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Pilot Study Comparing Patient ESE

Pilot Study Comparing Patient ESE. Manual vs. AEC Technique Factors. Decision Made at Start of QA Program. Test all equipment in manual mode AEC equipment mostly found in hospitals and large radiology suites

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Pilot Study Comparing Patient ESE

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  1. Pilot StudyComparing Patient ESE Manual vs. AEC Technique Factors

  2. Decision Made at Start of QA Program • Test all equipment in manual mode • AEC equipment mostly found in hospitals and large radiology suites • Facilities equipped with AEC equipment required to have manual technique charts for times when AEC not functioning • NJ test phantom could not be used to simulate patient anatomy in AEC mode • Design of Victoreen 4000 meter prevents measuring exposure parameters in AEC mode Bureau of Radiological Health

  3. Affect on ESE Numbers? • Physicists have raised concerns that our tests do not reflect “reality” at sites using AEC exposures • Bureau agreed that the time was right to re-evaluate its testing protocols for AEC radiographic machines and established a pilot study Bureau of Radiological Health

  4. Goals of Study • Measure ESE utilizing both manual and AEC exposure techniques • Determine if there is correlation or variance in the measured ESEs Bureau of Radiological Health

  5. Estimate of AEC Population Bureau of Radiological Health

  6. Pilot Study Testing Protocol • Verify that facility has manual technique charts available for AEC units tested • Ensure that radiographic machines chosen for study have functioning AEC and are stable by testing kVp, mAs and timer linearity and accuracy • Evaluate ESE for AP Lumbosacral Spine exposures at 40” SID Bureau of Radiological Health

  7. Testing Setup • Utilized CDRH NEXT Phantom simulating 21 centimeter patient • Utilized a calibrated Radcal MDH 1015-X with 10X5-6 Ion Chamber. Chamber setup 9” above the phantom to eliminate scatter affects • Measured mAs, ms, mR and ESE exposures using facility provided manual techniques Bureau of Radiological Health

  8. Testing Setup • Repeated measurements using AEC technique factors and center sensor • Four exposures were taken in each mode and average values were calculated • Calculated ESE measurements in both modes and compared differences Bureau of Radiological Health

  9. Photo of Testing Setup Bureau of Radiological Health

  10. Sample of Machine DataCollected

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  14. Composition of Study • 17 machines tested at four facilities • 2 machines discarded from study due to malfunctioning AEC • 5 machines used CR image receptors • 10 machines used film systems Bureau of Radiological Health

  15. Raw Data Bureau of Radiological Health

  16. Summary Of Results Bureau of Radiological Health

  17. Summary Data Bureau of Radiological Health

  18. Summary Of Results Bureau of Radiological Health

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  20. Reasons for Variance? • Manual Technique Charts Not Always Accurate • 5 machines not capable of being set at recommended technique factors • 3 machines varied by 5 kVp or more between manual and AEC technique settings • CDRH phantom not a perfect match for manual technique evaluation • 21 cm patient vs. 23-24 cm Techniques Bureau of Radiological Health

  21. Reasons for Variance? • AEC more efficient than manual techniques • For Same kVp settings, mAs was 2 to 8 times less than manual counterpart Bureau of Radiological Health

  22. Where Do We Go From Here? • Joint BRH/Physicist effort to improve the accuracy of manual technique charts? • Joint BRH/Physicist effort to develop an AEC test protocol including valid test phantom(s)? Bureau of Radiological Health

  23. BRH Preliminary Tests on Alternative Phantom Materials • CDRH Phantom not ideal and not practical • Suggestion from physicists and other state programs that copper or aluminum could simulate lumbar spine phantom • BRH conducted abbreviated tests using two different thicknesses of copper: 2.4 mm and 2.0 mm Bureau of Radiological Health

  24. ESE Difference Lucite vs Copper Bureau of Radiological Health

  25. Summary Of Results Bureau of Radiological Health

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  27. Physicist Input • Suggestions? • Phantom Materials? • Volunteers to Develop AEC Protocol? Bureau of Radiological Health

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