Medical ultrasound exposure measurements: update on devices, methods, and problems

Medical ultrasound fields span a wide range of exposure conditions, from the continuous, low-frequency vibrations of surgical fragmentation needles, to the intense, broadband pressure pulses produced by extracorporeal shock wave lithotripters. Each of these diverse conditions of use presents its own exposure measurement challenges. Furthermore, the sensors and techniques used to evaluate ultrasound exposures have had to evolve as new or expanded clinical applications have emerged. In this paper some of the more notable of these developments are presented and discussed. Topics covered include recent work on devices and techniques, methods of calibration, progress in standardization, and current problem areas, including the effects of nonlinear propagation. Emphasis is given to miniature hydrophones because of the prominent role they continue to play in ultrasound exposure measurements