ESTRO course on Image Guided Radiotherapy in Clinical Practice 2018

2.5 S + 0.7 s is a simplification

• Dose gradients (‘penumbra’ = s p ) shallower in lung  smaller margins for random errors

s ) ( 64.1 5.2 2 2 s

M

+S =

s  + 64 .1

p

p

• Number of fractions is small in hypofractionation • BUT: beam on time is very long  respiration only causes dose blurring

• Dose prescription at 80% instead of 95%

p 2

2

M

=

+S

s ( 84.0 5.2 +

s

)



.0

84

s

p