WO2009079695A1

WO2009079695A1 - Improved scanning apparatus

Info

Publication number: WO2009079695A1
Application number: PCT/AU2008/001873
Authority: WO
Inventors: Andrew Niemiec
Original assignee: Signostics Pty Ltd
Priority date: 2007-12-20
Filing date: 2008-12-19
Publication date: 2009-07-02

Abstract

A medical ultrasound scanning apparatus Including a control unit and a probe unit, the probe unit including at least one transducer unit housing an ultrasound transducer, wherein the transducer unit Is removably attached to the probe unit.

Description

TITLE

IMPROVED SCANNING APPARATUS

TECHNICAL FIELD

The present invention relates to an interchangeable transducer unit for an ultrasound scanning device.

BACKGROUND ART

Ultrasound was first Investigated as a medical diagnostic imaging too! in the

1940's. This was based on the use of A-modθ (amplitude mode) ultrasound, which is a form of echo ranging. This simply gives a plot of returned echo Intensity against time, which, by knowing the speed of sound in the target media, gives the dlstanoe of the features returning the eoho from the transducer. In order to obtain valid information from such a scanllne It is necessary that the direction of the transmitted ultrasound beam be constant and known. In the early 1950's there was constructed a B-mode scanning system using a mechanically mounted rotating transducer.

Ultrasound technology developed significantly In the 1960's with the development of articulated arm B-mode scanners. Articulated arm scanners, also known as static mode scanners, connect the ultrasonic transducer to a moveable arm, with movement of the arm mechanically measured using potentiometers. The articulated arm also ensures that the degree of freedom of movement of the transducer is limited to a defined plane. This allowed the position of the transducer to be known with considerable accuracy, thus allowing the scanlines recorded by the transducer to be accurately located In space relative to each other for display.

Static mode ultrasound scanners were In wide use until the early 1980s. The static mode scanners were large cumbersome devices, and the techniques used are not readily suited to a handheld ultrasound system.

In the mid 1970's real-time scanners were developed where an ultrasonic transducer wag rotated using a motor. These devices brought their own problems. The motor driving circuitry added size, power consumption, complexity and cost to the device. Additionally, the motor itself and associated moving parts reduced the reliability of the device.

A solution to these problems has been sought in electronic beam steering transducers, including a number of crystals where the transmitting pulse can be delayed in sequence to each crystal and thus effect an electronic means to steer the ultrasound beam. The basic technique Is still in wide use today, with nearly all modern medical ultrasound equipment using an array of ultrasonic crystals in the transducer. The early designs used at least 64 crystals, with modern designs sometimes using up to a thousand crystals or more.

These advances In ultrasound design have been accompanied by enormous advances in the field of electronics generally. These combined advance have seen practical medical ultrasound machines reduce In size from devices which required a dedicated room, to the situation today where devices may be no larger than a laptop computer.

Such small devices are, in principle, portable, able to be carried by a user to the bedside or even to the location of a casualty outside of a hospital or clinic setting.

In practice, most such devices remain cart bound in use. There are many reasons for this. One reason is the multitude of bulky and expensive probe units required by these systems.

When selecting the operating frequency of a probe for ultrasound applications, a trade-off needs to be made. High frequency probes provide relatively good axial resolution, but because attenuation in tissue increases with frequency, high frequency signals have a rather limited penetration depth. If a deeper scan is desired, the frequency can be reduced, but the cost is a corresponding reduction of axial resolution.

In order to maxlmlae the usefulness of ultrasound machines, such machines are usually designed In such a way that there is a probe unit, which Includes the ultrasound transducer or transducers, the probe unit being plug connectable to a main unit which receives signals from the probe unit, processes them and displays an Image. In order to scan at a different frequency, a user unplugs from the main unit a probe unit having transducers of one frequency, and plugs in a probe unit having transducers of a desired different frequency.

Thus, users of ultrasound often have a number of probes, each with a different frequency transducer, and they choose the one most appropriate for their application. However, each probe comes with its own case, cable, and in some case, its own electronics package. This means that there Is a significant bulk of material which must be transported around by a user who requires access to multiple frequency ultrasound scanning functionality.

The multiple probe units also contribute very significantly to the cost of the unit.

