DEVICE FOR CONTROLLING AND READOUT OF A GROUP OF ULTRASOUND TRANSMITTERS FOR ULTRASOUND COMPUTER TOMOGRAPHY AND ULTRASOUND COMPUTER TOMOGRAPHY

Description

Field of the invention

[0001] The present invention relates to a device for controlling and reading a group of ultrasound transducers for ultrasound computed tomography, and to an ultrasound computed tomography scanner comprising at least one such device. The ultrasound computed tomography scanner is particularly suitable for use in ultrasound-based imaging methods for early breast cancer detection. Other applications, particularly in non-destructive materials testing or testing technology, are also possible. State of the art

[0002] Ultrasound computer tomographs which can be used in particular for medical examinations comprise at least one ultrasound head, at least one ultrasound transducer and at least one control and evaluation unit which transmits control signals for the ultrasound transducer and receives measurement signals received at the ultrasound transducer as electrical signals, amplifies them and forwards them to a control and evaluation unit, in particular for reconstructing real-time images on a screen during a measurement.

[0003] WO 2002 / 030288 A1 discloses an ultrasound computed tomography scanner, which is particularly suitable for use in an ultrasound-based imaging method for early breast cancer detection. The ultrasound computed tomography scanner operates according to the transmission scattering and pulse-echo method and comprises an upwardly open container into which the body part to be examined is inserted; ultrasound transducers that are fixedly arranged on a container wall over the entire wall surface and whose main radiation direction is oriented perpendicularly from the wall surface into the container interior; a coupling medium that, when filled into the container, wets the body part to be examined and serves to couple and transmit ultrasound signals between the ultrasound transducers and the body part to be examined; and a computer-assisted control and evaluation unit with a working memory.which is interconnected with the ultrasonic transducers. The interconnection is designed in such a way that any number of ultrasonic transducers can be selected as both transmitters and receivers via an electronic switch. The ultrasonic signals emitted by the transmitters are ultrasonic pulses, and the signals received in parallel by all receivers are amplified as electrical signals, filtered, digitized, and stored in the RAM as data. From the data stored in the RAM, sound travel times and, based on these and the geometric relationships, individual sound velocities are determined. By mathematically dividing the container volume into numerous areas and correlating various data sets, the sound velocities in the individual areas are calculated.that all possible reflection points in the container are calculated from the sound velocities in the individual areas as well as from the amplitude and phase curve of the received signals, and the signals are summed as data for the possible reflection points from all measurements for each point in the container, from this a colour value corresponding to the height of the sum value is assigned to each point and this is assigned to at least one pixel in the three-dimensional reconstruction depending on the desired resolution.

[0004] Details on further evaluation and reconstruction methods which can also be used here can be found in EP 2 056 124 A1, WO 2011 / 124379 A2 and WO 2012 / 110228 A1.

[0005] One of the challenges in ultrasound computed tomography systems is the design of a suitable device for controlling and reading one or more ultrasound transducers. This device must be configured, in particular, to process the high-voltage signals required to generate sufficient acoustic pressure, as well as to amplify weak response signals. For this purpose, the device typically comprises a high-frequency pulse unit, a high-frequency isolation switch, and a low-noise, low-voltage preamplifier.

[0006] WO 2005 / 107962 A1 discloses ultrasonic transducers with transducer arrays comprising a number of transducer elements. Each ultrasonic transducer comprises at least one piezoelectric body, each having at least one lower and one upper electrode, as well as a coupling layer comprising at least one circuit board to which the ultrasonic transducer is connected to the lower electrode. Conductor track structures with a constant conductor track height are provided on the circuit boards below the piezoelectric bodies, which are in electrical contact with the lower electrode, and a remaining cavity between the circuit board and the piezoelectric body, adjacent to the conductor track structure, is completely filled with a binding agent.

[0007] US 2001 / 0043090 A1 discloses an integrated circuit as a device for controlling and reading an ultrasonic transducer. The circuit, arranged monolithically on a single substrate, comprises both a low-voltage circuit and a high-voltage circuit, wherein the low-voltage circuit is constructed on the basis of CMOS, while the high-voltage circuit comprises a high-voltage FET. The low-voltage circuit comprises, on the one hand, a digital logic circuit configured to generate signals and transmit them to an ultrasonic transducer element, and, on the other hand, an analog circuit for receiving and further processing signals from the ultrasonic transducer element, while the high-voltage circuit serves to control the ultrasonic transducer element.

[0008] Comparable devices can be found in US 2009 / 0146695 A1 and US 2016 / 0242739 A1, in which pulses are used to control the ultrasonic transducer element.

[0009] US 2015 / 0032002 A1 discloses an ultrasonic transducer probe with a plurality of ultrasonic transducer elements and associated circuits. It is proposed to construct the transmission amplifiers from CMOS components. Furthermore, the use of an N-well in the transistor structure achieves isolation from the substrate. Furthermore, an output switch is provided, which is configured to prevent the measurement signal from being applied to a low-voltage preamplifier, at least during the transmission pause. Multiplexer circuits are also disclosed.

[0010] DF Lemmerhirt, X. Cheng, RD White, CA Rich, M. Zhang, JB Fowlkes, and OD Kripfgans, "A 32 × 32 Capacitive Micromachined Ultrasonic Transducer Array Manufactured in Standard CMOS," IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 59, No. 7, 2012, describes a prototype of a transducer array in which the ultrasonic transducer and the circuitry for its control and readout are also integrated on a common substrate. Pulses are applied to the lower plate of each capacitive micromachined ultrasonic transducer. Capacitive Micromachined Ultrasonic Transducer, (CMUT for short), where a switch in an ON position protects the input of a CMOS electronics and in an OFF position converts an output current from the CMUT into a voltage value.

[0011] G. Gurun, M.S. Qureshi, M. Balantekin, R. Guldiken, J. Zahorian, S.-Y. Peng, A. Basu, M. Karaman, P. Hasler und L. Degertekin, Front-end CMOS Electronics for Monolithic Integration with CMUT Arrays: Circuit Design and Initial Experimental Results, 2008 IEEE International Ultrasonics Symposium Proceedings (ULTSYM) 0096; I. Cicek, A. Bozkurt und M. Karaman, Design of a Front-End Integrated Circuit for 3D Acoustic Imaging Using 2D CMUT Arrays, IEEE Transactions on Ultrasonics, Ferroelectrics, And Frequency Control, Vol. 52, No. 12, 2005; J. Song, S. Jung, Y. Kim, K. Cho, B. Kim, S. Lee, J. Nab, I. Yang, O.-K. Kwon und D. Kim, Reconfigurable 2D cMUT-ASIC Arrays for 3D Ultrasound Image, Proc. of SPIE Vol. 8320 83201A-1; S.-J. Jung, et al., Three-Side buttable integrated ultrasound chip with a 16x16 reconfigurable transceiver and capacitive micromachined ultrasonic transducer array for 3-D ultrasound imaging systems, IEEE Trans. Electron Dev., Vol. 60, No.10, S. 3562-3569, 2013; R.Wodnicki, Modular ultrasound arrays with co-integrated electronics, Proc. of the 14th International Symposium on Nondestructive Characterization of Materials, p. 23, 2015 and H.-K. Cha, CMOS ultrasonic analogue front-end with reconfigurable pulser / switch for medical imaging applications, Electronics Letters Vol. 51 No. 20, pp. 1564-1566, 2015 present further devices in which ultrasound transducers and the circuits for their control and readout are monolithically integrated on a common substrate, although only the low-voltage circuit is based on CMOS.

