Flipping Book - TVD

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Keeping things in perspective
• GTV  PTV margin
– All cells in the GTV are considered to be tumor
– Punderdosage = Pgeometrical miss
– Use margin prescription
• CTV  PTV margin
– In the CTV there is a probability of tumor cells
– Punderdosage = Pgeometrical miss x Ppresence of tumor cells
– Margin can probably be smaller
• Caveat: Tumor cell probability is needed