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Special Requirements for CR QC

Special Requirements for CR QC. In film screen systems the film is changed for every image With CR the IP is read up to 10,000 times Almost all plates suffer from wear artifacts If you are suspicious about an artifact take an image using the same plate and no patient

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Special Requirements for CR QC

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  1. Special Requirements for CR QC • In film screen systems the film is changed for every image • With CR the IP is read up to 10,000 times • Almost all plates suffer from wear artifacts • If you are suspicious about an artifact take an image using the same plate and no patient • Make sure there is a QC program to detect wear before you detect it clinically Hammerstrom et al J Digital Imaging 2006 19:226

  2. Observations

  3. Observations • Sharp particulates embedded in the felt lining under a plastic clip etched phosphor surface to create density on radiograph • Not enough pressure beside plastic clip to cause 2nd wear mark to effect radiograph

  4. Observations • Yellowing of phosphor • Virox

  5. Observations Scratches Dust

  6. CR QC Recommendations • Quality Control (QC) - perform monthly • Inspection – cassette and IP • Visual • Radiographic • CR Cassette cleaning • CR IP cleaning • Benefits • Fewer image artifacts and repeated exposures • Increased life cycle of cassettes, IPs, and readers • Compliance with vendor warranties

  7. Retake Analysis • Facilities must maintain records of every retake, including the reason and any corrective actions • An analysis must be done to identify and correct any errors or trends

  8. Retake Analysis • Optional Retake Analysis software • Agfa - NX Quality Assurance (2008 vers.) • Fuji - Retake Analysis • Kodak - Administrative Analysis and Reporting Software • Software records all exposures and rejected images and produce charts / graphs

  9. Retake Analysis - Fuji • Image is rejected (X’d) • Reject reason is assigned by technologist to rejected image • Image information is saved in an exposure log

  10. CR Reject/Repeat Analysis By Body Part and Menu Name

  11. CR – Repeat/Reject Analysis One month intervals (Feb, 2007 – Oct, 2008)

  12. CR – Repeat/Reject Analysis UBCH - IPs Usage (Nov 1 – Dec 31, 2007)

  13. Retake Analysis - Fuji • Retake Analysis • Select reject reason • Export as .csv for further data manipulation if desired

  14. Retake Analysis - DR • Philips – have electronic retake analysis capture software • Siemens – have promised retake analysis capture software for summer 2009 • Until then, use logsheet and manually record rejected images and reason for reject • Unreliable data due to “honor system” • May need to involve RIS team to supply period stats

  15. Digital System QC • Images are used to follow disease processes so it important that the whole digital chain is linear • Linearity should be checked after changes to software/hardware in any component Detector Reading Digital Processing Stored PACS Viewed Display

  16. Overview Session 1

  17. Radioscopy (RF + Angio) QC Normal Font – Required Test (“must do”) Italics - Recommended Test(“recommended”) Required Tests currently recommended by RPS

  18. Annual Radioscopy QC (1) Normal Font – Required Test (“must do”) Italics - Recommended Test(“recommended”) Required Tests currently recommended by RPS

  19. Annual Radioscopy QC (2) Normal Font – Required Test (“must do”) Italics - Recommended Test(“recommended”) Required Tests currently recommended by RPS

  20. Consistency Checks • Weekly/daily • Simple phantom to test reproducibility • To use if there seems to be a problem

  21. Low contrast circles High contrast mesh Vancouver Phantom • This phantom we have developed for routine constancy QC of digital systems • Field collimation • Standard operating conditions • Resolution • Contrast

  22. Overview Session 1

  23. Overview Session 2

  24. Weekly/Monthly CT QC Normal Font – Required Test (“must do”) Italics - Recommended Test(“recommended”) Required Tests currently recommended by RPS

  25. 3 and 6 monthly CT QC Normal Font – Required Test (“must do”) Italics - Recommended Test(“recommended”) Required Tests currently recommended by RPS

  26. Annual CT QC Normal Font – Required Test (“must do”) Italics - Recommended Test(“recommended”) Required Tests currently recommended by RPS ( annual)

  27. In-air calibration of scanner every 24 hours Adjusts sensitivity of all detectors May be required for each collimation Important to do this – build into schedule. QC in CT - Daily

  28. RPS CT QC Frequency

  29. Dosimetry • CT Dose Index - CTDI • Measured using special cylindrical acrylic phantoms for head and abdomen(FDA) • Special pencil ion chamber has uniform response • One or several slices can be measured

  30. QC Phantoms • ACR CT Accreditation Phantom (Gammex 464) • Alignment, noise, uniformity, CT number, resolution, MTF, low contrast, image slice width • Scanner QC phantoms • GE: noise, uniformity, resolution, MTF, low contrast • Siemens: noise, uniformity, MTF

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