Digital Stone Image Analyisi During Extracorporeal Shock Wave Lithotripsy (ESWL)

Abstract

Extracorporeal shock wave lithotripsy (ESWL) is one of the most important modalities in modern treatment of uroilithiasis. In this study, we designed a digital image analysis system that serves as an objective evaluation aid during ESWL procedure. Because the image quality is often interfered with by bowel contents, respiration, bone shadow and other factors, this system helps the operators to judge the end-point of ESWL treatment more accurately. A personal computer is connected to the lithotripter, Results of analysis can be readily read on the monitor of personal computer. The results of ESWL are on-line evaluated for optimal quantity of shock wave treatment. Our experiments showed the correlation between stone fragmentation speed and the slope of image density difference (IDD) curve. By monitoring the change of the IDD, we can evaluate the degree of stone fragmentation. When the IDD curve becomes flat, the stone is either completely broken or resistant to the shock waves. By applying this design in our in vitro experiment, we have found digital image analysis a useful aid of ESWL that helps to estimate optimal amount of shock waves and to decrease the unnecessary appliance of shock waves. According to our studies, we may decrease shock wave number by as much as 53% without affecting the effect of ESWL treatment.