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Margins ? ! ?
But margins for ………….
•
uncertainties in seed placement ?
- x/y direction – no problems
- z direction – corrections during implantation
•
change of volume ?
- only temporary problem
- edema resolves within the first ½ life of seeds
•
change of position ?
- eventual use of stabilization needles
- continuous on-line verification of position
So:
forget about margins for PTV definition PTV = CTV