Dose Course 2018_Flipping book

Factor-based dose calculations: basic dosimetric quantities S c : mini-phantom/buildup cap design – lateral considerations

1. The entire mini-phantom/build-up cap should always be enclosed by the radiation field (incl. margin for penumbra). 2. The mini-phantom/build-up cap should provide lateral CPE; r CPE  5.973· TPR 20,10 - 2.688 [g/cm 2 ] Experimental investigations suggest that a wall thickness  1 g/cm 2 is sufficient.

 1.85 g/cm 2  2.06 g/cm 2

r r

CPE

CPE

Divergence!

Jursinic PA (2006) , Med Phys 33, 1720-8, Li et al MedPhys 22 , 1995, 1167-1170