Dose Course 2018_Flipping book

Factor-based dose calculations: basic dosimetric quantities

S c : mini-phantom/buildup cap design – depth considerations

The effective measurement depth in the mini-phantom/build-up cap must be large enough to stop contaminating electrons.

24 MV

6 MV

d=4 cm

d=5 cm

d=10 cm

d=0.9 cm

d=2.3 cm

Two rules of thumb used to eliminate e - contamination:

d  2· d max d  MV/3 [cm]

Frye DM, et al (1995) Med Phys 22, 249-53