阅读说明：本技术 使用超声波进行医学检查的超声波设备 (Ultrasound apparatus for medical examination using ultrasound ) 是由 奥利弗·海德 于 2019-01-25 设计创作，主要内容包括：本发明涉及一种用于通过超声波进行医学检查的超声波设备,设备包括可移动的测声探头(TP),测声探头(TP)可定位在患者的身体上并且包括电声换能器的换能器阵列(TA),换能器阵列(TA)用于将超声信号发送到身体内并接收所发送的超声信号的超声回声作为模拟原始数据(RDA)。测声探头(TP)包括模数转换器(CON),模数转换器(CON)被配置成根据所接收的模拟原始数据(RDA)来生成数字原始数据(RDD),其中,数字原始数据(RDD)包括用于连续的测量时间间隔的测量数据集(MD)。测声探头(TP)经由数字数据接口(IF)耦合到单独的不属于测声探头(TP)的计算机设备(COM),并配置成经由数字数据接口(IF)来传输数字原始数据(RDD)。计算机设备(COM)包括原始数据缓冲存储器(BF),其中数字原始数据(RDD)的各个测量数据集(MD)被缓冲。此外,计算机设备(COM)被设计成使得其对每个缓冲的测量数据集(MD)进行数字波束成形过程,以便获得组织区的重建图像,以及使得基于重建图像,其以预定帧速率生成图像流,并将图像流提供给再现该图像流的显示工具(DI)。(The invention relates to an ultrasound device for medical examinations by ultrasound, the device comprising a movable sound-measuring probe (TP) which can be positioned on the body of a patient and comprises a Transducer Array (TA) of electroacoustic transducers for transmitting ultrasound signals into the body and receiving ultrasound echoes of the transmitted ultrasound signals as simulated Raw Data (RDA). The sound-measuring probe (TP) comprises an analog-to-digital Converter (CON) configured to generate digital raw data (RDD) from the received analog Raw Data (RDA), wherein the digital raw data (RDD) comprises a measurement data set (MD) for successive measurement time intervals. The sound-measuring probe (TP) is coupled via a digital data Interface (IF) to a separate computer device (COM) not belonging to the sound-measuring probe (TP) and is configured to transmit digital raw data (RDD) via the digital data Interface (IF). The computer device (COM) comprises a raw data buffer memory (BF), in which respective measured data sets (MD) of digital raw data (RDD) are buffered. Furthermore, the computer device (COM) is designed such that it performs a digital beam-forming process on each buffered measurement data set (MD) in order to obtain a reconstructed image of the tissue area, and such that, on the basis of the reconstructed image, it generates an image stream at a predetermined frame rate and supplies the image stream to a display tool (DI) which reproduces the image stream.)

1. An ultrasonic apparatus for medical examination using ultrasonic waves, wherein,

-the ultrasound device comprises a movable Transducer Probe (TP) which is positionable on the body of the patient and comprises a Transducer Array (TA) of electroacoustic transducers for transmitting ultrasound signals into the body and receiving ultrasound echoes of the transmitted ultrasound signals as analog Raw Data (RDA);

-the Transducer Probe (TP) comprises an analog-to-digital Converter (CON) configured to generate digital raw data (RDD) from the received analog Raw Data (RDA), wherein the digital raw data (RDD) comprises measurement data sets (MD) for temporally successive measurement time intervals, wherein each measurement data set (MD) comprises an ultrasonic echo from a tissue region of the body from a transmission operation of one or more ultrasonic signals by at least one transducer in a transmit mode as a sample for a sampling instant of each measurement time interval, respectively, from a plurality of receive channels of the at least one transducer in a receive mode;

-the Transducer Probe (TP) is coupled via a digital data Interface (IF) to a separate computer device (COM) not belonging to the Transducer Probe (TP) and configured to transmit the digital raw data (RDD) via the digital data Interface (IF);

-the computer device (COM) comprises a raw data buffer memory (BU), wherein respective measured data sets (MD) of the digital raw data (RDD) are buffered;

-the computer device (COM) is configured to perform a respective digital beamforming on the buffered measurement data set (MD) by time-delayed addition of the sample in order to determine image values of a plurality of tissue locations at different tissue depths, wherein there are several tissue locations for each tissue depth, thereby obtaining reconstructed images of the tissue area, and to generate an image stream of successive reconstructed images or images computed therefrom at a predetermined image refresh frequency based on the reconstructed images and to provide it to a display tool (DI) reproducing the image stream.

