aapm tg-100 : a new paradigm for quality management in...

M. Saiful Huq, PhD, FAAPM, FInstP

Professor and Director of Medical Physics

University of Pittsburgh Cancer Institute and UPMC CancerCenter

Pittsburgh, Pennsylvania, USA

AAPM TG-100 : A new paradigm for quality

management in radiation therapy

1

Saiful Huq – AAPM TG100: ORVC and Penn-Ohio Chapter Meeting, 2013

Disclosures

2

• I have nothing to disclose


Acknowledgement

3

• Special thanks to Frank Rath from the University of

Wisconsin because I have taken many slides shown in this

presentation from his summer school presentations.


Authors of TG100

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M. Saiful Huq

(Chair)

Benedick Fraass

Peter Dunscombe John Gibbons

Geoffrey Ibbott

Sasa Mutic

Jeffrey Williamson

Bruce Thomadsen

Frank Rath

Jatinder Palta

Arno Mundt

Ellen Yorke

(Vice Chair)


TG100 analysis of causes of failure for IMRT

5

Human

failure

35%

Lack of

standardized

procedures

15% Inadequate training

15%

Inadequate

communication

10%

Hardware/Software

failure

9%

Lack of resources

6%

Design failure

5%

Inadequate

commissioning

3%

Defective

materials/tools

2%


Recent reports

6

2000

2009

2008

2008 2012

As technology and processes change

Retrospective approaches to QM are not

sufficient

All-inclusive QC checks may not be

feasible

Develop proactive approaches to failure

modes

Evaluate risks from each failure mode

Develop risk based approaches to QM


• Hazard identification and control approach is the basis for

safety planning procedures for manufacturing

• The design phase of the ISO safety strategy includes

identifications of hazards

assessment of the associated risk

removal of the hazards as much as practicable

Safety approach in industry


Quality management in industry

• Systematic application of specific tools that improve process

controls producing more consistent and closer to optimal

outcomes and reduce the risk of mistakes, errors or

hazardous outcomes


• Process controls for grilling a steak

– Experience/training – how much charcoal to pile in the

middle of the grill, etc.

– Measurement tools – watch (steak goes on the grill 20

minutes after igniting the coals)

– Because there are some variables that are difficult to

control – meat thermometer (135 deg. F)

Process controls

9


• Can the concept of risk identification and process control be

applied to healthcare to improve the quality of care for patients?

• Yes, of course. Healthcare situations readily lend themselves to

a similar risk identification and control approach

Healthcare environment


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


• Process tree (mapping)

• Failure mode and effects analysis (FMEA)

• Fault tree analysis (FTA)

• Establishment of a risk based QM program

Used IMRT as a case

study

Risk assessment tools


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


Simple example of a process map

15

patient enters

linac vault

TP shift

instruction shift

treat

setup

patient to

CT marks

Courtesy: Darek Brown


Complicated example: TG100 IMRT process tree

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


TG100 IMRT process tree

17

Successful treatment

Imaging and

diagnosis

12 Subsequent

treatments

Chart filing

Immobilization

equipment

fabricated

Immobilization equipment

documented,

labeled, and stored

Immobilization for

Imaging study

Set up data

documented

Time out

Positioning

Imaging (port films, CBCT, etc) 27

Documentation

Treatment 3

Treatment 3

Documentation

Immobilization

equipment

documented,

labeled, and stored

Scheduling

Approve

plan 7, 20

7 RTP anatomy

contouring

1 Patient database

information entered

Data into electronic

Database 22

Data into written

chart 22

Review of patient

medical history

Immobilization

equipment fabricated

Import and fuse images 16

MD: delineate

GTV/CTV 2,5

PTV construction

Edit density map

for artifacts

Delineate ROIs and

planning structures

Indicate motion/uncertainty

Management 13, 14

Specify registration goals 23, 38

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

And planning constraints 18, 21, 45

Setup fields

Setup dose

calc parameters

Optimization/

Dose calculation 12, 31

Evaluate plan 10, 28

6 Initial treatment

planning directive

8 Treatment planning

2 Immobilization

and positioning

3 CT simulation

9 Plan

approval

11 Initial treatment

Patient Identified

Special Instructions

(pacemakers, allergies,

preps, etc.) 9

Account for previous treatments

or chemotherapy 4

Motion management 8

Tx Unit operation

and calibration 3Information on

Previous or

concomitant treatment 22

Protocol for delineation

of targets 17

Patient ID

Treatment Site

Treatment settings

Imaging

Motion

Management 8

Protocol for PTV

Margin 6

Specify PTV Margin

Select Images 25

4D imaging correct 13

Optimization

ROI 33, 44

Optimization

settings 45

Treatment accessories 24

Boolean operations 29, 46

Changes noted 32, 34

Patient information 35

Monitor Pt/Tx 37, 43

Monitor Pt/Tx 37, 43

Specify ROI for optimization 19

Treatment settings

Positioning

Pt prep 35

Changes correct 40, 42Run leaf sequencer

Pt changes noted 42

Imaging Studies

Patient prepped

(contrast, tattoos,

BBs etc.)

