Dose 2016

Lateral variation of beam quality

Double exponential, incl. depth parameterization and lateral beam quality variations (“off-axis softening”) for flattened beams

Laterally constant kernel:

r

out,

i

I

( , ; ) D d A x

1

p

; i A ⋅ ∑ ∫ Ψ

(

)

, ,HVL 2 r d π

rdr

≈

CAX

( ) M A M A ( )

ρ

i

1

=

r

in,

i

x

Including lateral beam quality shift:

r

out,

i

I J

( , ; ) D d A x

1

p

Ψ

, ; i j A ⋅ ∑∑ ∫

(

)

, , , HVL 2 i j r d π

rdr

≈

( ) M A M A ( )

J

ρ

i

1 1 j

= =

r

in,

i

x

T Nyholm, et al (2006) Phys. Med. Biol. 51 4111-4118

Olofsson et al (2006) Med Phys 33 , 3418-25