[0012] In contrast, in H. Kuruveettil, D. Zhao, CJ Hao and M. Je, Analog Front End Low Noise Amplifier in 0.18-µm CMOS for Ultrasound Imaging Applications, International Journal of Electrical, Computer, Energetic, Electronic and Communication Engineering, Vol. 7, No. 9, 2013, the ultrasonic transducer and a preamplifier configured for signal readout are arranged separately on different substrates.

[0013] Furthermore, K. Chen, H.-S. Lee, A.P. Chandrakasan, and C.G. Sodini, "Ultrasonic Imaging Transceiver Design for CMUT: A Three-Level 30-Vpp Pulse-Shaping Pulser With Improved Effciency and a Noise-Optimized Receiver," IEEE Journal Solid-State Circuits, Vol. 48, No. 11, 2013, describe a four-channel receiver for ultrasound computed tomography that serves as an interface for a micromachined ultrasound transducer (CMUT) and a high-voltage transmitter featuring a three-stage pulse-shaping unit. The receiver further includes a low-noise amplifier configured to amplify the weak input signal. A switch is turned OFF to prevent high-voltage transients from damaging the low-noise amplifier, which is equipped with low-voltage transistors.

[0014] WO 2017 / 066564 A1 discloses a method comprising the following steps: receiving a plurality of analog signals from a plurality of transducers arranged on a catheter probe; selectively sampling the plurality of analog signals; multiplexing to generate a sequence of samples; and transmitting the sequence of samples to a receiver circuit. The receiver circuit comprises a clock; an analog-to-digital converter in communication with the clock; and a sampling phase correction circuit in communication with the clock and the converter. The method further comprises: determining optimal sampling times based on measured signal delays associated with the system; adjusting a phase of the clock based on the measured signal delays; and transmitting the phase-adjusted clock to the transmitter circuit for selectively sampling the analog signals.

[0015] KR 2016 0021354 A discloses a device for controlling and reading out a group of ultrasonic transducers for ultrasonic computed tomography according to the preamble of claim 1. Another device for controlling and reading out a group of ultrasonic transducers for ultrasonic computed tomography is described in WO 2015 / 186193 A1.

[0016] Despite the improvements provided by the above-mentioned devices, many challenges remain unsolved in the design of devices for controlling and reading an array of ultrasound transducers in ultrasound computed tomography scanners. Object of the invention

[0017] Based on the description of the prior art, the object of the present invention is to provide a device for controlling and reading a group of ultrasound transducers and an ultrasound computed tomography scanner, which at least partially overcome the disadvantages and limitations of the prior art mentioned.

[0018] In particular, the device should enable reproducible sensor characteristics, a high signal-to-noise ratio, and high signal dynamics despite a small active sensor area, all at a low overall price. On the one hand, ultrasonic receivers should be configured for signal strengths of µV, while on the other hand, the signal strengths of the ultrasonic transmitters should be capable of reaching 80 V to 120 V excitation voltage for omnidirectional radiation characteristics, a wide bandwidth, and non-focused ultrasound. Furthermore, the ultrasonic transducer should be able to simultaneously register small reflection signals and large transmission signals and provide the high signal dynamics required for this.In addition, ultrasonic transmitters and ultrasonic receivers should have as similar bandwidths and high linearity as possible in order to enable good noise adaptation and high signal fidelity for signal recognition, in particular for detection and separation of transmission and reflection signals.

[0019] Furthermore, the ultrasound computed tomography system should be able to incorporate multiple groups of ultrasound transducers, thus enabling scanning of the space in three dimensions without requiring mechanical movement of the ultrasound transducers. In particular, at least 100 devices should be distributed across a three-dimensional measurement geometry, with each device having at least three ultrasound transducers that can function as transmitters and / or receivers, thus enabling rapid data acquisition. Disclosure of the invention

[0020] This object is achieved by a device for controlling and reading a group of ultrasound transducers for ultrasound computed tomography and by an ultrasound computed tomography scanner according to the features of the independent claims. Advantageous further developments, which can be implemented individually or in any combination, are presented in the dependent claims.

[0021] In the following, the terms "have," "have," "comprise," or "include," or any grammatical variations thereof, are used non-exclusively. Accordingly, these terms can refer both to situations in which, besides the features introduced by these terms, no further features are present, or to situations in which one or more further features are present. For example, the expression "A has B," "A has B," "A comprises B," or "A includes B" can refer both to the situation in which, apart from B, no further element is present in A (i.e., a situation in which A consists exclusively of B), and to the situation in which, in addition to B, one or more further elements are present in A, for example, element C, elements C and D, or even further elements.

[0022] Furthermore, it should be noted that the terms "at least one" and "one or more," as well as grammatical variations of these terms, when used in connection with one or more elements or features and intended to express that the element or feature may be provided singly or multiple times, are generally used only once, for example, when the feature or element is first introduced. Upon subsequent re-mention of the feature or element, the corresponding term "at least one" or "one or more" is generally no longer used, without this limiting the possibility that the feature or element may be provided singly or multiple times.

[0023] Furthermore, the terms "preferably," "in particular," "for example," or similar terms are used below in connection with optional features, without limiting alternative embodiments. Thus, features introduced by these terms are optional features, and these features are not intended to limit the scope of the claims, and in particular the independent claims. Thus, as those skilled in the art will recognize, the invention can also be carried out using other embodiments. Similarly, features introduced by "in one embodiment of the invention" or "in an embodiment of the invention" are understood as optional features, without limiting alternative embodiments or the scope of the independent claims.Furthermore, these introductory expressions are intended to leave untouched all possibilities of combining the features introduced thereby with other features, be they optional or non-optional.

[0024] In a first aspect, the present invention relates to a device for controlling and reading a group of ultrasound transducers for ultrasound computed tomography. This device comprises a common substrate, wherein the substrate has a first region configured as an input channel and a second region electrically separated therefrom and configured as an output channel, wherein the first region is separated from the second region by means of n-wells; at least one high-voltage signal input arranged on the first region, wherein the high-voltage signal input is configured to receive analog high-voltage signals; at least one high-voltage amplifier arranged on the first region, wherein the high-voltage amplifier is configured to receive and amplify the analog high-voltage signals provided by the high-voltage signal input, wherein the high-voltage amplifier has high-voltage CMOS semiconductor components;at least one group of ultrasonic transducers arranged on the first region, wherein at least one of the ultrasonic transducers is configured as an ultrasonic transmitter to generate ultrasonic signals during a transmission phase in which the high-voltage amplifier provides high-voltage signals at its output, and wherein at least one of the ultrasonic transducers is configured to receive ultrasonic measurement signals; at least one multiplexer configured to combine ultrasonic measurement signals received by at least two different ultrasonic transducers into a common measurement signal; at least one low-noise low-voltage preamplifier arranged on the second region, wherein the low-voltage preamplifier is configured to receive the measurement signal, wherein the low-voltage preamplifier has CMOS semiconductor components;at least one output switch arranged on the second region, wherein the output switch is configured to prevent the low-voltage preamplifier from being exposed to the measurement signal at least during the transmission phase; and at least one low-voltage signal output arranged on the second region, which is configured to transmit a pre-amplified measurement signal to an external control and evaluation unit.

