IMRT

Kernel-based methods: ‘Collapsed Cone’ approximation for efficient density rescaling

Further ‘smart’ approximations for efficient numerical implementation:

• separate treatment of deposited primary enery and deposited phantom scattered dose • further approximations for polyenergetic photon beams (details depend on implementation): Energy- averaged TERMA and point kernel; approximate or no modelling of beam hardening; …

primary photons

scattered primary photons

primary charged particles

charged particles from scattered prim. photons Direct beam phantom scatter dose

deposited primary energy deposited pri ary energy

Primary dose

Bremsstrahlung and annihilation photons

deposited scatter energy deposited scatter energy

charged particles from Bremsstrahlung and annihilation photons

Bremsstrahlung and annihilation energy deposited Bre sstrahlung and annihilation energy deposited

More details: Ahnesjö and Aspradakis 1999 (PMB 44(11))

ESTRO IMRT course 2015 Dose Calculation in Static and Rotational IMRT Brussels October 8th, 2015

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