Dose Course 2018_Flipping book

Variation of s

for ion chamber

water,air

measurements

10 7 photons

1.050

Inside beam

Outside beam

1.045

60Co 4 MV 6 MV

1.040

10 MV 15 MV 18 MV

1.035

1.030

1.025

1.020

1.015

1.010

1.005

1.000

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)

Constant spectra over the field

Calculations performed with sprrznrc

From T. Kn öos

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