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RC325C Personnel Protection during Fluoroscopic Procedures

RC325C Personnel Protection during Fluoroscopic Procedures. Beth Schueler, PhD, Mayo Clinic Rochester, MN. Learning Objectives. For staff performing fluoroscopically-guided interventional procedures: Summarize typical radiation exposure levels Understand issues related to lens exposure

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RC325C Personnel Protection during Fluoroscopic Procedures

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  1. RC325C Personnel Protection during Fluoroscopic Procedures Beth Schueler, PhD, Mayo Clinic Rochester, MN

  2. Learning Objectives • For staff performing fluoroscopically-guided interventional procedures: • Summarize typical radiation exposure levels • Understand issues related to lens exposure • Learn about new shielding devices and techniques • Review practical rules for occupational dose reduction Schueler RC325C

  3. Operator Exposure During Interventional Fluoroscopy Procedures 1. NCRP 168. Radiation Dose Management for Fluoroscopically-guided Interventional Procedures, 2011. 2. Kim KP, et al. Health Physics 2008; 94:211–227.

  4. Typical Operator Exposure Levels • Annual doses for a workload of 1000 procedures per year: • Potential for doses exceeding regulatory dose limits exists 1. NCRP 116. Limitation of Exposure to Ionizing Radiation, 1993. 2. ICRP 103. 2007.

  5. New ICRP Guideline on Lens Exposure* • Lower threshold for cataract formation: 0.5 Gy (previous threshold 2-5 Gy) • Lower occupational eye dose limit is recommended: 20 mSv/yr averaged over 5 years with no year > 50 mSv *International Commission on Radiological Protection (ICRP) Statement on tissue reactions. April 21, 2011. http://www.icrp.org/page.asp?id=123 Schueler RC325C

  6. Lowered Radiation-Induced Cataract Threshold Dose • Problems found with earlier cataract studies: • Short follow-up period – latency period is longer for low doses • Insufficient sensitivity to detect early lens changes • Few subjects with low lens dose • Recent additional significant studies indicate lower threshold: • Chernobyl nuclear reactor accident clean-up workers1 • US radiologic technologists2 1. Worgul BV, et al. Radiat Res 2007; 167:233–243. 2. Chodick G, et al. Am J Epdiemiol 2008; 168:620–631. Schueler RC325C

  7. Cataracts in Fluoroscopy Operators • In a survey of 59 interventional radiologists, 5 had posterior subcapsular cataracts (PSCs) 1 • In a survey of 42 interventional cardiologists, 17 had PSCs 2 1. Junk A. et al, RSNA 2004 Annual Meeting 2. Information and Preliminary results of the IAEA Cataract Study Retrospective Evaluation of Lens Injuries and Dose (RELID) 2009, https://rpop.iaea.org/RPOP/RPoP/Content/Documents/Whitepapers Schueler RC325C

  8. Lens Dose Estimation • Potential high dose levels require lens exposure monitoring or accurate estimation • Monitoring at or near the eye is difficult • Estimation from a neck dosimeter dose reading is a more practical solution Harstall R, et al. Spine 2005; 30:1893-1898. Schueler RC325C

  9. Lens Dose Estimation 4 2 1 0.25 mGy/hr 0.5 Under-table X-ray Tube: Lens:Neck 0.5 – 0.7 Over-table X-ray Tube: Lens:Neck 1.0 – 1.2 Schueler RC325C

  10. Lens Dose Estimation • Actual Lens:Neck dose ratio varies with C-arm angulation and operator position • For typical under-table x-ray tube configurations, the collar dosimeter reading provides conservative estimate of the lens dose Schueler RC325C

  11. Lens Exposure Reduction • Shielding specific to eye and head protection: - Leaded eyewear - Ceiling-mounted shields Schueler RC325C

  12. Leaded Eyewear • Typical lead equivalent thickness of radiation protective eyewear is 0.75 mm • 98% attenuation or attenuation factor = 50 • Actual lens dose is higher due to • Backscatter from head • Exposure from the side and from below the protective lenses Schueler RC325C

  13. Eye Exposure Conditions Schueler RC325C

  14. Leaded Eyewear Effectiveness Comparison • Traditional style • 0.75 mm lead-equivalent • 120 g • 28 cm2 surface area • Sport-wrap style • 0.75 mm lead-equivalent • 59 g • 16 cm2 surface area Schueler RC325C

  15. Leaded Eyewear Effectiveness Comparison • Panoramic Shield • 0.07 mm lead-equivalent acrylic • 43 g • 50 cm2 surface area Schueler RC325C

  16. Leaded Eyewear Effectiveness Comparison • Lens dose measured on a head phantom angled at 0, 45 and 90 to the scatter source Schueler RC325C

  17. Leaded Eyewear Effectiveness Comparison Schueler RC325C

  18. Leaded Eyewear Recommendations • Adequate side shields or wrap-around design is essential • Radiation attenuation factor for typical configuration is between 2 and 5 • Leaded eyewear alone may be insufficient for high exposure conditions if 20 mSv/yr lens dose limit is implemented Schueler RC325C

