Bubble measuring instrument and method

• US 6,457,346 B1
• Filed: 03/26/2002
• Issued: 10/01/2002
• Est. Priority Date: 02/04/2000
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Magari, Patrick J., Kline-Schoder, Robert
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Wiggins, David J.
• Application Number:
  US10/113,642
• Time in Patent Office: 189 Days
• Field of Search: 73/191, 73/190.3, 73/190.1, 738/66, 738/651, 735/89, 737/03, 73/617.1, 73/541.5, 422/68.1, 128/662, 128/916, 600/442-3, 600/364
• US Class Current: 73/19.03
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence
• CPC Class Codes: A61B 8/4209 by using holders, e.g. positioning frames
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: G01N 2291/014 Resonance or resonant frequency
• CPC Class Codes: G01N 2291/02433 Gases in liquids, e.g. bubbles, foams
• CPC Class Codes: G01N 2291/0421 Longitudinal waves
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: G01N 29/348 with frequency characteristics, e.g. single frequency signals, chirp signals measuring frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04; measuring frequency or analysing frequency spectra G01R23/00
• CPC Class Codes: G01N 29/42 by frequency filtering or by tuning to resonant frequency
• CPC Class Codes: G01N 29/46 by spectral analysis, e.g. Fourier analysis or wavelet analysis spectral signal processing per se G06F17/14
• CPC Class Codes: G01S 7/52026 Extracting wanted echo signals Doppler systems G01S15/50; Doppler short range imaging systems G01S15/8979
• CPC Class Codes: G01S 7/52036 using analysis of echo signal for target characterisation
• CPC Class Codes: Y10S 128/916 Ultrasound 3-D imaging

Abstract

Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer, respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.

Claims

1. A tissue phantom test system for simulating in-vivo bubbles, comprising:

a tube through which bubbles are entrained;

a housing having a covering of synthetic material to simulate skin, said tube extending through said housing;

a rod disposed within said housing for simulating bone; and

a gel disposed within said housing for simulating tissue.

2. The tissue phantom of claim 1, further comprising:

a video system for viewing said bubbles in said tubes.

3. The tissue phantom of claim 1, further comprising:

a bubble generating apparatus for producing said bubbles, said bubble generating apparatus being operable for generating bubbles having selected diameters.

4. The tissue phantom of claim 1, further comprising

a support for an ultrasonic transducer housing, said ultrasonic housing having a low-frequency transducer and a high-frequency transducer.