Recent Advances in Brachytherapy Dosimetry · 2010-08-18 · Treatment accessories 24 Boolean...
Transcript of Recent Advances in Brachytherapy Dosimetry · 2010-08-18 · Treatment accessories 24 Boolean...
Bruce Thomadsen
University ofWisconsin -Madison
Error Management and Patient Safety in Radiation Therapy:
Fault Tree Analysis
Administrative Stuff
Learning objectives:To understand fault trees.To understand how to use fault tree
analysis to design quality management.
Conflicts of Interest: The author has none.
Proactive Steps to Address Hazards:Initial Design
Design the procedure with the system in mind:
To facilitate communications To minimize energy (e.g., minimize
distances to move, have ready access to materials)
Provide all environmental support (e.g., lighting, sound control)
SEIPS Model Work system(Balance Theory; Smith and Carayon, 1989; Carayon and Smith, 2000)
Slide from Pascale Carayon
Technologyand Tools
Organization
EnvironmentTasks
Person
Proactive Steps to Address Hazards:Analysis and Actions
After initial design of a procedure (or looking at a procedure in place), assess the risks.
For the high risks, try to redesign them out. When not possible, develop interventions.
What to Do?
1. Understand the process2. Assess the hazards (e.g., FMEA)3. Establish the failure propagation patterns
(e.g., Fault tree analysis - FTA)4. Address the hazards5. Test and evaluate
1. APBI with Contura Process Map
Do not try to read the labels; enjoy the organization
Successful treatment
Consultation and decision to treat
Imaging and diagnosis
Plan approval
Subsequenttreatments
Weekly chart checks
Chart filing
Decision of treatmenttechnique
Physics Check
Treatment review
Decision of protocol
Immobilization equipment fabricated
Immobilization equipment documented,
labeled, and stored
Immobilization forImaging study
Set up data documented
Check anatomy
Check prescription
Check dose calc method
Check beams, machines, etc.
Check normal tissue and target goals, dose distributions
Check that previous treatmentswere accounted for
Time out
Positioning
Imaging (port films, CBCT, etc) 27
Documentation
Treatment 3
Treatment 3
Documentation
DosimetryPhysics
MD
Immobilization equipment
documented,labeled, and stored
DQA
Chart Check
Equipment Check
Scheduling
Construct BlocksCompensators
Bolus, Etc
Scheduling forplanning process
RTP anatomycontouringPatient database
information entered
MD review
Plan review bydosimetrist
Data into electronic Database 21
Data into written chart 21
Review of patient medical history
Immobilization equipment fabricated
Import and fuse images 16
MD: delineateGTV/CTV 1,2,5, 53, 56
PTV construction
Edit density map for artifacts
Delineate ROIs and planning structures
Indicate motion/uncertainty Management 13
Specify registration goals 23, 37
Specify protocol for delineating target and structures 17
Specify images for target/structure delineation 11
Specify dose limits and goals 26
Suggest initial guidelines for treatment parameters
Enter prescription 19, 47
Setup fields
Setup dose calc parameters
Optimization/Dose calculation 12, 29, 31
Evaluate plan 10, 28
Initial treatmentplanning directive
Treatment planning
Immobilizationand positioning
Imaging (CT/PET/MR)
Treatment preparation
Plan prep
Initial treatment
Patient Identified
Check that plan matches prescription
Special Instructions (pacemakers, allergies,
preps, etc.) 9
Account for previous treatmentsor chemotherapy 4
Check versionof the plan 20
Check plansatisfied objectives 7, 36
Motion management 8
Tx Unit operationand calibration 3
Information on previousor concomitant treatment 8
Protocol for delineationof targets 9, 17
Patient IDTreatment Site
Treatment settings
Imaging
Motion Management 8
Protocol for PTVMargin 6, 48
Specify PTV Margin
Select Images 25
4D imaging correct 14
Optimization ROI 18, 33, 44Optimization settings 22, 45, 51
Treatment accessories 24
Boolean operations 30, 46
Changes noted 32, 34
Pt prep 35
Monitor Pt/Tx 38, 42
Monitor Pt/Tx 38
Transfer patient data to treatment delivery 15
Manual data entry and plan modification 39
Specify treatment course
Delivery protocols
Scheduling
Automatic data entry and plan modification
Specify ROI for optimization 18
Check planidentity 36
Write finalprescription
Enter demographics, 49
Prepare DRR and other images 50
Treatment settings
Positioning
Pt prep 35, 52
Changes correct 40, 43
Transfer images and otherDICOM data: primary and
secondary data transferred 41
Run leaf sequencer 54
Pt changes noted 55
Imaging Studies
Patient prepped (contrast, tattoos,
BBs etc.)
