Hippocampal sparing whole brain RT
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Anthony Magliari
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Conflict of Interest disclosure
• Anthony Magliari
• Employed by Varian Medical Systems
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Overview
• What is HCSWB-RT?
• Why do it?
• What protocols exist?
• Beam arrangements
• Optimization strategies
• Additional resources
• 2015 AAMD / Sun Nuclear Plan Challenge
• 2016 AAMD Hippocampal Sparing presentation by Timothy Oh
• Knowledge Based Planning solution (RapidPlan) on Oncopeer
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What is Hippocampal Sparing WBRT?
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Why HCSWB-RT?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2997490/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3462659/
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Protocols: RTOG 0933 / NRG-CC001
• RTOG 0933 superseded by…
• NRG-CC001 (30Gy in 10Fx)
“treatment-planning
priorities should be
followed:
1.
2.
3.
4.
5.
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OpticChiasm
OpticNerve_L
OpticNerve_R
Hippocampus
PTV_3000
Lens_L or
Lens_R”
Other Protocols / planning guides
• NRG-CC003 (Prophylactic Cranial Irradiation)
• 25Gy in 10 Fx
• Scaled down version of NRG-CC001
• Prokic V, et al (Whole Brain Irradiation With Hippocampal
Sparing and Dose Escalation on Multiple Brain Metastases:
A Planning Study on Treatment Concepts)
• 30Gy in 12Fx with SIB for metastasis to 51Gy
• http://www.redjournal.org/article/S0360-3016(12)00302-1/pdf
• 2015 AAMD / Sun Nuclear Plan Challenge
• Combined Rx from Prokic V with RTOG 0933 contraints, and more
• http://planchallenge.sunnuclear.com/
• Oncopeer Rapidplan Solution and Description Document
• 30Gy in 10 Fx with 7Gy HCS goal and constraints from all the above
• Posted by Rob Foster http://www.oncopeer.com
•
menu > my groups > RapidPlan – Model Sharing > activity
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Beam arrangements
• Preferred: 3 or 4 arcs (6X or 6X FFF)
• 2 non-coplanar arcs 315*/45* collimator and 1 or 2 vertex ½ arcs
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Vertex ½ arc 90* couch and MLCs parallel to arc direction (0*) or
Vertex ½ arcs 90* couch and 315*/45* collimator
• Check jaws to ensure arcs open to entire brain throughout rotations
• 2 non coplanar arcs, same as above no vertex
• Non coplanar partial arcs with “sub PTVs”
• Shen J, et al Medical Dosimetry journal
• Referenced in Timothy Oh’s 2016 AAMD presentation
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Beam arrangements
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Optimization
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General tips
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Ask for reasonable goals (don’t drastically overshoot)
Never create conflicts in the optimizer
Use and tune with NTO (“rings” normally unnecessary in Eclipse)
Let the total cost function line get completely flat
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Pause VMAT optimizer at each step
Increase max seconds for static field IMRT
Specific tips
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Understand the lower you push dose to the Hippocampus the more
heterogeneous (hot spots), 115-120% Dmax not abnormal and OK
Use a “PTVopt” with an expansion from the hippocampus of 7-8mm
when shooting for ~7Gy min dose
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Optimization
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Other resources: 2015 plan challenge
• Includes video interviews with top performers from all TPS
• http://planchallenge.sunnuclear.com/webinars
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Other resources: 2016 AAMD meeting
http://atlanta2016.medicaldosimetry.org/2016AnnualConference/assets/File/Wednesday/Oh.pdf
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Other resources: RapidPlan on Oncopeer
https://varian.app.box.com/v/HCSWB
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Questions?
•
Anthony Magliari
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