AU2010101421A4

AU2010101421A4 - Ultrasound Probe Having Improved Manoeuvrability

Info

Publication number: AU2010101421A4
Application number: AU2010101421A
Authority: AU
Inventors: John Brydon
Original assignee: Signostics Ltd
Current assignee: Signostics Ltd
Priority date: 2009-12-18
Filing date: 2010-12-16
Publication date: 2011-01-27
Anticipated expiration: 2018-12-16

Description

IP0551P AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: Ultrasound Probe Having Improved Manoeuvrability Name of Applicant: Signostics Limited Address for Service: 40-46 West Thebarton Road Thebarton, S.A. 5031 The invention is described in the following statement: 2 TITLE ULTRASOUND PROBE HAVING IMPROVED MANOEUVRABILITY TECHNICAL FIELD The present invention relates to an ultrasound probe of a type employing a 5 single scanline and using a position sensor in order to create a B-mode ultrasound scan image. In particular it relates to a user wearable embodiment of such a system. BACKGROUND ART The use of ultrasound scanning of patients for medical diagnostic purposes 10 dates to the mid-20th century. An ultrasound transducer is used to project a beam of ultrasound energy into a patient. The same or another transducer detects the echoes returned from features within the body. These echoes, called a scanline, are then converted to a form suitable for recording or display. When a series of scanlines, spaced angularly apart, are acquired rapidly and 15 displayed on a display screen, the familiar B-mode sector scan is achieved. This is a sector of a circle, wherein the brightness of each pixel of the display is proportional to the magnitude of the ultrasound echo received from the corresponding point in the body being imaged. Nearly all modern medical ultrasound systems use an array of ultrasonic 20 crystals in the transducer. The early designs used at least 64 crystals, with modern designs sometimes using up to a thousand crystals or more. The cost of producing transducers with arrays of crystals is high. There is also a high cost in providing the control and processing circuitry, with a separate channel being required for each crystal. The transducers are usually manually 25 manufactured, with the channels requiring excellent channel to channel matching and low cross-talk. The power consumption for electronic systems is also high, and is generally proportional to the number of channels being simultaneously operational. The bulk and high cost of ultrasound systems has meant that ultrasound has 30 generally remained the province of specialists sonographers or radiologists.

3 These operators have an intimate knowledge of body structure as seen via ultrasound. They generally do not directly diagnose, but use their specialist skills to locate and image the required area of a patient's body, and interpret the images to a diagnostician. 5 However, the advent of cheaper, smaller portable ultrasound devices, such as the Signos produced by Signostics Pty Ltd, has led to ultrasound being available for use by non-specialists, including general practitioners, physiotherapists and veterinarians. These professionals have a practical knowledge of anatomy and engage in direct diagnosis. They may be more 10 comfortable locating major organs by external markers and by touch. Hand palpitation is used extensively for diagnosis of gross pathology. The sonographers practice of locating bodily structures by using the ultrasound image, and of touching the patient only with the ultrasound probe may not sit comfortably with their preferred way of working. 15 DISCLOSURE OF THE INVENTION In certain types of clinical examination that use a diagnostic ultrasound scanner it is advantageous to locate the ultrasound transducer in a highly manoeuvrable location such as the operator's hand or finger. For example, in transvaginal or prostate inspections or under circumstances where the operator's other hand 20 cannot be used to assist in the operation or location of the transmit/receive element such manoeuvrability is of considerable advantage in obtaining a clear ultrasound image. In one form of this invention there is proposed a finger mountable ultrasound transducer assembly including an ultrasound transducer which transmits and 25 receives a single scanline, an inertial sensor mounted in fixed spatial relationship to the transducer, mounting apparatus which releasably holds the assembly to at least one of a user's fingers. In preference the inertial sensor includes at least one gyroscope. In preference the inertial sensor includes at least one accelerometer. 30 4 In an embodiment, the transducer comprises separate receive and transmit elements. In a further form the invention may be said to lie in an ultrasound scanning device including a finger mountable transducer assembly including an 5 ultrasound transducer which transmits and receives a single scanline, an inertial sensor mounted in fixed spatial relationship to the transducer, mounting apparatus which releasably holds the assembly to at least one of a user's fingers wherein, in use, a user rotates said finger, with the assembly attached, in order to sweep the scanline through a sector of a circle within a body to be 10 imaged, output of the transducer being combined with output from the inertial sensor to produce a B-mode ultrasound scan. In a further form the invention may be said to lie in an ultrasound scanning device as in any one of the preceding claims wherein the transducer is an array transducer adapted to acquire B-mode scan data covering a scan plane, the 15 inertial sensor being adapted to sense movement and to provide movement data about movement in one or more directions substantially orthogonal to the scan plane concurrently with the acquisition of said B-mode scan data, the combined B-mode scan data and movement data being processed to produce a three dimensional image. 20 BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is shows an ultrasound scanning device according to the preferred embodiment of the present invention. Figure 2a is shows a finger mounted transducer assembly of the invention. Figure 2b shows an alternative embodiment of a finger mounted transducer 25 assembly of the invention. BEST MODE FOR CARRYING OUT THE INVENTION Now referring to the illustrations, and in particular to Figure 1 which shows an ultrasound device including the invention, there is a finger mounted transducer assembly 1 which is connected by cable 6 to probe unit 10. The probe unit is 30 further connected to a Display and Processing Unit (DPU) 11. The transducer assembly is adapted to be attached to a user's finger. This may be as a full 5 hand glove, as a single finger "glove", or as a shell which fits over the tip of one or more fingers. It may also be designed to clip between two fingers or to be adhesively attached to a user's finger or palm. It may also be attached to a finger or hand by easily removable straps, for example of hook and loop 5 fastener material. The probe unit is able to be attached to a user's body, preferably attaching to a user's forearm with straps. Alternatively, it may attach by use of a pocket into which the probe unit may be inserted, the pocket then attaching to the user's forearm. 10 The DPU provides the control unit for the ultrasound function. The user interface may be any convenient means including physical knobs and switches. In a preferred embodiment, the DPU includes a touchscreen interface, able to display the ultrasound images, and to display a user interface which is controlled by touching the screen. The interface may also include other controls 15 such as a thumbwheel and control buttons. In an embodiment, the transducer assembly and the probe unit are permanently connected in an assembly which is able to be submersibly sterilised. Alternatively, the transducer assembly may be submersibly sterilisable, and may attach by a plug at the end of cable 6 to the probe unit. In this 20 embodiment, the probe unit may be plug connected to the DPU or may be permanently connected to the DPU. Figure 2 shows the finger mounted transducer assembly. There is a shell 2 on which are located ultrasound transducer element 4 and inertial orientation sensor 5, connected by cable 6 to ultrasound processing probe unit 10. As 25 shown in Figure 2a, ultrasound energy is transmitted substantially in the direction of the finger axis and received from the same direct on. Transducer element 4 and inertial sensor 5 bear a constant physical relationship to each other such that changes in direction of the ultrasound beam and the spatial position of the transmitter are indicated by the outputs of the inertial sensor 5. 30 The inertial sensor is preferably a gyroscope but one or more accelerometers, or a combination of accelerometers and gyroscopes may be used.