2. Ultrasound device according to claim 1, characterized in that the raw data buffer memory (BU) is arranged for buffering a plurality of consecutive measured data sets (MD) simultaneously.

3. Ultrasound device as claimed in claim 2, wherein the computer device (COM) is configured to determine respective reconstructed images in parallel for several of the plurality of buffered measurement data sets (MD).

4. Ultrasound device according to one of the preceding claims, characterized in that the computer device (COM) is configured such that the images of the image stream are each calculated as an average of a plurality of successive reconstructed images.

5. Ultrasound device according to one of the preceding claims, characterized in that the predetermined image refresh frequency is 50Hz or higher.

6. Ultrasound device according to one of the preceding claims, characterized in that the computer device (COM) is configured to determine digital control data (CDD), on the basis of which digital control data, determining the operation of the transducers of the Transducer Array (TA) for transmitting ultrasound signals and for receiving ultrasound echoes during successive measurement time intervals, wherein the computer device (COM) comprises a control data buffer (BU'), said digital control data (CDD) being buffered in said control data buffer memory (BU'), and wherein the Transducer Probe (TP) is configured to read the digital control data (CDD) via a digital data Interface (IF) or a further digital data interface between the Transducer Probe (TP) and the computer device (COM), and controlling the transducers of the Transducer Array (TA) based on the read-out control data.

7. Ultrasound device according to one of the preceding claims, characterized in that the digital data Interface (IF) comprises a wired data interface and/or a wireless data interface.

8. Ultrasound device according to one of the preceding claims, characterized in that the digital data Interface (IF) comprises a PCI Express interface.

9. Ultrasound device according to one of the preceding claims, characterized in that the Transducer Probe (TP) comprises a high voltage Transmitter (TR) for generating a high voltage signal, which is provided via a switch array (SW) via a transmit-receive switch to the Transmitter Array (TA) for generating ultrasound waves by one or more transducers in a transmit mode, wherein the transducers of the Transducer Array (TA) can be switched to the transmit mode or the receive mode by means of the switch array (SW).

10. Ultrasound device according to one of the preceding claims, wherein the Transducer Probe (TP) comprises a Preamplifier (PA) configured to amplify the analog Raw Data (RDA) before providing the analog Raw Data (RDA) to the analog-to-digital Converter (CON).

Technical Field

The present invention relates to an ultrasonic apparatus for medical examination using ultrasonic waves.

Background

In medical diagnostics, ultrasound devices are commonly used for examining human or animal tissue by detecting ultrasound echoes. To do this, the transducer probe is pressed over the tissue region to be examined and ultrasound waves are transmitted into the tissue region by the array of electroacoustic transducers. The resulting ultrasonic echoes are detected by means of transducers, wherein, depending on the number and arrangement of the electroacoustic transducers, an image of the tissue region is reconstructed from these ultrasonic echoes, which image may be two-dimensional or three-dimensional.

During the processing of the detected ultrasound echoes, the obtained analog samples are digitized and subjected to so-called beamforming, wherein samples of the various electroacoustic transducers are appropriately time-shifted and added together to reconstruct the position of the reflectors in the direction of the tissue depth and in the angular direction with respect to the array of electroacoustic transducers. Typically, signal processing of the ultrasonic echoes detected by the transducer probe is performed in a bulky electronic box, in which the analog electrical receive signals of the transducer are transmitted via a coaxial cable bundle. For example, the device case may be mounted in a cart in combination with a keyboard and display unit.