[0025] The present device is preferably designed in the form of integrated circuits, in particular as at least one application-specific integrated circuit (ASI). application-specified integrated circuit; ASIC). Alternatively, the device could also be implemented as a general-purpose integrated circuit, particularly as an FPGA (FPGA). field-programmable gate array) or as FPAA (English field-programmable analog array ). However, other embodiments of the present device are possible.

[0026] The present device is applied to a common substrate to provide the integrated circuits. The substrate can preferably be a printed circuit board (PCB). printed circuit board, A printed circuit board (PCB), which is designed as a carrier for electronic components, can be applied. The printed circuit board can serve, on the one hand, to provide mechanical stability for the applied electronic components and, on the other hand, to provide electrical connections between the electronic components.

[0027] The substrate used for the present device has two electrically separated regions, with the two regions being separated by n-wells. The term "n-well" refers to a defined surface area on the substrate designed to collect charge carriers and remove them from a lateral current along the substrate. In this way, the n-well can be used to provide electrically separated regions on the substrate. The advantage of separating the two regions by n-wells is that low-voltage components on the second region can be protected from the high voltage occurring in the first region, and that the propagation of potential interference from the first region to the second region can be largely suppressed.

[0028] In the present case, a first region configured as an input channel and a second region separated therefrom, configured as an output channel, can be created in this way. While the first region can be configured to accommodate first electronic components designed to receive and process high voltage, the second region can be configured to accommodate second electronic components designed to receive and process low voltage. In the context of the present invention, the term "high voltage" refers to electrical voltages and potentials from 5 V to 120 V, while the term "low voltage" refers to electrical voltages and potentials from 0 V to 5 V.

[0029] The first area on the substrate, configured for receiving and further processing high voltage, comprises at least one high-voltage signal input, at least one high-voltage amplifier, and at least one group of ultrasonic transducers. The high-voltage signal input is configured to receive analog high-voltage signals, which can be provided in particular by an external high-voltage transmitter, and to feed them to the ultrasonic transducers via the high-voltage amplifier. The high-voltage signals used here can be specified in particular as alternating voltages of constant amplitude, the frequency of which can periodically and continuously pass through a specified range, and are therefore also referred to as "sweeps."However, other types of high-voltage signals, in particular signal processing chains with coded excitation, such as chirp, Golay or Barker codes, and with downstream correlation filters to increase the signal-to-noise ratio at high bandwidth, are also possible.

[0030] The high-voltage amplifier is configured to receive and amplify the analog high-voltage signals provided by the high-voltage signal input. For this purpose, the high-voltage amplifier has at least one analog, linear, feedback amplifier, which comprises at least three separate amplifier stages. The electronic components, in particular the transistors used in the high-voltage amplifier, are designed as high-voltage CMOS semiconductor components. Electronic components based on so-called 0.35 µm high-voltage CMOS technology or 0.18 µm high-voltage CMOS technology can preferably be used for this purpose. While the term "CMOS" (English: complementary metal-oxide-semiconductor ) refers to semiconductor devices in which both p-channel and n-channel metal-oxide-semiconductor field-effect transistors (MOS) are used. metal oxide semiconductor field-effect transistorsWhile high-voltage CMOS semiconductor components (MOSFETs) are used on a common substrate and are usually designed for low-voltage operation even without further information, high-voltage CMOS semiconductor components are special components that are suitable for use at high voltage, in particular because they have a dielectric strength of up to 120V.

[0031] In a particularly preferred embodiment, the proposed device and the ultrasound transducers comprised thereby have the highest possible bandwidth in order to be able to achieve the highest possible contrast and thus the highest possible clarity of an image of complex objects, such as a patient's breast, when using linear imaging methods through complete coverage of the spatial frequency image space. In addition, more complex imaging methods, which can in particular be based on wave-based inversion methods, can also benefit from lower frequency components. A large dynamic range of the high-voltage amplifier is also advantageous because the ultrasound transducers used for 3D ultrasound computed tomography can be regarded approximately as point sources with a small area and low radiation pressure, despite their omnidirectional radiation characteristics.Therefore, in this particularly preferred embodiment, the high-voltage amplifier comprises a linear, feedback amplifier with high gain. This allows a large relative bandwidth of at least 50%, preferably at least 100%, particularly preferably at least 150%, to be achieved. For example, the relative bandwidth can be 160% around a center frequency of 2.5 MHz, which corresponds to a bandwidth of approximately 4 MHz at 2.5 MHz.

[0032] To achieve the desired high gain, the analog, linear, feedback amplifier comprises at least three separate amplifier stages, each of which has at least two high-voltage CMOS transistors. In a preferred embodiment, a differential amplifier is located at the input of a first amplifier stage, which is designed such that a difference between the absolute values ​​of the output currents is proportional to the difference between the input voltages applied to the two inputs of the differential amplifier. Furthermore, the first amplifier stage and a second amplifier stage are each arranged between two current mirrors. This can, in particular, enable a current flowing out of one input to approximately correspond to a current flowing out of another output, so that the first and second amplifier stages can each be supplied with the same currents independently of one another.Furthermore, in the second amplifier stage and in a third amplifier stage, the high-voltage CMOS transistors are each connected to one another via their sources, in particular to enable a low resistance and / or a high capacitance to be connected to the output of the high-voltage amplifier without significantly reducing the high-voltage gain. The described design of the analog, linear, feedback amplifier enables a constant, linear gain for the high voltages used with a dielectric strength of at least 80 V, preferably at least 120 V.

[0033] As already mentioned, at least one group of ultrasonic transducers is also arranged on the first area, designed as an input channel. The group of ultrasonic transducers can comprise a plurality of ultrasonic transducers, in particular 2, 3, 4, 5, 6, 8, 9, 10, 12, 13, 15, 16, 18, 20, 24, 25, or more. However, a different number of ultrasonic transducers is possible. The term "ultrasonic transducer" refers to an electronic component configured to convert an electrical quantity, in particular an electrical current or, preferably, an electrical voltage, into ultrasonic signals or, conversely, to convert ultrasonic signals into an electrical quantity, in particular an electrical current or, preferably, an electrical voltage. The ultrasonic transducers can, in particular, be ultrasonic transducers that operate on the basis of piezoelectric components.Alternatively or additionally, capacitive microstructured ultrasonic transducers (engl. . capacitive micromachined ultrasonic transducers, CMUT), which operate on the basis of changes in the capacitance of a microcavity introduced into a silicon substrate using microstructural technology.

[0034] At least one of the ultrasonic transducers, preferably a plurality of ultrasonic transducers, is configured as an ultrasonic transmitter. The term "ultrasonic transmitter" refers to an ultrasonic transducer equipped to generate ultrasonic signals during a transmission phase, in which the high-voltage amplifier provides high-voltage signals at its output. These signals can be used, in particular, to impinge on an object under investigation. The ultrasonic transmitters can have a high bandwidth and an omnidirectional radiation pattern, making focusing of the ultrasonic signals unnecessary.The "object" can in particular be a body part of a patient, preferably a patient's breast, which is exposed to the ultrasound signals generated in this way directly or, preferably, indirectly via a coupling medium located between the ultrasound transmitter and the object, which wets the object to be examined.

