Multiparametric MRI-guided High-dose-rate Prostate Brachytherapy with Focal Dose Boost to Dominant Intraprostatic Lesions

摘要

The use of multiparametric MRI (mp-MRI) can reliably identify dominant intra-prostatic lesions (DILs) within prostatecancer. Dose escalation to DILs using high-dose-rate (HDR) brachytherapy may improve tumor control probability. Inthis study, we retrospectively investigated a total of 17 patients treated by HDR prostate brachytherapy, each of whomhas mp-MRI and CT images acquired pre-treatment. 21 DILs were contoured based on mp-MRI and propagated to CTimages after registration using a newly developed deformable image registration method. A boost plan was created foreach patient and optimized on the original needle pattern. In addition, separate plans were generated using a virtuallyimplanted needle around the DIL in order to simulate mp-MRI guided needle placement. Both plans were optimized tomaximize DIL V150 coverage while meeting OAR sparing constraints. DIL V150, prostate coverage, and OAR sparingwere compared with original plan results. Overall, optimized boost plans significantly escalate dose to DILs whilemeeting OAR constraints. The addition of mp-MRI guided virtual needles facilitate increased coverage of DIL volumes,achieving a V150 >90% in 85% of DILs compared with 57% of boost plan without an additional needle. These resultsstrongly indicate that the proposed mp-MRI guided DIL boost in HDR brachytherapy is feasible without violating OARconstraints. This retrospective study suggests the use of mp-MRI-defined DIL to optimize needle placement through thedeformable MRI-ultrasound registration in the operating room may represent a strategy to personalize treatment deliveryand improve tumor control.