DISCLOSURE OF THE INVENTION

Having a single probe with interchangeable transducer unit heads would be advantageous, since the required electronics and cabling would be contained within a single probe, and a user desiring to use multiple frequencies would be only required to carry a number of physically quite small transducer units around In addition to the single probe. This would result in a system significantly cheaper and more portable than the current state of the art.

In one form of this Invention there is proposed a medical ultrasound scanning apparatus including a control unit and a probe unit, the probe unit including at least one transducer unit, said transducer unit Including an ultrasound transducer, the probe unit further including circuitry adapted to apply to the transducer a driving voltage selected to cause the transducer to emit scanning ultrasound energy, wherein the at least one transducer unit Is adapted to be removably attached to said probe unit. In preference the transducer unit is removably attached to the probe unit by a screw thread.

In the alternative the transducer unit is removably attached to the probe unit by a bayonet connector.

A user Is then able to change the frequency of operation of the apparatus by removing the transducer unit which is physically small and replacing It with another unit having a different ultrasound transducer. It Is advantageous for the transducer unit to provide identification and calibration data about the transducer to the probe unit and to the control unit. This ensures that no user action beyond the physical changing of the transducer units is required. In preference there is electronic circuitry in the transducer unit associated with a transducer which is adapted to provide information about the transducer to said probe unit or control unit.

In preference the Information about the transducer includes the frequency of operation of the transducer. In preference the Information about the transducer includes a unique identifier for the particular transducer.

The information may be provided in any convenient manner. In a preferred embodiment the identification electronic circuitry includes a digital data store to ^•hold the information. In the alternative the information may be encoded Into the response to an electrical signal of any combination of resistors, capacitors or Inductors.

Ultrasound transducers are driven at high voltages. In order to keep the transducer unit to the smallest possible size and cost, the power supply generating these voltages will be located in the probe unit. Accordingly, if it were possible for the probe unit to produce these voltages when no transducer unit is attached, there would be a risk of exposing a user to these high voltages.

Preferably, there are means provided to ensure that the driving voltage is not applied during periods when the transducer unit is removed from the probe unit,

In preference the information about the transducer provided to the probe unit or the control unit Includes the state of connection of the transducer unit to the probe unit.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 Illustrates an ultrasound scanning system Incorporating an embodiment of the invention. Figure 2 shows a partial exploded view of a probe unit in accordance with the Invention. Figure 3 shows a simplified block diagram of the electronic components of a probe unit of the system of Figure 1 ,

Figure 4 shows a diagrammatic representation of the manner In which the high voltage power is applied to the transducer PCB in an embodiment of the invention.

Figure 5 shows a diagrammatic representation of a transducer PCB of an alternative embodiment.

Figure 6 shows a timing diagram of the signals for use with the embodiment of Figure 5.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to Figure 1, there Is Illustrated an ultrasound scanning system incorporating an embodiment of the invention. There Is a hand held ultrasonic probe unit 10, a display and processing unit (DPU) 11 with a display screen 16 and a cable 12 connecting the probe unit to the DPU 11, The probe unit 10 includes an ultrasonic transducer 13 adapted to transmit pulsed ultrasonic signals into the body of a patient 14 and to receive returned echoes from the subject to be scanned, in this medical application being the patient 14.

The transducer Is adapted to transmit and receive in only a single direction at a fixed orientation to the probe unit, producing data for a single scanlinβ 15. The system is a simple, low cost portable ultrasound scanning system. Additional transducers may be provided, at the expense of increased cost and complexity.

The probe unit further includes an orientation sensor 18 capable of sensing orientation or relative orientation about one or more axes of the probe unit. Thus, in general, the sensor is able to sense rotation about any or all of the axes of the probe unit.

The sensor may be implemented In any convenient form. In an embodiment the sensor consists of three orthogonally mounted gyroscopes. In further embodiments the sensor may consist of two gyroscopes, which would provide Information about rotation about only two axes, or a single gyroscope providing information about rotation about only a single axis. Since the distance between the mounting point of the sensor 18 and the tip of the transducer 13 Is known, ft would also be possible to implement the sensor with accelerometers.

In further embodiments, the sensor is a position and/or orientation sensor which may be implemented as any combination of gyroscopes and accelerometers mounted in relative position to one another so as to give information about the linear and angular displacement of the probe unit. Full relative position data for the probe unit can be obtained with three orthogonally mounted accelerometers and three orthogonally mounted gyroscopes. This arrangement provides measurement of displacement in any direction and rotation about any axis. This allows for direction information for a scanline to be given for all six degrees of freedom.

