Radiation Dose Informatics: Using the Tools of
Six Sigma to Improve Radiation Exposure
Prescription
Lots of Commercial Dose
Management Software!
3
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•
William Pavlicek
AAPM Clinical Meeting
Monday March 18, 2013
Phoenix AZ
©2011 MFMER | slide-1
©2011 MFMER | slide-2
Problem: Good IQ with high (or even too high) dose
Image Quality and Dose
Increasing
Image Quality
Increasing
Image Quality
Increasing
Radiation Dose
Increasing
Radiation Dose
©2011 MFMER | slide-3
Too high dose prescription must be avoided
Increasing
Image Quality
©2011 MFMER | slide-4
Narrow the range of x-ray prescriptions!
Increasing
Image Quality
Increasing
Radiation Dose
Increasing
Radiation Dose
©2011 MFMER | slide-5
©2011 MFMER | slide-6
Toyota reduced Variation ..Improved
Quality 1960s
“Inventor” of Six Sigma
W. Edwards Deming
• Physicist PhD (Yale, 28)
• Taught engineering,
physics in the 1920s
• Long career in
government statistics,
USDA, Bureau of the
Census
• Worked with Japan
W. Edwards Deming, 1900 – 1993
post war.
* From Montgomery, D. C. (2009), Introduction to Statistical Quality Control 6th edition, Wile y, New York
8
7
©2011 MFMER | slide-7
©2011 MFMER | slide-8
The Motorola Six-Sigma Concept 1980 - pagers
X-ray
Tubes
1990s
• Motoroloa found process subject to disturbances that could cause it to shift
by as much as 1.5 standard deviations off target.
• No process or system is ever truly stable!
• Thus 3.4 parts per million for this system
* From Montgomery
“The mean never happens,” — a 4-day delivery time on one order, with an awful 20day delay on another, and no real consistency! This customers in this chart feel
nothing. Their life experience hasn’t changed; one bit. The customer only feels the
variance that we have not yet removed. … Variation is evil in any customer-touching
process. *
*Jack Welch, General Electric Company 1998 Annual Report
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10
©2011 MFMER | slide-9
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Repeatability of device?
eg. New ACR Daily CT Phantom
What diagnostic medical physicists measure?
©2011 MFMER | slide-11
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These devices were repeatable with accurate
output,…..!!!
Reproducibility!!!
Different
Procedures/Protocols, Operator Training,
Patients!
©2011 MFMER | slide-13
©2011 MFMER | slide-14
Reduce System Variability
Six Sigma
Process Improvement with an Emphasis
on Achieving Significant Impact!
DMAIC (duy–may–ick)
• All work is performed in (interconnected) processes
• Easy to see in some situations (manufacturing)
• Harder in others
• Any process can be improved
• An organized approach to improvement is necessary
15
©2011 MFMER | slide-15
©2011 MFMER | slide-16
Basic Tenets of Quality
• It is the process that creates variability
• Belief that things can be improved
• A blameless environment is needed for team
solutions
• People closest to the product are most able to
affect quality
• Everyone has responsibility for quality
©2011 MFMER | slide-17
Measure, Analyze and Improve!
The Primary Six Sigma Tools
Reduce Exam Prescription Variability….
• Process map
• Cause and effect analysis
• Measurement systems analysis*
• Capability study*
• Failure mode and effects analysis
• Observational study (regression)*
• Designed experiments*
• Control charts and out-of-control-action-plans*
* Statistical Tools
Measure, Analyze and Improve!
19
©2011 MFMER | slide-19
GE ‘Dose Watch’
Reduce Exam Prescription Variability….
Executive Summary
Exams are grouped by the dose range
in 1 Gy increments,
The number of cases exceeding the
Dose Threshold (set by the customer)
are shown to the right.
