535 / 1119
•
48 nodes, 15 patients, repeat MRI during EBRT
•
Position shift in 6 directions assessed
•
Affected nodes also change their position
•
Order of magnitude lower than for primary GTV
(< 10 mm)
Maximal margins (computer)
0
1
2
3
4
5
6
7
8
9
med
lat
ant
post
sup
inf
margin (ml)
Inter-fraction motion of nodal CTV
Nodes also move! (a little)
Schippers M, et al. 2011