Dose Course 2018_Flipping book

Dose per MU formalisms: factor-based dose calculations

Calculations at points off-axis (asymmetric fields)

2

(

)

(

)

; , , SSD xdsD

d cD

,

 SAD xd OAR d s TPR

  

  

( ) ( eqsq  p

)

(

)

( ) ,

d

ref

ref

 sS cS

=



,



c

eqsq d,

eqsq d,

M

M

d SSD

+

For off-axis positions up to 5cm no significant variation from the values CAX On-axis data used

Off-Axis Ratio: representing off-axis variations of primary fluence; different approaches to determine this experimentally