PC-BASED PORTABLE ULTRASONIC DIAGNOSTIC IMAGING SYSTEM

This invention relates to portable ultrasonic diagnostic imaging systems and, in particular, to portable ultrasound systems which are based upon the architecture of a personal computer.

As semiconductor devices have become more miniaturized and capable of ever-increasing functionality, it has become possible to produce ever-smaller ultrasonic imaging devices. This reduction in size was initially made possible by the personal computer (PC) , which provided significant processing power in a desktop unit. US Pat. 6,063,030 (Vara et al . ) shows one of the earliest efforts at using a PC as the core of a desktop ultrasound system. Fig. 6 of that patent shows a desktop PC case containing standard PC printed circuit boards and a specialized printed circuit board which provides ultrasound image scan conversion. The transducer probe used is one which steers the beams over an image area by mechanically oscillating the transducer or a mirror, thereby obviating the need for a beamformer. The signal processing and mechanical control system for the transducer probe are contained in an external unit 1120 which plugs into the scan conversion board inside the PC case. US Pat. 5,795,297 (Daigle) shows how an electronically scanned transducer probe can be integrated into a PC-based design by adding beamformer channel printed circuit boards as expansion cards to the standard PC architecture.

While these two patents illustrate ultrasound systems based upon desktop PCs, smaller, more portable ultrasound systems generally are based upon

proprietary system architecture and printed circuit boards rather than off-the-shelf PC components. These proprietary designs, dedicated exclusively to ultrasound functionality, provide the most compact designs. Typical of such designs are the portable ultrasound units shown in Figs. 31-35 of US Pat. 5,690,114 (Chiang et al . ) ; Figs. 1-4 of US Pat. 5,722,412; Fig. 2 of US Pat. 6,441,451 (Wing et al . ) ; Fig. Ic of US Pat. Application Pub. 2004/0150963 Al (Holmberg et al . ) ; Figs. 3-4 of US Pat. Application Pub. 2004/0179332 (Smith et al . ) ; and Fig. 20 of US Pat. Application Pub. 2004/0138569 (Grunwald et al . ) However, such specialty designs can be expensive since they must be specially designed and manufactured and are done so in lesser quantities than are typical of personal computer components . Accordingly it is desirable to have a PC-based ultrasound system which is both portable and makes extensive use of standard PC components and system architecture.

In accordance with the principles of the present invention, a portable ultrasound system is based upon a portable PC system architecture. The portable ultrasound system comprises a modified portable PC such as a laptop or notebook PC. The portable system scans with a multi-element array transducer which is electronically steered by acquisition circuitry interfaced to a standard serial or parallel PC port such as a USB or PCMCIA port. The acquisition circuitry can be integrated into the portable PC by being integrated as a PCMCIA module or circuitry located in an accessory bay such as a disk drive or battery compartment of the portable PC. Such a portable system is inexpensive, as it is based substantially upon standard portable PC architecture,

enclosures, and interface protocols. In the drawings :

FIGURE 1 illustrates in block diagram form an ultrasonic diagnostic imaging system constructed in accordance with the principles of the present invention.

FIGURES 2a and 2b illustrate two embodiments of a portable ultrasound system docked in a cart-like docking station in accordance with the principles of the present invention.

FIGURES 3a and 3b illustrate in block diagram form one embodiment of the acquisition subsystem of a portable ultrasound system of the present invention. FIGURES 4a and 4b illustrate in block diagram form another embodiment of the acquisition subsystem of a portable ultrasound system of the present invention .

Referring first to FIGURE 1, an ultrasonic diagnostic imaging system constructed in accordance with the principles of the present invention is shown in block diagram form. An ultrasound probe 10 transmits and receives ultrasound waves from the piezoelectric elements of an array of transducer elements 12. For imaging a planar region of the body a one-dimensional (1-D) array of elements may be used, and for imaging a volumetric region of the body a two-dimensional (2-D) array of elements may be used to steer and focus ultrasound beams over the image region. A transmit beamformer actuates elements of the array to transmit ultrasound waves into the subject. The signals produced in response to the reception of ultrasound waves are coupled to a receive beamformer 14. The beamformer delays and combines the signals from the individual transducer elements to form coherent beamformed echo signals.

When the probe includes a 2-D array for 3D imaging, it may also include a microbeamformer which does partial beamforming in the probe by combining signals from a related group ("patch") of transducer elements as described in US Pat. 6,709,394. In that case the microbeamformed signals are coupled to the main beamformer 14 in the system which completes the beamforming process.