Currently, the above-mentioned beamforming is performed in synchronization with the timing of an analog-to-digital converter used to digitize an analog sample. The problem here is that in a measurement operation comprising transmitting at least one ultrasound pulse and receiving an echo thereof within a predetermined time period, the tissue position in one angular direction along the beam can only be reconstructed by means of beamforming. Therefore, in order to obtain an image of the entire tissue region, the same measurement operation has to be repeated a number of times, wherein for each measurement operation the beamforming is adjusted accordingly in order to reconstruct the tissue position in different angular directions. In this way, sectors of different angular directions are obtained, which are added to the image. In practice, there are also ultrasound apparatuses that use a plurality of beamforming calculation units in parallel for different angular directions. However, this increases the complexity of the ultrasound device.

In order to reduce the size of the ultrasound apparatus, it is known from the prior art to integrate also part of the signal processing that is usually performed in the device box in the transducer probe. In particular, it is known to mount an analog-to-digital converter in combination with a beamforming computer unit in a transducer probe and then transmit image data obtained from beamforming to an image forming and display unit via a data interface. However, there is the problem that the beamforming computer unit requires high computational power and thus leads to intense heating, which is undesirable in transducer probes that are usually manually guided by a user. As a result, only a small number of electroacoustic transducers are mounted in the transducer probe to limit the computational power required for beamforming. However, this results in a low image resolution and a low image refresh frequency. Furthermore, the problem remains that the beamforming operation can always be performed only for one angular direction of the respective tissue region.

Disclosure of Invention

It is an object of the present invention to create an ultrasound apparatus for medical examination using ultrasound waves which provides high quality ultrasound images while being simple in structure and inexpensive to manufacture.

This object is achieved by an ultrasound device according to claim 1. Further developments of the invention are defined in the dependent claims.

The ultrasound device according to the invention is used for medical examination of the human or animal body. To this end, the ultrasound device comprises a movable transducer probe, which can be positioned on the body of the patient. The patient may be a human or an animal. Preferably, the movable transducer probe is configured such that it can be held and guided by a hand of a user (in particular a physician). This allows the user to place the transducer probe anywhere on the patient's body in order to examine the underlying tissue by means of ultrasound.

The movable transducer probe includes a transducer array of electroacoustic transducers to transmit ultrasonic signals into the body and to receive ultrasonic echoes of the transmitted ultrasonic signals as analog raw data. Preferably, the electroacoustic transducer is a piezoelectric element. The number of electroacoustic transducers may vary depending on the configuration of the ultrasound device. A transducer array of 128 electroacoustic transducers is typically used. Each transducer may generate ultrasound waves in a transmit mode by applying a voltage. In addition, each transducer can also detect ultrasound in a receive mode, where no voltage is applied to the respective transducer.

The movable transducer probe of the ultrasound device according to the invention comprises an analog-to-digital converter configured to generate digital raw data from received analog raw data, wherein the digital raw data comprises measurement data sets for temporally successive measurement time intervals. Each measurement data set comprises ultrasonic echoes from a (two-dimensional and optionally also three-dimensional) tissue region of the body, wherein the ultrasonic echoes come from a transmit operation of one or more ultrasonic signals by at least one transducer in a transmit mode. The ultrasonic echoes represent samples at sampling instants of respective measurement time intervals from a plurality of receive channels of the at least one transducer, respectively, in a receive mode. In a preferred variant of the invention, the number of receiving channels corresponds to the number of transducers, i.e. each transducer represents a receiving channel through which the respective sample is detected in the receiving mode on the basis of the reflected ultrasonic echoes. In a variant of the invention, only a single transducer is used to transmit the ultrasonic echo during the transmitting operation. Typically, different transducers are used for transmission during successive measurement intervals. Typically, after a transmit operation, all transducers of the array switch to a receive mode.

The ultrasound device according to the invention further comprises a digital data interface by which the transducer probe is coupled to a separate computer device not belonging to the transducer probe. In other words, the computer device is a separate component from the movable transducer probe. The transducer probe is also configured to transmit digital raw data directly, preferably without buffering, via the digital data interface. In other words, digital raw data is streamed by the transducer through the digital data interface. Preferably, the data rate for transmitting the original data via the data interface is at least 1 GB/s.

A separate computer device, which is part of the ultrasound device according to the invention, comprises a raw data buffer memory, in which the individual measurement data sets of the digital raw data are buffered. In other words, each measurement data set sent via the digital data interface is temporarily stored in the raw data buffer memory for a certain period of time, wherein the period of time depends on the size of the buffer memory. In a preferred variant, a so-called ring buffer is used as buffer memory.