Check version ofplan and patient ID 7
Treatment accessories 24
2. Assess the Risk
Eric just discussed this.
3. Establish the Failure Propagation Pattern
This is the fault tree analysis.For the fault treeBegin at the failureAsk what are all the possible causesRelate the causes through logical gatesFor each cause, ask what would be the causeRepeat as needed
Example: Calculation Fault Tree
Error in Calculation
Error in Input Data
Error in Data Entry
Error in Calculation Algorithm
Error in Prescription
Example: Calculation Fault
Tree with QM Error in Calculation
Error in Input Data
Error in Data Entry
Error in Calculation Algorithm
Error in PrescriptionError in QC Error in QC
Error in QCError in QC
Error in QA
Error in PT Calculation
Process Tree for Prostate Implants with Loaded Needles
Successful treatment
2 Prepare patient
Identify patient
Anesthetize patient
RO holds styletand removes needle
RO inserts needle intoindicated hole in template
RO rotates probe and mountingbracket to match previous images
5 Reviewimplant
1 Gatheringmaterials
MP brings plan to procedure room identifying needle
location and depth
MP brings needles toProcedure room
RO checks images along whole superior-Inferior range
RO scans throughImages looking for gaps
RO adds extra sourcesif needed and available
3 Position USprobe
4 Insertion ofneedles and sources
MP finds needle inpackage or container
MP brings planning imagesto procedure room
RO pushes needle untiltip shows at desired depth
Prepare and insert US probe
MP hands needleto RO
RO determinesstarting needle
Bring patient into procedure room
Move patient to table
Scrub patientRO selects next needle
1, 4,6,7
2,5,21
3,9,19
8,16,17,18
10,11
12,13,24
14,25
15,2022,23
1,6,7,18,20
2,5
3,4
8
9,11,12,13
14,15,16,17
10,19
One Step of the Process Tree
RO holds styletand removes needle
RO inserts needle intoindicated hole in template
4 Insertion ofneedles and sources
MP finds needle inpackage or container
RO pushes needle untiltip shows at desired depth
MP hands needleto RO
RO determinesstarting needle
RO selects next needle
2,5,21
10,11
14,25
15,20
10,19
Fault Tree for Prostate
Implants with Loaded Needles
Or
Sources placed in wrong location
Patient misidentified
US probe misaligned
Incorrect dose, dose
distribution, location
US images inadequate
Human error: Omission – Time-out not performed
Training – patient identified incorrectly
Or
Training – Probe cover not correctly
filled
Human Failure: Inattention/Poor performance -Temp/ate not
seated properly
Human Failure: Inattention/Poor performance -
Probe cover not correctly filled
Or
RO fails to match the volume study
images
US images inadequate – QA
failure
Human Failure: Poor performance
Changes in prostate
Or
RO fails to align images along the
range
Training failure
Human Failure: Inattention/Poor
performance
US images inadequate – QA
failure
Or
Or
Training failure: US images
inadequate – Needle order
Human failure: US images inadequate
– Needle order
RO fails to image adequately Or
MP fails to hand the correct needle
to ROPoor demarcation
of needles
Human Failure: Inattention/Poor
performance
Confusion between packagesOr
MP drops needle OrPoor room layout
Human failure: MP slips
RO fails to insert needle properly
RO fails to insert into correct hole
RO fails to insert needle to correct
depth
Or
Human Failure: Inattention
Bad viewing conditions
Confusion between holes
Or
US images inadequate – QA
failure
Training Failure
Human Failure: Inattention/Poor
performanceOr
Confusion between planes
RO fails to hold stylet stable during
retraction
Human failure: RO fails to hold stylet
Human failure: RO pushes on stylet
Or
RO selects next needle that obscures
subsequent needles
Training Failure
Human Failure: Inattention/Poor
performance
Or
Or
RO erroneously modifies source
distribution
RO adds unnecessary
sources
Or
RO fails to add necessary
additional sources
US images inadequate – QA
failure
Training Failure
Or
US images inadequate – QA
failure
Training Failure
Or
Again, don’t worry about reading it, this is for scale.
