Dose Course 2018_Flipping book

Head scatter: equivalent square of a rectangular field

Head of a treatment unit

Linac head

Empirical approach to account for different influence of collimator layers

primary collimator

S f

(

)

yx1G  

+

flattening filter

y) (x, c e

=

S U

wedge monitor chamber

y xG

+ 

S L

upper Y-jaws

lower X-jaws

➔

x

lower jaw

y upper jaw G weighting factor depends on: ➔

MLC leaf

➢ treatment head design ➢ beam energy ➢ beam modifiers

isocentre

Vadash P and Bjärngard B E (1993) Med. Phys. 20, 733-734.