Chuong C J, Zhong P, Preminger G M
Joint Biomedical Engineering Program, University of Texas, Arlington 76019.
J Urol. 1992 Jul;148(1):200-5. doi: 10.1016/s0022-5347(17)36553-9.
A standard stone phantom was used to compare stone damage after extracorporeal shock wave administration from electrohydraulic, electromagnetic and piezoelectric lithotripters. For each machine, a low and high shock wave intensity setting was chosen: 18 & 24 kV for electrohydraulic; 16 & 19 kV for electromagnetic; power levels 1 and 4 for piezoelectric. The shock wave was focused either at the front (surface facing the wave source) or back surface of the stone and 50, 100, 200 or 400 shocks were delivered to different stone groups. Effects of varying physical properties in the stone phantom were also investigated. Stone damage was described in terms of volume loss and both depth and width of the resulting damage crater. At the lower intensity settings, all three machines produced stone volume loss which was linearly related to the number of shock delivered. At higher intensity settings, volume loss increased rapidly as the number of shocks increased. With the same number of shocks, stone volume loss was greatest with the electrohydraulic machine, followed by electromagnetic and piezoelectric lithotripters for both low and high intensity settings. Damage craters from the piezoelectric device were narrow and deep; those from the electromagnetic machine were of the shape of a right angle circular cone; whereas those from the electrohydraulic lithotripter were shallow and wide. At the high intensity settings, damage from the piezoelectric and electrohydraulic lithotripters appeared to depend upon the position of the focal point with a higher volume loss when the shock waves were targeted at the front surface of the stone. For the electromagnetic device, a higher volume loss was found when we positioned the focal point at the back surface of the stone phantom. Stone phantoms with lower mechanical strength and acoustic impedance were more easily damaged than those with higher values. Finally, a computer regression model was developed to express volume loss in terms of the intensity setting, focal position and number of shocks for each lithotripter.
使用标准结石模型来比较电液压、电磁和压电碎石机进行体外冲击波治疗后的结石损伤情况。对于每台机器，选择了低和高两种冲击波强度设置：电液压碎石机为18 kV和24 kV；电磁碎石机为16 kV和19 kV；压电碎石机为功率水平1和4。冲击波聚焦于结石的前表面（面向波源的表面）或后表面，并向不同的结石组施加50、100、200或400次冲击。还研究了结石模型中不同物理性质的影响。结石损伤通过体积损失以及所形成损伤坑的深度和宽度来描述。在较低强度设置下，所有三台机器都产生了与施加冲击次数呈线性相关的结石体积损失。在较高强度设置下，随着冲击次数增加，体积损失迅速增加。在相同冲击次数下，对于低强度和高强度设置，电液压碎石机造成的结石体积损失最大，其次是电磁碎石机和压电碎石机。压电装置产生的损伤坑窄而深；电磁碎石机产生的损伤坑呈直角圆锥形状；而电液压碎石机产生的损伤坑浅而宽。在高强度设置下，压电和电液压碎石机造成的损伤似乎取决于焦点位置，当冲击波瞄准结石前表面时体积损失更大。对于电磁装置，当我们将焦点置于结石模型后表面时发现体积损失更大。机械强度和声学阻抗较低的结石模型比那些值较高的更容易受损。最后，开发了一个计算机回归模型，以根据每种碎石机的强度设置、焦点位置和冲击次数来表示体积损失。
