Dose Course 2018_Flipping book

Modelling of source size & electron transport

energy fluence profile for an ideal point source

TPR 20/10 =0.68 20%->80%=0.23 cm

Penumbra width influenced by source size

TPR 20/10 =0.80 20%->80%=0.52 cm

Only at very high beam energies (or in low density regions) lateral electron transport alone dominates penumbra shaping

Energy fluence profile: finite source size 0.35 cm

Energy fluence profile: finite source size 0.70 cm

-2

-1

1

2

g/cm 2

0

Nyholm et al Rad. Onc. 78, pp 347-51 and PMB 51 pp 6245-62 (Anders Ahnesjö)

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