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A 3D optimization-based thermal treatment planning platform has been developed for the application of catheter-based
ultrasound hyperthermia in conjunction with high dose rate (HDR) brachytherapy for treating advanced pelvic tumors.
Optimal selection of applied power levels to each independently controlled transducer segment can be used to conform
and maximize therapeutic heating and thermal dose coverage to the target region, providing significant advantages over
current hyperthermia technology and improving treatment response. Critical anatomic structures, clinical target outlines,
and implant/applicator geometries were acquired from sequential multi-slice 2D images obtained from HDR treatment
planning and used to reconstruct patient specific 3D biothermal models. A constrained optimization algorithm was
devised and integrated within a finite element thermal solver to determine a priori the optimal applied power levels and
the resulting 3D temperature distributions such that therapeutic heating is maximized within the target, while placing
constraints on maximum tissue temperature and thermal exposure of surrounding non-targeted tissue. This optimizationbased
treatment planning and modeling system was applied on representative cases of clinical implants for HDR
treatment of cervix and prostate to evaluate the utility of this planning approach. The planning provided significant
improvement in achievable temperature distributions for all cases, with substantial increase in T90 and thermal dose
(CEM43T90) coverage to the hyperthermia target volume while decreasing maximum treatment temperature and reducing
thermal dose exposure to surrounding non-targeted tissues and thermally sensitive rectum and bladder. This
optimization based treatment planning platform with catheter-based ultrasound applicators is a useful tool that has
potential to significantly improve the delivery of hyperthermia in conjunction with HDR brachytherapy. The planning
platform has been extended to model thermal ablation, including the addition of temperature dependent attenuation,
perfusion, and tissue damage. Pilot point control at the target boundaries was implemented to control power delivery to
each transducer section, simulating an approach feasible for MR guided procedures. The computer model of thermal
ablation was evaluated on representative patient anatomies to demonstrate the feasibility of using catheter-based
ultrasound thermal ablation for treatment of benign prostate hyperplasia (BPH) and prostate cancer, and to assist in
designing applicators and treatment delivery strategies.
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