ESTRO course on Image Guided Radiotherapy in Clinical Practice 2018

2D vs 3D setup

2D vs 3D setup

 33 patients, 100 paired CBCT-planar images  Varian OBI

 Phantom test: identical  Detected error in CBCT is larger in all directions  CBCT measurements better reproducible

2009

Fuller et al. 2009

Overall Conclusion 2D vs 3D setup correction  Planar imaging underestimates the setup error, especially if you do it manually  Deformation might contribute to this (Li et al., Fuller et al.)

Main reason for 3D setup

 But is 3D enough?

How flexible is the neck ?

How flexible is the neck ?

• Purple: reference CT scan

• PTV conflicts with OAR

• You cannot align all at the same time: Compromise!

• Green: daily

localization Cone Beam CT scan

• Need for choices in alignment!

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