Optimization of breast cancer ablation volume by ultrasonic pressure field characterization

Abstract

In order to favor the potential in improving both oncologic and cosmetic results in breast cancer therapy, an Ultrasound (US) probe that increases cancer ablation volume and preserves neighboring healthy tissues in a modeled realistic breast from being ablated is designed using a finite element analysis (FEA) tool in this work. The acoustic pressure field and focal point of the Focused Ultrasound (FUS) are characterized by optimizing the transducer's frequency at 1.3 MHz and the initial water temperature at 20 °C. These optimal conditions yield qualitative properties of the FUS at the focal point, which are extended to wider areas to achieve quantitative results by displacing the probe at reduced time intervals of less than 60s. An elliptical focal volume of 10.2 mm (along the beam axis) × 4 mm (in the transverse direction) at 50s of dosing for a tumor diameter of 10 mm has been generated. Furthermore, a fractional healthy tissue damage of 2.1%, a rise in temperature of 99 °C above the ablation threshold temperature (42 °C) at 100 s of sonication, and an increase in pressure oscillation (favoring cavitation) at the focus are achieved. The optimal conditions of the setup are subjected to sensitivity tests and are found to be mostly sensitive to variations of the transducer frequency on which depend the attenuation coefficient and thermal conductivity of the tissue as well as the surface intensity of the transducer.