Microsoft PowerPoint - Physics Bucharest

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Variance Reduction Techniques
 Particle Splitting
 To get more particles to the patient
 Split particle close to the patient and simulate track for
both particles independently
 Statistical weight is adjusted
 Often used for the brehmsstrahlung photons in the target
inside the linac head
 History Repetition
 Applied to electrons
 …
Danger of not probing all parts of the geometry
Reducing calculation time per history means simplifying the physics