Imaging Studies Used for:
Staging
Image Registration:
The Challenge for QA Centers
Protocol Eligibility
Target Volume Definition
Adaptive Radiation Therapy
Treatment Delivery
Assessment of Response
Outcome Analysis
Kenneth Ulin, Ph.D.
Marcia M. Urie, Ph.D.
Quality Assurance Review Center
Types of 3D Imaging:
CT
MRI
PET
Kapoor, V. et al. Radiographics 2004;24:523-543
Copyright ©Radiological Society of North America, 2004
QA for Multi-Institutional Studies
Requiring Registration of Different Imaging Sets
QARC: Image Fusion Benchmark
(Developed For COG Low Grade Glioma Protocol)
MR –CT for Target Delineation
Two Approaches to QA:
Require a credentialing exercise to ensure that an
institution has the tools and expertise to
adequately perform the image registration required
by the protocol.
And/or
Verification of the image registration for individual
patients on protocol.
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QARC FUSION Benchmark
QARC FUSION Benchmark
Outline target on
2 MR slices
“fuse” DICOM
CT & MR
scans
Display on CT
QARC FUSION Benchmark
QARC FUSION Benchmark
Results from 11 software systems
Report the center
of the target and
the center of this
rod on the most
inferior CT slice.
Software System
Type of matching
Software System
BrainScan
automatic
Philips Pinnacle
manual & auto
Type of matching
automatic
manual & auto
match points
manual
Corvus
match points
Pinnacle/Syntegra
automatic
Varian Eclipse
automatic
Plato
match points
manual & auto
PLUNC
manual
Radionics XKnife
match points
Oncentra MasterPlan
automatic
manual & auto
match points
CMS Focal
automatic
manual & auto
In-House
manual
2
QARC FUSION Benchmark
QARC FUSION Benchmark
True target center: average of all submissions.
Error Distribution
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Average error in the position of the center of the target: 1.4 mm
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One standard deviation in the displacement of the target center from the
true target center: 1.7 mm
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No. in each range
The uncertainty (one standard deviation of the mean): 0.2 mm
8
6
4
Acceptability criteria
2
(from first 17 submissions): 3 mm
0
0.0 - 0.5 0.6 - 1.0 1.1 - 1.5 1.6 - 2.0 2.1 - 2.5 2.6 - 3.0 3.1 - 3.5
Error Range (mm)
QARC FUSION Benchmark
QARC FUSION Benchmark
Results:
Registration Method
# benchmarks
Average Error (mm)
51 submissions from 45 institutions
Manual
11
1.1
Automatic
27
1.6
15 by dosimetrists
Manual & Automatic
8
1.3
35 by physicists
Match Points
5
1.4
1 by radiation oncologist
51
1.4
Overall
~80% approved on first submission
3
QARC FUSION Benchmark
Credentialing of institutions for use of image registration
in a clinical trial can be best accomplished by:
20%
Conclusion: Studies requiring registration
of MR and CT for target delineation need
to add 2-3 mm to PTVs and PRVs to
account for registration uncertainties.
20%
20%
20%
20%
A.
B.
C.
D.
E.
A questionnaire that asks detailed questions about the
institution’s software and procedures.
Distribution of two scan sets of a specially designed phantom, for
which the correct transformation matrix is known.
Re-registering the image sets for the first patient enrolled on the
study.
Distribution of two scan sets of an actual patient, for which the
correct transformation matrix is approximately known.
Requiring the involvement of radiation oncologist, physicist, and
dosimetrist in the credentialing exercise.
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Answer: (D) Credentialing of institutions for use of image
registration in a clinical trial can be best accomplished by
distribution of two scan sets of an actual patient, for which
the correct transformation matrix is approximately known.
Explanation:
A. A questionnaire does not test ability to perform the image
fusion.
B. A phantom test is too easy.
C. Re-registering the image sets for the first patient enrolled
on the study is labor intensive, and the correct answer is
not known.
E. Involvement of radiation oncologist, physicist, and
dosimetrist in the process is desirable, but is not a
credentialing test and does not usually happen in practice.
PET
&
PET/CT
DICOM
coordinates
registration
between
PET and CT
scans
Kostakoglu, L. et al. Radiographics 2004;24:1411-1431
Copyright ©Radiological Society f North America, 2004
4
PET
PET
CT
CT
Using fiducial markers
Fiducial markers : mark alignment locations for PET and CT study
Lavely et al.: Validation of CTPET image registration
Medical Physics, Vol. 31, No. 5,
2004
Magenta
8.0 mm
Yellow
4.0–6.0 mm
Robinson et al.: Copper fiducial markers for CT and PET
Medical Physics, Vol. 31, No. 9, September 2004
PET & CT
Green
2.0–4.0 mm
Quantitative PET
SUV calculations (Standardized Uptake Values):
great interest in clinical trials to assess
staging
response
outcome
SUV calculation:
Kostakoglu, L. et al. Radiographics 2004;24:1411-1431
Copyright ©Radiological Society of North America, 2004
Clinical trials (and QA centers) allowing subjective expertise of
radiation oncologists for correlation of PET with CT planning scans.
DICOM standard does not include all required information
for SUV calculations,
so recalculation by QA centers is difficult.
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Image Guided Adaptive Therapy
Challenge for QA Centers of
Image Guided Adaptive Therapy
Planning CT
MV CT
Tomotherapy
MV CT
kV CT
Cyberknife
ultrasound
Challenge for QA Centers of
Image Guided Adaptive Therapy
Planning CT
kV CT
on board
imaging
Challenge for QA Centers of
Image Guided Adaptive Therapy
Planning CT DRR
on-board plain images
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Challenge for QA Centers of
Image Guided Adaptive Therapy
CT
Challenge for QA Centers of
Image Guided Adaptive Therapy
Ultrasound
Cost-benefit of individual patient review must be weighed relative to
the time & labor to:
gather
transmit
organize
archive
review
Challenge for QA Centers of
Image Guided Adaptive Therapy
Currently QA centers are concentrating on verifying the
accuracy of the entire process for each institution.
ATC (Advanced Technology Consortium) is
developing credentialing criteria
QA for Multi-Institutional Studies
Requiring Registration of Different
Imaging Sets
Challenge
verifying institutions’ systems and capabilities
(credentialing)
verifying individual protocol patient’s treatment
We wish to acknowledge the companies that have provided
many of the images shown in this presentation.
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References
Phantom validation of coco-registration of PET and
CT for imageimage-guided radiotherapy, W. C. Lavely
et al, Med. Phys. 31(5):108331(5):1083-1092, 2004.
Image registration and data fusion in radiation
therapy, M. L. Kessler, BJR 79:S9979:S99-S108, 2006.
Results of a MultiMulti-Institutional Benchmark Test
for Cranial CT/MR Image Registration, K. Ulin
and M. Urie,
Urie, Med. Phys. 33(6): 2048, 2006.
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