6 Figure 2b shows a transducer assembly 6 with an alternative location of transducer element 7 in the side of shell 2 such that ultrasound energy is transmitted in a direction substantially at right angles to the axis of the finger and received from the same direction. 5 In another configuration (not shown) the axis of transmission and reception of the ultrasound beam is variable between the extremes indicated in Figures 1 and 2. In a further embodiment a separately located transmit element and a receive element replace the dual functionality of transducer elements 4,7. A block diagram of the ultrasonic scan system is shown in Fig 3. There is a 10 probe unit 10 and a DPU 11. The probe unit is connected to the finger mounted transducer assembly 1. The transducer assembly includes transducer element 4 and inertial sensor 5. The probe unit includes a controller 351 which controls all of the functions of the probe. The DPU includes a main CPU 340. 15 The probe unit 10 communicates with the DPU 11 via a low speed message channel 310 and a high speed data channel 320. The message channel is a low power, always on connection. In another embodiment, not shown, the probe unit and the DPU may be a single unit with a single controller. In this embodiment, the finger mounted 20 assembly connects directly to the combined unit using a pluggable lead. The message channel and the data channel are not provided. The data channel is a higher speed and hence higher power consumption bus which is on only when required to transmit data from the probe unit to the DPU. The probe unit includes a transducer 13 which acts to transmit and receive 25 ultrasonic signals. A diplexer 311 is used to switch the transducer between transmit and receive circuitry. On the transmit side the diplexer is connected to high voltage generator 312, which is controlled by controller 351 to provide a pulsed voltage to the transducer 13. The transducer produces an interrogatory ultrasonic pulse in 30 response to each electrical pulse.

