Ultrasound transducer array
By embedding tilted transducer elements in the ultrasound transducer array, the problem of maternal abdominal curvature limiting the field of view is solved, achieving a larger field of view and stable fetal heart rate monitoring, while reducing acoustic risks and system costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- KONINKLIJKE PHILIPS NV
- Filing Date
- 2020-10-27
- Publication Date
- 2026-05-12
AI Technical Summary
Existing ultrasound transducer arrays have limited overall field of view due to the curvature of the maternal abdomen, resulting in overlapping ultrasound beams, which increases the risk of acoustic dose and makes it difficult to stably monitor fetal heart rate, especially when the fetus is moving.
By embedding transducer elements in the ultrasonic transducer array at specific tilt angles θe and θa, the curvature of the mother's abdomen is compensated, ensuring that the transducer elements are arranged at angles opposite to the curved surface, thereby counteracting field convergence, increasing the overall field of view, and reducing beam overlap.
It achieves a larger overall field of view, reduces acoustic dose, improves the stability and coverage of fetal heart rate monitoring, and reduces system costs.
Smart Images
Figure CN114630623B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an ultrasonic transducer array having multiple transducer elements. Background Technology
[0002] US 3780725 discloses a fetal heart rate monitoring system in which multiple ultrasound beams are transmitted into the expectant mother's uterus at different angles. Multiple receiving transducers are tilted at different angles to receive signals reflected from the fetus and / or the uterine wall, the frequency of the reflected signals being different from the frequency of the transmitted signals, where the different amounts correspond to the rate of fetal heartbeat. A system for calculating the rate based on the generated Doppler fetal heartbeat signals is employed, utilizing frequency domain techniques. The heart rate signal is extracted from the Doppler heartbeat signals using a diode demodulator and a low-frequency bandpass filter.
[0003] US 2018 / 130457 discloses an ultrasonic array comprising a plurality of ultrasonic transducer elements located on a carrier, the carrier also carrying an actuator arrangement structure formed of a material having an adjustable shape responsive to electromagnetic stimulation, such as an electroactive polymer or an optically responsive polymer.
[0004] US 2003 / 135135 discloses an ultrasonic irradiation device that can easily irradiate a large area (range) of an object with a three-dimensional curved surface using ultrasonic waves. Summary of the Invention
[0005] Among other things, the object of the present invention is to provide an improved ultrasonic transducer array. The invention is defined by the independent claims. Advantageous embodiments are defined in the dependent claims.
[0006] One aspect of the invention provides an ultrasonic transducer array having a plurality of transducer elements, each transducer element having a corresponding field of view. The ultrasonic transducer array is capable of being positioned around an object having a curved surface, thereby causing convergence of the respective fields of view of the transducer elements. The transducer elements are arranged or can be arranged on the ultrasonic transducer array in a manner opposite to the curvature of the curved surface to counteract the convergence of the respective fields of view. Here, the concept of "around" does not necessarily mean "completely around"; it refers to the transducer array being positioned along the curved surface of the object, for example, on top of a pregnant woman's abdomen, such that the transducer elements point inwards towards the abdomen for fetal monitoring purposes.
[0007] This invention is based on the understanding that in existing arrangements, due to the curvature of the mother's abdomen, all individual ultrasonic transducer elements point to the same area of the abdomen because the propagation of ultrasound waves is only perpendicular to the skin surface. This limits the overall field of view (FOV) of the employed ultrasonic transducer array. Moreover, the ultrasonic beams of multiple transducer elements may overlap significantly, potentially leading to high levels of acoustic dose (safety risk). In embodiments of this invention, transducer elements are positioned in the ultrasonic transducer array at specific tilt angles to compensate for the curvature of the mother's abdomen and create a large overall FOV. Here, complete and perfect compensation is not required, and the concept of "cancellation" should be understood accordingly; undercompensation or overcompensation is permissible if the corresponding tilt angle (at which the individual transducer elements are positioned in the transducer array) reduces the net angle resulting from the positioning of the transducer array on the curved surface of the object, as it is sufficient. Therefore, the concepts of "opposite angle" and "opposite to the curvature of the curved surface" should also not be understood as angles with exactly the same absolute value.
