|Title: A stochastic optimization approach accounting for uncertainty in HDR brachytherapy needle Placement|
|Written by: T. Yu, F.-A. Siebert, A. Schlaefer|
|in: International Journal of Computer Assisted Radiology and Surgery CARS 2018 Jun 2018|
|Volume: 13 Number: Suppl 1|
|on pages: 34-35|
Abstract: HDR brachytherapy requires the optimization of dwell times to shape the dose distribution according to the planning target volume (PTV) and organs at risk (OAR). Often, this is done after needle placement, i.e., when the needle geometry is already fixed. However, the flexibility in arranging the needles can impact the plan quality. We include the selection of the needle geometry in the inverse planning problem and study whether uncertainties due to tissue deformation and needle deflection can be handled by a novel stochastic optimization scheme. To evaluate and illustrate the approach we consider a prostate brachytherapy scenario. Particularly, we consider uncertainty in the needles tip position, e.g., due to overly conservative insertion to avoid risking bladder damage, due to errors defining the needle tip in the images, or due to the limited seed positioning repeatability of the afterloading unit.