Iterative learning control for high-intensity focused ultrasound treatments

Divyadeep Upadhyay; Christoph Schaal

doi:10.1117/12.2583539

22 March 2021 Iterative learning control for high-intensity focused ultrasound treatments

Proceedings Volume 11593, Health Monitoring of Structural and Biological Systems XV; 1159311 (2021) https://doi.org/10.1117/12.2583539
Event: SPIE Smart Structures + Nondestructive Evaluation, 2021, Online Only

Abstract

High-intensity focused ultrasound (HIFU) is currently being used for the ablation of tissue, such as in the case of prostate cancer. However, targeting tissue deeper inside the body remains challenging due to a variety of complications, including the increased scattering and attenuation of the ultrasonic waves. This work addresses the problem of exciting HIFU waves of a specific, desired wave form. That is, the utilized HIFU transducers are typically driven at their resonance frequency to maximize power output, which leads to significant distortions of the excited wave forms. In turn, these ringing effects can also have an impact on laboratory experiments as the resulting excess oscillations can obscure observations of visualization techniques, and in the clinic may cause unintended energy deposition at the target location. To mitigate this, an iterative learning control (ILC) approach is utilized with the intent of generating precise wave packets. Specifically, a PD-type and an H-infinity Synthesis approach are used to generate the ILC. It is shown that both ILCs lead to significant improvement of the excited pressure waves in simulation, i.e. the waveform more closely represents the desired tone burst. Furthermore, the model-based ILC design is shown to outperform the PD-type ILC, thus providing a systematic methodology. In addition to demonstrating its usefulness for developing new therapies through shadowgraph experiments, the methodology’s feasibility for future clinical use is discussed through an energy deposition analysis of more realistic wave forms for potential HIFU therapies.

Conference Presentation

Citation Download Citation

Divyadeep Upadhyay and Christoph Schaal "Iterative learning control for high-intensity focused ultrasound treatments", Proc. SPIE 11593, Health Monitoring of Structural and Biological Systems XV, 1159311 (22 March 2021); https://doi.org/10.1117/12.2583539

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