7 This interrogatory pulse travels into the body and is reflected from the features of the body to be imaged as an ultrasonic response signal. This response signal is received by the transducer and converted into an electrical received signal. The depth from which the echo is received can be determined by the time delay 5 between transmission and reception, with echoes from deeper features being received after a longer delay. Since the ultrasound signal attenuates in tissue, the signal from deeper features will be relatively weaker than that from shallower features. The diplexer 311 connects the electrical receive signal to time gain 10 compensation circuit (TGC) 313 via a pre-amp 316. The TGC applies amplification to the received signal. The characteristics of the amplification are selected to compensate for the depth attenuation, giving a compensated receive signal where the intensity is proportional to the reflectiveness of the feature which caused the echo. In general, the amplification characteristics may 15 take any shape. This compensated signal is passed to an analogue to digital converter (ADC) 314, via an anti-aliasing filter 317. The output of the ADC is a digital data stream representing the intensity of the received echoes over time for a single ultrasonic pulse. 20 In use, a user applies the shell 2 to a body to be imaged. A scan is initiated by the user, by means of a control either on the probe unit or on the DPU. There may also be a pressure sensor in the shell which initiates scanning when pressure above a selected threshold is applied to the patient's body. The activation of the control is detected by the controller 351 and communicated to 25 the DPU 11 via the message channel 310. The DPU responds with a message which includes any parameters which have been selected for the scan. The controller 351 controls the high voltage driver to produce the required pulse sequence to be applied via the diplexer to the transducer in order to perform a scan according to the parameters set by the 30 user, or set as defaults in the DPU.

8 The user moves the finger to which the transducer assembly is attached as required to sweep the ultrasound beam over the desired area, keeping linear displacement to a minimum. At the same time, data is received from the orientation sensor 5. This is the 5 rotation about the sensed axes of the transducer. It may be the angular change in the position of the probe unit since the immediately previous transducer pulse, or the orientation of the transducer in some defined frame of reference. One such frame of reference may be defined by nominating one transducer pulse, normally the first of a scan sequence, as the zero of orientation. 10 The sensor data and the response signal are passed to the controller 351 where they are combined to give a scanline dataset. A scanline dataset comprises a sequential series of intensity values of the response signal combined with orientation information. The scanline dataset is generated in the controller 351. The scanline dataset is 15 then passed to a protocol converter to be converted to a protocol suitable for transmission via the data channel. Any suitable protocol may be used. In this embodiment the protocol chosen for use on the data channel is 8blOb, which is well known in the art. The 8b10b data is passed to an LVDS transmitter 338 and is transmitted via the 20 data channel 320 to the DPU 11. The LVDS data channel is received by the DPU via LVDS receiver 321 and phase locked loop 322. The 8b10b data is passed to the DPU processor 340. Protocol conversion is performed by processor 340 to recover the original scanline dataset. 25 An application is now run by the DPU processor 340 to process the scanline dataset for display on the display 16 of the DPU 11. The high voltage generator 312 continues to provide the pulsed voltage to the transducer under control of the microcontroller and each pulse results in a scanline. 30 In order to produce a real time display, the user continues to rotate the transducer assembly and hence the scanline, through a planar sector in a 9 reciprocating manner. The transducer is continuously pulsed, providing a stream of scanline datasets which are displayed on the display 16 to form a real time moving image. In a further embodiment, the transducer is an array transducer able to produce 5 more than one scanline at a time. It may be a phased array, which will allow for beam steering and beam focusing. In this embodiment, the array transducer is able to produce a B-mode scan in a single scan plane, without the transducer assembly being rotated. The inertial sensor is mounted in such a way as to detect rotation or movement in a direction orthogonal to the scan plane. In use 10 the user moves or rotates the transducer in a direction orthogonal to the scan plane, while multiple B-mode scans are made. This allows for the isonification and imaging of a three dimensional volume. Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognised 15 that departures can be made within the scope of the invention, which is not to be limited to the details described herein but is to be accorded the full scope of the appended claims so as to embrace any and all equivalent devices and apparatus.

Claims

1. A finger mountable ultrasound transducer assembly including an ultrasound transducer which transmits and receives a single scanline, an inertial sensor mounted in fixed spatial relationship to the transducer, mounting apparatus 5 which releasably holds the assembly to at least one of a user's fingers.

2. The assembly of claim 1 wherein the inertial sensor includes at least one functional element selected from a gyroscope and an accelerometer.

3. The assembly of claim 1 wherein the transducer comprises separate receive and transmit elements. 10

4. An ultrasound scanning device including a finger mountable transducer assembly including an ultrasound transducer which transmits and receives a single scanline, an inertial sensor mounted in fixed spatial relationship to the transducer, mounting apparatus which releasably holds the assembly to at least one of a user's fingers wherein, in use, a user rotates said finger, with 15 the assembly attached, in order to sweep the scanline through a sector of a circle within a body to be imaged, output of the transducer being combined with output from the inertial sensor to produce a B-mode ultrasound scan.

5. An ultrasound scanning device as in any one of the preceding claims wherein the transducer is an array transducer adapted to acquire B-mode 20 scan data covering a scan plane, the inertial sensor being adapted to sense movement and to provide movement data about movement in one or more directions substantially orthogonal to the scan plane concurrently with the acquisition of said B-mode scan data, the combined B-mode scan data and movement data being processed to produce a three dimensional image.