In use, a user places the probe unit 10 against the body of the patient 14. The user then Initiates a scan, by means of controls which may be located on the probe unit or the DPU 11. Pulsed ultrasound energy is transmitted Into the body of the patient, and the resultant echoes received by the transducer.

The user rotates the probe unit in an arc, minimizing translational movement and rotation about unsensed axes. This causes a planar sector of the body of the patient to be scanned with ultrasound energy. The orientation sensor provides information about the relative movement of the probe unit. This information Is combined with the returned echo information by a processor in the probe unit to form scanllnas. These scanlines are transmitted to the DPU. The DPU processes the scanlines for display on the screen 16. Thθ intensity of echo Is displayed as relative brightness, with scanlines being displayed in correct relative position to each other. Scanlines are displayed as they are received, or In groups of a size less than the group size which would constitute a full sector of a B-mode scan, giving a continuously updated B- mode sector scan display.

It can be seen that the probe unit forms a significant part of the bulk of the unit. It can also be seen that a significant part of the electronics, beyond the transducer, are located In the probe unit.

This means that the probe unit forms a very significant part of the cost and bulk of the ultrasound system. Providing for additional transducers by providing swappable probe units would greatly Increase the cost of the system. More significantly, requiring a user to carry multiple probe units would make the total bulk of the system so great that it would no longer be able to be conveniently carried In a pockθt or around a user's neck. To provide the advantages of multiple transducers, having different operating frequencies, without the bulk and cost disadvantages, swappable transducers are provided. Figure 2 shows a partial exploded view of a probe unit In accordance with the invention. Referring now to Figure 2, there is a transducer 202 which is surrounded and protected by transducer cover 201. There Is a transducer PCB 203. The transducer, the transducer cover, and the transducer PCB make up a transducer unit, which, in use, is a fixed unit.

In this embodiment, the transducer unit includes a moulded thread which screws to the probe unit body, but any readily removable means of attachment may be used. The join between the transducer unit and the probe unit body is protected against dust or liquid ingress by O-ring 204.

The transducer unit is small in relation to the size of the probe unit or the control unit. In a preferred embodiment the largest dimension of the transducer unit is no greater than 4cm. In a more preferred embodiment, the largest dimension of the transducer unit Is no greater than 2cm.

In use, a user may desire to make an ultrasound scan where a frequency of ultrasound radiation different to that supplied by the transducer of the transducer unit attached to the probe unit. The user unscrews the transducer from the probe unit, selects another transducer unit of the appropriate frequency, and screws this to the probe unit.

Figure 3 shows a simplified block diagram of the electronic components of the probe unit 10.

There Is a transducer 301 which Is connected via diplexer 302 to a transmitter 303. Under the control of main processor 305, the transmitter applies pulses of a high voltage provided by a high voltage power supply 304 to the transducer to stimulate emission of ultrasound pulses from the transducer. The transducer receives returned echoes from these emitted pulses and produces a corresponding electrical signal. The dlplθxer directs these returned signals to an analogue signal conditioning stage 306. The signal is filtered and amplified and passed to analogue to digital converter (ADC) 307. The signal Is converted to a digital data stream and passed to digital fitter 308. The filtered data stream is then passed to main processor 305.

At the same time, the orientation sensor, In this embodiment gyroscope 309, provides the relative movement of the probe unit since the immediately preceding pulse. This data is transmitted to the main processor, where It Is combined with the echo data to form a scanllnβ data set The scaπline data set is transmitted to the DPU 11 as shown In Figure 1 for display.

The system allows Interchanging of different frequency transducers, and there is provided means for Identifying the frequency of the transducer which is currently attached. Associated with the transducer, mounted on the transducer unit PCB, is identification chip 310, which can store information about the centre frequency of the transducer {and potentially other data such as bandwidth, serial number, calibration records, etc).

At system startup and whenever the system detects that the transducer unit has been removed, or alternatively, before each scan, microprocessor 311 Interrogates the ID chip to determine the characteristics of the attached transducer.

This Information is communicated to the DPU. The DPU Is then able to command any changes to operating parameters which may be required to ensure optimum operation with the attached transducer.

