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IGRT for Head and Neck
Coen Rasch
Head and Neck
No disclosures
Contents
Delineation
2D vs 3D setup accuracy
Deformation during RT course
Delineation of GTV in H&N
10 patients with NPC (cT2b – cT4, Nx)
10 Observers from 6 institutes in NL, D and US
Phase I
– Delineation of GTV on CT
– Diagnostic MRI copy available
Phase II, after > 1 year
– Improved delineation protocol
– Delineation on co-registered CT/MRI
– Computer aided delineation tool (Snake algorithm)
3-D median surface with local SD
0.0 – 0.5
0.5 – 1.0
1.0 – 1.5
1.5 – 2.0
2.0 – 2.5
2.5 – 3.0
3.0 – 3.5
3.5 – 4.0
4.0 – 4.5
4.5 – 5.0
5.0 – 5.5
5.5 – 6.0
6.0 – 6.5
6.5 – 7.0
7.0 – 7.5
> 7.5
LOCAL SD (mm)
Overall observer variation (SD)
Anatomical regions
Phase 1
Phase 2
SD CT (mm)
Agreement
(%)
SD CT/MRI
(mm)
Agreement
(%)
All regions 4.4
36
3.3
64
Anterior – Air
3.4
62
2.7
79
Dorsal – Bone
3.6
49
2.7
84
Contra lateral
4.2
16
3.5
66
Pterygoid M.
4.3
35
3.1
61
Parapharyngeal
4.4
31
3.3
59
Soft Palate
4.7
37
3.0
67
Sphenoid
5.0
28
4.2
48
Caudal side
7.7
5
3.3
56