[0035] Furthermore, at least one of the ultrasonic transducers from the group of ultrasonic transducers, preferably a plurality of ultrasonic transducers, is configured as an ultrasonic receiver for receiving ultrasonic measurement signals that can be generated by transmission through the object or a part thereof and / or by reflection from the object or a part thereof. Although the ultrasonic signals emitted by the ultrasonic transmitters can reach high signal intensities of 10 V to 120 V, preferably 80 V to 120 V, while the detected ultrasonic measurement signals can reach low signal intensities of only 1 nV to 10 mV, preferably 1 µV to 100 µV, the present device is designed in such a way that it nevertheless allows separation of the detected ultrasonic measurement signals from the generated ultrasonic signals.

[0036] In this case, on the one hand, each of the ultrasonic transducers can be used simultaneously as an ultrasonic transmitter and as an ultrasonic receiver. On the other hand, however, ultrasonic transducers can also be used which can serve either solely as an ultrasonic transmitter or solely as an ultrasonic receiver. Furthermore, a larger number of ultrasonic receivers can be provided compared to the ultrasonic transmitters in order to achieve a higher resolution, preferably a higher spatial resolution, of the ultrasonic signals. In order to enable the present device to be designed as space-saving as possible and to scan the object to be examined as closely as possible in three dimensions, in the latter case, some of the ultrasonic transducers can be used simultaneously as both ultrasonic transmitters and ultrasonic receivers, while other ultrasonic transducers can serve solely as ultrasonic receivers. Further configurations are, however, possible.Furthermore, it may be sufficient for the use of the present device if the ultrasound receivers used are designed as less complex, non-focused sensor devices.

[0037] In a preferred embodiment, the first region configured as an input channel can further comprise an input switch that can be set to at least one of the values ​​ON or OFF. In this way, if the input switch is set to "ON," the external analog high-voltage signals can be applied to the high-voltage amplifier, or, alternatively, if the input switch is set to "OFF," the input switch can be prevented.

[0038] In a further preferred embodiment, the first region configured as an input channel can further comprise an adjustable filter, which can be configured to filter out low-frequency components from the ultrasonic measurement signals received by the ultrasonic receiver. In a particular embodiment, the adjustable filter can comprise an adjustable electrical resistor and a capacitor arranged in parallel. However, other types of filters are also possible, e.g., so-called switched capacitor filters, GmC filters, ADC filters, or digital filters.

[0039] The first region, acting as the input channel, is equipped to transmit at least one measurement signal to the second region on the substrate, which is configured as the output channel. The measurement signal can be an unfiltered ultrasonic measurement signal provided by an ultrasonic receiver, alternatively, or a correspondingly filtered signal, in particular an output signal of the described adjustable filter. The measurement signal can generally be transmitted from the input channel to the output channel by means of a simple electrically conductive connection between the input channel and the output channel. According to the invention, however, a multiplexer device is used for this purpose, which can have at least one multiplexer, preferably a plurality of multiplexers.The "multiplexer" is a circuit configured to combine ultrasonic measurement signals received from at least two different ultrasonic transducers, either directly or after optional filtering, into a common measurement signal that can be passed to the output channel. In a particularly preferred embodiment, the at least one multiplexer can be configured as a 3:1 multiplexer, which can combine three separate measurement signals into a common measurement signal. Other types of multiplexers, in particular a 2:1 multiplexer, which can combine two measurement signals into a common measurement signal, or a 4:1 multiplexer, which can combine four measurement signals into a common measurement signal, are also possible. The use of multiplexers can, in particular, reduce the number of signal channels required for signal evaluation.

[0040] The second area, designed as an output channel, comprises at least one low-noise low-voltage preamplifier, at least one output switch, and at least one low-voltage signal output. The at least one low-noise low-voltage preamplifier is equipped to receive the measurement signal provided by the associated multiplexer. The low-voltage preamplifier comprises CMOS semiconductor components, in particular CMOS transistors, which, in contrast to the high-voltage CMOS semiconductor components in the high-voltage amplifier, are configured for receiving, further processing, and outputting low voltage. A standard amplifier circuit, which may comprise a folded cascade and an input transistor, is particularly suitable for this purpose. To increase the gain, two such amplifiers can be connected in series. The amplifier is preferably located in an n-well.

[0041] With regard to the bandwidth of the amplifiers used in the present device and the linearity of the associated amplification, the high-voltage amplifier located in the input channel can have a first bandwidth and a first linearity, and the low-voltage preamplifier arranged in the output channel can have a second bandwidth and a second linearity. In a particularly preferred embodiment, the first bandwidth and the second bandwidth and / or the first linearity and the second linearity can correspond to one another within a usual tolerance. This particularly preferred embodiment can thus enable good noise adaptation and high signal fidelity for the recognition of the ultrasonic measurement signals, particularly with regard to the detection and separation of reflection signals from transmission signals.

[0042] The output switch in the second range can be set to at least one of the values ​​ON or OFF. In this way, at least during the transmission phase of the at least one ultrasonic transmitter, if the output switch is set to "ON," the low-voltage preamplifier can be exposed to the measurement signal, or, if the output switch is alternatively set to "OFF," it can be prevented. The advantage of this function of the output switch is that, during the transmission phase of the at least one ultrasonic transmitter, it can be prevented that high-voltage signals used to operate the ultrasonic transmitter can be applied to the low-voltage preamplifier and thus potentially damage or destroy it.

[0043] The low-voltage signal output, also located in the output channel, is configured to transmit a measurement signal pre-amplified by the low-voltage preamplifier to an external control and evaluation unit, which may be part of an ultrasound computed tomography scanner equipped with the present device. The external control and evaluation unit can also be used to provide analog high-voltage signals to the at least one high-voltage signal input located in the input channel.

[0044] In a further aspect, the present invention relates to an ultrasound computed tomography system. The ultrasound computed tomography system comprises a container configured to receive an object to be examined and a coupling medium; at least one device for controlling and reading a group of ultrasonic transducers mounted on at least one wall of the container; and a control and evaluation unit for providing analog high-voltage signals for at least one high-voltage signal input of the device, as well as for receiving and evaluating ultrasonic measurement signals provided by at least one low-voltage signal output of the device.

[0045] As mentioned, the ultrasound computed tomography system comprises a container, preferably mounted on a patient bed, which has a group of ultrasound transducers on at least one wall and is configured to accommodate the object to be examined and a coupling medium that wets the object. This ensures that the coupling and transmission of ultrasound signals between the ultrasound transducers and the object to be examined is as loss-free as possible.

[0046] Particularly for medical purposes and non-destructive testing, the ultrasound computed tomography scanner can have a large number, preferably at least 100, of ultrasound transducer heads ("ultrasound transducer arrays"), wherein each of the ultrasound transducer heads can have several, preferably 4 to 18, emitters and several, preferably 9 to 18, receivers, which can be read out via a large number of data channels, preferably 320 data channels. Preferably, the number of emitters and the number of receivers are the same.