An example of a suitable ID chip is the DS2502, a 1kbit add-only memory from Maxim, which can Implement an ID system with only two additional connections to the transducer, but those skilled In the art would realise that there are numerous other components which could be used for this purpose. The centre frequency Information provided by the identification chip is used to determine the frequency of the driving pulse provided to the transducer by the transmitter. The centre frequency Information provided may be the nominal centre frequency of the transducer, and the transmitter may then provide drive to the transducer at that nominal frequency.

In other embodiments, the transducer may be tested to ascertain its exact centre frequency, which will vary slightly from the nominal value for each Individual transducer. The drive frequency may be adjusted for this slight variation to provide the best possible power transfer from the transmitter to the transducer.

In an alternative embodiment (not illustrated) identification of the transducer frequency is provided by one or more resistors attached to the transducer PCB, in such a way that the resistance value can be measured by the probe circuitry when the transducer is connected (via measuring the voltage In the middle of a resistor divider network, measuring the current flow, or using one of the numerous other techniques known to those skilled in the art). Different frequency transducers have different resistor values, allowing software running on the main processor 305 or on the DPU 11 to identify the transducer frequenoy based on resistance value. This method of Identification is relatively cheap, but it would be difficult to store additional information such as a serial number. In a similar way, capacltor(s), inductors) or some combination thereof could be used as an identification means, with the probe circuitry applying an AC signal and measuring the frequency response.

In a further alternative embodiment there Is provided a pattern of connections on a PCB connected to each transducer unit, with a unique combination of connections being associated with transducers of each nominal frequency. This method does require a larger number of connections between the probe and the transducer unit than the preferred embodiment employing an Identification chip.

In a yet further alternative embodiment, software running on the main processor Is adapted to send a number of different shape pulses to the transducer, and to measure the response. It Is known to those skilled in the art that optimum power transfer to a transducer occurs when the frequency of the excitation pulse is at the centre frequency of the transducer. Software on the main processor or the DPU determines which pulse shape produces the largest response, or determines the frequency of maximal response using a Fast Fourier Transform. The frequency with the largest response is taken to be the nominal frequency of the attached transducer. This method has the advantage of not requiring any additional connections to the transducer other than those already required for the TX/RX pulse. It Is less preferred because the probe needs to be held still against a particular target for some of the mentioned processing techniques to be effective, and the method does not Inherently indicate that transducer Is actually attached without applying a pulse to the TX/RX lines, which has potential safety implications. Analogue signal conditioning stage 306 Includes an analogue filter to Increase the signal to noise ratio. This analogue filter has a fixed response. In order to accommodate the use of several transducers of different frequencies, thla analogue filter is a broadband filter.

The digital filter 308 Is able to be changed to match the attached transducer. Parameter sets defining digital filters appropriate to the frequency and bandwidth of possible transducers are stored in digital memory located on the probe unit. In other embodiments, the memory may be located In the DPU₁ or on the transducer PCB. In a further embodiment, the parameters may be custom generated, based on the transducer characteristics, and rules programmed into the main processor.

The analogue filter is selected to be of a bandwidth broad enough to accommodate all the transducers expected to be connected. For example, If a probe is to be used with two swappable transducers, one with a centre frequency of 3MHz and a passband of 2-4 MHz, another with a centre frequency of 6MHz and a passband of 4-8 MHz, it would be desirable to have an analogue filter with a passband of 2-8 MHz. As those skilled in the art would appreciate, the ADC sample rate must be sufficiently above the maximum analogue pass frequency to avoid aliasing problems. The digital filter would then be chosen to approximately match the transducer which has been determined to be connected.

In an alternative embodiment the analogue filter characteristics are not fixed, but can be modified, for example by switching certain components in or out of the filter circuit. This may be instead of or in addition to the customlsable digital filter. This has the disadvantage that the analogue electronics are more complicated than In embodiments with a fixed analogue filter, but the advantage of allowing a lower the sampling rate to be used by the ADC when lower frequency probe Ie connected without aliasing. This results in power and data size savings.

Referring to Figure 2 and Figure 3, the diplexer 302 is located within the probe unit body 205. When the transducer unit is removed from the probe unit body 205, terminals of the connector between the probe unit and the transducer are exposed. A high differential voltage, typically over 100V, is applied to these terminals during a scan. Although the voltage is applied only In very brief pulses, and the current which can be drawn for a sustained period of time is relatively low, it is still desirable for safety reasons to prevent the scan pulaøg being generated if the transducer is not attached.

