Advanced Physics for Brachytherapy 2018

Practical significance of f(Q), k bq

(Q)

➢ Using a detector at the same quality as calibration (Q 0

) is straightforward:

D

Qw

M

Q

) i factor corr .

N

QwAD

) 0(

=

) 0(

(

)0(



,

i

➢ Using a detector at a quality Q different than calibration (Q 0 ):

)0( , ) ( , QwADN QwADN =

) i i factor corr QMQwD  . ( )0(

)0( , QwADN

) ( =

) ( Qbqk

)0( , Qf QwADN

) (

QM

) i factor corr .

=

( )0( 

=

Qf

Qbqk

)0(

)0(

i

QM

) i factor corr .

)0 , ( bq kQQ rel f QwADN )0 , ( QQ rel

=

( )0( 

)0( ,

i

cannot be generally assumed energy independent must be calculated must be measured or taken from the literature for matching exp. conditions (Q, Q 0 bq k rel f , rel f rel bq k rel

, detector make,

size, set up, …)

f rel or k rel >1 => detector under-responds …! f rel or k rel <1 => detector over-responds …!