Design of the dual stone locating system on an extracorporeal shock wave lithotriptor.

Extracorporeal Shock Wave Lithotriptors are very popular for the treatment of urinary stones all over the world. They depend basically upon either X-ray fluoroscopy or ultrasound scans to detect the stones before therapy begins. To increase the effectiveness of treatment this study took advantage of both X-ray and ultrasound to develop a dual stone locating system with image processing modules. Its functions include the initial stone locating mode with stone detection by fluorescent images and the follow-up automatic stone tracking mode made by constant ultrasound scanning. The authors have integrated both apparatus and present the operating principles for both modes. The system used two in vitro experiments to justify its abilities of stone location in all procedures.

In vitro study of the revised ultrasound based real-time tracking of renal stones for shock wave lithotripsy: Part 1.

PURPOSE: Extracorporeal shock wave lithotripsy has been popular since the 1980s. Only 30% to 50% of the shock waves of all conventional lithotripters are focused on stones. We developed an ultrasound based, real-time stone tracking system (version 1) to improve accuracy and treatment efficiency. However, some problems remained. We revised the existing system (version 2) and tested its reliability and performance. MATERIALS AND METHODS: We revised the system by adding more algorithms to decrease renal stone misidentification. We verified the advanced system by 2 tests using no tracking and tracking with 13 stone trajectories for versions 1 and 2. We performed the coincidence test to evaluate the accuracy of targeting the stone within the effective focal area and the stone fragmentation efficiency test to clarify the decrease in the number of shocks needed for stone fragmentation. RESULTS: In the coincidence test the mean ± SD results of the nontracking system, and tracking versions 1 and 2 were 68.8% ± 18.8%, 89.9% ± 5.2% and 94.3% ± 4.5%, respectively. Version 2 was statistically significantly better than version 1 (p = 1.5 × 10(-4)). In the stone fragmentation efficiency test the mean results of the nontracking system, and versions 1 and 2 were 49.5% ± 14.2%, 85.1% ± 4.5% and 89.5% ± 4.2%, respectively. Version 2 was statistically significantly better than version 1 (p = 1.9 × 10(-8)). CONCLUSIONS: The revised tracking system is better than version 1. It improves treatment efficiency, decreases stone misidentification and can shorten treatment time.

Ultrasound image analysis for renal stone tracking during extracorporeal shock wave lithotripsy.

Although extracorporeal shock wave lithotripsy (ESWL) is the standard procedure for treating renal stones, little work has been done on ways to minimize the side effects and on treatment optimization. A system that uses ultrasound imaging for real time renal stone monitoring is presented here and some aspects of the image analysis module are described. The improved system has proved to be more robust than the unmodified system. With such a system, the injury on healthy tissues is reduced while the treatment time is shortened.