Dose Course 2018_Flipping book

Beam Profiles: Penumbra measurements using detectors of different sizes The volume effect

6 MV, d

(1.4 cm depth)

6 MV, 30 cm depth

max

31002 is a 125 mm 3 air ion chamber (PTW)

31002 is a 125 mm 3 air ion chamber (PTW)

80/20%

80/20%

Krauss [20]

Penumbra widening due to overestimated beam tails (scattered radiation outside beam – energy dependence)

Pin point 2.9mm