The beamformed echo signals are coupled to a signal processor 16 which processes the signals in accordance with the desired information. The signals may be filtered, for instance, and/or harmonic signals may be separated out for processing. The processed signals are coupled to a detector 18 which detects the information of interest. For B mode imaging amplitude detection is usually employed, whereas for spectral and color Doppler imaging the Doppler shift or frequency can be detected. The detected signals are coupled to a scan converter 20 where the signals are coordinated to the desired display format, generally in a Cartesian coordinate system. Common display formats used are sector, rectilinear, and parallelogram display formats. The scan converted signals are coupled to an image processor for further desired enhancement such as persistence processing. The scan converter may be bypassed for some image processing. For example the scan converter may be bypassed when 3D image data is volume rendered by the image processor by direct operation on a 3D data set. The resulting two dimensional or three dimensional image is stored temporarily in an image memory 24, from which it is coupled to a display processor 26. The display processor produces the necessary drive signals to display the image on a system image display 28 or the

flat panel display 38 of the portable system. The display processor also overlays the ultrasound image with graphical information from a graphics processor 30 such as system configuration and operating information, patient identification data, and the time and date of the acquisition of the image.

A central controller 40 responds to user input from the user interface and coordinates the operation of the various parts of the ultrasound system, as indicted by the arrows drawn from the central controller to the beamformer 14, the signal processor 16, the detector 18, and the scan converter 20, and the arrow 42 indicating to the other parts of the system. The user control panel 44 is shown coupled to the central controller 40 by which the operator enters commands and settings for response by the central controller. The central controller 40 is also coupled to an a.c. power supply 32 to cause the a. c. supply to power a battery charger 34 which charges the battery 36 of the portable ultrasound system when the portable system is docked in the docking station.

The central controller 40 is also responsive to a signal indicating whether the portable ultrasound system is docked or undocked, as indicated by the "Docked/Undocked" input to the central controller. This signal can be supplied by the operator pressing a Docked/Undocked button, a switch which changes state when the portable system is docked or undocked, or other suitable sensor of the docked/undocked condition. When the central controller is informed that the portable ultrasound system is docked in the docking station, the central controller responds to inputs from the user control panel 44, and causes the image to be displayed on the docking station display

28. The central controller also controls the graphics processor 30 during docking to omit the display of any softkey controls which duplicate the control functions of controls on the user control panel 44. The central controller may command the a. c. supply 32 and charger 34 to charge the battery 36 when the portable ultrasound system is docked, and/or power the docked portable system from a power supply on the docking station. When the central controller is informed that the portable ultrasound system is undocked, these control characteristics are different. The controller now knows that user commands will not be received from the docking station control panel 44. The controller now causes some or all of the controls of the control panel 44 to be displayed when needed on the portable system display 38, as well as the ultrasound images produced by the ultrasound signal path. The a.c. supply 32 and the charger 34 are no longer controlled, as those subsystems are resident on the docking station. Probes will now be controlled through a probe connector on the portable system rather than through connectors on the docking station. The portable ultrasound system is now fully operable as a stand-alone ultrasound system.

It is thus seen that, in this embodiment, the partitioning of the components of FIGURE 1 is as follows. The central controller 40, beamformer 14, signal processor 16, detector 18, scan converter 20, image processor 22, image memory 24, display processor 26, graphics processor 30, flat panel display 38, and battery 36 reside in the portable ultrasound system. The control panel 44, display 28, a.c. supply 32 and charger 34 reside on the docking station. In other embodiments the partitioning of

these subsystems may be done in other ways as design objectives dictate.

FIGURES 2a and 2b illustrate two embodiments of a docking station 50 and portable ultrasound system constructed in accordance with the principles of the present invention. This docking station 50 greatly resembles a conventional cart-borne ultrasound system with a base unit 52 supporting the user control panel 44 on an adjustable support 46 which enables the control panel to be raised or lowered to accommodate the comfort of different users. The display 28 is mounted above the control panel 44, preferably on an adjustable support 48. An articulating adjustable support which serves this purpose is described in US patent application serial no. 60/542,893 and international application no. PCT/IB2005/050405. The base unit 52 houses peripheral devices which the ultrasound system may use such as a printer, disk drive, and video recorder. The docking station 50 can be rolled to an exam room or patient bedside on wheels 54. The base unit also houses the a.c. power supply 32 and battery charger 34. The base unit may also have connections to connect the ultrasound system to a data network. The base unit 52 has an enclosure 58 in the front into which a portable ultrasound system 60 can be located. When the portable ultrasound system 60 is inserted into enclosure 58 a connector on the portable system 60 engages a mating connector of the docking station. It is this engagement which, directly or indirectly, results in the "Docked" control signal being delivered to the central controller 40 of the portable system. The connector also provides the necessary connections to the control panel 44, the display 28, and the a.c. power

supply 32, as well as the connection of the portable system battery 36 to the charger 34. This connector or another connector may also connect the portable system to one or more probe connectors 56 on the docking station. Alternatively, the probes may be connected to the portable system directly as they are in the portable mode, as by an opening on the side of the base unit 52 which permits the probe connector to directly engage probe connectors on the portable system 60.