4. So What?
Start with the branches of the fault tree that corresponds to the branches of the process tree with the greatest hazard, either PRN or severity.
Might as well start with the top of the branch, even though that is completely arbitrary.
Consider the possible interventions.
Possible Interventions
First correct any environmental problems – that usually is a relatively inexpensive but effective operation.
Then consider the key core components identified by TG 100 Training Communication Standardized policies and procedures
Make sure resources are allocated as needed (i.e., staffing and equipment.
Fault Tree with
Interventions
Again, don’t worry about reading it, this is for scale.
Or
Sources placed in wrong location
Patient misidentified
US probe misaligned
Incorrect dose, dose
distribution, location
US images inadequate
Human error: Omission – Time-out not performed
Training – patient identified incorrectly
Or
Training – Probe cover not correctly
filled
Human Failure: Inattention/Poor performance -Temp/ate not
seated properly
Human Failure: Inattention/Poor performance -
Probe cover not correctly filled
Or
RO fails to match the volume study
images
Human Failure: Poor performance
Changes in prostate
Or
RO fails to align images along the
range
Training failure
Human Failure: Inattention/Poor
performanceOr
Or
Training failure: US images
inadequate – Needle order
Human failure: US images inadequate
– Needle order
RO fails to image adequately Or
MP fails to hand the correct needle
to ROPoor demarcation
of needles
Human Failure: Inattention/Poor
performance
Confusion between packagesOr
MP drops needle OrPoor room layout
Human failure: MP slips
RO fails to insert needle properly
RO fails to insert into correct hole
RO fails to insert needle to correct
depth
Or
Human Failure: Inattention
Bad viewing conditions
Confusion between holes
Or
Human Failure: Inattention/Poor
performanceOr
Confusion between planes
RO fails to hold stylet stable during
retraction
Human failure: RO fails to hold stylet
Human failure: RO pushes on stylet
Or
RO selects next needle that obscures
subsequent needles
Human Failure: Inattention/Poor
performance
Or
Or
RO erroneously modifies source
distribution
RO adds unnecessary
sources
Or
RO fails to add necessary
additional sources
US images inadequate
Or
Taken care of by the generally complete training, establishing clear communication
modalities (possibly forms) and establishing protocols, policies and
procedures
Systemic corrections
Training failure
Training failure
Training failure
AN
D
US images inadequate
OrTraining failure
AN
D
US images inadequate
AN
D
US QA failure
US images inadequate
AN
D
US QA failure
US images inadequate
AN
D
US QA failure
AN
D
QC failure: Time out formQuality assurance
Quality control
Managerial changes
AN
D
QC failure: Time out for image
evaluation
AN
D
QC failure: Time out form
AN
D
QC failure: Prostate image
time out
Or
Procedural changes
AN
D
Failure of call and response
AN
D
Failure of call and response
AN
D
Failure of call and response
US QA failure
US QA failure
AN
D
Post-proceduralCT
KeyTaken care of by the generally complete
training, establishing clear communication modalities (possibly forms) and
establishing protocols, policies and procedures
Systemic corrections
Quality assurance
Quality control
Managerial changes
Procedural changes
Quality Management
Quality Control – Activities that force specific quality on a process. Often operates on inputs.
