Abstract:
A method and system are disclosed for a compact, inexpensive ultrasound system using an off-the--shelf personal digital assistant (PDA) device interfacing to a hand-held probe assembly through a standard digital interface. The hand-held probe assembly comprises a detachable transducer head attached to a beamforming module that performs digital beamforming. The PDA runs Windows applications and displays menus and images to a user. The PDA also runs ultrasound data processing software to support a plurality of imaging modes. An internal battery is provided in the PDA to power the system. The transducer head is detachable from the beamforming module.

Description:
RELATED APPLICATIONS 
       [0001]    The applicants claimed priority based on provisional application No. 60/332,023 filed Nov. 21, 2001 in the names of Nahi Halmann and Shinichi Amemiya. 
     
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    [Not Applicable] 
       BACKGROUND OF THE INVENTION 
       [0003]    Certain embodiments of the present invention relate to a medical diagnostic ultrasound scanner. More particularly, certain embodiments relate to a method and system for configuring a personal digital assistant (PDA) device as an integral part of a portable, hand-held ultrasound system. 
         [0004]    Traditional ultrasound systems are often large and bulky and do not lend themselves for ease of portability and tend to be expensive. Therefore, traditional ultrasound systems are not practical for certain market segments such as emergency medical personnel in ambulances, medical school students in training, and physicians and nurses at remote locations. 
         [0005]    For example, today, emergency medical personnel (EMP) may use a stethoscope to listen to a patient&#39;s chest for lung rattles, or abdominal sounds such as bowel noise, or heart murmurs, etc. If equipped with ultrasound, the EMP could see fluid in the lungs, movement of the bowel, or blood flow in the heart. A more portable type of ultrasound system is required for such an application. 
         [0006]    Smaller systems exist but are often still too expensive and/or do not provide desired features. For example, in U.S. Pat. No. 6,106,472 to Chiang et al., a portable ultrasound imaging system is described that uses charge coupled device (CCD) technology and performs beamforming in the analog domain. Such an implementation is limited by the specialized CCD technology and by performing beamforming in the analog domain. 
         [0007]    It is more desirable to perform beamforming in the digital domain by first converting ultrasound data from the analog domain to the digital domain by, for example, using a simple analog-to-digital converter (ADC). Beamforming in the digital domain provides more flexibility and potentially better accuracy than beamforming in the analog domain. 
         [0008]    A need exists for a small, inexpensive, highly portable ultrasound system employing existing technology that may be used quickly and easily for basic diagnosis in emergency situations at remote locations and for training purposes. A need also exists to perform digital beamforming in a highly portable ultrasound system in order increase beamforming flexibility and remove the need for specialized hardware. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    An embodiment of the present invention provides for a compact, inexpensive ultrasound system using an off-the-shelf, commercially available personal digital assistant (PDA) device interfacing to a signal beamforming module through a standard digital interface. A detachable ultrasound transducer head also interfaces to the beamforming module to form a hand-held probe assembly. The PDA runs Windows applications and displays menus and images to a user. The PDA is also modified to include ultrasound data processing and application software to support a plurality of ultrasound imaging modes. An internal battery is provided in the PDA to power the system. Digital beamforming is performed within the beamforming module by a beamforming ASIC. 
         [0010]    A method is provided for attaching a detachable transducer head to a beamforming module to form a hand-held probe assembly that includes the beamforming module and the detachable transducer head. Ultrasound signals are received with the hand-held probe assembly from a region of interest to generate a plurality of received digital signals within the hand-held probe assembly. The plurality of received digital signals are digitally beamformed within the hand-held probe assembly to generate beams of digital data corresponding to the region of interest. The beams of digital data are transmitted to a commercially available personal digital assistant (PDA) over a standard digital interface to be further processed and displayed to a user as a displayed image representing the region of interest. 
         [0011]    Certain embodiments of the present invention afford an approach to interface a standard, off-the-shelf, inexpensive PDA device to a hand-held ultrasound probe assembly to provide ultrasound scanning capability that is highly portable and affordable. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a schematic block diagram of a portable diagnostic ultrasound system formed in accordance with an embodiment of the present invention such that digital beamforming is performed within a hand-held probe assembly. 
           [0013]      FIG. 1B  shows a realistic illustration of the portable diagnostic ultrasound system of  FIG. 1 . 
           [0014]      FIG. 2  illustrates the formation of ultrasound beams in a scan plane originating at certain locations with respect to transducer elements in accordance with an embodiment of the present invention. 
           [0015]      FIG. 3  illustrates an image frame made up of multiple received beams in accordance with an embodiment of the present invention. 
           [0016]      FIG. 4  is a schematic block diagram of a diagnostic ultrasound system formed in accordance with another embodiment of the present invention such that digital beamforming is performed in a PDA device. 
           [0017]      FIG. 5  is a schematic block diagram of a diagnostic ultrasound system formed in accordance with a third embodiment of the present invention. 
