Lithotripsy pulse measurement errors due to non-ideal hydrophone and amplifier frequency response

Abstract

To study the potential effects of bandwidth-limited behavior on lithotripsy pulse measurements, the mathematical model for diagnostic-type pulses of G.R. Harris (1989) was modified. Several parameters of a simulated lithotripsy pulse were compared before and after being filtered by hydrophone and amplifier response functions, both separately and in combination. Errors were computed for the peak positive and negative pressures, rise-time, pulse duration, and pulse intensity integral as functions of hydrophone and amplifier bandwidths. Although most of the energy in a shock wave pulse lies at frequencies below a few megahertz, significant errors can occur unless measurement bandwidths are much wider. However, accuracy for the combined response can be maintained at lower bandwidths if the amplifier's cutoff frequency is less than the hydrophone's thickness resonance peak.<>