22
5/3/2011
Six Sigma/Informatics and
Fluoroscopy
Three ‘steps’
to improve fluoroscopy x-ray
prescriptions
1. Adding Copper filtration
2. Lower pulse and frame rates
3. Table-Detector positioning
©2011 MFMER | slide-24
ANALYZE: Lucite 15 cm to 35 cm
20% Iodine solution for CNR measures
Slightly (~8-10%) reduced CNR
0.1 mm copper
CNR vs mm Cu Acquisition
160
140
120
15cm Lucite
CNR
100
20cm Lucite
25cm Lucite
80
27.5cm Lucite
30cm Lucite
60
35cm Lucite
40
20
0
0
0.2
0.4
0.6
0.8
1
mm Cu
©2011 MFMER | slide-25
BUT ~40% Lower Skin Dose 0.1mm Cu!
©2011 MFMER | slide-26
Step 1: EASY IMPROVEMENT!
Differential Dose Acquisition
P e rc e n t C h a n g e in D o s e fo r
A d d itio n o f C o p p e r
0%
-10% 0.0
0.2
0.4
0.6
0.8
• 0.1mm Copper minimum ADDED TO:
• 100% Stationary Fluoroscopy devices
• 100% protocols
• 100% Patients have 40% reduced exposure!
1.0
-20%
15cm Lucite
20cm Lucite
25cm Lucite
27.5cm Lucite
30cm Lucite
35cm Lucite
-30%
-40%
-50%
-60%
-70%
-80%
-90%
mm Cu
©2011 MFMER | slide-27
©2011 MFMER | slide-28
Step 2:Operator Frame Rate Behaviors
DMAI Control
• Lowering pulse and frame rates
• Important!: Can you see what is needed?
• Tool 1: Collect pilot examples
• Tool 2: Share results (data - Shine a light)
• Tool 3: Educate
©2011 MFMER | slide-29
©2011 MFMER | slide-30
7.5 FPS
cine
New
½ Dose
(70-75 bpm, II)
15 FPS
cine
Old
Dose
Tool 2
Data can Shine a
light!
(70-75 bpm, flat panel)
Names blocked out
Shine a light!
©2011 MFMER | slide-31
Ufors RaySafe
©2011 MFMER | slide-32
GE ‘Dose Watch’
Cumulative Dose (ESAK)
Incidence Map
Shows Cumulative dose (ESAK) with
respect to gantry angulations. The
horizontal axis indicates gantry positions
with respect to LAO/RAO patient
positioning, and the vertical axis indicates
cranial/caudal gantry positions. The dose
(ESAK) is displayed on the incidence map
indicating how much of the exam dose was
distributed to the patient with respect to the
position of the gantry in 30 degree
increments.
For purposes of reporting high skin dose
events, add up the max total dose in any
four contiguous blocks (four blocks with a
corner in common). This represents the
worst possible overlap of the collimated
fields, producing a "hot spot" that is
potentially higher dose than any one of the
fields
Unfors RaySafe
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5/3/2011
©2011 MFMER | slide-35
©2011 MFMER | slide-36
NEED TOOL!
Post Procedure
(Informatics)
• Was the 3.8 Gy skin exposure optimized?
• Analyze what happened!
• Educate to Improve behaviors
• Good Geometry?
• When was DSA
or Cine used?
©2011 MFMER | slide-38
DMAIC-Improve: Informatics Tool
ALARA Review
Informatics Tool 3
ALARA Review
3.8 Gy Total
3.8 Gy Total
Good!
Low detector!
High table
©2011 MFMER | slide-39
DMAIC-Improve: Informatics Tool
ALARA Review
©2011 MFMER | slide-40
DMAIC-Improve: Informatics Tool
ALARA Review
3.8 Gy Total
3.8 Gy Total
Detector
too high!
Max mag
needed?
Table too low!
Below IRP!
©2011 MFMER | slide-41
©2011 MFMER | slide-42
NOW!
Six Sigma/Informatics and
Computed Tomography
Dose Informatics and Analytics
CT Value Stream
(Process Map)
• Value is created via efforts of people as product
created (knowledge).