       
    
    
       [0018]    The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. It should be understood, however, that the present invention is not limited to the arrangements and instrumentality shown in the attached drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0019]      FIG. 1  is a schematic block diagram of a portable ultrasound system  5  in accordance with an embodiment of the present invention. Certain illustrated elements of the ultrasound system  5  include a detachable transducer module  10 , a beamforming module  40 , a PDA device  120 , and, optionally, an external battery/power source  110 . The transducer module  10  attaches to the beamforming module  40  to form a hand-held probe assembly  2 . In an embodiment of the present invention, the PDA  120  includes an internal battery to power the PDA  120  and the hand-held probe assembly  2 . A battery power interface  140  connects between the PDA  120  and the hand-held probe assembly  2 .  FIG. 18  shows a more realistic illustration of the ultrasound system  5 . 
         [0020]    The transducer module  10  comprises a 64-element transducer array  20  and a 64 channel to 16 channel multiplexer  30 . The beamforming module  40  comprises a pulser  60 , a TX/RX switching module  35 , a folder module  50 , a voltage controlled amplifier (VCA)  70 , an analog-to-digital converter (ADC)  80 , a beamforming ASIC  90 , and a PDA interface controller  100 . The PDA device  120  is a standard, off-the-shelf device such as a Palm Pilot running Windows applications such as Windows-CE applications and having a touch-screen display  125 . The PDA  120  is also modified to include ultrasound data processing and application software to support a plurality of ultrasound imaging modes. 
         [0021]    In the transducer module  10 , the transducer array  20  is connected to the multiplexer  30 . When the transducer module  10  is connected to the beamforming module  40 , the multiplexer  30  is then connected to an input of TX/RX switching module  35 . 
         [0022]    In the beamforming module  40 , the output of the TX/RX switching module  35  connects to the input of the folder module  50  and the output of the folder module  50  connects to the input of the VCA  70 . The output of the VCA  70  connects to the input of the ADC  80 . The output of the ADC  80  connects to the input of the beamforming ASIC  90 . The output of the beamforming ASIC  90  connects to the input of the PDA interface controller  100 . The output of the 16-channel pulser  60  connects to an input of TX/RX switching module  35 . Optionally, an external battery/power source  110  connects to beamforming module  40 . 
         [0023]    The PDA interface controller  100  connects to the pulser  60 , and to the PDA device  120  through a standard digital interface  150 . In an embodiment of the present invention, the standard digital interface  150  is a Universal Serial Bus (USB) interface and the PDA interface controller  100  is a USB controller. Optionally, the standard digital interface  150  may be a parallel interface where the PDA interface controller  100  is a PC card. As a further alternative, the standard digital interface may be a wireless interface such as Bluetooth providing RF communication between the PDA interface controller  100  and the PDA  120 . 
         [0024]    The various elements of the portable ultrasound system  5  may be combined or separated according to various embodiments of the present invention. For example, the folder  50  and VCA  70  may be combined into a single processing element. Also, the external battery  110  may be integrated into the beamforming module  40 , becoming an internal battery. 
         [0025]    A function of the PDA-based ultrasound scanner  5  is to transmit ultrasound energy into a subject to be imaged, and receive and process backscattered ultrasound signals from the subject to create and display an image on the display  125  of the PDA device  120 . A user selects a transducer head  10  to connect to the beamforming module  40  to form a hand-held probe assembly  2  to be used for a particular scanning application. The transducer head is selected from a group of transducers including linear arrays, curved arrays, and phased arrays. An imaging mode may be selected from a menu on the display  125  of the PDA device  120  using a touch-screen stylus, 
         [0026]    To generate a transmitted beam of ultrasound energy, the PDA device  120  sends digital control signals to the PDA interface controller  100  within the beamforming module  40  through the standard digital interface  150 . The digital control signals instruct the beamforming module  40  to generate transmit parameters to create a beam of a certain shape that originates from a certain point at the surface of the transducer array  20 . The transmit parameters are selected in the pulser  60  in response to the digital control signals from the PDA device  120 . The pulser  60  uses the transmit parameters to properly encode transmit signals to be sent to the transducer array  20  through the TX/RX switching module  35  and the multiplexer  30 . The transmit signals are set at certain levels and phases with respect to each other and are provided to individual transducer elements of the transducer array  20 . The transmit signals excite the transducer elements of the transducer array  20  to emit ultrasound waves with the same phase and level relationships as the transmit signals. As a result, a transmitted beam of ultrasound energy is formed in a subject within a scan plane  200  (see  FIG. 2 ) along a scan line  210  when the transducer array  20  is acoustically coupled to the subject by using, for example, ultrasound gel. 