Quality Assurance – Activities that demonstrate the level of quality of a process. Often checks outputs.
One Example
Patient misidentified
Human error: Omission – Time-out not performed
Training – patient identified incorrectly
OrAN
D
QC failure: Time out form
Systemic corrections
Quality assurance
Quality control
Managerial changes
Procedural changes
Another Example
MP fails to hand the correct needle
to ROPoor demarcation
of needles
Human Failure: Inattention/Poor
performance
Confusion between packagesOr
MP drops needle OrPoor room layout
Human failure: MP slips
AN
D
Failure of call and response
Systemic corrections
Quality assurance
Quality control
Managerial changes
Procedural changes
Another Example
RO fails to align images along the
range
Training failure
Human Failure: Inattention/Poor
performanceOr
US images inadequate
AND
US QA failure
Systemic corrections
Quality assurance
Quality control
Managerial changes
Procedural changes
No Preventing Human Error
RO fails to align images along the
range
Training failure
Human Failure: Inattention/Poor
performanceOr
US images inadequate
AND
US QA failure
AND
QC failure: Prostate image
time out
Or
Add some QC down stream
CommissioningOr
Error in delineating
GTV/CTV (MD) and other
structures for planning and optimization
>3*sigma error contouring errors:
wrong organ, wrong site, wrong
expansions (1)
Inadequate or lack of procedures /
practices
Defective materials/tools/equipment (2.1,
2.2, 2.3)
User Error (2.5, 2.6)
Inadequate design specification (3.2)
Inadequate assessment of
operational capabilities (3.5)
Inadequate programming (3.6)
Inattention, Rushed process,
lack of time or staff, fatigue,
failure to review work
Or
Excessive delineation errors resulting in <3*
sigma segmentation
Errors (2)
Inadequate or lack of procedures /
practices
Availability of defective
materials/tools/equipment (2.1,
2.2)
Materials/tools/equipment used
incorrectly or inadequate
assessment of materials/tools/
equipment for task (2.5, 2.6)
Inadequate design specification (3.2)
Inadequate assessment of
operational capabilities (3.5)
Inadequate programming (3.6)
Inattention, Rushed process,
lack of time or staff, fatigue,
failure to review work
Inadequate training /
orientation (6.1)
OrPoorly drawn
contours (spikes, sloppy, etc) (3)
Inadequate or lack of procedures /
practices
Availability of defective
materials/tools/equipment (2.1,
2.2)
Materials/tools/equipment used
incorrectly or inadequate
assessment of materials/tools/
equipment for task (2.5, 2.6)
Inadequate design specification (3.2)
Inadequate assessment of
operational capabilities (3.5)
Inadequate programming (3.6)
Inattention, Rushed process,
lack of time or staff, fatigue,
failure to review work
Inadequate training /
orientation (6.1)
Or
250
255
260
265
270
366
326
212
Taken care of by the generally complete training, establishing clear communication
modalities (possibly forms) and establishing protocols, policies and
procedures
Key item for commissing
Key item for facility managerial changes
Taken from TG 100
Levels of QM
Commissioning Periodic Testing Per patient
Good Beginnings
Acceptance Testing is making sure the procedure works as specified. Usually applied to hardware and software. Also applies to walking through new procedures.
Commissioning gets a procedure started Gathers all the data needed. Gives confidence that systems work as expected. Finds when the system fails.
Essential to any procedure.
What to Do?
1. Understand the process2. Assess the hazards (e.g., FMEA)3. Establish the failure propagation patterns
(e.g., FTA)4. Address the hazards5. Test and evaluate – Quality
Improvement: a different presentation
Conclusions
Fault tree analysis facilitates quality planning:Redesigning to eliminate hazards.Adjusting resources.Ensuring the key core components.Performing comprehensive
commissioning.Establishing quality management.