Physics Bucharest 2017

Measured peripheral photon and neutron equivalent doses

Prostate IMRT plans

Peripheral equivalent dose: photons % of tumor dose

Peripheral equivalent dose: neutrons % of tumor dose

1.5

1.5

1.0

1.0

6MV 10MV 15MV 18MV

6MV 10MV 15MV 18MV

0.5

0.5

0.0

0.0

Equivalent dose

0

20

40

60

0

20

40

60

distance from central axis [cm]

distance from central axis [cm]

Neutrons: important for energies > 10 MV For 18 MV, neutrons are more important than photons for large distances

Kry et al 2005

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