[0047] For further details regarding the ultrasound computer tomograph, reference is made to the embodiment below and the description of the device according to the invention.

[0048] This device and an ultrasound computed tomography scanner equipped with it are particularly suitable for use in ultrasound-based imaging procedures for early breast cancer detection. Other applications, particularly in non-destructive materials testing or testing technology, are also possible. Advantages of the invention

[0049] The proposed device for controlling and reading a group of ultrasound transducers for ultrasound computed tomography has significant advantages compared to devices known from the prior art.

[0050] This device features reproducible sensor characteristics and, despite its small active sensor area, a high signal-to-noise ratio and high signal dynamics at a low overall price. The ultrasonic receivers are configured for signal strengths from 1 nV to 10 mV, while the signal strengths of the ultrasonic transmitters can reach 80 V to 120 V for omnidirectional radiation characteristics, a wide bandwidth, and non-focused ultrasound. Due to the resulting high signal dynamics, the ultrasonic transducer can simultaneously register small reflection signals and large transmission signals. Furthermore, the ultrasonic transmitters and receivers have largely identical bandwidths and good linearity, enabling good noise adaptation and high signal fidelity for signal recognition, particularly for the detection and separation of transmission and reflection signals.By omitting the integration of a focusing technique for spatial signal sampling into the present device, which can also be carried out in the reconstruction in the proposed ultrasound computed tomography scanner, the structure of the present device is considerably simplified, whereby the data acquisition can also be carried out much faster.

[0051] Furthermore, one or more groups of ultrasound transducers of the ultrasound computed tomography scanner can enable scanning of the space in three dimensions without requiring mechanical movement of the ultrasound transducers, although this remains possible. In particular, at least 100 devices can be distributed across a three-dimensional measurement geometry in the form of an "aperture," with each device having at least 3, preferably at least 18, ultrasound transducers that can function as transmitters and / or receivers, thus enabling rapid data acquisition. Nevertheless, it remains possible to adapt each individual ultrasound transducer to different attenuations occurring in an object to be examined, in particular a body part, in particular to the size, composition, and / or structure of the object in question. Short description of the characters

[0052] Further details and features of the present invention will become apparent from the following description of preferred embodiments, particularly in conjunction with the dependent claims. The respective features can be implemented individually or in combination with one another. However, the invention is not limited to the embodiments. The embodiments are schematically illustrated in the following figures. Identical reference numerals in the figures designate identical or functionally identical elements, or elements that correspond to one another in terms of their functions.

[0053] In detail: Figure 1 shows a block diagram of a preferred embodiment of a device for controlling and reading a single ultrasonic transducer; Figure 2 shows a block diagram of a preferred embodiment of a multiplexer device for controlling and reading a group of ultrasonic transducers; Figure 3 shows a schematic representation of an input signal via three amplifier stages ( Fig. 3a to 3c ) and an associated signal response ( Fig. 3d ); Figure 4 is a circuit diagram of a preferred embodiment of a high-voltage amplifier; Figure 5 is a circuit diagram of a preferred embodiment of a feedback circuit comprising the high-voltage amplifier Figure 4 and Figure 6 shows a schematic representation of a preferred embodiment of an ultrasound computer tomograph according to the invention. Description of the embodiments

[0054] Figure 1shows a block diagram of a device 110 according to the invention for controlling and reading a group of ultrasonic transducers, wherein Figure 1 For reasons of simplicity of illustration, only a single ultrasonic transducer 112 is shown. A preferred embodiment for the control and readout of a plurality of ultrasonic transducers 112 is shown in Figure 2 which shows a block diagram of a multiplexer device 114 set up for this purpose.

[0055] The Figure 1The device 110 shown for controlling and reading a group of ultrasonic transducers 112 has a common substrate 116 which is designed to accommodate electronic components. The common substrate 116 has a first region 118 and a second region 120 electrically separated therefrom, wherein a separation 122 of the first region 118 from the second region 120 is effected by means of n-wells (not shown). The separation 122 of the two regions 118, 120 by n-wells can, in particular, make it possible to protect low-voltage components in the second region 120 from the high voltage occurring in the first region 118 and to suppress the propagation of possible interference from the first region 118 to the second region 120 as far as possible.While the first area 118 is designed as an input channel 124 to receive high-voltage elements that can be controlled by external, analog high-voltage signals, the second area 120 is designed as an output channel 126 to receive low-voltage elements that are designed to pre-amplify an ultrasonic measurement signal and to forward it to an external control and evaluation unit.

[0056] The input channel 124, designed to receive the high-voltage elements, includes a high-voltage signal input 128, which is configured to receive analog high-voltage signals provided by an external high-voltage transmitter (not shown) and to feed them to the ultrasonic transducer 112 via an input switch 130 and a high-voltage amplifier 132. The input switch 130 can be set to ON or OFF to enable (input switch 130 ON) or prevent (input switch 130 OFF) the external analog high-voltage signals from being applied to the high-voltage amplifier 132. The Figure 1 The schematically illustrated high-voltage amplifier 132 comprises electronic components configured as high-voltage CMOS semiconductor components. The high-voltage amplifier 132 comprises at least one analog, linear feedback amplifier 134, which is Figure 4is shown in detail. The high-voltage amplifier 132 enables a simple adaptation of the control of each individual ultrasonic transducer 112 to different attenuations occurring in an object to be examined, in particular a body part, preferably an adaptation to the size, composition and / or structure of the object.

[0057] A particularly preferred embodiment of the high voltage amplifier 132 is found in Figure 4 .

[0058] The input channel 124 of the device 110 further comprises the above-mentioned group of ultrasonic transducers 112, of which Figure 1only a single ultrasonic transducer 112 is schematically shown. The ultrasonic transducer 112 serves, on the one hand, as an ultrasonic transmitter 136 and, in this capacity, is configured to generate ultrasonic signals during a transmission phase in which both the input switch 130 is set to ON and the high-voltage amplifier 132 provides high-voltage signals other than zero intensity at its output. The ultrasonic transducer 112 can, in particular, be designed as a piezoelectric component. The piezoelectric component can comprise a composite of lead, zirconate, and titanate, usually abbreviated as "PZT," preferably in the form of a thin platelet. The platelet is applied, in particular glued, to the first region 118 of the substrate, and contact is made by means of wire bonding ( wire bonding). However, other types of design of the ultrasonic transmitter 136 are possible. The ultrasonic signals generated by the ultrasonic transmitter 136 are used in particular to apply pressure to the object to be examined, in particular the body part, or, preferably, a coupling medium which wets the object to be examined, for coupling and transmitting the ultrasonic signals between the ultrasonic transducer 112 and the object to be examined. For further details, reference is made to the illustration in Figure 6 referred to.

[0059] The Figure 1The schematically illustrated ultrasonic transducer 112, in the present exemplary embodiment, also serves simultaneously as an ultrasonic receiver 138 for receiving ultrasonic signals. In general, however, ultrasonic transducers can also be used which can be used either only as ultrasonic transmitters or only as ultrasonic receivers. In this case, in particular, a larger number of ultrasonic receivers can be provided in order to be able to achieve a higher resolution, preferably a higher spatial resolution, of the ultrasonic signals. In order to design the device 110 as space-saving as possible, in the latter case, some of the ultrasonic transducers can serve simultaneously as both ultrasonic transmitters and ultrasonic receivers, while other ultrasonic transducers can be used only as ultrasonic receivers. However, further designs are possible.