  19. Ceiling-Mounted Shields • Overhead lead shields provide head and neck protection in addition to lens protection • May be cumbersome for certain procedures: • C-arm angulation • Biliary/transjugular access Schueler RC325C

  20. Ceiling-Mounted Shield Effectiveness Fetterly KA, et al. JACC Intv 2011;4:1133-9. Schueler RC325C

  21. Lens Exposure Reduction Ceiling- Mounted Shield Leaded Eyewear Eyewear + Shield

  22. Learning Objectives • For staff performing fluoroscopically-guided interventional procedures: • Summarize typical radiation exposure levels • Understand issues related to lens exposure • Learn about new shielding devices and techniques • Review practical rules for occupational dose reduction Schueler RC325C

  23. Orthopedic Complications from Lead Apron Use • Back pain was reported by 50-75% of interventional physicians surveyed * • Compare to incidence of 27% in US adults • 25-30% reported that back problems had limited their work • Options for relief • Lightweight aprons • Vest/kilt design * Klein LW, et al. J Vasc Interv Radiol 2009; 20:147–152. Schueler RC325C

  24. Lightweight Protective Aprons Weight reduction of 20-30% possible McCaffrey JP, et al. Med Phys 2007;34:530-7. Schueler RC325C

  25. Radiation Protection Cabin • Provides whole-body shielding from an external support system • Include head and neck protection • Eliminates need for • lead apron • thyroid shield • leaded eyewear • other ceiling-mounted or mobile shields Schueler RC325C

  26. Radiation Protection Cabin Marichal DA, et al. J Vasc Interv Radiol 2011; 22:437-442. Schueler RC325C

  27. Radiation Protection Cabin Marichal DA, et al. J Vasc Interv Radiol 2011; 22:437-442. Schueler RC325C

  28. Radiation Protection Cabin Dragusin O, et al. Eur Heart J 2007; 28:183–189. Schueler RC325C

  29. Radiation Protection Cabin Dragusin O, et al. Eur Heart J 2007; 28(2),183–189. Schueler RC325C

  30. Radiation Protective Drapes • Placed on patient surface, sterile, disposable • Various sizes, shapes and cut-outs for different procedures • Exposure reduction factors measured: • Eyes: 12, Thyroid: 25, Hands: 29 King JN, et al. AJR 2002; 178:153–157. Schueler RC325C

  31. Learning Objectives • For staff performing fluoroscopically-guided interventional procedures: • Summarize typical radiation exposure levels • Understand issues related to lens exposure • Learn about new shielding devices and techniques • Review practical rules for occupational dose reduction Schueler RC325C

  32. Practical Rules for Dose Reduction • Minimize fluoroscopy time and number of fluorographic images acquired • Last-image-hold • Fluoroscopy loop recording • Reduced acquisition frame rates • Virtual collimation Schueler RC325C

  33. Practical Rules for Dose Reduction • Minimize fluoroscopy time and number of fluorographic images acquired • Use available patient dose reduction technologies • Pulsed fluoroscopy at low frame rates • Low dose rate settings • Spectral beam filtration • Increased minimum kVp • Grid removal 11/29/2011 Schueler RC325C 33

  34. Practical Rules for Dose Reduction Minimize fluoroscopy time and number of fluorographic images acquired Use available patient dose reduction technologies Use good imaging-chain geometry 11/29/2011 Schueler RC325C 34

  35. Practical Rules for Dose Reduction Minimize fluoroscopy time and number of fluorographic images acquired Use available patient dose reduction technologies Use good imaging-chain geometry Use collimation to the area of interest 11/29/2011 Schueler RC325C 35

  36. Practical Rules for Dose Reduction Minimize fluoroscopy time and number of fluorographic images acquired Use available patient dose reduction technologies Use good imaging-chain geometry Use collimation to the area of interest Use all available information to plan the interventional procedure 11/29/2011 Schueler RC325C 36

  37. Practical Rules for Dose Reduction • Position yourself in a low-scatter area Schueler RC325C

  38. Practical Rules for Dose Reduction Position yourself in a low-scatter area Use protective shielding 11/29/2011 Schueler RC325C 38

  39. Practical Rules for Dose Reduction • Position yourself in a low-scatter area • Use protective shielding • Use appropriate fluoroscopic imaging equipment • Optimized for the procedure and body part • High dose procedures should utilize fluoroscopy equipment with dose reduction technologies and dose display 11/29/2011 Schueler RC325C 39

  40. Practical Rules for Dose Reduction • Position yourself in a low-scatter area • Use protective shielding • Use appropriate fluoroscopic imaging equipment • Obtain appropriate training • Operators should be thoroughly familiar with the particular equipment used • Residents and fellows should be trained in safe operating procedures 11/29/2011 Schueler RC325C 40

  41. Practical Rules for Dose Reduction Position yourself in a low-scatter area Use protective shielding Use appropriate fluoroscopic imaging equipment Obtain appropriate training Wear radiation monitoring dosimeters and review your dose reports 11/29/2011 Schueler RC325C 41

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