Title :
In-vivo fetal ultrasound exposimetry
Author :
Daft, Christopher M W ; Siddiqi, T.A. ; Fitting, D.W. ; Meyer, R.A. ; O´Brien, W.D., Jr.
Author_Institution :
GE Corp. Res. & Dev. Center, Schenectady, NY, USA
Abstract :
An instrument has been developed to measure the acoustic pressure field in vivo during an obstetric ultrasound examination. This provides for improved intensity values for exposure calculations, to assist in assessment of bioeffects. The ultrasonic field is sampled using a calibrated seven-element linear array hydrophone of poly(vinylidene difluoride) transducers, which is placed as close as possible to the ovary, embryo, or fetus using a vaginal approach. The RF signals from the hydrophone are digitized at 50 MHz, and the maximum amplitude waveform received in the examination is recorded. The output of the clinical B-scanner is calibrated by a measurement with the hydrophone in a water bath. From the hydrophone measurements, the in vivo I/sub SPTA/, I/sub SPTP/, and I/sub SPPA/ are computed. Further analysis allows the frequency-dependent tissue attenuation to be assessed.<>
Keywords :
acoustic field; biomedical equipment; biomedical ultrasonics; hydrophones; patient diagnosis; 50 MHz; RF signals; acoustic pressure field measurement; calibrated seven-element linear array hydrophone; clinical B-scanner; diagnostic ultrasound; embryo; fetus; frequency-dependent tissue attenuation; in-vivo fetal ultrasound exposimetry; maximum amplitude waveform; obstetric ultrasound examination; ovary; poly(vinylidene difluoride) transducers; ultrasonic field; vaginal approach; water bath; Acoustic measurements; Acoustic transducers; In vivo; Instruments; Pressure measurement; Sonar equipment; Ultrasonic imaging; Ultrasonic transducer arrays; Ultrasonic transducers; Ultrasonic variables measurement;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
