Assessing Heterogeneity Correction Algorithms Using the Radiological Physics Center Anthropomorphic Thorax Phantom

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1 Assessing Heterogeneity Correction Algorithms Using the Radiological Physics Center Anthropomorphic Thorax Phantom David Followill, Ph.D. Associate Director Radiological Physics Center

2 RPC History Lesson Formed by agreement between AAPM and Committee for Radiotherapy Studies (CRTS) chaired by G. Fletcher Founded in 1968 to monitor institution participation in clinical trials Funded continuously by NCI as structure of cooperative group programs have changed Now 43 years of experience of monitoring institutions and reporting findings to study groups and community

3 Mission Assure NCI and cooperative groups that institutions participating in clinical trials deliver prescribed doses that are comparable and consistent. (Minimize dose uncertainty) Help institutions to make any corrections that might be needed. Report findings to the community.

4 Clinical Trial Participants Number of Active Institutions 1,650 ~3,300 megavoltage machines ~20,000 active megavoltage beams # of Institutions # of Machines Active Machines Active Institutions Year Year

5 Purpose of Credentialing Educate Evaluate ability to deliver dose using advanced technologies Improve understanding of protocol Reduce deviation rate

6 Credentialing Technique Previous patients treated with technique Facility Questionnaire Knowledge Assessment Questionnaire Benchmark Case Electronic data submission Protocol patient dosimetry review Rapid Review Phantom Irradiation (end to end test)

7 What are Advanced Technologies in clinical trials? TRACKING TPS IMRT DOSE PAINTING HETERO CORRECTION IGRT KV OR MV IMRT Respiratory Control GATING SBRT

8 IMRT/SBRT Planning and Delivery - QA required at each step Positioning and Immobilization Image Acquisition (CT, MR) Structure Segmentation Black Box IMRT/SBRT treatment planning and dose calc. File transfer and management Plan validation Position verification treatment delivery What You See Is NOT What You Always Get

9 Delivery Plan OAR PTV Cord/bone

10 4 SRS phantoms RPC Phantoms family 10 prostate phantoms (IMRT) 10 thorax phantoms (SBRT) 30 H&N phantoms (IMRT) 3 Spine phantoms 2 liver phantoms (SBRT)

11 RPC Lung phantom

RPC Phantom Design Anthropomorphic shape Water filled Plastic inserts containing targets and organs at risk (heterogeneity) The phantom is to be Point dose treated (TLD) and planar as if

12 RPC Phantom Design Anthropomorphic shape Water filled Plastic inserts containing targets and organs at risk (heterogeneity) The phantom is to be Point dose treated (TLD) and planar as if (radiochromic it were film) a dosimeters patient. Purpose is to evaluate the complete treatment process 1. Imaging and transfer of images to planning computer 2. Development of treatment plan 3. Phantom set up on treatment couch 4. Dose delivery

13 Some institutions go overboard!!

14 Dose distribution - CERR

15 Phantom Analysis Development Electronic TLD analysis Electronic film analysis Import and view digital data Gamma calculation

16 Initial Phantom Results TPS Precise BrainLab Eclipse Ergo RenderPlan Pinnacle XiO Dose Calc. Algorithm # irradiations Center of Tumor TPS D hetero /D homo Scatter Int. Clarkson ± 2.6% Clarkson & Pencil beam ± 2.2% Pencil Beam ± 4.3% 3D Convol.. Pencil Beam ± 0.1% Change in primary attenuation Adaptive convolve ± 2.1% Superposition/Convolution ± 2.3% Clearly, there are two groupings

17 PTV Periphery and Lung Points PTV = Tumor (CTV) cm in axial plane + 1 cm in longitudinal plane. Lung constraint: points 2 cm from the PTV X PTV Periphery X CTV X X X CTV X Lung points Axial Plane Longitudinal Plane

18 Initial Phantom Results (PTV Periphery) TPS TPS Dose Calc. Algorithm # irradiation D hetero/ D homo Axial plane Precise BrainLab Eclipse Ergo Pinnacle XiO Scatter Int. Clarkson ± 3.2% Clarkson & Pencil beam ± 1.6% Pencil Beam ± 4.3% 3D Convol.. Pencil Beam ± 1.3% Adaptive convolve ± 4.2% Superposition/Convol Convol ± 5.3% Two separate groupings again

19 Initial Phantom Results (PTV Periphery) Measurements TPS Precise Dose Calc. Algorithm # irradiation PTV Periphery measured D TLD/film /D hetero Scatter Int. Clarkson BrainLab Eclipse Ergo Pinnacle XiO Clarkson & Pencil beam Pencil Beam D Convol.. Pencil Beam Adaptive convolve Superposition/Convol Convol Two separate groupings again

20 Initial Phantom Results (Lung points) TPS TPS Dose Calc. Algorithm # irradiation D hetero/ D homo Axial plane Precise BrainLab Eclipse Ergo Pinnacle XiO Scatter Int. Clarkson ± 4.2% Clarkson & Pencil beam ± 5.5% Pencil Beam ± 8.3% 3D Convol.. Pencil Beam ± 5.3% Adaptive convolve ± 5.8% Superposition/Convol Convol ± 6.4% Two separate groupings again