Thus, a means of detecting whether the transducer is attached is provided. In the Illustrated embodiment, prior to the Initiation of a scan, the microprocessor 311 Initiates communication with the Identification chip 310 via an appropriate communications protocol. If no response or an incorrect response Is received, initiation of a scan Is suppressed.

For embodiments incorporating other means for identification of the attached transducer, such as those based on resistors or PCB patterns, the presence of a transducer Is checked by the microprocessor applying a voltage on one terminal, and determining that the voltage on the other terminal is at an appropriate level.

The microcontroller will check for the presence of the transducer before starting the scan, suppressing the scan, and thus preventing the powering up the high- voltage circuitry if a transducer Is not found.

The microcontroller software continually monitors the transducer presence whilst scanning. If a transducer Is not detected, power to the high voltage components Is removed, halting the scan. A further protection against the danger of high voltage excitation being present at exposed terminals may be provided by a hardware control in an embodiment. Figure 4 shows a diagrammatic representation of the manner in which the high voltage power from the transmitter, via the dlplexer, is applied to the traπsducar PCB.

The underside of the transducer PCB, the side proximal to the probe unit, Includes a conductive disk 401 , a first conductive annulus 402 and a second conductive annulus 403. The transducer is fixedly electrically connected between the first annuius and the conductive disk.

On the probe unit, there Is provided a first pair of electrically conductive pins 404. These pins carry the high voltage excitation pulses which are directed to the transducer from the transmitter. These are positioned such that when the transducer unit is attached to the probe unit, one of the first pair of pins makes electrical contact with the central disk 401 while the other makes electrical contact with the first annulus 402. This provides an electrical path from the transmitter 303 via diplexer 302 to the transducer. There is further provided a second set of electrically conductive pins 405. These are positioned such that when the transducer unit Is attached to the probe unit, each of the pins makes contact with the second conductive annulus 403. Thus, when, and only when, the transducer unit Is attached to the probe unit, there is direct electrical connection between the second pair of pins. In an embodiment, the microprocessor applies a voltage to one of this pair of pins and monitors the voltage on the other, Only when the transducer unit is connected and the conductive path between the pins Is provided by the second annulus will these voltages be approximately equal. The microprocessor uses this to determine if the transducer unit Is attached. When the transducer unit is not attached, the microprocessor ensures that power is not provided to the high voltage power supply. This ensures that a high voltage does not appear at the first set of pins when the pins are exposed.

In a further embodiment, the low voltage power supply which is provided to power the high voltage power supply 304 may bθ directly routed through the second set of pins 405, This ensures that when the transducer unit Ie removed, power to the high voltage supply is removed. Figure 5 shows a diagrammatic representation of the transducer PCB of an embodiment In which the presence of the transducer unit is determined by the response of an ID chip to a presence pulse.

Figure 5 shows the underside of the transducer PCB, the side proximal to the probe unit The PCB includes a conductive disk 501 , a first conductive aππulus 502, second conductive annulus 503 and third conductive annulus 504.

The^" transducer is fixedly electrically connected between the first annulus and the conductive disk.

On the probe unit, there is provided a first pair of electrically conductive pins 506. These pins carry the high voltage excitation pulses which are directed to the transducer from the transmitter. These are positioned such that when the transducer is attached to the probe unit, one of the first pair of pins makes electrical contact with the central disk 501 while the other makes electrical contact with the first annulus 502. This provides an electrical path from the transmitter 303 via dlplexer 302 to the transducer.

ID chip 505 is connected between second conductive annulus 503 and third conductive annulus 504. An example of a suitable chip is the Maxim DS2502, which has a 1-wire communications interface, so that only two electrical connections need to be made being a signal connection and a ground connection. The signal connection is bl-dlrectlonal and also supplies power for the chip.

When the transducer unit Is attached to the probe unit, signal pin 507 connects to second conductive annulus 503, and ground pin 508 connects to third conductive annulus 504, thus providing a circuit for communications with ID chip 505,

The presence of a 1-wire ID chip is determined by transmitting an appropriate Interrogation pulse to the chip over signal pin 507 and receiving a particular presence pulse generated by the chip in response. An example of the presence pulse for detecting the DS2502 is shown in figure 6. The probe unit, or the DPU via the probe unit, sends the Interrogation pulse which is called a reset pulse in the terminology used by the chip manufacturer, via pin 507 and monitors the same pin for the presence pulse. Figure 6 is a simplified timing diagram showing the voltage levels on signal pin 507 associated with detecting the presence of a functional DS2502 chip.