The separate computer device is further configured to perform a respective digital beamforming on each buffered measurement data set by time delay adding the samples in order to determine image values from a plurality of tissue locations at different tissue depths, wherein each tissue depth has several tissue locations (i.e. for different angular directions and different tissue depths). The tissue site preferably covers the entire tissue region. In this way, a reconstructed image of the tissue region is obtained. Depending on the configuration of the transducer probe, two-dimensional or three-dimensional images can thus be reconstructed.

In other words, digital beamforming is decoupled from the timing of the analog-to-digital converter and therefore asynchronous to this timing, due to the use of the raw data buffer memory. Due to the buffering of the individual measurement data sets, digital beamforming may be performed multiple times for the respective measurement data sets of different angular directions, so that a reconstructed image of the entire tissue region may be generated using one measurement data set.

The computer device used in the ultrasound device according to the invention is further configured to generate, based on the reconstructed images, an image stream of temporally successive reconstructed images or images calculated therefrom at a predetermined image refresh frequency and to supply it to a display means (in particular a display) reproducing the image stream. In other words, the reproduction of the image can be appropriately adjusted to the duration of the beamforming so that an image stream having a desired image refresh frequency can be generated and displayed. The display means are an integral part of the ultrasound device according to the invention.

The ultrasound device according to the invention has the advantage that no special real-time requirements have to be made on the computer device due to the decoupling of the beam forming from the digitization of the raw data. Thus, commercially available PC components are available for computer devices, wherein the operation of beamforming and the generation of the image stream can be achieved by software running on a processor of a commercially available PC motherboard. In addition, the ultrasound apparatus according to the invention ensures that the beamforming process is not performed in the transducer probe, which means that the requirements for as low a heat generation as possible in the transducer probe can be met.

In a preferred variant of the ultrasound device according to the invention, a synchronizable display is used as display means, the image refresh frequency of which can be changed. In this way, any fluctuations in the image refresh frequency of the generated image stream can be compensated, thereby avoiding image artifacts that may occur in unsynchronized displays. Examples of synchronizable displays are known as AMDFreesync or Nvidia G-Sync.

In a particularly preferred embodiment of the ultrasound apparatus according to the invention, the raw data buffer memory is adapted for simultaneously buffering a plurality of consecutive measurement data sets, i.e. several measurement data sets are provided simultaneously in the raw data buffer memory. This variant is preferably combined with a computer device configured to determine respective reconstructed images for several of the plurality of buffered measurement data sets in parallel in time. In this way, the determination of the reconstructed image can be accelerated, so that a higher image refresh frequency can be achieved.

In a further preferred variant of the ultrasound device according to the invention, the computer device is configured such that the images of the image stream are each calculated as an average of a plurality of temporally successive reconstructed images. In this way, the image quality can be improved.

In another preferred variant, the specified image refresh frequency of the image stream is 50Hz or higher, for example 60Hz or 75 Hz. With these frequencies it is ensured that the images of the image stream merge into each other for the human eye so that no flicker or jitter is perceived.

In a further preferred variant of the ultrasound device according to the invention, the computer device is further configured to determine digital control data, based on which the operation of the transducers of the transducer array for transmitting ultrasound signals and for receiving ultrasound echoes during successive measurement time intervals is determined. Thus, the computer device comprises a control data buffer memory (preferably a circular buffer), wherein the digital control data is buffered. Furthermore, the transducer probe is configured to read out the digital control data, preferably without buffering, directly via a digital data interface or a further digital data interface between the transducer probe and the computer device and to drive the transducers of the transducer array based on these read out control data.

Thus, the control data is predetermined by the computer device and then used during driving of the transducer. By using the control data buffer memory, the generation of control data is decoupled from the use of control data in the transducer probe. In this way, control data can be generated by the computer device without special real-time requirements. In particular, a conventional PC may be used to generate the control data, wherein software for generating the control data is run on its processor. Preferably, the data rate for reading out the control data via the respective digital data interface is at least 1 GB/s.

