title: A comparison of acoustic cavitation detection thresholds measured with piezo-electric and fiber-optic hydrophone sensors.
abstract: A Fabry-Perot interferometer fiber-optic hydrophone (FOH) was investigated for use as an acoustic cavitation detector and compared with a piezo-ceramic passive cavitation detector (PCD). Both detectors were used to measure negative pressure thresholds for broadband emissions in 3% agar and ex vivo bovine liver simultaneously. FOH-detected half- and fourth-harmonic emissions were also studied. Three thresholds were defined and investigated: (i) onset of cavitation; (ii) 100% probability of cavitation; and (iii) a time-integrated threshold where broadband signals integrated over a 3-s exposure duration, averaged over 5-10 repeat exposures, become statistically significantly greater than noise. The statistical sensitiviy of FOH broadband detection was low compared with that of the PCD (0.43/0.31 in agar/liver). FOH-detected fourth-harmonic data agreed best with PCD broadband (sensitivity: 0.95/0.94, specificity: 0.89/0.76 in agar/liver). The FOH has potential as a cavitation detector, particularly in applications where space is limited or during magnetic resonance-guided studies.
authors.affiliation: Division of Radiotherapy and Imaging, Institute of Cancer Research, Sutton, Surrey, United Kingdom; and Royal Marsden Hospital NHS Foundation Trust. Electronic address: victoriabull1@googlemail.com.
authors.forename: Victoria
authors.initials: V
authors.lastname: Bull
authors.forename: John
authors.initials: J
authors.lastname: Civale
authors.forename: Ian
authors.initials: I
authors.lastname: Rivens
authors.forename: Gail
authors.initials: G
authors.lastname: Ter Haar
mesh_terms: D000818:Animals; D002417:Cattle; D054459:Elasticity Imaging Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D019220:High-Energy Shock Waves; D057086:High-Intensity Focused Ultrasound Ablation / Q000295:instrumentation*; D008099:Liver / Q000601:surgery*; D008365:Manometry / Q000295:instrumentation*; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D011312:Pressure; D011874:Radiometry / Q000295:instrumentation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers
keywords: Cavitation thresholds; Fiber-optic hydrophone; Focused ultrasound surgery; High-intensity focused ultrasound; Passive cavitation detection