Patent Application
20090036778
The present invention relates generally to an ultrasonic probe for non-invasive measurement of fluid flow within the human body. More specifically, the present invention relates to an ultrasonic Doppler probe for measuring fluid flow within the human body that incorporates a dual frequency acoustical transducer, thereby allowing operation of the probe at both higher and lower frequencies without the need for the operator to change probes.
As ultrasonic technology has improved, non-invasive ultrasonic diagnostic equipment has become an indispensable tool for clinical use. For many years, real-time B-mode ultrasound imagers have been used in connection with the investigation and imaging of stationary soft tissue structures within the human body. In addition, the more recent development of Doppler ultrasound scanners has facilitated the non-invasive investigation of moving fluids within the human body. In fact, Doppler ultrasound has become the standard in available techniques for non-invasively detecting and measuring the velocity of moving structures within the human body, and particularly to provide a real time estimate of the blood velocity traveling at various points within the body.
The basic scientific principal underlying Doppler ultrasonography is based on the fact that ultrasonic waves, when directed at a moving object, undergo a frequency shift upon reflection and/or scattering by that object. Generally, the magnitude and the direction of the frequency shift in turn provides information regarding the motion of the object being observed. In other words, the magnitude of the frequency change is dependent upon how fast the object is moving. In this context, there are several different depictions of blood flow that are produced through medical Doppler imaging, including color flow imaging, power Doppler and spectral sonograms. Color flow imaging (CFI), is employed for imaging a whole region of the body and displays a real-time image of mean velocity distribution. CFI provides an estimate of the mean velocity of flow with a vessel by color coding the information and displaying it, super positioned on a dynamic B-mode image or black and white image of anatomic structure. While CFI displays the mean or standard deviation of the velocity of observed objects, such as the blood cells, in the given region, power Doppler (PD) in contrast displays a measurement of the amount of moving objects in the area. A PD image is an energy image wherein the energy of the flow signal is displayed. Thus, PD depicts the amplitude or power of the Doppler signals rather than the frequency shift. This allows detection of a larger range of Doppler shifts and thus better visualization of small vessels. In all of these technologies, however, the images produced show only the direction of flow and do not provide any no velocity information. Finally, spectral Doppler or spectral sonogram utilizes a pulsed wave system to interrogate a single range gate or sampling volume and displays the velocity distribution as a function of time.
It is also of note that in the prior art, Doppler imaging is done using different acoustical frequencies, where the selection of acoustical frequency is a compromise between resolution and the ability to perceive the internal structure being imaged. This compromise is based generally on the fact that while higher frequency Doppler waves provide higher resolution they do not penetrate into the body as deeply, lower frequencies penetrate more deeply but the penetration depth is achieved at the expense of resolution. A processor is then employed to receive the electrical signals from the Doppler probe and operate upon them to determine the information that is to be provided to the user on the display. In some systems, the processor generates an electrical signal that is converted and translated in the probe as an acoustic signal, while in other systems the probe itself generates the signal to be transmitted. Similarly, in some systems, the probe simply converts the received acoustic signal to an electrical signal that is transferred to the processor while in others, the probe processes the electrical form of received acoustic signal so that it at a different (lower) frequency and then provides the converted data to the processor.
The difficulty that is encountered in the prior art is that the currently available ultrasound probes operate at only a single frequency. As a result the operator must change probes to employ a different acoustical frequency for a portion of the examination. Accordingly, there is a need for a single ultrasonic probe that can be selectively operated at more than one frequency, thereby eliminating the need for the operator to switch probes during the investigation process.
In this regard, the present invention provides for a Doppler probe that can be selectively operated at more than one frequency during the course of a Doppler imaging examination. The probe of the present invention employs piezo-electric materials for the formation of acoustic transmitting and receiving transducers that are positioned within the probe to allow the probe to be operated at a number of different frequencies spanning no more than one octave in frequency range.
In one embodiment the probe of the present invention includes an acoustic transducer, a receiver and an operator control switch to selectively to select the frequency of operation from either of two predetermined frequencies and to show which frequency of operation is being used.
In an alternate embodiment the switching function is transferred from the probe and implemented via a processor based control selector.
In another alternate embodiment the transmitting and receiving components are provided in the processor so that the probe itself essentially contains only the acoustic transducer and the probe accepts a high frequency electrical signal from the processor for acoustic transmission and the probe provides the processor with the high frequency signal received by the receiving section of the acoustic transducer.