• Relentless pursuit of waste elimination as
competitive leverages
Value Stream for CT Radiology
Scheduling
Pt
check in
Pt prep
CTScan
Protocol
determined
Report
completed
Clinician Orders a CT
Clinician needs a CT
• Value to Patient/Physician customer is knowledge for
optimal next action
Clinician
Orders
Pt
check in
Protocol
determined
Pt prep
CTScan
Report
completed
• Value to Patient/Physician customer is knowledge for
optimal next action - ‘medical, surgical or
interventional’
Clinician
Orders
Patient
checks in
Protocol
determined
Pt prep
CTScan
Are there useful Prior Exams?
Eliminate Repeat?
Note Changes?
Report
completed
Clinician Reviews
Prior Exams
RSNA Image Share (NIBIB)
AWARE
AWARE
Unfors RaySafe
ClinicianOrders
Clinician
Orders
NEW
Exam
CT
MEANWHILE…. Technologist manages the
Protocol Book- the CT Exam ‘Scripts’
• Is this efficient?
Clinician
Orders
Patient
checks in
Protocols
Pt prep
CTScan
Unfors RaySafe
What set of acquisitions are on the
scanner?
On ALL scanners?
All the SAME?
Unfors RaySafe
Support for multiple scanners in
a single protocol
Full document control including
•
•
•
•
Track revisions to protocols
Review reminders
Web-based access
Customizable style sheets and
entry forms
Order in EMR transfers to
RIS – generates Order
Protocol Manager Tool
Protocol Manager Tool
Bayer HealthCare
EXPOSURE
Bayer
Protocol Management
In Com plia nce With HIPAA regulations. Pa tie nt informa tion liste d on the GUI are exam ples only and do not contain any actua l pa tient information
Exposure
Report
completed
Radiologists selects a CT ‘Script’
Radiologists selects a CT ‘Script’
• Prescribing an optimal CT exam
Clinician
Orders
Patient
checks in
Protocols
Pt prep
• Prescribing an optimal CT exam
CTScan
Report
completed
Clinician
Orders
Patient
checks in
Protocols
Pt prep
CTScan
Report
completed
Do radiogists standardize prescription
for indications?
What set of acquisitions create
optimal diagnostic content?
What set of acquisitions create
optimal diagnostic content?
CT tech and Nurse: Closest to Prescription
can highly affect quality!
Clinician
Orders
Patient
checks in
Protocol
determined
Correct Patient? Order? Exam?
Prep? Allergies?
Protocol
Pt prep
CTScan
Report
completed
Correct Patient? Order?
Protocol?
Scanner
• Scanners are NOT a node on the network!
• Scanner settings differ from Protocol Book!
• Differ between scanners
• Established console settings – good!
• On the fly changes – variability in exams
• Console settings complicated – need virtual
scanner
Tech Administers X-ray Script
Selects from CT Scanner
Individuals closest to ‘product’ most able to
affect quality
• Toyota Assembly Line worker STOPS the Line!
• Procedural Pause – Operating Room
Dose Check!
GE: Establish Dose Check Values by Protocol
Centering the Patient in the Gantry
Process Variability
1. Magnification Errors
Table Height in gantry
True
2. FOV Cut-off AP
3. FOV Cut-off Zaxis
• Lateral Laser Lights – Table Height
• Table Height – affects mA modulation
• Table more LIKELY to be too LOW
Perceived
Configure x-ray tube at top!
20 15 10 5
0
1. Mag Error - mA modulation
PA Scout
Table Low
5 10 15 20
52 cm
20 15 10 5
0
5 10 15 20
Tube: below
AP Scout
Table Center
45 cm
above
AP Scout
Table High
47 cm
above
AP Scout
PA Scout
©2011 MFMER | slide-68
2. FOV Cut-off AP
Patient low on
lateral scout.
Patient low on
lateral scout.
Raise table in
gantry.
Raise table in
gantry.
Acquire AP scout.
3. FOV Cut-off Zaxis
Scout misrepresents
patient position for FOV.
Re-acquire lateral Acquire AP scout. Scout represents
scout.
patient position for FOV.
©2011 MFMER | slide-70
Exam 1
FOV INSIDE of CT Radiograph!
