Advanced Physics for Brachytherapy 2018

) ( QD

Phantom correction

ww

,

p

=

phant

) ( Q D

, phant w

• Phantom material MUST be checked for density variation and composition (Ca or other high Z content variation that can be up to 30%) to minimize type B uncertainty.

• High purity plastics (PMMA, polystyrene) might be preferable since p phant deviation from unity is greater for LE source dosimetry BUT type B uncertainty of the correction will be lower.

1

p

phant

Figure from: Luxton, Med. Phys. 21(5), 631 (1994)