Depending on the configuration, the digital data interface may include or represent a wired data interface and/or a wireless data interface. The further digital data interfaces mentioned above may be configured in the same way. In a preferred embodiment, the digital data interface and/or the further digital data interface comprises or is a PCI Express interface known per se. High data rates can be achieved via such an interface. The PCI Express standard is known from the prior art, and the PCI Express interface is not limited to a particular version of the standard or a particular version of the data lines used therein.

In another preferred embodiment, the transducer probe of the ultrasound device according to the invention comprises a high voltage transmitter for generating a high voltage signal which is provided to the transducer array via a switch array of the transmit-receive switch for generating the ultrasound waves in a transmit mode by one or more transducers, wherein the transducers of the transducer array can be switched into the transmit mode or into the receive mode by the switch array. If the above-described buffering of the control data is used in this variant, the control data is processed by a high-voltage transmitter, which generates a corresponding high-voltage signal on the basis of the control data. In addition, the control data switches the switch array so that all transducers are decoupled from the high voltage transmitter in the receive mode.

In another embodiment of the ultrasound device according to the invention, the transducer probe comprises a preamplifier configured to amplify the analog raw data before providing it to the analog-to-digital converter. In this case, the analog-to-digital converter digitizes the amplified raw data.

Drawings

Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:

fig. 1 shows a schematic view of a medical ultrasound device according to the prior art; and

fig. 2 shows a schematic view of an embodiment of an ultrasound device according to the invention.

Detailed Description

Before describing an embodiment of an ultrasound device according to the invention, the structure of a per se known ultrasound device as shown in fig. 1 is first described.

The ultrasound device according to fig. 1 comprises a movable Transducer Probe (TP), which can be guided by a user's hand and placed on the skin of a patient in order to examine a part of the body located under the skin by ultrasound. For this purpose, the transducer probe comprises a transducer array TA consisting of a plurality of electroacoustic transducers (e.g. 128 transducers), wherein the array is only schematically represented by a representation of a single transducer. Generally, an electroacoustic transducer is designed as a piezoelectric element through which an ultrasonic signal can be emitted by applying a high voltage. Likewise, a corresponding ultrasonic echo may be received by the piezoelectric element. The ultrasonic signal is emitted as acoustic pulses with a repetition frequency of several kilohertz.

Switching between transmit and receive modes of the respective piezoelectric elements or transducers is enabled by a switch array of transmit/receive switches, which is denoted by reference sign SW in fig. 1 and described in more detail below. For clarity, the switch array is represented by only one switch.

The movable transducer probe TP is connected by a coaxial cable bundle CX to a cassette SB, which is also referred to hereinafter as a scanning cassette. The device case is a bulky component that contains the necessary components for signal processing of the ultrasonic echoes received by the transducer probe TP. A computer COM in the form of a data processor or PC is connected to the device box, which PC is then connected to the display DI. Typically, the scanning box, the computer and the display form one unit, which is integrated in e.g. a trolley. In addition, the computer may be a part of the apparatus box.

The scan box SB comprises three ports T1, T2 and T3, which are coupled to a multiplexer MX, by which one of these ports can be selected. At each port, a separate transducer probe may be connected by a respective bundle of coaxial cables. The multiplexer MX is used to select the transducer probe that is currently to be used for detecting the ultrasound echo. Fig. 1 shows only a single transducer probe TP which is coupled to port T3 where it is connected to the other components of the scan box SB by a multiplexer MX.

Following the multiplexer MX is the switch array SW described above, which includes a number of transmit-receive switches corresponding to the number of transducers in the transducer array TA. In other words, one transmit-receive switch is provided for each transducer. By switching the respective transmit-receive switch into a transmit mode, the associated transducer is connected to a high voltage transmitter TR which generates ultrasound waves by supplying a respective high voltage signal to the transducer. On the other hand, if the respective switch is switched to the receive mode, a sample of the ultrasonic echo detected by the transducer probe TP is forwarded to a receive path comprising a preamplifier PR, an analog-to-digital converter CON and a beamformer BF.

