Diapositive 1

T Knöös

0.990

0.995

1.000

1.005

1.010

1.015

1.020

1.025

1.030

1.035

1.040

1.045

1.050

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)

Relative mass stopping power ratio

60Co

4 MV

6 MV

10 MV

15 MV

18 MV

photons

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

Field limit

Constant spectra over the field

Calculations performed with SPRrznrc

Outside beam

Inside beam

Variation of

water,air

for ion chamber measurements