[0060] From the ultrasonic measurement signals 140 received by the ultrasonic receiver 138, low frequency components can first be filtered out of the ultrasonic measurement signals 140 by means of an adjustable filter 142, which can have an adjustable resistor 144 and a capacitor 146 connected in parallel, and transferred as a measurement signal 148 from the input channel 124 to the output channel 126 of the device 110. In particular, frequency components below a cutoff frequency can be filtered out of the ultrasonic measurement signals 140, wherein the "cutoff frequency" specifies an adjustable frequency below which the filter 142 can filter out at least a predetermined value, for example, half (50%) or 1 / e (≈ 36.8%), of the associated ultrasonic measurement signals 140. The measurement signal 148 can be transferred, as in Figure 1shown schematically, by means of a simple electrically conductive connection. However, according to the invention, the Figure 2 schematically illustrated multiplexer device 114 is used.

[0061] The output channel 126, designed to accommodate the low-voltage elements, comprises an output switch 150, at least one low-voltage preamplifier 152, and a low-voltage signal output 154. The output switch 150 can be set to ON or OFF to enable (output switch 150 ON) or prevent (output switch 150 OFF) the low-voltage preamplifier 152 from being acted upon by the measurement signal 148. Thus, the output switch 150 is configured to prevent, at least during the transmission phase of the ultrasonic transmitter 136, the low-voltage preamplifier 152 from being acted upon for further processing of the measurement signal 148 provided by the input channel 124.

[0062] The low-voltage preamplifier 152 comprises at least one low-noise preamplifier configured to receive ultrasonic signals. The low-voltage signals amplified therein are fed to the low-voltage signal output 154, which is configured to communicate with an external control and evaluation unit. The amplified low-voltage signals can preferably be forwarded to the external control and evaluation unit, for example, to enable reconstruction of real-time images on a screen during a measurement of the object, in particular the body part.

[0063] The low-voltage preamplifier 152 comprises CMOS semiconductor components, in particular transistors, which are designed as conventional CMOS transistors for use at low voltages. The low-voltage preamplifier 152 used in the present embodiment has a standard amplifier circuit comprising a folded cascade and an input transistor, with the amplifier preferably located in an n-well. To increase the gain, two such amplifiers can be connected in series (not shown).

[0064] As already mentioned, Figure 2A block diagram of a multiplexer device 114, which, in the exemplary embodiment shown, is configured to combine three measurement signals 148 from at least three input channels 124, each arranged on the first region 118 of the substrate 116, into a common measurement signal by means of a 3:1 multiplexer 156. Other types of multiplexers 156, for example, a 2:1 multiplexer, which can combine two measurement signals 148 into a common measurement signal, or a 4:1 multiplexer, which can combine four measurement signals 148 into a common measurement signal, are also possible. The internal structure of a multiplexer 156 is known to the person skilled in the art, e.g., from DF Lemmerhirt, see above.

[0065] To manufacture a device according to the invention, a special high-voltage CMOS technology from AMS can preferably be used, which allows standardized low-voltage CMOS transistors (35 µm or 18 µm) and high-voltage CMOS transistors to be provided simultaneously on a single substrate (chip), whereby a dielectric strength of at least 100 V, preferably up to 120 V, can be achieved. In contrast, the use of pure high-voltage technology would be disadvantageous, since it would not be possible to achieve low-noise preamplifiers with a signal-to-noise ratio of at least 60 dB and with bandwidths of at least 1 MHz. Rather, a combination of high-voltage and low-voltage technologies on a common substrate proposed here enables the construction of an ultrasound computed tomography scanner for three-dimensional measured value acquisition under the specific requirements given for this purpose.

[0066] The Figures 3a to 3c show a normalized signal amplitude I / I 0 of a broadband input signal, which is represented by the three consecutive amplifier stages 158, 160, 162 of the high-voltage amplifier 132 in the time domain t [s]. Figure 3d shows a respective signal response of the high-voltage amplifier 132 across the three amplifier stages 158, 160, 162 in the form of signal amplitude I in the frequency range f [Hz]. This shows that the broadband signal is maintained across its entire bandwidth; apart from a slight attenuation of the amplitude at higher frequencies, no significant phase jumps or phase shifts occur between the frequencies. This property can be advantageous, in particular, for subsequent signal processing, including with a so-called Matched Filter procedures enable.

[0067] Figure 4shows a schematic circuit diagram of a preferred embodiment of the analog, linear, feedback amplifier 134, which is used in the control of the ultrasonic transducer 112. The analog, linear, feedback amplifier 134 comprises at least three blocks A, B, C, which are configured as described in detail below.

[0068] Block A comprises a differential amplifier 164, which has two inputs InP and InN and two outputs OutP and OutN. The two outputs OutP and OutN each generate an output current IOutP and IOutN, respectively, where a difference between the absolute values ​​of the output currents |IOutP-IOutN| according to equation (1) is proportional to the difference between the input voltages UInP and UInN at the two inputs InP and InN: IOutP − IOutN ∼ UInP − UInN .

[0069] Regarding the direction of the output currents IOutP and IOutN, it should be noted that the output current IOutP flows into block A at the output OutP, while the output current IOutN flows out of block A at the output OutN.

[0070] The output OutP of the differential amplifier 164 in block A is connected to a first transistor M1, while the output OutN of the differential amplifier in block A is connected to a second transistor M2. As in Figure 4As shown, the first transistor M1 is an n-channel MOSFET (NMOS), while the second transistor M2 is a p-channel MOSFET (PMOS). Each of the transistors M1 and M2 has the outputs Source S, Drain D and Gate G. The gate G of the first transistor M1 is connected to a low voltage VDD, while the gate G of the second transistor M2 is connected to a low voltage ground GRD, whereby the low voltage VDD and the low voltage ground GRD also serve to supply voltage to the differential amplifier in block A. A typical voltage for the low voltage VDD can be 3.3 V, while the low voltage ground is set to 0 V. Other values ​​for the low voltage VDD from 1 V to 5 V are also possible.

[0071] The Figure 4The embodiment shown has the particular consequence that the first transistor M1, in the form of an NMOS, is designed to maintain a high voltage with a positive sign between the drain D and its other outputs, wherein the high voltage can assume values ​​of up to 60 V. Similarly, the second transistor M2, in the form of a PMOS, is designed to maintain a high voltage with a negative sign between the drain D and its other outputs, wherein the high voltage can assume values ​​of up to -60 V. In both cases, this type of drain D can also be referred to as a "high-voltage drain".

