740 / 1359
• To quantify variations in energy fluence
incident on the patient
• Function of the collimator
setting
• Depends on the photon beam quality and
on treatment head design
• Depends on the field orientation for
rectangular beams (CEE)
• Almost independent of the
source-detector distance
• Does not depend on depth
if z > R contam. electrons
Summary: in-air output ratio, Sc
isocentric conditions
E lekta
P rec is e
0,93
0,95
0,97
0,99
1,01
1,03
1,05
0 5 10 15 20 25 30 35 40
S quare F ield s iz e [c m]
O
O
6 MeV
10 MeV
25 MeV
6 MeV
0,94
0,96
0,98
1,00
1,02
1,04
1,06
1,08
1,10
0 5 10 15 20 25 30 35 40
S quare F ie ld s iz e [cm]
O
O
E lekta P rec is e (ML C )
G E S at 43 (ML C )
G E S at 43 (C C )