Auto mA is working!
Exam 4
FOV OUTSIDE of CT Radiograph!
Auto mA is confused!
Properly Centered – No Mag
Patient LOW – CT Radiograph is
Magnified!
John DOE
PID : 12345
Series description : CAP
AN : 235647
Study description : CAP CT
I 56
LAT + AP =
646 mm
Diametereff = 31,5 cm
Protocol name = 5.1 CAP WO
Patient position : FFS
DLP = 597 mGy.cm
fSSDE =
Quality Review of CT Dose
1,16
IEC BODY PHANTOM
CTDIvol = 28,5 mGy
SSDE = 33,06 mGy
S703
LAT = 375 mm
AP = 271 mm
mA modulation
Off isocenter shift
Delta X = 28 mm
Delta Y = 33 mm
mA range :
Mean = 368 mA
Min = 149 mA
Max = 475 mA
Delta Y
Table height = 163
Delta X
• ACR National Radiation Dose Registry
• ACR CT Accreditation - Medical Physics Review
• Joint Commission SE #47
• California SB 1237
IEC BODY DOSIMETRY PHA NTOM
REDRAW
ACCEPT
New Requirements for CT ACR
Accreditation
ACR CT Quality Control Manual
©2011 MFMER | slide-75
©2011 MFMER | slide-76
JC: Institute a process for the review of all
dosing protocols…
NRDR – ACR Informatics for CT
Routine Head – No Contrast
©2011 MFMER | slide-77
©2011 MFMER | slide-78
JC: Investigate Doses outside the range
• 6030_Abdomen_Pelvis scan length 40-60 cm
Toolkit
©2011 MFMER | slide-79
mSv
Bayer HealthCare
Bayer HealthCare
Exposure
Exposure
Integrated Dosimetry
Examination Analysis
In Com plia nce With HIPAA regulations. Pa tie nt informa tion liste d on the GUI are exam ples only and do not contain any actua l pa tient information
In Com plia nce With HIPAA regulations. Pa tie nt informa tion liste d on the GUI are exam ples only and do not contain any actua l pa tient information
Informatics - Powerful tools for your toolbox!
Thank you!
a
Bayer HealthCare
Paden, Robert G. (Gene)
Boltz, Thomas F. III
PHYSICIST-DIAGNO STICIM… SPEC-DIAG RAD PHYSICS…
Hanson, James A .
Zhang, Min
SPEC-DIAG RAD PHYSICS… SCIENTIST/PRO GRAMMER…
Loprino, Shi rley A ., R.T.(R)
MGR-RAD IMAG-AZ
Ermer, Ellen R.
ANALYST III-BUS SYS…
Sabyan, Stephen J., R.T.
…
SUPV-IR/CATH-AZ
Ledoux, Elaine M., R.T. ...
TECH-CT IMAG II-AZ
Leyk, Linda L., R.T.(R)... Osborn, Howard H., R.N.
TL-CT IMAG-AZ
SUPV RN-INPT/365-AZ
Wilt, Michelle A ., R.T.(R)
SUPV-GEN RAD IMAG-AZ
Naidu, Sailendra G., M.D.
CO NS-DIAGNO STIC RAD
Exposure
Integrated Dosimetry
In Com plia nce With HIPAA regulations. Pa tie nt informa tion liste d on the GUI are exam ples only and do not contain any actua l pa tient information
Kriegshauser, Jef f ry S. , M.D.
CO NS-DIAGNO STIC RAD
Hara, A my K., M.D.
CO NS-DIAGNO STIC RAD
Wu, Lin-Wei
Mango Kaise r, Janice H. …
SCIENTIST/PRO GRAMMER… SUPV-CT IMAG-AZ
Fike, Rachel D.
TECH I-CLINICAL ENG-AZ
Huettl, Eric A ., M.D.
CO NS-DIAGNO STIC RAD
Sanche z, Juan J .
TL-BIO MED/IMAG-AZ
Wellnitz, Clinton V., M.D.
CO NS-DIAGNO STIC RAD