Robust kidney stone tracking for a non-invasive ultrasound theragnostic system-Servoing performance and safety enhancement-

We propose a non-invasive ultrasound theragnostic system that tracks movement in an affected area (kidney stones, in the present study) by irradiating the area with high-intensity focused ultrasound (HIFU). In the present paper, the concept behind a novel medical support system that integrates therapy and diagnostics (theragnostics) is illustrated. The required functions for the proposed system are discussed and an overview of the constructed system configuration is illustrated. The problems associated with kidney stone motion tracking by ultrasonography are described. In order to overcome these problems, we consider two approaches. The first approach is to minimize the servoing error so as to enhance both the efficiency of the therapy and the safety of the patient. The second approach is to reduce the effect of the servoing error. With respect to the first approach, we propose a robust detection method of the stone position based on shape information. With respect to the second approach, we propose a solution for controlling the HIFU irradiation power in accordance with the servoing error, primarily in order to enhance the safety of the patient.