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GTV-N
CTV-N
PTV-N
Affected node
Individualized margin for microscopic ECE
5 mm Isotropic
margin around
CTV
Visible ECE
Combine extension from MRI & CT (≈ITV concept)
Typically up to 3 mm around GTV
Exclude muscle, bone, bowel
From GTV to CTV to ITV to PTV
EMBRACE 2 Protocol, Section 9
GTV: 0.5 cm
3
PTV 2.2 cm
3
For a 1 cm node:
≈
“Tight Margin”
Strategy
Daily image guidance