[0008] These and other aspects of the invention will become apparent and will be illustrated from the embodiments described below. Attached Figure Description
[0009] Figure 1 An existing ultrasonic transducer array is shown;
[0010] Figure 2 An embodiment of the ultrasonic transducer array according to the present invention is shown; and
[0011] Figure 3 The azimuth and elevation components of the tilt angle of a single transducer element in a flexible transducer array are shown; and
[0012] Figure 4 A schematic diagram of an ultrasonic system including an ultrasonic transducer array and a processor is shown. Detailed Implementation
[0013] Figure 1 A prior art ultrasound transducer array T is shown, which has multiple transducer elements TE, formed by five transducer elements TE in this embodiment. Each transducer element has a corresponding field of view FOV-1, FOV-2, FOV-3, FOV-4, and FOV-5, schematically indicated by arrows representing the central axis of the cone-shaped field of view. When the ultrasound transducer array T bends along the skin S of the pregnant woman's abdomen, as... Figure 1As shown in the lower section, the fields of view (FOV-1 to FOV-5) converge, causing the cones to overlap. Therefore, the overall field of view of the ultrasonic transducer array T is reduced, and where the cones overlap, the ultrasonic pressure (acoustic dose) may be relatively high, even higher than the expected amount for unborn children.
[0014] Monitoring fetal heart rate before and during labor is a standard method for assessing fetal health. The most common technique for measuring fetal heart rate is based on Doppler ultrasound. For stable monitoring of fetal heart rate, the fetal heart needs to be within the overall field of view (FOV) of the ultrasound transducer used. In clinical practice, the fetus moves, causing the fetal heart to move out of the ultrasound beam, resulting in signal loss for extended periods and frequently. Flexible multi-element ultrasound transducer arrays (T-arrays) can be wrapped around the maternal abdomen and have the potential for continuous monitoring of fetal heart rate across various fetal heart positions, including the possibility of monitoring twins or triplets. Figure 1 As shown, a drawback of the flexible ultrasound transducer array T is that, due to the curvature of the maternal abdomen, all individual transducer elements TE point towards the same area of the maternal abdomen because the ultrasound propagation is only perpendicular to the skin surface. This limits the overall field of view (FOV) of the ultrasound transducer array T. In this invention, we propose embedding the transducer elements TE within the ultrasound transducer array T at a specific tilt angle to compensate for the curvature of the maternal abdomen and generate a large overall field of view (FOV).
[0015] Figure 2 An embodiment of the ultrasonic transducer array T according to the present invention is shown. Here, in Figure 2 In the static state of the ultrasound transducer array T shown above, each transducer element TE is pre-tilted to counteract the convergence of the fields of view (FOV-1, FOV-2, FOV-3, FOV-4, FOV-5) caused by the curvature of the ultrasound transducer array T around the skin S of the pregnant woman's abdomen. Figure 2 As shown in the lower part. In Figure 2 In the idealized scenario illustrated, the fields of view FOV-1 to FOV-5 are perfectly parallel; in reality, they may still converge or diverge depending on the relationship between the pre-tilt and the curvature of the individual woman's abdomen, the surface of which fluctuates due to breathing and / or infant movement, and the claims should be understood accordingly to cover this reality.
[0016] Figure 3 The azimuth and elevation components of the tilt angle of a single transducer element in a flexible transducer array are shown. Using two tilt angles allows for compensation of the curvature of the abdomen in both directions. Multiple transducer elements TE can be arranged, for example, in a circular pattern to increase the overall field of view (FOV) of the ultrasonic transducer array T.
[0017] In embodiments of the invention, multiple ultrasonic transducer elements TE, such as piezoelectric transducer elements (PZT), are thus embedded in a flexible ultrasonic transducer array T. The flexible substrate of the ultrasonic transducer array T can be made of a silicone resin such as polydimethylsiloxane (PDMS), or any other material that can be made flexible and has suitable acoustic properties. PDMS is a silicone resin that is flexible and has acoustic properties similar to human tissue, and is therefore used in many biomedical ultrasound applications. To prevent the transducer elements TE from all pointing in the same direction when positioned on the maternal abdomen, the transducer elements TE are embedded in the ultrasonic transducer array T at a specific tilt angle θ = [θeθa], where θe and θa are the elevation and azimuth angles, respectively. The transducer elements TE within the two-dimensional ultrasonic transducer array T are tilted at elevation and azimuth angles (see...). Figure 3 This allows for compensation of the curvature of the abdomen in two directions.
