2017_SBRT_Course Book

Motion compensation techniques

è The tumour is ~10% of the time at 50% of the dose è This only accounts for about 5% underdose è Even with large amplitudes, the margin needs not to be large. è Mid-ventilation or Mid-position approach

4D

• The radiation beam does not necessarily need encompass the complete breathing amplitude Ø Broad beam penumbra in the lung tissue Ø Time spend at edges of “ITV” is short Ø Dose loss at edges can be compensated for by higher doses at the centre

SBRT 2017 - D. Verellen