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