In yet another alternate embodiment, the signals obtained by the receiving section of the acoustic transducer are converted to digital form by an analog-to-digital converter (A/D) and the resulting digital information is transferred to the processor for further processing such as complex demodulation and Doppler frequency extraction.
In still a further alternate embodiment, a self-contained probe is provided that includes a wireless interface and a battery in order to provide its own power. The probe converts the received signals to a digital signal that is transmitted via the wireless interface to the processor.
It is therefore an object of the present invention to provide a probe assembly for use in connection with ultrasonic Doppler imaging, which includes acoustical transducers therein that allow selective operation across at least two different frequencies. It is a further object of the present invention to provide a probe for use in ultrasonic Doppler imaging that includes acoustical transmitter and receiver components capable of selectively operating across at least two distinct frequencies while transmitting the information collected by the receiver to a processing device. It is still a further object of the present invention to provide a self contained probe for use in ultrasonic Doppler imaging that can be selectively operated across at least two distinct frequencies while wirelessly transmitting the information collected by the receiver to a processing device.
These together with other objects of the invention, along with various features of novelty that characterize the invention, are pointed out with particularity in the claims annexed hereto and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated a preferred embodiment of the invention.
In the drawings which illustrate the best mode presently contemplated for carrying out the present invention:
Now referring to the drawings, a schematic depiction of the ultrasonic probe of the present invention is shown and generally illustrated at 10 in
As will be appreciated by one skilled in the art, the transmit section 14 in the acoustical transducer 12 is formed from a piezo-electric material that vibrates in response to electrical signals, thereby generating sound waves corresponding to the electrical signal. In this regard, a driver in the form of an oscillator 20 is used to generate a high frequency electrical signal having a wavelength that corresponds to the frequency at which the transmitter 14 in the transducer 12 is to be operated. In other words, the oscillator 20 generates a high frequency electrical signal that causes the piezo-electric material in the transmitter 14 to vibrate thereby emitting ultrasonic waves. In contrast to the prior art, the present invention employs a controllable oscillator 20 that generates a selectively variable frequency electrical signal in response to the frequency selection switch 18. As a result, with the frequency selection switch 18 in a first position, the controllable oscillator 20 generates a first electrical signal that in turn drives the transmit section 14 of the acoustic transducer 12 at a first frequency. When the selection switch 18 is moved to a second position, the controllable oscillator 20 generates a second electrical signal that in turn drives the transmit section 14 of the acoustic transducer 12 at a second frequency. Further, the selector switch 18 also provides a signal to a processor 22 with which the ultrasonic probe 10 is interfaced thereby alerting the processor 22 to the frequency at which the acoustical transducer 12 is operating. This information is necessary so that the processor 22 can properly interpret the signal being transmitted by the transmit section 14 and returned by the receiver section 16, so that it can display the frequency in use to the operator and so that it can include the information regarding the frequency being used in the data record of the test.
In this regard, the probe 10 of the present invention includes an acoustical transducer 12 that can be selectively operated at a variety of different frequencies thereby allowing a comprehensive Doppler examination to be performed without the need for switching between multiple probes. Preferably, the range of multiple frequencies is limited to a range that falls into a single octave range. For example, the probe 10 can be selectively operated at the pair of frequencies of 5 MHz and 8 MHz or the pair of frequencies of 2.1 MHz and 3.9 MHz.
Turning now to
In addition to the embodiment detailed above, there are a number of possible alternative embodiments of the present invention. In a first alternative embodiment, as depicted in
In a second alternative embodiment, depicted at
Finally, in a fourth alternative embodiment depicted at
It should be appreciated that in the scope of the present invention the important point of novelty is that the probe assembly allows operation over at least two different signal frequencies without requiring that the user switch probes. In this regard, it can therefore be seen that the present invention provides a novel and useful ultrasonic probe assembly that enhances the operator's ability to perform non-invasive ultrasonic examinations while enhancing the overall image obtained and reducing the time required to obtain a high quality image. By allowing the operator to selectively operate at multiple frequencies, Doppler images can be obtained that have both improved resolution with an increased depth of penetration within the human body. For these reasons, the instant invention is believed to represent a significant advancement in the art, which has substantial commercial merit.
While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.
This application is related to and claims priority from earlier filed U.S. Provisional Patent Application No. 60/953,014, filed Jul. 31, 2007.
| Number | Date | Country | |
|---|---|---|---|
| 60953014 | Jul 2007 | US |