[0018] The tilt angle θ should be selected to compensate for the curvature of the maternal abdomen. The curvature of the maternal abdomen depends on gestational age and maternal body mass index (BMI). The maternal abdomen can be considered as a hemisphere with radius r, i.e., curvature κ = 1 / r. The curvature κ determines the tilt angle θ. For a full-term average maternal abdomen, the radius of the sphere is in the range of r = 25cm-40cm. It should be noted that it is not necessary for the transducer element TE to tilt exactly to correspond to the curvature of the abdomen. Pre-tilting the transducer element TE will always compensate for the average curvature of the maternal abdomen to some extent, and therefore always increases / improves the FOV of the ultrasound transducer array T.
[0019] In another embodiment, instead of a one-fit-all solution, different styles of ultrasonic transducer arrays T can be produced to fit, for example, the lower abdomen, middle abdomen, or large abdomen. In real life, the curvature of the abdomen can be determined manually, for example, by a caregiver or expectant mother, or automatically, through, for example, camera technology. A flexible ultrasonic transducer array T with a corresponding pre-tilted transducer element TE can be selected for optimal fit to achieve the best overall field of view (FOV). In this embodiment, the user will therefore be provided with a set of ultrasonic transducer arrays T, which includes:
[0020] A first ultrasonic transducer array T, having a first transducer element TE, the first transducer element TE being arranged in the first ultrasonic transducer array T at a first corresponding tilt angle; and
[0021] A second ultrasonic transducer array T has a second transducer element TE, which is arranged in the second ultrasonic transducer array T at a second corresponding tilt angle, each of the second corresponding tilt angles exceeding the corresponding one of the first corresponding tilt angles.
[0022] In another embodiment, the tilt angle θ (both azimuth and elevation) can be adjusted when the ultrasonic transducer array T is positioned on the pregnant woman's abdomen. This can be achieved using a liquid or ultrasonic gel, and the floating transducer element T is moved by one or more actuators, which can be controlled using, for example, accelerometers, cameras, or fiber optic curvature sensors. If the transducer element floats in, for example, a sodium acetate liquid, the position of the floating transducer element can be fixed, wherein the sodium acetate liquid solidifies when a crystallization nucleus is provided by an actuator (e.g., mechanical, as in a ClickHeat heating pad, but alternative actuators such as light or temperature are also conceivable). Furthermore, the tilt angle θ can be continuously adjusted over time to compensate for respiratory movements. In such an embodiment, the user would thus be provided with an ultrasonic transducer array T in which the corresponding orientation of the transducer element TE can be adjusted, and preferably with an ultrasonic transducer array T in which the transducer element TE is arranged in a medium that allows its state to change from liquid to solid, thereby fixing the corresponding orientation.
[0023] Figure 2 This illustrates a concept of pre-tilting the transducer element TE in a flexible array. (This is in contrast to the prior art.) Figure 1 In this configuration, the transducer elements TE are embedded parallel to the surface of the transducer array; therefore, after positioning, all transducer elements TE point towards the center of the abdomen. See also: [This refers to the process of pre-tilting the transducer elements TE.] Figure 2 After positioning, the transducer element TE is not parallel to the skin surface, which allows for a larger field of sound transmission compared to the case where the transducer element TE is not pre-tilted, thus allowing for stable fetal heart rate monitoring in response to changes in fetal heart position.
[0024] Another advantage of using pre-tilted transducer elements (TEs) is that the corresponding ultrasound beams do not overlap. This reduces the occurrence of destructive and / or constructive interference and / or the accumulation of multiple ultrasound beams over time. Furthermore, aligning multiple transducer elements (TEs) to the same location does not necessarily improve the estimation of fetal heart rate. Pre-tilted transducer elements (TEs) enable coverage of a larger measurement volume with a reduced number of transducer elements (TEs), ultimately reducing the cost of the system.
[0025] In another embodiment of the invention, an ultrasonic transducer array T with pre-tilted transducer elements TE allows for the generation of a large field of view (FOV) sufficient to transmit sound across the entire fetus, thereby allowing monitoring of fetal movements, such as limb movements.
