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Skin marks versus daily bony registration
Daily image guidance with bony fusion
Initial set-up according to skin marks
Image fusion according to bone
Verification of fusion
Couch correction
Typically 5mm PTV margin
Set-up on skin marks (no daily image guidance):
Imaging at first RT or
e.g. weekly
Typically 7-10mm PTV
margin
L.Laursen, RO 105 (2012) 220–225
Variable
Vertical
[mm]
Lateral
[mm]
Longitudinal
[mm]
Mean (M)
0,4
2,7
0,4
Σ
3,6
2,9
2,6
σ
3,6
3,2
2,4
Margin*
11,6
9,6
8,2
*Van Herk formalism:
2,5*Σ+0,7*σ
Semin Radiat Oncol 2004; 14:52-64
CT
CBCT