[0072] The drain D of the first transistor M1 is connected to the other block B. Block B has an input In, an output Out, and a connection Sup for a voltage supply. A current IInB flowing out of the input In roughly corresponds to a current IOutB flowing out of the output Out. Due to this property, block B can also be referred to as a "current mirror." The connection Sup for the voltage supply is connected to a power rail VHigh. A typical potential in this case can be 60 V. Block B is designed to maintain a high voltage between the connection Sup for the voltage supply and the output Out. This allows a voltage of up to 120 V to be applied to block B without damaging it.As already mentioned, the current IInB flowing out of the In input can be approximately equal to the current IOutB flowing out of the Out output, provided the potential between the Sup power supply terminal and the Out output exceeds a value of approximately 500 mV. For potentials below this value, the current IOutB flowing out of the Out output is lower than the current IInB flowing out of the In input. In the latter case, block B is therefore said to be "saturated."

[0073] The drain D of the second transistor M2 is connected to a block C. The other block C is also designed as a current mirror. Due to this property, a current IInC flowing into the input In roughly corresponds to a current IOutC flowing into the output Out. The connection Sup for the voltage supply is connected to a power rail VLow. A typical potential in this case can be -60 V. Block C is designed to maintain a high voltage between the connection Sup for the voltage supply and the output Out. This means that a voltage of up to 120 V can be applied to block C without it being damaged. Here, too, the current IInC flowing into the input In can roughly correspond to the current IOutC flowing into the output Out, provided the potential between the connection Sup for the voltage supply and the output Out has a value of approx.exceeds 500 mV, while for lower potentials below this value, block C saturates so that the current IOutC flowing into the output Out is lower than the current IInC flowing into the input In.

[0074] Output Out1 of block B is connected to a third transistor M3, while output Out2 of block C is connected to a fourth transistor M4. The third transistor M3 is an n-channel MOSFET (NMOS), while the fourth transistor M4 is a p-channel MOSFET (PMOS). Here, too, each of the transistors M3 and M4 has the outputs Source S, Drain D, and Gate G, which are connected according to the Figure 4 The transistors M3 and M4 are each connected in series at their source outputs S.

[0075] The described and in Figure 4The interconnection of blocks B and C and transistors M3 and M4 shown results in the equilibrium direct currents IOutB and IOutC being equal. On the other hand, the currents IInB and IInC correspond to the output currents IPOutN and IOutP applied to the outputs OutN and OutP of block A, whereby the difference between the output currents IPOutN and IOutP is proportional to the voltage difference |UInP-UInN| at the inputs InN and InP of block A. Consequently, with a low voltage difference |UInP-UInN| applied to block A, either block B or block C will saturate, whereas with a higher voltage difference |UInP-UInN| applied to block A, there will be a high-voltage gain at the outputs Out1 of block B and Out2 of block C.

[0076] Furthermore, the output Out1 of block B is connected to the gate G of transistor M5, while the output Out2 of block C is connected to the gate G of transistor M6. Here, transistor M5 is of the same type as transistor M3. A width of transistor M5 corresponds to the width of transistor M3, or the width of transistor M5 is a factor m1 larger than the width of transistor M3, while the lengths of transistors M3 and M5 are the same. Analogously, transistor M6 is of the same type as transistor M4, with the width of transistor M6 corresponding to the width of transistor M4 or a factor m2 larger, while the lengths of both transistors M4 and M6 are also the same. Furthermore, the two factors m1 = m2 = m are the same.

[0077] Transistors M5 and M6 also have high-voltage drains, allowing them to maintain a high voltage between drain D and the other outputs. The potential at drain D of transistor M5 can assume a value of up to +120 V relative to the potential of other transistor outputs, while the potential at drain D of transistor M6 can assume a value of up to -120 V relative to the potential of other transistor outputs without damaging the respective transistor.

[0078] A subcircuit of the Figure 4The circuit shown, wherein the subcircuit comprises the transistors M3, M4, M5 and M6, can be used in such a way that the current flowing through the transistors M5 and M6 corresponds to the current flowing through the transistors M3 and M4, multiplied by a factor m. If no load is applied to the output Out, according to equation (2), the potential UOut at the output Out approximately corresponds to the potential UOutMid at the output OutMid in the connection between the transistors M3 and M4. Thus, the potential applied to the output Out is UOut = UOutMid + 1 2 UOut 1 + UOut 2 .

[0079] Consequently, there is a high-voltage gain between the output Out with respect to the voltage difference |UInP-UInN| applied to block A. Transistors M5 and M6 ensure that a low resistance or a high capacitance can be connected to the output Out without affecting the high-voltage gain in the circuit according to Figure 4This property is based on the connection of the sources S of transistors M5 and M6. In a case where the potential UOut applied to the output Out follows a rise in the potential UOut1 applied to the output Out1, the voltage between gate G and source S of transistor M5 will increase such that transistor M5 will generate a higher current. This increased current will usually cause a change in the potential UOut at the output Out, thus counteracting the original rise.

[0080] The Figure 4 The circuit shown schematically is preferably suitable for use as a high-voltage amplifier 132, in particular for controlling a piezoelectric ultrasonic transducer 112. As Figure 5shows, the voltage amplifier can be equipped with a negative feedback circuit 166. In this case, a signal amplitude at the output Out of the high-voltage amplifier 132 corresponds to the signal amplitude at the input InN of the voltage amplifier, multiplied by a ratio Rfb / RfIn of the resistors Rfb and RfIn, respectively. A capacitance Cfb can serve to increase the stability of the negative feedback circuit 166. For this purpose, it can be particularly advantageous, as in Figure 5 shown, connect the capacitance Cfb to the output Outl of the voltage amplifier.

[0081] Figure 6schematically shows an ultrasound computed tomography scanner 200 known from WO 2002 / 030288 A1, which is particularly suitable for use in an ultrasound-based imaging method for early breast cancer detection. The ultrasound computed tomography scanner 200 comprises an upwardly open container 202 into which a body part to be examined, here a breast 204 of a patient 206 lying on a patient couch 208, is inserted. In contrast to the illustration in WO 2002 / 030288 A1, the container 202 is preferably designed in the form of a partial sphere in order to enable better spatial adaptation to the breast 204 as the body part to be examined.

[0082] The Figure 6The schematically illustrated ultrasound computer tomograph 200 further comprises a group of ultrasound transducers 112, each of which is fixedly arranged on a wall of the container 202, distributed as evenly as possible over the entire surface of the wall, and each of which has a main radiation direction that is oriented substantially perpendicularly from the surface of the wall into an interior of the container 202. A coupling medium 210 can be filled into the container 202, which can wet the body part to be examined and, in particular, can serve for better coupling and transmission of ultrasound signals between the ultrasound transducers 112 and the body part to be examined. The group of ultrasound transducers 112 is controlled and read out in particular with the device 110 according to the Figures 1 and 2 , wherein the high voltage amplifier 132 preferably corresponds to the Figures 4 and 5 can be designed.

[0083] The ultrasound computed tomography scanner 200 shown here further comprises a computer-aided control and evaluation unit 212, which preferably has a working memory and can be connected to the device 110, preferably via coaxial cables 214. Other types of cables or, alternatively or additionally, a wireless transmission of data into and / or out of the device 110 is also possible.The interconnection is designed such that any number of ultrasonic transducers 112 can be selected as ultrasonic transmitters 136 and / or as ultrasonic receivers 138, such that the ultrasonic signals emitted by the ultrasonic transmitters 136 are applied to the body part to be examined via the coupling medium 210, while the ultrasonic measurement signals received in parallel by the ultrasonic receivers 138 are amplified as electrical signals, filtered, digitized, and stored as data in the working memory of the control and evaluation unit 212. This data can be evaluated, as described in particular in WO 2002 / 030288 A1, EP 2 056 124 A1, WO 2011 / 124379 A2, or WO 2012 / 110228 A1, and used to reconstruct the body part being examined. However, other evaluation and reconstruction methods can also be used.Real-time images reconstructed in this way can be displayed in an output unit 216, in particular on a screen, during a measurement, particularly for medical purposes. However, other types of display are possible.

