Dose Course 2018_Flipping book

Variation of s

for ion chamber measurements

water,air

10 7 photons

1.050

Outside beam

1.045

60Co 4 MV 6 MV

1.040

10 MV 15 MV 18 MV

1.035

1.030

1.025

Inside beam

1.020

1.015

1.010

1.005

1.000

Constant spectra over the field

0.995 Relative mass stopping power ratio Field limit

0.990

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 Off axis distance (cm)

Stopping power ratios along a radii at 10 cm depth in water

Calculations performed with SPRrznrc

T Knöös