         [0027]    In an embodiment of the present invention, a single ultrasound beam is formed along a particular scan line (e.g.  210 ) using 16 transducer elements. For example, elements  301  through  316  may be used to form a first ultrasound beam along a scan line  210  and elements  302  through  317  may be used to form a second adjacent ultrasound beam along a scan line  212  and so on. As a result, 64 ultrasound beams may be formed to create an image if the transducer array  20  has 64 transducer elements. Alternatively, elements  301  to  316  may be used to form a first ultrasound beam along a scan line  210  and elements  302  through  316  may be used to form a second adjacent ultrasound beam along a scan line  211  and elements  302  through  317  may be used to form a third ultrasound beam along a scan line  212  adjacent to the second ultrasound beam and so on. As a result,  128  ultrasound beams may be formed to create an image if the transducer array  20  has 64 transducer elements. In any event, the pulser  60  sends 16 transmit signals at a time through multiplexer  30  to form a given transmit ultrasound beam along a given scan line. The multiplexer  30  routes the transmit signals to the correct subset of transducer elements in the transducer array  20  to form a particular transmit beam along a particular scan line. 
         [0028]    The transducer elements form a two-way transducer array  20 . Once ultrasound waves are transmitted into a subject, the ultrasound waves are backscattered off of tissue and blood samples within the structure. The backscattered waves arrive at the transducer array  20  at different times, depending on the distance into the subject they return from and the angle with respect to the surface of the transducer array  20  at which they return. The transducer elements are responsive to the backscattered waves and convert the ultrasound energy from the backscattered waves into received electrical signals. 
         [0029]    The received electrical signals are routed through the multiplexer  30 , 16 signals at a time, to the folder module  50  by way of the TX/RX switching module  35  in beamforming module  40 . The folder module  50  uses the symmetry of the ultrasound beam to process the signals from the 8 right-most transducer elements in the same manner as the signals from the 8 left-most transducer elements since the ultrasound beam originates from the center of 16 transducer elements. The folder module  50  amplifies and weights the received signals and collapses the original 16 received signals into 8 received signals due to the symmetry of the transducer elements about the received beam to be formed. 
         [0030]    Next, the received signals are passed to the VCA  70 . The VCA  70  provides the function of gain compensation as a function of time (distance into the image). Next, the ADC  80  digitizes the received signals. The beamforming ASIC  90  then takes the digitized received signals and creates a received beam of data along a scan line (e.g.  210 ). The beamforming ASIC  90  operates on the digitized received signals by performing time delaying and summing to create the received beam of data corresponding to sample volumes along a scan line (e.g.  210 ) in the scan plane  200  within the subject. The beamforming ASIC  90  is a digital ASIC performing beamforming in the digital domain and providing beamforming flexibility. For example, the beamforming ASIC  90  may be digitally loaded with various beamforming coefficients and instructions from the PDA  120  to perform different types of digital beamforming. 
         [0031]    The received beam of digital data is sent to the PDA device  120  by the PDA interface controller  100  over the standard digital interface  150 . The process is repeated for the next receive beam to be formed and so on to generate all of the received beams  260  that make up the image frame  250  for the region of interest (see  FIG. 3 ). 
         [0032]    The PDA device  120  collects and processes the received beam data for the entire set of received beams  260  that make up an image frame  250  and displays the resultant image to the user on the display  125  of the PDA device  120 . The PDA device  120  performs ultrasound data processing including the ultrasound functions of demodulation, parameter estimation, scan conversion, and display processing. A plurality of ultrasound modes may be supported including Doppler processing modes and non-Doppler processing modes, 
         [0033]    Frame rates on the order of 10 frames per second may be achieved and the system may consume less than 5 watts of power, allowing for operation over approximately a 2-hour period of time. 
         [0034]    As an alternative, the function of the beamforming ASIC  90  may be performed by software in the PDA device  120  as shown in  FIG. 4 . Instead of the transducer head attaching to a beamforming module  40 , it attaches to a signal processing module  45  that does not include the beamforming ASIC  90 . The data out of the ADC  80  is sent to the PDA interface controller  100  and the pre-beamformed data is sent to the PDA  120 . Digital beamforming is performed by software within the PDA  120  along with the other subsequent data processing functions. 
         [0035]    As a further alternative, the hand-held-probe assembly may include an internal battery to provide power. A docking station may also be provided for the hand-held probe assembly to provide the function of battery recharging. 
         [0036]    As still a further alterative, the transducer module  10  may be a sterile probe for use in an operating room (OR), such as in a sterile wireless probe assembly. 
         [0037]    As yet another alternative, the beamforming module (or signal processing module) may be designed to perform 16 bit processing. For example, the folder module  50  may be eliminated and the VCA  70  and the ADC  80  may be designed to handle 16 bits instead of just 8 bits as shown in  FIG. 5 . 
         [0038]    The various configurations and interfaces within the system  5  may be combined or separated according to various embodiments of the present invention. For example, the beamforming module  40  may comprise custom hardware elements such as a small circuit board with digital signal processors or may comprise readily available off-the-shelf components. 
         [0039]    In summary, the advantages and features include, among others, a light-weight, portable ultrasound system based on inexpensive, off-the-shelf PDA technology to provide high portability and ease of use for certain users. Digital beamforming provides maximum beamforming flexibility, and a transducer head may be selected from a set of detachable transducer heads to connect to a beamforming or signal processing module to form a hand-held probe assembly. A user may easily change applications by attaching a different transducer head to the beamforming module or signal processing module and/or by selecting a new imaging application on the touch-screen display of the PDA. 
         [0040]    While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.