1504 / 1542
0.0
0.5
1.0
1.5
0
20
40
60
distance from central axis [cm]
6MV
10MV
15MV
18MV
Peripheral equivalent dose:
neutrons
% of tumor dose
0.0
0.5
1.0
1.5
0
20
40
60
distance from central axis [cm]
6MV
10MV
15MV
18MV
Peripheral equivalent dose:
photons
% of tumor dose
Kry et al 2005
Neutrons:
important for energies > 10 MV
For 18 MV,
neutrons
are more important than
photons
for large distances
Prostate IMRT plans
14
Equivalent dose
Measured peripheral photon and neutron
equivalent doses