Physics Bucharest 2017

6/3/2017

The inverse problem How do we create the cost function Optimise:

Physical dose  Target coverage (min, max, …)  Target homogeneity  OAR exposure (max, …)  Surrounding tissues  …

Biological effect  TCP, NTCP  EUD  …

DVH goals

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ESTRO physics course 2017

Cost function

Penalty for not having uniform dose d 0 (optimising uniformity in target)

 Is the relative weight factor

1







2



T 





C

d d

i

0

n



Ti

T

1







d

Penalty for any dose to OAR (minimising the mean of the OAR)

OAR

1

i

n



OAR i

1

OAR

1

1











 

H

d d d d

OAR

2

i

0

i

0

n



OAR i

2

OAR

2

Penalty for dose above “tolerance dose d 0 (keeping max dose below d 0 )

“ in OAR

H(x)

22