ESTRO course Dose Modelling and Verification 2017

Beam energy spectra - spectral filtering by the flattening filter

barn / Sr

cm 2 /g

Bremstrahlung production cross section, Z=74, 10 MeV

1000

10

attenuation coefficient, Z=74

5

100

1

0.5

10

1

0.1

0.05

MeV

8 MeV

0

10

20

30

40

50

0

2

4

6

 E

Direct beam spectrum, principal shape. Spectrum distorted offaxis towards lower energies due to less filtration & decreasing energy with increasing brem angle

23

energy