Thesis defense: Development of an extracorporeal torus-shaped transducer and a novel multi-toroidal focalization strategy for the treatment of mammary adenocarcinomas by high intensity focused ultrasound.

Author: Marine Sanchez
Time: 15H00
Language: French
Place: Visioconference (need to subscribe with the button below the summary)

Summary: 
High Intensity Focused Ultrasound (HIFU) is a technique commonly used in the medical field for the treatment of solid tumors. This therapeutic strategy allows for the localized destruction of biological tissue by temperature elevation. This manuscript describes the design and utilization of a therapeutic system and a novel, patented focalization technique for non-invasive treatment of mammary adenocarcinomas. In a first instance, an existing device that has been previously used for intraoperative treatment of hepatic metastases, and one that is currently undergoing clinical trials, was used. An ex vivo study on human mammary samples demonstrated the possibility of applying pressures on deep tissue layers in a non-invasive manner. Based on this study, the development of a new focalization modality was developed to provide larger treated volumes while yielding treatment times under a minute and eliminating the need for mechanical steering of the device. This new modality provided treated volumes 30% larger than those produced by the existing device with no changes to treatment time. Given the limitations of the existing device, in addition to the need of integrating the new focalization strategy, a new device was designed and specifically fabricated to meet the demands for treating mammary adenocarcinomas. The natural focalization of this novel transducer allows for depositing pressure deep in tissue. When the new focalization modality is used, a larger pressure field produces increased treated volumes. The performance provided by the novel probe was first characterized through modeling studies. These results were then validated through preliminary in vitro studies on hepatic tissues as well as in ex vivo studies on human mammary tissue samples. This work represents the first stage of development of a HIFU treatment for mammary adenocarcinomas using a novel, non-invasive and image-guided HIFU device that can be used manually.