Dose Course 2018_Flipping book

Dose per MU formalism: Elekta Oncentra MasterPlan

Including monitor signal M b

caused by backscatter depending on collimator setting

(

)

(

)

, ; D A x y ;

z

; , D A x y ;

z



−

1

(

)

( ) A

0

b

=

1  +

Includes head scatter and phantom scatter

M

M



0

0

(

)

ref ref ; , D A x y z M ref ref ,

 

 



0

Meas

= 

−

1

M

 

(

)

(

)

(

)

( ) ref A

D A

ref x y ,

z

b

;

,



1  +

0

ref

ref

ref

0



Calc

Empirical factor from S c measurements

z

mon

z

2 mon 2 coll

z

coll

( ) b A k F = back

3

cos



M b

Monitor chamber

F

A

=

d



z

2

(

)

z

z



−

M

Irradiated collimator area

0

coll

mon

(

)

D w 

D A

;prescription conditions

presc ; at prescription point/conditions from field i i

i

M

=

w

= 

i

(

)

i

all fields

D A

i

(

)

D A

;prescription conditions

i

M

i

=1