Towards Model Based Conformal Ablation using Robotically Driven Interstitial Ultrasound

Gandomi, Katie Y.

Etd

Towards Model Based Conformal Ablation using Robotically Driven Interstitial Ultrasound

Public

The treatment of malignant brain cancers remains a challenge, especially for tumors with low survival rates with standard care or those located near eloquent tissues where surgical resection may be more complicated. Thermal ablation is a treatment option in oncology being researched for these clinical cases which may be ineligible for conventional interventions. There are several modalities for administering the required thermal energy to coagulate cancerous cells, however, in this work, we pursue the use of needle based therapeutic ultrasound (NBTU) for minimally invasive interstitial thermal ablation. Achieving appropriate margins during these procedures is vital to reduce the chance of tumor recurrence as well as to protect nearby sensitive biological structures. However, the accessibility, size, and shape of the cancer can make accomplishing these margins a challenge. Directional heating by an NBTU applicator can be robotically rotated to produce ablation patterns that conform to the tumor boundary and selectively target malignant cells while conserving surrounding healthy or delicate tissues. In this work, we study and investigate the use of a wide beam NBTU applicator that can be used to perform conformal tumor ablation. Toward this goal, we first developed a software architecture that can be used to control an MRI compatible neurosurgery robot for conformal ablation. Next we developed three numerical models to predict the thermal propagation produced by our NBTU applicator. These numerical models allowed for a research ecosystem within which we developed a novel reinforcement learning algorithm for optimal pre-operative path planning for interstitial conformal ultrasound ablation. Finally, in this dissertation we also present a novel closed-loop controller for preforming real-time MR-guided conformal ablation using a multi-system integration that incorporates a robot-rotated NBTU applicator with experimental validations in tissue mimicking phantoms.

Creator