The 'resting level' voltage on the signal pin 507 is at logical high Which is 3.3V in this embodiment. To detect a DS2502, the probe unit first sends a "reset pulse¹, which consists of pulling the data bus voltage down to a logical low voltage level which is OV In this embodiment for a tome period of 480μs, then releasing it. The voltage then rises back to its the logical high level. The DS2505 will detect this and after a period of 40μs the DS2505 will pull the voltage low for around 100μs. This Is the presence pulse, Indicating that the ID chip Is present.

The probe unit controller can determine whether a DS2505 is present by measuring the voltage level It the signal pin 507 during what should be the 'low' portion 601 of the presence pulse. If the voltage level Is not low it will be Inferred that the chip, and hence the transducer unit, is absent The probe unit or the DPU will regularly transmit the interrogation pulse and check for the presence pulse. When the presence pulse is not detected in response, the probe unit or the DPU will immediately shut down the high voltage pins 506. The time between successive Interrogation pulses time will be shorter than the time it would require for a user to remove the transducer unit. The user is thus protected from exposure to high voltage.

In addition to simple transducer detection, there is a benefit In using an ID chip in that the 1-wire protocol can be used to extract Information stored on the chip. This Information can include data relating to the frequency of the transducer, as disclosed above. The embodiment described In Figure 5 is more complex in that It requires one ^' more conductive annulus than the embodiment of Figure 4, but there Is the advantage that information about the transducer may be stored on the ID chip physically associated with an Individual transducer Instead of merely ascertaining whether It Is present or absent. Although the Invention has been herein shown and described In what is conceived to be the most practical and preferred embodiment, it Is recognised 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

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS

1. A medical ultrasound scanning apparatus Including a control unit and a probe unit, the probe unit including at least one transducer unit, said transducer unit Including at least one ultrasound transducer, the probe unit further including circuitry adapted to apply to the transducer a driving voltage selected to cause the transducer to emit scanning ultrasound energy, wherein the at least one transducer unit Is removably attached to said probe unit.

2. The apparatus of claim 1 wherein the transducer unit Is removably attached to the probe unit by a screw thread.

3. The apparatus of claim 1 wherein the transducer unit is removably attached to the probe unit by a bayonet connector.

4. The apparatus of claim 1 wherein the largest dimension of the transducer unit is less than 4cm. 5. The apparatus of claim 1 wherein the largest dimension of the transducer unit is less than 2cm.

6. The apparatus of clalmi further including Identification electronic circuitry associated with said transducer unit which provides Information about the transducer to said control unit or probe unit. 7. The apparatus of claimi including electronic circuitry and program logic to ensure that the driving voltage is not applied during periods when the transducer is removed from the probe unit.

8. The apparatus of claim 6 wherein the Information about the transducer includes the state of connection of the transducer unit to the probe unit. 9. The apparatus of claim 6 wherein the Information about the transducer includes the frequency of operation of the transducer.

1O.The apparatus of claim 6 wherein the Information about the transducer Includes a unique identifier for the particular transducer.

11.The apparatus of claim 6 wherein the identification electronic circuitry includes a digital data store.

12.Thθ apparatus of claim 11 wherein thθ Identification electronic circuitry is a one wire identification chip,

13. A probe unit for a medical ultrasound scanning apparatus including at least one transducer unit having an ultrasound transducer the transducer unit being adapted to be removably attached to said probe unit, the probe unit and the transducer unit including Identification electronic circuitry adapted to provide Information about the transducer.

14.A transducer unit Including an ultrasound transducer, said transducer unit adapted to be removably connected to a medical ultrasound scanning apparatus including identification electronic circuitry adapted to provide information about the transducer.

15.The transducer unit of claim 14 wherein the identification electronic circuitry Includes a digital data store.

16.The transducer unit of claim 14 wherein the identification electronic circuitry includes a one wire identification chip.

17. A medical ultrasound scanning apparatus substantially as described In the specification with reference to and as illustrated by any one or more of the accompanying drawings.

18.A transducer unit adapted to be removably connected to a medical ultrasound scanning apparatus substantially as described in the specification with reference to and as illustrated by any one or more of the accompanying drawings.

19. A probe unit for a medical ultrasound scanning apparatus substantially as described in the specification with reference to and es illustrated by any one or more of the accompanying drawings.