[0084] A particularly preferred ultrasound computer tomograph can comprise 157 devices according to the invention, which can also be used as Transducer Array Systems(TAS), whereby each of the devices can have 4 ultrasound transmitters and 9 ultrasound receivers. This means that the ultrasound computed tomography scanner can have a total of 628 ultrasound transmitters and 1413 ultrasound receivers, which can be distributed as evenly as possible across a partial sphere. Each of the devices can in particular have a multiplexer device with a 3:1 multiplexer, so that a total of 471 measurement signals are present at the low-voltage signal outputs of the devices, which can be processed by 480 parallel channels set up for this purpose. In addition, 28888 virtual ultrasound transmitters and 64998 virtual ultrasound receivers can be provided through 46 different movements of the aperture.

[0085] Here, 2 × 2 ultrasonic transducers can be used in the form of an array with an area of ​​0.9 mm × 0.9 mm, with each ultrasonic transducer having an individual area of ​​0.4 mm × 0.4 mm. The maximum excitation voltage provided by the high-voltage amplifiers can be 80 V. This device can enable an opening angle for ultrasound radiation of approximately 38° at a resonant frequency of approximately 2.7 MHz and a bandwidth of approximately 1.5 MHz, whereby a sound pressure of approximately 6 kPa can be achieved at a distance of 12 cm from the ultrasonic transducer. However, other configurations of the present ultrasound computed tomography system are possible. List of reference symbols

[0086] 110Device 112Ultrasonic transducer 114Multiplexer device 116Substrate 118First region 120Second region 122Separator 124Input channel 126Output channel 128High-voltage signal input 130Input switch 132High-voltage amplifier 134Analog, linear, feedback amplifier 136Ultrasonic transmitter 138Ultrasonic receiver 140Ultrasonic measurement signals 142Adjustable filter 144Adjustable resistor 146Capacitor 148Measurement signal 150Output switch 152Low-voltage preamplifier 154Low-voltage signal output 156Multiplexer 158First amplifier stage 160Second amplifier stage 162Third amplifier stage 164Differential amplifier 166Negative feedback circuit 200Ultrasound computed tomography scanner 202Container 204Breast 206Patient 208Patient bed 210Coupling medium 212Control and evaluation unit 214Coaxial cable 216Output unit

Claims

1. Device (110) for actuating and reading a group of ultrasound transducers (112) for ultrasound computer tomography, comprising - a common substrate (116), wherein the substrate (116) has a first region (118) configured as input channel (124) and a second region (120) configured as output channel (126), said second region (120) being separated electrically from said first region (118); - at least one high-voltage signal input (128) arranged on the first region (118), wherein the high-voltage signal input (128) is configured to receive analogue high-voltage signals; - at least one high-voltage amplifier (132) arranged on the first region (118), wherein the high-voltage amplifier (132) is configured to receive and to amplify the analogue high-voltage signals provided by the high-voltage signal input (128), wherein the high-voltage amplifier (132) has high-voltage CMOS semiconductor components; - at least one group of ultrasound transducers (112) arranged on the first region (118), wherein at least one of the ultrasound transducers (112) is configured as ultrasound transmitter (136) to generate ultrasound signals during a transmission phase, in which the high-voltage amplifier (132) provides high-voltage signals at its output, and wherein at least one of the ultrasound transducers (112) is configured for receiving ultrasound measurement signals (140); - at least one low-noise low-voltage preamplifier (152) arranged on the second region (120), wherein the low-voltage preamplifier (152) is configured for receiving the measurement signal (148), wherein the low-voltage preamplifier (152) has CMOS semiconductor components; - at least one output switch (150) arranged on the second region (120), wherein the output switch (150) is configured to prevent the measurement signal (148) from being applied to the low-voltage preamplifier (152) at least during the transmission phase; and - at least one low-voltage signal output (154) arranged on the second region (120), which is configured for transmitting a preamplified measurement signal (148) to an external control and evaluation unit (212), characterized by - at least one multiplexer (156) configured to combine ultrasound measurement signals (140) that have been received from at least two mutually different ultrasound transducers (112) to form a common measurement signal (148), wherein a separation (122) of the first region (118) from the second region (120) on the substrate (116) is effected by means of n-wells, wherein the high-voltage amplifier (132) has at least one analogue linear feedback amplifier (134) having at least three separate amplifier stages (158, 160, 162), and wherein the analogue linear feedback amplifier (134) has a dielectric strength of at least 80 V.

2. Device (110) according to the preceding claim, wherein the first region (118) is designed for reception and further processing of electrical voltages and potentials of 5 V to 120 V and the second region (120) is designed for reception and further processing of electrical voltages and potentials of 1 nV to 10 mV.

3. Device (110) according to either of the preceding claims, wherein the high-voltage amplifier (132) has a first bandwidth and wherein the low-voltage preamplifier (152) has a second bandwidth, wherein the first bandwidth and the second bandwidth correspond to one another.

4. Device (110) according to any of the preceding claims, wherein each of the amplifier stages (158, 160, 162) has in each case at least two high-voltage CMOS transistors (M1, M2; M3, M4; M5, M6).

5. Device (110) according to the preceding claim, wherein a differential amplifier (164) is situated at the input of a first amplifier stage (158), wherein the first amplifier stage (158) and a second amplifier stage (160) are arranged in each case between two current mirrors (B, C), and wherein the high-voltage CMOS transistors (M3, M4; M5, M6) are connected to one another in each case in the second amplifier stage (160) and in a third amplifier stage (162).

6. Device (110) according to any of the preceding claims, wherein the first region (118) furthermore has an input switch (130) configured to enable or to prevent the external analogue high-voltage signals from being applied to the high-voltage amplifier (132).

7. Device (110) according to any of the preceding claims, wherein the first region (118) furthermore has an adjustable filter (142) configured to filter out frequency components below a cut-off frequency from the ultrasound measurement signals (140).

8. Device (110) according to any of the preceding claims, wherein the device (110) is present in the form of an application-specific integrated circuit (ASIC).

9. Ultrasound computer tomography machine (200) for examining a body part, comprising - a container (202) configured for receiving an object to be examined and a coupling medium (210); - at least one device (110) according to any of the preceding claims for actuating and reading a group of ultrasound transducers (112) fitted to at least one wall of the container (202); and - a control and evaluation unit (212) for providing analogue high-voltage signals for at least one high-voltage signal input (128) of the device (110) and also for receiving and evaluating ultrasound measurement signals provided by at least one low-voltage signal output (154) of the device (110).

10. Ultrasound computer tomography machine according to the preceding claim, furthermore comprising an output unit (216) configured for representing reconstructed real-time imagings.