Advanced Physics for Brachytherapy 2018

TLD: absorbed dose energy dependence

) QwD

)0( Q TLDDQwD Q TLDD ) (

(

QQ rel f =

)0 , (

)0(

Best practice example for I-125 dosimetry with 6 MV linac calibration:

• f rel is close to 0.7 but varies with point around the source • Uncertainties: Type A=0.56%, type B=1%

Neglecting f rel would introduce a type B uncertainty (dose overestimation) of 40%...!

Moutsatsos et al. Experimental determination of the Task Group-43 dosimetric parameters of the new I25.S17plus (125)I brachytherapy source, Brachytherapy, 13(6), 618 (2014).