693 / 1245
d
2·
d
max
d
MV/3 [cm]
The effective measurement depth in the mini-phantom/build-up cap must be large enough to stop
contaminating electrons.
6 MV
d=0.9 cm
d=5 cm
24 MV
d=4 cm
d=10 cm
d=2.3 cm
Frye DM, et al (1995) Med Phys 22, 249-53
Two rules of thumb
used to eliminate
e
-
contamination:
Factor-based dose calculations: basic dosimetric quantities
S
c
: mini-phantom/buildup cap design – depth considerations