Physics Bucharest 2017

Uncertainties

• IMRT/PT are generally more vulnerable to uncertainties mainly because of the steeper dose gradient and highly inhomogeneous in field fluence distribution. • Many sources of uncertainty need to be taken into account in treatment planning and delivery: → Patient positioning uncertainties → TPS Dose calculation algorithm approximations → Segmentation of tumor and critical structures based on medical images → Anatomical changes (and motion) during imaging and

treatment (inter-fraction and intra-fraction). → Machine technical delivery uncertainties

• RBE-weighted dose definition (only particle therapy)