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Practical Mitigation Strategies Following Failure Mode and Effect Analysis of Liver SBRT Program

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I Rusu

I Rusu*, J Roeske , T Thomas , J Price , E Melian , M Surucu , Loyola Univ Medical Center, Maywood, IL


WE-RAM1-GePD-TT-4 (Wednesday, August 2, 2017) 9:30 AM - 10:00 AM Room: Therapy ePoster Theater

Purpose: To identify and implement mitigation strategies addressing high risk failure modes (FM) detected in a previous Failure Mode and Effect Analysis (FMEA) applied to liver Stereotactic Body Radiotherapy (SBRT) program and to understand the impact of these implementations on the clinical process.

Methods: Based on the results of FMEA applied to our liver SBRT program, 16 out of 102 FMs were identified significant by risk priority number and severity scores. Twelve FMs were considered in the mitigation program: breathing amplitude changes during 4DCT scan, range of tumor motion not confirmed on 4D scan, inaccurate rigid registration, suboptimal deformable image registration, incorrect target delineation, target or OAR contours unintentionally changed, inaccurate normal liver effective dose (Veff) calculation, inaccurate cone beam CT (CBCT) registration, inconsistent inter-fraction CBCT alignment, intra-fraction patient movement, and prior irradiation not accounted for. FMs such as inaccurate prescription, patient not diagnosed by multidisciplinary group, and inter-fraction variation in organ at risk’s position shape had either sufficient checks in place, or effective mitigation was not deemed practical.

Results: Eleven specific mitigation strategies were implemented. The following physics tasks were introduced to verify: breathing curve during 4DCT scan, target encompassing range of tumor motion, multi-modality image registration, OAR contours, Veff calculation and image guidance before treatment. Radiation oncologist tasks included: patient specific image registration goals for planning, written guidance for covering oncologists for daily image guidance, and consulting with radiologist for target contouring and approving contours. Changes in workflow were: hard-stop in process to account for previous irradiation and use of 3D surface imaging system (3DSI) to monitor intra-fraction patient motion. All strategies were implemented immediately and added about 2 hours to the entire process.

Conclusion: Based on the failure modes identified in our liver SBRT program, practical and effective strategies were implemented to reduce the risk of errors.

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