risk assessment introduction –tg100
TRANSCRIPT
Risk assessment introduction – TG100
M. Saiful Huq, PhD, FAAPM, FInstPUniversity of Pittsburgh Cancer Institute and
UPMC CancerCenter
Learning Objectives
To understand how risk assessment can be performed for radiation therapy processes
• Highlighted the need to make patient safety a high priority
• Priority has focused on identifying and reducing preventable events
• Adapt tools of ultra safe systems such as aviation industries ?
Institute of Medicine, 1999
How safe is safe: Risk in radiotherapy
Ford and Terezakis; Red Journal 78, 321‐322, 2010
• Rate of misadministration in RT is 0.2 % ( 1 in 600)
• Rate of serious injury: airline accidents is 1 in 10 million– 16,000 times lower than that of RT
• Rate of serious injury in RT is 1000 times higher
• In reality no one knows
• Risk profiles of anesthesia: similar to airline industry
10‐1
Alpinism Artisanal fishing Road Traffic Nuclear industry
10‐2 10‐3 10‐4 10‐5 10‐6 Risk accident
10‐7
Chemical industry
ULM/AgricultureRail road
Commercial flightsCharter
Medicine
Emergency unit Blood transfusion
Very safeVery unsafe
No system
be
yond
this point
Magnitude of risk
Anesthesiology
Himalaya Mountaineering
Objectives of “Towards Safer Radiotherapy” report
• Look at ways of reducing errors in RT caused by individual human error or failure of systems of work
• The introduction of new techniques needs to be carefully planned with thorough risk assessment, review of staffing levels and skills required, and documentation updated
Objectives of ICRP 112 report
• Provide guidance on proactive approaches to the reduction of risk of accidental exposures in radiation therapy
• Summarize lessons learned from radiotherapy errors, incidents and near misses
Reactive vs proactive approaches
• Reactive or retrospective approaches to avoidances to accidental exposures
• Proactive approach– Failure modes and effects analysis– Probabilistic safety assessment– Risk matrix
Prospective approaches to avoiding unintended exposure
• Redesigning of infrastructure and clinical processes
• Strengthening of QM program and safety measures
• As technology & processes change– Retrospective approaches are not sufficient
– All‐inclusive QC checks may not be feasible
– Develop proactive approaches to anticipation of failure modes
– Evaluate risks from each failure mode
ICRP 112 Conclusions and recommendations
Prospective risk assessment
• Before introducing a new technology or technique, or developing a QM program figure out, through a formal process, what could go wrong and what the consequences might be
What is risk?
• Risk: frequently defined as the answers to three questions
– What can go wrong?– How likely is it to go wrong?– What are the consequences if it goes wrong?
Risk assessment
• Risk assessment is the process of analyzing the
hazards involved in a process
• Many risk assessment and analysis tools/techniques exist in industry
• These tools can be easily adapted to RT to enhance safety and quality of treatment process
• TG100 used some of these tools to develop new guidelines for RT QM
TG100 risk analysis methodology
• Process tree (mapping)
• Failure modes and effects analysis (FMEA)
• Fault tree analysis (FTA)
• Establishment of a risk based QM program
Used IMRT as a case study
What is a process tree?
• Visual representation of the various steps in a
process
• Demonstrates the flow of steps from process start to end
• Delineate and then understand the steps in the process
Patient database information entered
Immobilization and positioning
CT simulation
Other pre-treatment imaging
Transfer images and other DICOM data
Initial treatment planning directive
RTP anatomy contouring
Treatment planning
Plan approval
Plan preparation
Initial tx(Day 1)
Subsequent tx(Day N)
End of tx
Start of tx
Example: TG100 IMRT process tree
What is FMEA?
• A proactive methodology to systematically
evaluate and identify risks or weaknesses in
product design or other processes and to
identify process controls that address them
FMEA• FMEA looks at each process and at each step asks the questions– What could possibly go wrong (potential failure mode)?– How could that happen (potential causes of failure)?– What effects would such a failure produce (potential effects of failure)?
– The overall risk of each identified failure mode is then scored and prioritized
• A good FMEA then identifies corrective actions to prevent failures from reaching patient
Fault Tree
• Fault tree analysis (FTA) is a top‐down approach to failure analysis, starting with a potential undesirable event (accident) called a TOP event, and then determining all the ways it can happen.
• The analysis proceeds by determining how the TOP event can be caused by individual or combined lower level failures or events
• The causes of the TOP event are “connected” through logic gates (both AND, OR)
Fault Tree
• Visual representation of propagation of failure
• Begins on the left with a failure mode
• Works backwards in time (to the right) to
identify causes of failure
Organization of TG100
• Two parts : Part I and Part II
• Five appendices
• Four Tables, four figures, five example
checklists
• Glossary
Organization of TG100• Part I
– Preface
– Charge and scope of the report
– Problems with traditional approaches to QM in RT
– Introduction
– Quality and safety : An overview
– TG100 risk analysis methodology
– TG100 methodology for designing a QM program in RT
– Comparisons with previous work
– Recommendations for applying risk analysis in RT
– Conclusions
Organization of TG100• Part II : Application of risk analysis methodologies developed in Part I to design radiation therapy quality management programs. Use a generic IMRT case study to – Design
– Process mapping
– FMEA
– FTA
– Design a QM program
Organization of TG100
• Appendices:
– Appendix A : FMEA by process
– Appendix B: FMEA by severity
– Appendix C: FMEA by RPN
– Appendix D: Fault tree
– Appendix E: Fault tree with QM codes