Tracking kidney stones in a homogeneous medium using a trilateration approach

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Nephrology

Background:

• Kidney stone treatment via shock wave lithotripsy can cause unintended tissue trauma.
• Current lithotripsy methods deliver numerous shock waves, many not impacting the stone.
• Reducing renal trauma during lithotripsy is a critical clinical goal.

Purpose of the Study:

• To develop and evaluate a monitoring system for real-time kidney stone localization.
• To enable precise gating of shock waves, thereby minimizing collateral tissue damage.
• To improve the safety and efficacy of shock wave lithotripsy.

Main Methods:

• A monitoring system with a 22-transducer (0.5 MHz) array was designed for clinical lithotripters.
• An algorithm incorporating threshold detection, signal rejection, and triangulation was developed for stone localization.
• The system was tested in a water tank using gypsum cement stone models.

Main Results:

• The stone localization system achieved accuracy better than 4 mm laterally and 2 mm axially within ±15 mm of the lithotripter's focus.
• The algorithm processed stone positions in real-time, calculating locations every 1 second.
• Off-the-shelf hardware was utilized, demonstrating practical implementation.

Conclusions:

• The developed monitoring system accurately locates kidney stones in real-time during lithotripsy.
• This technology has the potential to significantly reduce renal trauma associated with the procedure.
• The system offers a practical solution for enhancing the safety of shock wave lithotripsy.