426 / 1601
2.5
S
+ 0.7
s
is a simplification
•
Dose gradients (‘penumbra’ =
s
p
) shallower in
lung
smaller margins for random errors
•
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
p
M
s
s
s
64
.1
)
( 64.1 5.2
2
2
+
+S =
p
p
M
s
s
s
84
.0
)
(
84.0 5.2
2
2
+
+S
=