ESTRO course on Image Guided Radiotherapy in Clinical Practice 2018

Head and Neck

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IGRT for Head and Neck

Coen Rasch

Contents

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

 Delineation  2D vs 3D setup accuracy  Deformation during RT course

 Phase II, after > 1 year

– Improved delineation protocol – Delineation on co-registered CT/MRI – Computer aided delineation tool (Snake algorithm)

Overall observer variation (SD)

3-D median surface with local SD

Phase 1

Phase 2

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)

Anatomical regions

Agreement (%)

SD CT/MRI (mm)

Agreement (%)

SD CT (mm)

All regions 4.4

36

3.3

64

3.4

62

2.7

79

Anterior – Air

3.6

49

2.7

84

Dorsal – Bone

4.2

16

3.5

66

Contra lateral

4.3

35

3.1

61

Pterygoid M.

4.4

31

3.3

59

Parapharyngeal

4.7

37

3.0

67

Soft Palate

5.0

28

4.2

48

Sphenoid

7.7

5

3.3

56

Caudal side

1