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Table 2 Radiotherapy Planning targets, Organs at Risk and Dose Guidance

From: Randomised prospective phase II trial in multiple brain metastases comparing outcomes between hippocampal avoidance whole brain radiotherapy with or without simultaneous integrated boost: HA-SIB-WBRT study protocol

Volume Description Dose Target/ Limits Variation Acceptable Notes
GTV_45Gyb Contoured using fused contrast enhanced MRI images. 45Gy
98% covered by 100% dose
Hotspot > 110% within GTV
95% covered by 95% dose Lesion visible on at least 2 scan slices.
Coverage to be comprised to meet OAR constraints
PTV_45Gyb GTV + 0-2 mm isotropic margins 45Gy
98% covered by 95% dose
90% covered by 90% dose Coverage to be comprised to meet OAR constraints
GTV_40Gyb Tumour volume within/ ≤5 mm from OAR 40Gy
95% covered by 95% dose
Hotspot > 110% within GTV
90% covered by 95% dose Lesion visible on at least 2 scan slices.
Coverage to be comprised to meet OAR constraints
PTV_40Gyb PTV_40Gy = GTV_40Gy; i.e. no expansion 40Gy
95% covered by 95% dose
90% covered by 90% dose Coverage to be comprised to meet OAR constraints
GTVall_5mmb All GTVs + 5 mm isotropic margins For plan optimisation
Left & Right Hippocampus Contoured using fused MRI as per RTOG contouring atlas (http://www.rtog.org//corelab/contouringatlases/hippocampalsparing.aspx), excluding any GTV D100% (Dose to 100% volume) ≤ 9Gy
Dmax ≤16Gy
Dmax ≤33Gya
D100% ≤ 10Gy
Dmax ≤17Gy
Dmax ≤44Gyab
Dmax to 0.03 cc
Hippocampal Avoidance Zone (HAZ) Hippocampus + 5 mm isotropic margins For plan optimization
Left & Right Optic chiasm Dmax ≤33Gy Dmax ≤37.5Gyb
Dmax ≤40Gyab
Dmax to 0.03 cc
Left & Right Optic nerve Dmax ≤33Gy Dmax ≤35Gyb Dmax to 0.03 cc
Left & Right Orbits Dmax ≤33Gy Dmax ≤35Gyb Dmax to 0.03 cc
Left & Right Lens Dmax ≤6Gy Dmax ≤10Gyb Dmax to 0.03 cc
Brain Stem Dmax ≤33Gy Dmax ≤37.5Gyb
Dmax ≤40Gyab
Dmax to 0.03 cc
Left & Right
Cochlear
Dmax ≤33Gy Dmax ≤35Gya Dmax to 0.03 cc
Brain Brain parenchyma down to cranial margin of dens 30Gy
PTV_Brain (Brain + 3 mm isotropic margins) – (GTVall_5mmb + HAZ) 95% of volume covered by 30Gy
D2% ≤ 37.5Gy
D98% (Dose to 98% of volume) ≥ 25Gy
90% of volume covered by 30Gy
D98% ≥ 22.5Gyb
D2% ≤ 40Gyb
  1. aApplicable if tumours within/ ≤5 mm from OARsbOnly applicable to HA-SIB-WBRT plans