IROC Houston QA Center end-to-end QA phantom program key findings - - PowerPoint PPT Presentation

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 Extent of

• f Acti

Activities vities

• 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 inserts 24 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 Phantoms

Phantom Patient Phantom Patient

Photon Phantom Results

Phantom H&N Liver insert Lung 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

10 20 30 40 50 60 70 80 90 520 540 560 580 600 620 640 660 680 700 Distance along line Dose Value Calc Meas

Criteria: 3%/2 mm

Varian 6 MV IMRT H&N

P Axial

9

10 20 30 40 50 60 70 80 90 520 540 560 580 600 620 640 660 680 700 Distance along line Dose Value Calc Meas

Measurement vs. Monte Carlo

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 50 100 150 200 250 Irradiation RPC/Inst

Average = 0.967 +/- 2.9% 274 irradiations Algorithms included: AAA/Superposition/MonteCarlo

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 50 100 150 200 250 Irradiation RPC/Inst

Average = 0.967 +/- 2.9% 274 irradiations Algorithms included: AAA/Superposition/MonteCarlo Average = 0.994 +/- 3.3% 30 irradiations Algorithms included: MonteCarlo

Lung Phantom Results Percent of pixels passing 5%/3mm gamma criteria

96 90 50 86 52 85 94 31 61 20 40 60 80 100 Pinnacle SC Eclipse AAA Eclipse PB XiO SC XiO Clarkson TomoTherapy SC MultiPlan MC MultiPlan PB Corvus PB

Percent of pixels passing ±5%/3mm criteria

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?