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Purpose: Structure-based deformable image registration (DIR) can be used to calculate accumulated dose volume histogram parameters for cervical cancer brachytherapy (BT). The purpose of this study is to investigate dose warping uncertainties for the accumulated dose to the 2 cm 3 receiving the highest dose [Formula: see text] in the rectal wall, using a physically realistic model (PRM) describing rectal wall deformation., Methods and Materials: For 10 patients, treated with MRI-guided pulsed dose rate BT (two times 24 × 0.75 Gy, given in two applications BT1 and BT2), the planning images were registered with structure-based DIR. The resulting transformation vectors were used to accumulate the total rectum dose from BT. To investigate the dose warping uncertainty, a PRM describing rectal deformation was used. For point pairs on rectum BT1 and rectum BT2 that were at the same location according to the PRM, the dose for BT1 and BT2 was added (D PRM ) and compared to the DIR-accumulated dose (D DIR ) in the BT2 point. The remaining distance after DIR between corresponding point pairs, defined as the residual distance, was calculated., Results: For points within the [Formula: see text] volume, more than 75% was part of the [Formula: see text] volume according to both PRM and DIR. The absolute dose difference was <7.3 Gy EQD2 , and the median (95th percentile) of the residual distance was 8.7 (22) mm., Conclusions: DIR corresponded with the PRM for on average 75% of the [Formula: see text] volume. Local absolute dose differences and residual distances were large. Care should therefore be taken with DIR for dose-warping purposes in BT., (Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: Graphical optimization (GrO) is a common method for high-dose-rate/pulsed-dose-rate (PDR) prostate brachytherapy treatment planning. New methods performing inverse optimization of the dose distribution have been developed over the past years. The purpose is to compare GrO and two established inverse methods, inverse planning simulated annealing (IPSA) and hybrid inverse treatment planning and optimization (HIPO), and one new method, enhanced geometric optimization-interactive inverse planning (EGO-IIP), in terms of speed and dose-volume histogram (DVH) parameters., Methods and Materials: For 26 prostate cancer patients treated with a PDR brachytherapy boost, an experienced treatment planner optimized the dose distributions using four different methods: GrO, IPSA, HIPO, and EGO-IIP. Relevant DVH parameters (prostate-V100%, D90%, V150%; urethra-D(0.1cm3) and D(1.0cm3); rectum-D(0.1cm3) and D(2.0cm3); bladder-D(2.0cm3)) were evaluated and their compliance to the constraints. Treatment planning time was also recorded., Results: All inverse methods resulted in shorter planning time (mean, 4-6.7 min), as compared with GrO (mean, 7.6 min). In terms of DVH parameters, none of the inverse methods outperformed the others. However, all inverse methods improved on compliance to the planning constraints as compared with GrO. On average, EGO-IIP and GrO resulted in highest D90%, and the IPSA plans resulted in lowest bladder D2.0cm3 and urethra D(1.0cm3)., Conclusions: Inverse planning methods decrease planning time as compared with GrO for PDR/high-dose-rate prostate brachytherapy. DVH parameters are comparable for all methods., (Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)