Typically, a voltage between 10V to 100V is supplied to the transducer through the high voltage reflector TR. The high voltage transmitter is connected to a waveform memory WM and a so-called pulse sequencer PS. The pulse sequencer represents a sequence control system that determines the transmission of ultrasound pulses and the reception of ultrasound echoes at corresponding measurement intervals. In order to emit an ultrasonic pulse, the pulse sequencer reads the waveform of the respective pulse from the waveform memory in the form of a voltage pattern of high voltage. The voltage pattern is provided to a high voltage transmitter to generate a corresponding high voltage. In addition, the pulse sequencer controls the switches of the switch array SW so as to switch the respective switches to the transmission state or the reception state according to a desired measurement sequence. For example, the pulse sequencer PS is implemented as an FPGA (field programmable gate array). The pulse sequencer is connected to the processor PRO (i.e. CPU) of the computer COM. Instructions to perform the ultrasound measurements are sent by the processor to the pulse sequencer.

The ultrasonic echoes received by the transducer probe TP are amplified by a preamplifier PA (PA — preamplifier). The amplifier comprises a preamplifier element for each individual transducer, which amplifies the received signal of the respective transducer. The data received in the preamplifier PA represents analog raw data comprising a continuous set of measured data. The respective measurement data set refers to the individual measurements made with the transducer probe TP. In such a single measurement, one or more transducers of the transducer array TA emit one or more ultrasound signals according to a predetermined scheme, and then within a predetermined measurement time interval, detect ultrasound echoes caused by reflections in the tissue region, wherein the ultrasound signals are radiated by the transducer probe TP. The length of the measurement time interval may be used to determine the depth of tissue at which the ultrasound echo is to be received and further processed.

Typically, after transmitting the ultrasonic signal, all the transducers are switched to a receive mode by the switch array SW. Thus, samples are obtained for each transducer, which samples are obtained at a plurality of sampling instants within a measurement time interval corresponding to a sampling frequency. For a respective measurement time interval, the raw data thus comprise a respective measurement data set, which for a plurality of sampling instants comprises a respective sample for all transducers, wherein the respective sample represents the ultrasound echo received at the sampling instant.

The amplified analog raw data are provided to an analog-to-digital converter CON comprising an a/D converter element for the sample of each electroacoustic transducer. The amplified sample is digitized in a separate a/D converter element. The analog-to-digital converter CON is clocked at a predetermined frequency and generates a number of digital data streams corresponding to the number of electroacoustic transducers, which represent the ultrasound echoes from increasing tissue depths for the respective measurement time intervals. The digital data stream of the analog-to-digital converter is then supplied to a beamforming computer unit BF (BF ═ beamforming), which is also referred to below as a beamformer, for example implemented as an FPGA. In this beamformer samples of different electroacoustic transducers are time-delayed according to a phased array in a manner known per se, so that the time-delayed samples represent the reception of ultrasonic echoes starting from the same reflection point in the tissue. The samples of the respective time delays are summed and represent a position in the examined tissue at a predetermined angular orientation and a predetermined tissue depth from the transducer array. The corresponding positions represent image points in later-generated ultrasound images.

As a result of the beamforming performed in the beamformer BF, pixel values (i.e. the sum of samples that are correspondingly time-delayed) are finally obtained for each measurement time interval (i.e. for different points in time and thus different tissue depths, but only in a single angular direction). This is due to the fact that: the beamforming of the beamformer BF is performed synchronously with the generation of digital data by the analog-to-digital converter CON, so that the beamformer can always set only one time delay for each sample, and thus can determine only pixel values for one angular direction. Thus, in order to reconstruct a two-dimensional image, possibly also a three-dimensional image, of the entire tissue region, it is necessary to carry out a plurality of identical measurements in succession by emitting corresponding ultrasonic signals, wherein for each measurement the beamforming is carried out by adjusting the time delay for a different angular direction. Alternatively, it is also possible to install a plurality of beamformers BF in parallel in the apparatus box SB, but this results in a considerable extra effort and a considerable extra cost.

