TABLE X.
The ten highest average RPN steps and the corresponding potential failure modes, potential causes of failure, and potential effects of failure from the TG100 FMEA.
| Rank (process tree step#) | Subprocess#_description | Step description | Potential failure modes | Potential causes of failure | Potential effects of failure | Avg. O | Avg. S | Avg. D | Avg. RPN |
|---|---|---|---|---|---|---|---|---|---|
| 1 (#31) | 4—Other pretreatment imaging for CTV localization | 6—Images correctly interpreted (e.g., windowing for FDG PET) | Incorrect interpretation of tumor or normal tissue | Inadequate training (user not familiar with modality), lack of communication (inter-disciplinary) | Wrong volume | 6.5 | 7.4 | 8.0 | 388 |
| 2 (#58) | 7—RTP anatomy | Delineate GTV/CTV (MD) and other structures for planning and optimization | 1—>3*sigma error contouring errors: Wrong organ, wrong site, wrong expansions | Lack of standardized procedures, hardware failure (defective materials/tools/equipment), inadequate design specification, inadequate programming, human failure (inadequate assessment of operational capabilities), human failure (inattention), human failure (failure to review work), lack of staff (rushed process, lack of time, fatigue) | Very wrong dose distributions, very wrong volumes | 5.3 | 8.4 | 7.9 | 366 |
| 3 (#204) | 12—Day N treatment | Treatment delivered | LINAC hardware failures/wrong dose per MU; MLC leaf motions inaccurate, flatness/symmetry, energy—all the things that standard physical QA is meant to prevent | Poor design (hardware), inadequate maintenance, software failure, lack of standardized procedures (weak physics QA process), human failure (incorrectly used procedure/practice), standard Linac performance QM failure (not further considered here), inadequate training | Wrong dose, wrong dose distribution, wrong location, wrong volume | 5.4 | 8.2 | 7.2 | 354 |
| 4 (#48) | 6—Initial treatment planning directive (from MD) | Retreatment, previous treatment, brachy etc. | Wrong summary of other treatments. Other treatments not documented | Lack of staff (rushed process, lack of time, fatigue), human failure (inattention), lack of communication, human failure (reconstructing previous treatment), human failure (wrong info obtained), information not available | Wrong dose | 5.3 | 8.6 | 7.3 | 333 |
| 5 (#59) | 7—RTP anatomy | Delineate GTV/CTV (MD) and other structures for planning and optimization | 2—Excessive delineation errors resulting in <3*sigma segmentation errors | Lack of standardized procedures, availability of defective materials/tools/equipment, human failure (materials/tools/equipment used incorrectly), human failure (inadequate assessment of materials/tools/equipment for task), inadequate design specification, inadequate programming, inadequate training, human failure (inadequate assessment of operational capabilities), human failure (inattention), human failure (failure to review work), lack of staff (rushed process, lack of time, fatigue) | Wrong dose distribution, wrong volumes | 5.9 | 6.6 | 8.0 | 326 |
| 6 (#65) | 7—RTP anatomy | PTV construction | 3—Margin width protocol for PTV construction is inconsistent with actual distribution of patient setup errors | Lack of standardized procedures, lack of communication, inadequate training, human failure (inattention), human failure (failure to review work), lack of staff (rushed process, lack of time, fatigue) | Wrong dose distribution, wrong volumes or suboptimal plan | 7.3 | 5.4 | 7.9 | 316 |
| 7 (#136) | 9—Plan approval | 1—Plan OK to go to treatment | 3—Bad plan approved | Lack of communication, human failure (inattention), lack of standardized procedures, human failure (incorrectly used procedure/practice), inadequate training | Very wrong dose, very wrong dose distribution, very wrong volume | 4.9 | 8.0 | 7.9 | 313 |
| 8 (#200) | 12—Day N treatment | Set treatment parameters 2 | Special motion management methods (e.g., gating, breath-hold) not applied or incorrectly applied | Poor design (software), poor design (hardware), inadequate training human failure (operator not observing counterintuitive patterns on screen) | Wrong dose, wrong dose distribution, wrong location, wrong volume | 6.2 | 6.7 | 7.11 | 310 |
| 9 (#46) | 6—Initial treatment planning directive (from MD) | Specify special instructions, viz. pacemaker, allergies, voiding, bowel prep, etc. | Special instructions not given wrong special instruction (e.g., allergy, pacemaker) | Lack of standardized procedures (documentation), lack of staff (rushed process, lack of time, fatigue), human failure (inattention), lack of communication, human failure (wrong or inadequate information obtained) | Non-radiation related injury | 5.3 | 8.8 | 6.5 | 306 |
| 10 (#126) | 8—Treatment planning | 13—Evaluate plan (DVH, isodose, dose tables, etc.) | 1—Inadequate evaluation | Human failure (not enough time/effort spent), inadequate training poor evaluation strategy, human failure (incorrect final prescription) | Wrong dose, wrong dose distribution | 5.6 | 7.0 | 7.1 | 303 |