In FIGURE 2b the portable ultrasound system 60 is of the form of a notebook PC with a display screen 38 located on an outer surface of the portable ultrasound system. In this configuration the portable ultrasound system 60 is mounted in the position of the display 28 in FIGURE 2a, and its display 38 is the display used when the portable system is docked on the docking station 50. Docking is done by mounting the portable ultrasound system to a connector on support 48. The portable ultrasound system thus is in communication with the docking station 50 by conductors passing through the support 48. In this view the portable ultrasound system probe connectors 156 can be seen on the side of the portable system 60. Probes can be connected to these connectors 156 or to connectors on the base unit 52 of the docking station if present.

In one embodiment of the present invention the ultrasound probe comprises a matrix array probe as described in US Pats. 6,375,617 (Fraser et al . ) and 5,997,479 (Savord et al . ) The matrix array probe contains not only a transducer array but also microbeamformer circuitry which performs at least some of the beamforming of the signals received by the probe. A matrix array probe can also make

efficient and compact use of a two-dimensional array transducer which can perform three dimensional imaging, either images of a volumetric region or of several planes occupying a volumetric region. When some of the beamforming is performed in the probe, a reduced processing burden is imposed on the ultrasound system to which the matrix probe is connected and operates .

FIGURE 3a illustrates an embodiment of the portable ultrasound system 60 in which the portable system utilizes the conventional packaging of a laptop PC. By taking advantage of the processing power and existing packaging of a laptop PC, no specialized packaging components are needed, reducing the cost of the portable system. Much of the signal processing and all of the display processing and user interface control can be performed using the microprocessor (s) of the portable PC unit and its associated components such as RAM, its network and peripheral connections, and disk drive. The power supply of the portable PC unit can power the entire portable ultrasound system including the ultrasound probe. Images can be displayed on the flat panel display 38 of the portable PC unit 60, as well as softkeys for the user interface. The keyboard and pointing device of the standard PC unit controls can be adapted to control the portable ultrasound system. In addition, connectors for interfacing laptop PCs to docking stations are well developed and commercially available, reducing that cost of system development. When realized in a laptop PC package use can be made of the conventional keyboard and controls 62 of the laptop PC including the touchpad or joystick pointing device commonly integrated into the laptop keyboard. The portable ultrasound system display 38 is provided

by the conventional flat panel display 38 of the laptop PC, which can be modified to be at least partly or wholly a touchscreen display.

Another advantage of laptop or notebook PC packaging for the portable ultrasound system is the convenience of interfacing to a matrix array or ID array probe. FIGURE 3b illustrates a first such interface in block diagram form. This probe interface is bounded by a vertical dashed line 202 on the left and a vertical dashed line 206 on the right. To the left of dashed line 202 is a matrix array probe, connected to the signal lines indicated by the arrows. To the right of dashed line 206 is the laptop or notebook PC system. In the embodiment of FIGURE 6b the interface is connected to the standard lines of a USB connection, including the USB data lines and the USB DC (power) line shown to the right of dashed line 206. Thus, the ultrasound probe in this embodiment is interfaced to the portable PC by a standard USB interface, reducing the cost and complexity of the interface to the PC.

The probe-PC interface can be divided into two regions of data circuitry. The region between dashed lines 204-206 is a region of digital circuitry which may, if desired, be fabricated as a digital circuitry module. The region between dashed lines 202-204 may be viewed as a region of analog circuitry which may, if desired, be fabricated as an analog circuitry module. Alternately, both modules may be fabricated on a common printed circuit board. Such a board or boards can conveniently be located in a standard laptop PC compartment such as the extra battery or disk drive bay. Thus, the interface can be realized as modules which are located inside the case of the laptop PC rather than as a separate module box that

is used between the probe and the portable PC.

