Cervix BT - 2016

Example: random uncertainties for target OAR

Random variation of rectum D 2cm³ e.g. random intra-/inter-fraction variation of organ position or shape

Random variation of target D 90, e.g. random inter-observer variation

For target – differences in TCP < 0.5%

• ∆ D 2cm³

=±10%/fx -> observed morbidity 7.5 % (vs 7.3% model prediction) =±20%/fx -> observed morbidity 8.9 %

• ∆ D 2cm³ • ∆ D 2cm³

=±30%/fx -> observed morbidity 10.5 % • Model prediction: 10.5% NTCP@ 80Gy EQD2

“Can reduction of uncertainties in cervix cancer brachytherapy potentially improve clinical outcome?” Nesvacil et al. 2016, submitted to R&O