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Strategy
PTV Design Method
ICRU 50
Consideration of net effect of all possible geometric
variations
Estimation
Based on clinical perceived impact of geometric
uncertainties
Standard deviation
multiple
Standard deviation of uncertainty multiplied by
factor (e.g. 2x)
Bounding volume
Union of GTVs imaged at multiple instances
(4DCT)
Margin recipes
Weighted sum of random and systematic
uncertainty standard deviations
Adaptive radiation
therapy
Imaging from initial fractions used to determine
individualized PTV
PTV Margins