The USB DC lines are coupled to power control circuitry 212 which distributes DC power to digital power circuitry 214 and analog power circuitry 216. The digital power circuitry 214 distributes power to the digital components of the digital module including in this embodiment a USB microcontroller 210 and an acquisition controller FPGA 220 and its accessory components such as RAM 222. The USB microcontroller 210 exchanges USB data with the portable PC over the USB data line and with the FPGA 220 over data, clock and control lines. The USB microcontroller is the means by which the FPGA and the portable PC communicate through a USB port. The acquisition controller FPGA (field programmable gate array) is a programmable hardware device that performs most or all of the ultrasound acquisition functions of the portable ultrasound system, such as transmit and receive beamforming, filtering, demodulation, harmonic separation and, if desired and given sufficient FPGA circuitry, amplitude and/or Doppler detection.

In the analog module the analog power circuitry 216 of the digital module is coupled to power conditioning circuitry 240 which distributes power to the components of the analog module and is also connected to provide power to the power distribution circuitry of the probe. The FPGA 220 provides beamformer data and clock signals for the microbeamformer of the matrix array probe on lines 230 and 232. In this embodiment these lines pass through the analog module for connection to the probe. Bipolar drive signals for the transducer elements of the probe are provided by the FPGA 220 on lines 228, amplified by amplifiers 252, and coupled

to the probe by transmit/receive switches 250. Ultrasound signals received by the transducer elements of the probe are microbeamformed and amplified, then coupled through the transmit/receive switches 250 to TGC amplification stages 248. The TGC amplified signals are digitized by analog to digital converters (ADCs) 244 and coupled digitally to the FPGA over lines 226. TGC control is also effected by a TGC signal on lines 224 which is converted to an analog signal by dual TGC DAC 242, then distributed to TGC amplification stages 248 and to gain control circuitry in the probe by amplifier 246. A portion of the TGC control may also be performed digitally in the FPGA 220. In a typical configuration the ultrasound signals received by dozens or hundreds of transducer elements in the probe are initially microbeamformed and combined down to a lesser number of ultrasound signal channels, such as sixteen or thirty-two channels. The final beamforming of these sixteen or thirty-two channels may be performed by the FPGA 220 when programmed for configuration as a sixteen- channel or thirty-two-channel receive beamformer. The final beamformed line signals, which may also undergo other signal processing in the FPGA as described above, are coupled to the portable PC over the USB interface for image processing and display on the display 38 of the portable ultrasound system. The portable ultrasound system is controlled by a user interface such as that illustrated in concurrently filed US patent application serial number [ATL-381] , entitled "PORTABLE ULTRASONIC DIAGNOSTIC IMAGING SYSTEM WITH DOCKING STATION." When the portable ultrasound system 60 is docked in the docking station 50, the probe may be connected to

the analog module by a multiplexer between probe connector 56 (when present) on the docking station and the analog module by way of the docking connector between the docking station and the portable ultrasound system. When docked the ultrasound system is controlled by the control panel 44 with controls coupled to the docking connector and the ultrasound images are displayed on the docking station display 28. FIGURE 4a again illustrates a portable ultrasound system 60 packaged as a portable PC. In this embodiment the digital communication between the acquisition system and the portable PC is by means of a parallel data interface rather than a serial data interface. This embodiment is configured with a PCMCIA interface between the FPGA 220 and the portable PC as shown in FIGURE 4b. Most portable PCs have a connector slot for PCMCIA cards inside the case of the PC. This means that the digital module between dashed lines 204 and 206 can be fabricated as a PCMCIA card which is located in such a slot and communicates directly with the portable PC by way of its PCMCIA interface. Optionally, if desired, the module can extend from the card slot with components which cannot be accommodated within the slot located on that part of the module which extends from the slot, in the same way that the antenna of a wireless network transceiver card extends from the card slot. Thus, no specialized parallel digital interface needs to be developed to communicate with the portable PC. The analog module can be located in a similar slot or in an accessory bay of the portable PC.

The PCMCIA interface includes a PCMCIA microcontroller 260 which is connected to PCMCIA address and data lines of the portable PC. A

standard microcontroller can be used such as an 8051 with specific hardware and firmware integrated to support the PCMCIA command set and interface on one logical side and a generalized interface on the other logical side to devices such as FPGA 220, an I ² C channel or similar devices. The microcontroller serves as an interface and data translator between the PCMCIA port of the PC and the acquisition processor. The DC conductors of the PCMCIA interface are coupled to provide DC power to the power control circuitry 212. The FPGA 220 can thus communicate through the PCMCIA interface to receive programs and data from the portable PC and to forward acquired ultrasound data to the portable PC for display. The use of native PC interfaces of a laptop or notebook PC enables the production of an inexpensive and conveniently packaged portable ultrasound system 60.