Treatment accessories 24

4 Other imaging

Patient informed

Of imaging requirements

Images

Interpreted 1

Position

patient

Make images

5 Transfer

images

Transfer

Other datasets

Transfer CT

Dataset 41

Create case

4D representation

Save patient

Calculate dose

to optimization points

and dose distribution 12, 31

Heterogeneity correction 30

Evaluate leaf sequencer

Evaluate delivery

system limitations

Complete formal

prescription 36

Manual data entry and plan modification 39

Specify treatment course

Delivery protocols

Scheduling

Automatic data entry and plan modification

Prepare DRR and other images

Check version of

plan and patient ID

Annotate localization anatomy

Order fields

Prepare paper chart

Prepare electronic chart 15

Transfer patient data to treatment delivery 15

Define localization imaging

10 Plan

preparation

Enter demographics

Patient Position

Recorded in database

Patient information

Tx Unit operation

and calibration 3


FMEA

• A risk assessment tool used to identify weaknesses or

deficiencies (inadequate controls) in processes that could

lead to mistakes, errors, and potential hazardous outcomes


Strategy for improving patient safety: FMEA & FTA

• Begins with a complete and thorough understanding of the

process – flow charts, process maps

• Perform a Process FMEA (P-FMEA) to identify weaknesses

or inadequate controls in the process

• Develop process controls that either reduce the risk or

improve the process

• Use FTA to identify root causes of potential process failures

and develop recommendations to improve quality control of

the process


Completing an process FMEA

• Create a team

Ideally cross functional representing every function involved in the

process

Oncologists, medical physicists, dosimetrists, therapists, IT

personnel, administrators

Effort should be led by a facilitator trained in or familiar with the tools

used in the analysis

Consider providing training


Completing an process FMEA

• Select a process – key step

Scale is important

Opportunity – Quality issues, past problems, not happy with the level

of success, …

Realistic opportunity to make improvements

Complexity or size


Process FMEA – for each step in a process

Failure Modes

Cause

Detect

Effects

FM: Inability of a process

step to produce the

desired optimal outcome


Completing an FMEA

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Step Potential

failure

modes

Potential

causes of

failure

Potential

effects of

failure

O S D RPN Comment

For a given process:

RPN = O x S x D [ 1 ≤ RPN ≤ 1000 ]


Completing an FMEA

1. For each process step – identify all potential failure modes

– always best to define failure modes as “not” meeting

process requirements

2. For each potential failure mode – identify all of the causes

that could produce that failure

a. Focus on process related causes of failure modes


Completing an FMEA

3. For each potential failure mode – identify the effects of that

failure mode


Completing an FMEA

4. Current controls – judge the current capabilities of

the process controls to:

a. Prevent the cause of a failure from occurring

b. Detect a failure when it occurs

c. Moderate the severity of a failure when it

occurs


Completing an FMEA

• Most effective and lowest cost controls are those that

prevent causes of failure modes


FMEA ranking scales for Occurrence, Detection, Severity*

Occurrence of the cause of failure mode : O

Detection of failure mode: D

Severity of the effect when failure mode occurs: S

*Not used by TG100


• Risk Priority Number (RPN)

Occurrence ranking X Severity ranking X Detection ranking

Range of RPNs (1 -1000)

RPN of 125 or higher is problematic either in terms of safety or

process capability

Typical scenario –RPNs over 400!

Highest RPNs must be addressed first

Then work down to lower risk process steps

Completing an FMEA

29


• Risk Priority Number (RPN)

– Beware of patterns potentially hidden by low overall RPNs

Occurrence = 10, Severity =10, Detection=1 - RPN of 100 but

……

Occurrence=1, Severity=10, Detection=10 – RPN of 100 but ….

Severity of 10 – even if Occurrence and Detection are both a 1

can you or do you want to risk it?

Completing an FMEA

30


Top/Down FMEA approach

• Start with the major “branches” of the selected process

• Perform a PFMEA to identify which ‘branches” are the

weakest (most likely to produce sub-optimal results or

errors/mistakes

• Drill down deeper into those “branches” – more detailed

process map and PFMEA


Evaluates propagation of failures

Visual representation of propagation of failures

Begins on the left with a failure mode

Works backwards in time

(to the right to identify causes of failure)

Fault Tree

32


Evaluates propagation of failures

Visual representation of propagation of failures

Begins on the left with a failure mode

Works backwards in time

(to the right to identify causes of failure)

Fault Tree

33

Error in calculated value

for patient

Error in data

Error in data input

Error in calculation algorithm

Error in prescription

OR


Fault Tree

34

Errorin data

Errorin QC

Error in data input

Errorin QC

Error in Calculation algorithm

Errorin QC

Error in prescription

Errorin QC

Error in calculation

Errorin QA

Error in Calculated value for patient

Saiful Huq – AAPM TG100: ORVC and Penn-Ohio Chapter Meeting, 2013 TG100


• Current QA guidance documents are based on prescriptive

approaches evaluating technical performances of

radiotherapy equipment

• There has been a growing recognition that quality and

safety impairment arises from weakness in radiotherapy

processes

• Hence the change in approach in QM in TG100

Summary

36


Our job is not to prevent

errors, but to keep the

errors from injuring the

patients.

Lucian Leape

It is useful to report

all accidents before

consequences appear

It is impossible to make anything

foolproof because fools are so

ingenious.

Arthur Bloch, Murphy’s law

Thank you

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