Finally, the pixel values obtained by the beamformer BF are transferred to a computer COM which generates a corresponding image on a display DI using an image former unit IMF (IMF ═ image former) in a manner known per se. The function of the image former unit is usually implemented by a graphics chip of the computer COM, which may also be part of the central processor PRO. Typically, the image is used for a depiction on the display DI, which represents an average of a plurality of consecutive images obtained by beamforming. The image refresh frequency of the display DI is fixed such that the displayed image sequence suffers from image artifacts such as jitter and tearing (switching between images during image formation).

The speed of sound in biological tissue is about 1450m/s, so that an ultrasound echo from a depth of e.g. 15 cm has a travel time of about 200 μ s. Therefore, 5000 measurements per second can be made for this tissue depth. Depending on the set maximum measurement depth, the number of angular directions and the number of images used for averaging, the data acquisition for the tissue region, for example 125 angular directions, therefore takes between approximately 1ms and approximately 100ms, for example.

As can be derived from the above description, the conventional ultrasound device according to fig. 1 has the disadvantage that several measurements are required to reconstruct an image of the tissue region by means of beamforming. This is due to the fact that the beamforming, which is synchronized with the timing of the analog-to-digital converter, can always only calculate pixels from one angular direction per measurement. Although a variety of beamformers can be used to circumvent this problem, this is very laborious and costly. In addition, image artifacts may occur when displaying the image stream. In addition, since signal processing requires a device box combined with a computer, the size of the ultrasonic apparatus is very large.

The above-mentioned disadvantages are eliminated by the embodiment of the ultrasound device according to the invention as shown in fig. 2. Like the device shown in fig. 1, the ultrasound device comprises a movable transducer probe TP having a transducer array TA consisting of electroacoustic transducers. Similar to the transducer probe of fig. 1, the transducer probe of fig. 2 is also manually pressed against the body of the patient to be examined in order to examine tissue by means of ultrasound waves in the pressed position of the transducer probe.

In contrast to the transducer probe of fig. 1, the transducer probe of fig. 2 comprises, in addition to the transducer array TA, further components which are part of the scan box SB in the embodiment of fig. 1. These are a switch array SW, a transmitter TR, and a preamplifier PA and an analog-to-digital converter CON. These components operate similarly to fig. 1 and therefore they will not be described in detail. In particular, the analog raw data (denoted RDA in fig. 2) output via the switch array is first amplified via a preamplifier PA and then digitized in an analog-to-digital converter CON.

It is now essential for the present invention that the digital data generated by the analog-to-digital converter is not immediately beamformed, but is first buffered in order to subsequently perform beamforming on the buffered data in synchronism with the timing of the analog-to-digital converter. To do this, the digital raw data output from the analog-to-digital converter CON are passed directly (i.e. without buffering) to a digital data interface IF, which writes the data into a buffer memory BU, preferably a ring buffer. The raw data transmitted via the digital data interface IF are denoted by reference numeral RDD in fig. 2. These raw data comprise respective measurement data sets corresponding to respective measurement time intervals, wherein the structure of the measurement data sets has been described above. The measurement data set is generally denoted by reference numeral MD in fig. 2. The buffer memory BU is part of a separate computer device COM, which is preferably a conventional PC. Thus, the computer device is a separate unit, which does not belong to the transducer probe.

In the embodiment described herein, a bidirectional interface based on the PCI Express standard is used as the digital data interface IF. Any version of the standard may be used if the data rate of the raw data output from the analog-to-digital converter is reached, with current versions 1.0/1.1, 2.0/2.1, 3.0/3.1, 4.0, and 5.0 being known. Likewise, the number of lines for data transmission can be selected differently, wherein it is known to use one, two, four, eight and sixteen lines. For example, PCIe3 x 16 (PCI Express version 3.0/3.1 with 16 lines) or PCIe2 x 8 (PCI Express version 2.0/2.1 with 8 lines) may be used as the data interface. In the embodiment described here, the PCI Express interface is also used for the transmission of digital control data CDD from the computer COM to the high-voltage transmitter TR described below. The data transfer mechanism via interface IF has the ability to read from and write to buffer memory BU directly, and also has the ability to read from and write to buffer memory BU' as described below. In this way, the data transfer rate and the transfer latency do not depend on the response time of the operating system of the computer device COM.

