Post on 15-May-2022
IROC Houston QA Center end-to-end
QA phantom program key findings over
the past 15 years
David Followill, Ph.D.
AAPM 2017 Summer Meeting
Denver, CO
July 30, 2017
Extent of Activities
• 1,837 RT facilities
participate in NCTN and
monitored by IROC
Houston
• 329 other sites (primarily
international also audited
• 56 countries monitoring a
total of 2166 sites
• Largest QA audit program
• Shipping >700 phantoms/yr
Imaging, Planning and Delivery - QA required at each step
Positioning
and
Immobilization
Image
Acquisition
(CT, MR)
Structure
Segmentation
treatment
planning
File
transfer and
management
Plan
validation
Position
verification
treatment
delivery
Black Box
Thus the need for an end-to-end
QA audit tool to verify the
intended treatment goal.
Deliver the correct dose
to correct location
as planned
Phantom Family
2 prostate phantoms
19 SRS phantoms
33 lung phantoms
8 Spine
phantoms 10 liver inserts24 H&N
phantoms
• Anthropomorphic shape with targets and OARs
• Independent “end to end” audit
• Imaging• Planning/dose calculation• Setup• delivery
• Uniform phantoms and dosimeters
• Standardized analysis
• Uniform pass/fail criteria
• Allows inst. to inst. comparison
• Established infrastructure
Benefits of IROC-H PhantomsPhantom Patient
PhantomPatient
Photon Phantom Results
Phantom H&NLiver
insertLung Prostate Spine
Irradiations 2052 165 1109 566 336
Pass 1755 (86%) 120 (73%) 921 (83%) 484 (86%) 261 (78%)
Fail 297 45 188 82 75
Criteria 7%/4mm 7%/4mm 5%/5mm 7%/4mm 5%/3mm
Comparison between institution’s plan and delivered dose.
Problems that have been
detected
0 10 20 30 40 50 60 70 80 90520
540
560
580
600
620
640
660
680
700
Distance along line
Do
se V
alu
e
Calc
Meas
Criteria: 3%/2 mm
Varian 6 MV IMRT H&N
PAxial
9
0 10 20 30 40 50 60 70 80 90520
540
560
580
600
620
640
660
680
700
Distance along line
Do
se V
alu
e
Calc
Meas
Measurement vs. Monte Carlo
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2.0
LATERAL
L
R L
Lung Phantom TLD results
TLD results
Irradiation Lung Phantom
0.90
0.92
0.94
0.96
0.98
1.00
1.02
1.04
1.06
1.08
1.10
0 50 100 150 200 250
Irradiation
RP
C/I
nst
Average = 0.967 +/- 2.9%
274 irradiations
Algorithms included:
AAA/Superposition/MonteCarlo
Lung Phantom TLD resultsTLD results
Irradiation Lung Phantom
0.90
0.92
0.94
0.96
0.98
1.00
1.02
1.04
1.06
1.08
1.10
0 50 100 150 200 250
Irradiation
RP
C/I
nst
Average = 0.967 +/- 2.9%
274 irradiations
Algorithms included:
AAA/Superposition/MonteCarloAverage = 0.994 +/- 3.3%
30 irradiations
Algorithms included: MonteCarlo
Lung Phantom ResultsPercent of pixels passing 5%/3mm gamma criteria
9690
50
86
52
85
94
31
61
0
20
40
60
80
100
Pin
nac
le S
C
Ecl
ipse
AAA
Ecl
ipse
PB
XiO
SC
XiO
Cla
rkso
n
TomoThera
py SC
Multi
Pla
n MC
Multi
Pla
n PB
Corv
us PB
Pe
rce
nt
of
pix
els
pa
ss
ing
±5
%/3
mm
cri
teri
a
Proton Phantom Audits
• 136 proton phantoms irradiated, analyzed
Brain Liver Lung Prostate Spine TOTAL
Total Irradiations 25 14 38 38 21 136
# Passed 24 7 24 30 17 102
Pass Rate [%] 96% 50% 63% 79% 81% 75%
Lung Phantom Results
Lung Phantom Results
Lung Phantom Results
Summary
• Introduction of new technologies present challenges that need to be verified prior to treating patients
• End-to-end QA phantoms detect errors, improve dose delivery accuracy and provide confidence
• Improved compliance with protocol prescription specifications and reduced deviation rate
Questions?