IMRT Course 2016

adapted from Woo and Cunningham 1990 (Med. Phys. 17(2))

Kernel-based methods: Rectilinear density rescaling of the kernel

r

r srEh rr = ρ

)(

(

)

(

) ) () ,( , − ⋅

water

2

rr

s r sr r r rr

, ,

) ,( ⋅

E h sr

ρ

ρ

s

⋅

rel

rel

ρ

water

‘Rectilinear’ rescaling with the mean relative density along the path between s and r:

this would be the kernel dose in a homogeneous medium: h water !

s r

( ) ′ s r

1

ρ

∫

( ) ,

r sd ′

rr sr

=

ρ

rel

s r r r r

−

ρ

water

r

…and after rectilinear rescaling

→ The point kernel dose is dependent on location inside of inhomogeneous media (patient!) → efficient numerical dose calculation w. fast fourier transform not possible without further approximations

r

ESTRO IMRT course 2016 Dose Calculation in Static and Rotational IMRT London April 7th, 2016

-31-