Buffer memory BU has a size such that a plurality of consecutive measurement data sets MD are stored therein simultaneously. The stored measurement data sets are processed in blocks. During this process, the generation of the beamformed and reconstructed image is carried out by means of a software BIF (BIF ═ beam and image former) running on the processor PRO of the computer device COM for display on the display DI.

The beamforming is performed according to the same principle as in the beamformer BF of fig. 1, but during beamforming several accesses can be made to the respectively buffered sample of the measurement data set, since these are buffered in the buffer memory BU for a certain period of time. As a result, a reconstructed image of the entire tissue region with a plurality of different angular directions and tissue depths is obtained for each measurement data set during beamforming. In other words, only a single measurement data set is required to reconstruct an image of the entire tissue region, whereas in the ultrasound device of fig. 1, multiple measurement data sets are required to obtain a reconstructed image of the tissue region.

The image reconstructed by beamforming is then converted into an image stream using software BIF. Preferably, several temporally successive reconstructed images are averaged and displayed as a single image on the display DI. The image sequence shown on the display DI preferably has an image refresh frequency which is higher than the flicker frequency of the human eye, for example a refresh frequency of 60Hz or 75 Hz. A synchronizable display with an adjustable image refresh frequency is used as the display DI. This allows compensating for limited short term fluctuations in the image rate of the image stream. Such synchronizable displays are known per se. These are, for example, AMD Freesync or Nvidia G-Sync type displays.

The ultrasound device of fig. 2 also differs from the device of fig. 1 in that control data CDD for setting the transmission mode and the reception mode of the electroacoustic transducer for continuous measurement are also generated in the computer device COM. For this purpose, software TDG (TDG) is used, which runs on the processor PRO of the computer device COM. These control data are buffered in a buffer memory BU', which may be implemented as a ring buffer similar to buffer memory BU. The high-voltage reflector reads out the control data CDD directly from the buffer BU' via the interface IF without further buffering. According to the control data, the high voltage transmitter then generates the high voltage required for transmitting the ultrasound signal in the transmit mode by means of the respective transducer. The control data also specifies which transducers are to be operated at which times in either the transmit mode or the receive mode. Based on this information, the switches of the switch array SW are then switched by the signal of the high voltage transmitter TR. By using the buffer BU', the transmission of the control data CDD is no longer dependent on the response time of the operating system of the computer device COM.

A typical configuration of an ultrasound device comprises 128 electroacoustic transducers, for example a sample using 2 bytes of ultrasound echo and a sampling frequency of 15MHz within a measurement time interval of 200 mus. This results in a data volume of 750kB and therefore a data rate of about 4 GB/s. In this case, therefore, the data rate of the data interface IF in the direction towards the buffer BU should be above 4 GB/s. When storing 125 data sets, the size of the buffer memory BU must be a few 100 MB. A typical sampling frequency for driving the transducers is 15MHz, with each transducer having a 2-bit sample value. This also results in a data rate of 4GB/s, which in this case must at least be provided by the interface IF in the direction towards the high-voltage transmitter TR.

The embodiments of the invention as described above have many advantages. In particular, a central processing unit in the form of a computer COM asynchronously processes the buffered receive data block by block into an image and is decoupled from ongoing measurements of the transducer. The measurement synchronization timing without the beamformer enables implementation of beamforming based on software by standard hardware components often installed in PCs. In software, beamforming may therefore be combined with image formation to generate an image on a display.

The buffering of the digitized raw data in the buffer memory allows multiple accesses and thus the complete image information of the tissue region to be reconstructed sequentially, i.e. for a plurality of angular directions and tissue depths. Thus, a complete two-dimensional image or possibly a three-dimensional image can be obtained from a single measurement data set without multiplying by beamforming calculations.

In addition, the above-described image reconstruction is performed based on the data of the moving time interval. This allows a substantially constant image rate to be achieved, independent of the timing of measurements performed in parallel by means of the transducer probe. As mentioned above, an image rate higher than the human eye flicker frequency is advantageous. Furthermore, to compensate for short term fluctuations in the image rate, a synchronizable display is preferably used to display the image sequence.