration in equipment performance

  15. Facility Responsibility • Designate One Lead Interpreting Physician

  16. Lead Physician’s Responsibilities • Ensure technologists have adequate • orientation • based on procedure manual • training • continuing education • Ensure effective QC program

  17. Radiologist’s Responsibilities • Designate one technologistresponsible for QC • QC tech can delegate responsibilities

  18. Radiologist’s Responsibilities • Ensure availability of appropriate test equipment • Arrange staffing / scheduling to allow time for QC

  19. Radiologist’s Responsibilities • provide frequent consistent positive & negative feedback to technologists about film quality & QC • Review technologist’s test results • no less than every 3 months • more often if inconsistentresults

  20. Radiologist’s Responsibilities • Select a medical physicist • administers QC program • performs physicist’s tests • Review physicist’s test results

  21. Radiologist’s Responsibilities • Oversee or designate qualified individual to oversee radiation protection program for • employees • patients • individuals in surrounding area

  22. Radiologist’s Responsibilities • Ensure proper maintenance of records in QC procedures manual • employee qualifications • mammography technique / procedures • quality control / safety / protection • infection control

  23. Radiologist’s Responsibilities • “The radiologist is ultimately responsible for the quality of films produced under his or her direction and bears ultimate responsibility for both proper QC testing and QA procedures in mammography.”

  24. The Proliferation of Digital Mammography • Total mammography units in US (10/1/2010) • 12,445 • Total digital mammography units (10/1/2010 • 8748 (70.3%) • Total digital mammography units (4/1/2010 or 6 months ago) • 8195 (65.2%) • Increase in digital units • ~ 92/month

  25. Physicists & Digital Mammoraphy • Physicist must insure equipment meets manufacturer’s specifications • Equipment specs now defined by manufacturer, not ACR/FDA

  26. Physicist’s Responsibilities • Note: All physicist’s tests are to be done annually or after tube replacement or major service

  27. Physicist’s Responsibilities: Mammography Unit Assembly Evaluation • mechanical stability / identification of sharp edges • receptor stability • locks / motions / detents • operator shielding • thickness scale accuracy • indicator lights working • technique chart posted (see next slide)

  28. Technique Chart • Even though most mammo is phototimed, still need technique chart • For given breast size, density, view specify machine set-up • Phototimer mode (auto standard, contrast, dose, …) • Density (-2, -1, 0, …)

  29. Technique Chart • Wrong (my opinion) • Display kVp, mAs, target, filter calculated by machine for given image • Correct (my opinion) • Display machine settings selectable by technologist for this breast and view • Should provide enough guidance to allow a technologist who has not worked in this room or facility to properly set up a study

  30. Physicist’s Responsibilities: Mammography Unit Assembly Evaluation Film • Cassettes slide smoothly into/out of holder • Override available for auto-decompression • display must indicate when auto-decompression turned off • Manual release of compression if power lost

  31. Collimation Assessment • x-ray light field alignment • beam does not exceed receptor by > 2% SID • compression paddle / receptor alignment at chest wall within 1% SID • paddle not visible on image • Image should fill film • Many units by design will not do this Film

  32. Physicist’s Responsibilities • Focal Spot Performance • limiting resolution pattern • kVp accuracy / reproducibility • Beam quality (HVL) • minimum & maximum • minimum: patient dose • maximum: image contrast

  33. Automatic Exposure Control (AEC / Phototiming) • kVp tracking • Thickness tracking • image mode tracking (cassette sizes, w w/o grid) • automatic mode tracking • unit selects kVp, target, filter • density control • even steps of ~ 15-20%

  34. Physicist’s Responsibilities: Film • Screen Uniformity • compare O.D. of each cassette using phototimer • AEC Reproducibility

  35. Physicist’s Responsibilities • Breast Entrance Exposure, Average Glandular Dose, • RMI-156 “accreditation” phantom used for entrance exposure / average glandular dose

  36. Breast Average Glandular Dose Limits • 0.3 rad (300 mrads, 3 mGy) maximum per view for screen-film receptors using a grid • Same for film and digital • 0.1 rad (100 mrads, 1 mGy) maximum per view for non-grid screen-film receptors • Radiation output rate > 800 mR/sec

  37. Image Quality Evaluation • use RMI-156 “accreditation” phantom • record • fibers • speck groups • masses • optical densities • technique

  38. A Poor Phantom Image

  39. Artifact Identification • Artifact evaluation / description • determination of artifact source • processor • other equipment • Done with phantomfilm Film

  40. Physicist’s Responsibilities • Viewing conditions • ambient light • viewbox brightness • My experience • Ambient lighting often ignored Film

  41. Technologist’s Responsibilities All QC must not only be performed but must be documented! • Daily • darkroom cleanliness • processor quality control • sensitometric data • Weekly • screen cleanliness • viewboxes and viewing conditions • Phantom images Film Film

  42. Technologist’s ResponsibilitiesMonthly: Visual Checklist • visual checklist • SID indicator • angle indicator • locks • field light • smooth motions

  43. Technologist’s ResponsibilitiesMonthly: Visual Checklist • cassette lock • Is cassette held firmed in place when tubestand tilted • Compression device & firm compression • Smooth edges • Holds pressure • hand switch placement • visibility • switches/ lights/ meters • cones/ collimators

  44. Technologist’s ResponsibilitiesQuarterly Film • Fixer retention analysis • Fixer affects archivability of films • Repeat analysis • breakdown by cause • motion • positioning • technique • static • etc.

  45. Semi-Annual Technologist’s Responsibilities: Darkroom Fog Film • must use sensitized film • partially cover previously exposed phantom film in darkroom for 2 minutes • up to .05 O.D. increase acceptable

  46. Semi-annual Technologist’s Responsibilities Film Screen Film Contact • 40 lines/inch Copper mesh • subjective results • poor contact can result if time (15 minutes) not provided for air to bleed out of cassette after closing • NOTE: 15 minutes between cassette loading & exposure must be provided for all clinical films to insure good contact

  47. Semi-annual Technologist’s Responsibilities Screen Film Contact Film

  48. Semi-Annual Technologist’s Responsibilities Compression • can use bathroom scale covered with towel • 25 - 40 pounds for automatic systems • at least 25 pounds for manual compression

  49. The End Questions?

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