21 Eclipse AAA Profile 8 Left Right 6 Dose (Gy) 4 2 PTV Distance (cm) RPC Film Institution values AAA

22 Eclipse Pencil-Beam Profile Left 8 Right 6 Dose (Gy) 4 2 PTV Distance (cm) RPC Film Institution values PB

23 Gamma Analysis results Pass 99.7% Pass 60.6%

24 Pinnacle Convolution R-L Profile Left Right Left Profile Axial plane Righ Average displacement Left side: on: 3 mm off: 1 mm Prescribed D Average displacement Rigth side: on: 1 mm off: 5 mm Dose (Gy) D2cm 10 PTV Distance (cm) RPC Film ITC off ITC on RPC Regression Institution Regression

25 Brain Lab Pencil-Beam Profile Right Left Profile Axial plane Left 30 Right Average displacement Left side: on: -2 mm off: -6 mm Prescribed D 20 Average displacement Right side: on: -5 mm off: -2 mm Dose (Gy) D2cm 10 PTV Distance (cm) RPC Film ITC off ITC on RPC Regression Institution Regression

26 Pinnacle Calculation and Delivery Medial-Left Lateral Profile Pinnacle Absolute Dose (cgy) GTV PTV Film Avg Pinnacle -5% or 3mm +5% or 3mm Distance (mm) ISODOSE: Pinnacle, Axial, Film #2 16 Jul 7 Anterior to Posterior (mm) Medial to Distal (mm) GTV Measured Calculated GTV 96% PASS ±5%/3mm >99% PASS ±7%/7mm FAIL

27 Eclipse AAA Calculation and Delivery Medial-Left Lateral Profile Eclipse AAA Absolute Dose (cgy) GTV PTV Film Avg Helios-AAA -5% or 3mm +5% or 3mm Distance (mm) ISODOSE: Eclipse AAA, Axial, Film #5 16 Jul 7 Anterior to Posterior (mm) Medial to Distal (mm) GTV GTV Measured Calculated

TomoTherapy, Axial, Film #2 16 Jul 7 Anterior to Posterior (mm) Medial to Distal (mm) 0 20 40 60 80 100 120

28 500 TOMO Calculation and Delivery Medial-Left Lateral Profile TomoTherapy Absolute Dose (cgy) GTV PTV Film Avg TOMO -5% or 3mm +5% or 3mm Distance (mm) ISODOSE: TomoTherapy, Axial, Film #2 16 Jul 7 Anterior to Posterior (mm) Medial to Distal (mm) GTV GTV Measured Calculated

29 Eclipse PB Calculation and Delivery Medial-Left Lateral Profile Eclipse PB Dose (cgy) GTV Film Avg Eclipse PB +5% or 3mm -5% or 3mm PTV Distance (mm) ISODOSE: Eclipse PBC, Axial, Film #5 16 Jul 7 Anterior to Posterior (mm) Medial to Distal (mm) GTV GTV Measured Calculated

30 CyberKnife ray-tracing GTV Film 1 Film 2 Film 3 Film Avg TPS +5%/3mm -5%/3mm Initial results were not good with ray-tracing algorithm PTV TLD measured doses in the center of the PTV to be ~13% low compared to calculated values. Profiles were correct shape, but wrong absolute dose.

31 CyberKnife 11 Left Average displacement Left side: 1 mm Prescribed D Right-Left Profile Axial plane 8 Right Average displacement Right side: 2 mm Monte Carlo 6 Dose (Gy) D 2cm 4 Average TLD RPC/Inst = PTV Distance (cm)

32 Binary Agreement Map Analysis Percent of pixels passing ±5%/3mm criteria Pinnacle SC Eclipse AAA Eclipse PB XiO SC TomoTherapy SC MultiPlan MC MultiPlan PB Corvus PB

33 Stationary vs. Motion lung target No difference in the results New criteria are ±5% dose to TLD and average percent of pixels passing 5%/5 mm must be 85% and no single film with < 80% of pixels passing

34 Phantom Results Comparison between institution s plan and delivered dose. Phantom Thorax Irradiations 237 Pass 178 Fail 59 (25%) Criteria 5%/5mm Year introduced 4

35 Phantom Results Comparison between institution s plan and delivered dose. Phantom Thorax Irradiations Pass Fail 59 (25%) 121 (51%) Criteria 5%/5mm 5%/3mm Year introduced 4 4

36 More Good News >80% Pass Rate RPC H&N and Lung Phantoms Percent of Passing Irradiations H&N lung Year

37 Acceptable Brain Lab / Monte Carlo Eclipse / AAA Pinnacle / Collapsed Cone Convolution Adaptive Convolve XiO / Superposition Fast Superposition Helax / Collapsed Cone TomoTherapy / Convolution Superposition Corvus / Monte Carlo Multiplan / Monte Carlo In House TPS / Monte Carlo Unacceptable Brain Lab / Pencil Beam Eclipse / Pencil Beam Pinnacle / Fast Convolve XiO / Modified Clarkson Convolution Helax / Pencil Beam Corvus / Pencil Beam Multiplan / Ray Tracing In House TPS / Pencil Beam or Clarkson base

38 Phantom Accomplishments Use of heterogeneity corrections for modern algorithms Test ability to hit a moving target(s) Corrected many dosimetry errors that might have impacted on patient doses Testing proton therapy planning and dose calculations (in development)

39 Thank You Questions?

SBRT Credentialing: Understanding the Process from Inquiry to Approval

SBRT Credentialing: Understanding the Process from Inquiry to Approval David Followill, Ph.D. (presented by Andrea Molineu, M.S.) IROC Houston QA Center July 15, 2015 What is credentialing? Verification