1 RapidArc: Clinical Implementation Fang-Fang Yin, PhD Q. Jackie Wu, PhD Duke University Medical Center Acknowledgements • Team efforts from staff at Duke Radiation Oncology, especially to Dr. J Chang, Dr. J O’Daniel for providing slide information • Technical and financial supports from Varian Medical Systems Clinical Implementation of VMAT • Infrastructure/Installation • Acceptance testing/commissioning • Planning • Delivery • Quality assurance • Fundamentals for RapidArc Fundamentals for VMAT • Intensity Modulated arc therapy (VMAT) – An arc-based approach to IMRT – To be delivered on a conventional linear accelerator with a conventional MLC – During an arc, the leaves of the MLC move and dose rate changes continuously as the gantry rotates • RapidArc is one format of VMAT
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Acknowledgements RapidArc: Clinical Implementation · 1 RapidArc: Clinical Implementation Fang-Fang Yin, PhD Q. Jackie Wu, PhD Duke University Medical Center Acknowledgements •Team
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1
RapidArc: Clinical
Implementation
Fang-Fang Yin, PhD
Q. Jackie Wu, PhD
Duke University Medical Center
Acknowledgements
• Team efforts from staff at Duke Radiation
Oncology, especially to Dr. J Chang, Dr. J
O’Daniel for providing slide information
• Technical and financial supports from Varian
Medical Systems
Clinical Implementation of VMAT
• Fundamentals for RapidArc
• Infrastructure/Installation
• Acceptance testing/commissioning
• Planning
• Delivery
• Quality assurance
• Fundamentals for RapidArc
Fundamentals for VMAT
• Intensity Modulated arc therapy (VMAT)
– An arc-based approach to IMRT
– To be delivered on a conventional linear
accelerator with a conventional MLC
– During an arc, the leaves of the MLC
move and dose rate changes
continuously as the gantry rotates
• RapidArc is one format of VMAT
2
The Principle of IMRT: Dose Painting
Beam ProfilePTV
OAR
Conventional 3-field RT Expected 3-field IMRT
PTV
OAR
Typical dose
distribution
Static and Rotational IMRT
One aperture
At each angle
VMAT
Multiple apertures
At each angle
Static gantry IMRT
One arc from 179o 181o
Count-clockwise
Rotational IMRTStatic Gantry IMRT
Field1 @180o
One of 7 fields
The Format of Cone-Beam IMRT Volumetric Rotational IMRT Options
• Existing Planning Systems• Eclipse (Varian) – Duke choice
• ERGO++/Monaco (Elekta)
• Pinnacle SmartArc (Philips)
• Prowess (Prowess)
• Existing Delivery Systems• RapidArc (Varian) – Duke choice
• VMAT (Elekta)
• Cone-beam Therapy (Siemens) (WIP)
• Existing QA Systems• Matrixx – Duke choice for routine QA
• Film – Duke choice for commission
• SunNuclear
• Delta 4 – Duke choice for future QA device
• Optical Scanner ……
3
Where Are We (Duke)?
• Started investigation in June 2008
– A research RapidArc planning station from Varian
• Clinical installation in October
– Acceptance testing, commissioning, QA programs
– Single arc, no couch rotation, partial arc
• First patient treatment
– December 2008
• New versions in August 2009 and May 2011
– Allow multiple arcs, couch rotation, partial blocking, etc.
Clinical Implementation of RapidArc
• Fundamentals for RapidArc
• Infrastructure/Installation
• Acceptance testing/commissioning
• Planning
• Delivery
• Quality assurance
• Infrastructure/Installation
Infrastructure/Installation
• Staff (dedicated and trained)
• Existing machines:
– 21EX machine with 120-leaf millennium MLC
– NovalisTx with 120-leaf HD MLC (SRS, SRT,SBRT)
• ARIA version 8.6 or above (v10 now)
• Eclipse planning station (hardware and software)
• QA equipment
Clinical Implementation of RapidArc
• Fundamentals for RapidArc
• Infrastructure/Installation
• Acceptance testing/commissioning
• Planning
• Delivery
• Quality assurance
• Acceptance testing/commissioning
4
Acceptance Testing
• Machine readiness
• Verification of installation against items included in the
purchase order
• Inspections of safety and quality of installation and
components
• VMAT performance
• Testing of functionality of each component and system
performance against specifications.
• End-to-end testing
• Dry-runs for a few test case from simulation to delivery
Acceptance Testing Sample
• Test 1.1: Gantry Angle Calibration
– Tolerance: + 0.5°
• Test 1.2: Isocenter Calibration
– Tolerance: + 1 mm
• Test 1.3: General Arc Dosimetry
– Range: 0.2 MU/° to 5.0 MU/°
– Tolerance: + 1%
Acceptance Testing Sample
• Test 1.4
• dMLC Dosimetry
• 0.5cm MLC slit sliding over 4 cm range
• Gantry:0°, 90°, 270°, 180°
• Tolerance: + 2% (over mean value)
Acceptance Testing Sample
• Test 2.1:
• Accuracy of dMLC position vs. gantry position
• Tolerance: + 1 mm
5
Acceptance Testing Sample
• Test 2.2:
• Accuracy of dMLC position during arc
• Tolerance: + 1 mm
Acceptance Testing Sample
2.1: Picket Fence vs. Gantry Angle (static)
Acceptance Testing Sample
2.1: Picket Fence vs. Gantry Angle (static)
Acceptance Testing Sample
6
Acceptance Testing Sample
• Test 2.3:
• Ability to accurately detect MLC position error
• Criteria: detect sub-millimeter error in position
Acceptance Testing Sample
2.3: Picket Fence with Errors
• Test 2.4:
• Accuracy of dose rate and gantry speed control during RapidArc
• Tolerance: + 2%
Acceptance Testing Sample
• Test 2.5:
• Ability to control leaf speed/position during RapidArc
• Tolerance: + 2%
Acceptance Testing Sample
7
Acceptance Testing Sample
-200 -150 -100 -50 0 50 100 150 2001.00
1.02
1.04
1.06
1.08
1.10
1.12
1.14
1.16
1.18
1.20
Off x-axis Position (mm)
Rela
tive
Do
se
Off y-axis : -100 mmOff y-axis : 0 mmOff y-axis : 100 mm
Gantry speed
vs.
Dose rate
(Tolerance 2%)
Acceptance Testing Sample
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
Perc
en
t D
evia
tio
n (
%)
-60 -40 -20 0 20 40 60
Off X-axis Position (mm)
Off y-axis: -100 mmOff y-axis: 0 mmOff y-axis: 100 mm
Variation of gantry speed and dose
rate (tolerance 2%)
Commissioning
• Validate that VMAT is capable of delivering
radiation beams as good as SG-IMRT could
• Define the limitations of planning optimization,