[0026] Advantageously, the transducer element TE is a capacitive micro-manufactured ultrasonic transducer (CMUT).
[0027] Figure 4A schematic diagram of an ultrasound system 100 is shown, comprising an ultrasound transducer array 110 (as described above) and a processor 120. The ultrasound transducer array 110 includes a plurality of transducer elements 130 (corresponding to the transducer element TE described above) and is adapted to conform to the body 140 of a subject. At least two of the plurality of transducer elements 130 are adapted to acquire multiple ultrasound signals from a region of interest 150 in different orientations relative to the region of interest. Each individual transducer element 130 is adapted to transmit and receive ultrasound waves. The transducer element 130 may include a piezoelectric transducer or a CMUT unit.
[0028] The transducer array 110 can be adapted to conform to the body 140 of the subject in a variety of ways. For example, multiple transducer elements 130 can be embedded in a flexible silicone layer.
[0029] In other words, the transducer array 110 can be adapted to conform to the subject's body 140 to ensure good contact between the transducer elements and the body surface. Furthermore, the material layer positioned below the transducer element 130 and between the transducer element 130 and the subject can be selected to have an appropriate acoustic impedance suitable for ultrasound propagation. The transducer array 110 can be made of any suitable material, for example, by integrating the transducer element 130 into a fabric or band that can be wrapped around the subject's body.
[0030] Furthermore, the flexible array does not need to be completely enclosed. For example, individual elements can be interconnected via any flexible connector that defines the approximate position of the elements relative to each other.
[0031] Alternatively, a single transducer element 130 can be attached directly to the subject's skin in a manner similar to that of an electrocardiogram (ECG) measurement electrode that is attached directly to the skin.
[0032] Furthermore, the transducer element 130 can be formed by a transducer subarray of seven elements placed on a rigid plate, which can then be positioned on the skin. In this way, multiple such subarrays can be used to cover a large area while also following the curvature of the subject being measured.
[0033] exist Figure 4 In the example shown, ultrasound system 100 is used to measure the fetal heartbeat. More specifically, transducer array 110 is positioned adjacent to the mother's abdomen to transmit sound through the fetal region.
[0034] The ultrasonic transducer array 110 may also include a sensor 160, in which case the processor 120 is adapted to determine the curvature of the ultrasonic transducer array 110 based on the output of the sensor 160. The sensor 160 may include one or more of the following: a strain gauge; an accelerometer; a piezoelectric sensor; and a camera. For example, the camera may be used to determine the curvature of the array and, in addition, to determine the position of the array on the mother's abdomen.
[0035] The processor 120 is adapted to receive and process the ultrasonic echo signals acquired by the ultrasonic transducer array 110.
[0036] The present invention, wherein the transducer elements (TE) are arranged or can be arranged on an ultrasonic transducer array (T) in a manner opposite to the curvature of the curved surface (S) in order to counteract the convergence of the corresponding field of view, is advantageously used to modify the system of our earlier application PCT / EP2019 / 060648 (our document number 2018P00415WO), by application of which is incorporated herein.
[0037] It should be noted that the above embodiments are illustrative and not limiting of the invention, and those skilled in the art will be able to devise many alternative embodiments without departing from the scope of the appended claims. Any reference numerals placed in parentheses in the claims should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps other than those listed in the claims. The words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements. In device claims enumerating several means, several of these means may be embodied by the same item of hardware. Measures recited in mutually different dependent claims may be advantageously combined.
Claims
1. An ultrasonic transducer array (T) having a plurality of transducer elements (TE), each transducer element having a corresponding field of view (FOV-1 to FOV-5), the ultrasonic transducer array (T) being oriented around an object having a curved surface (S), thereby causing the corresponding field of view of the transducer elements (TE) to converge, wherein the transducer elements (TE) are arranged or can be arranged on the ultrasonic transducer array (T) in a manner opposite to the curvature of the curved surface (S) to counteract the convergence of the corresponding field of view, wherein the corresponding orientation of the transducer elements (TE) is adjustable, and the transducer elements (TE) are arranged in a sodium acetate liquid, the sodium acetate liquid being oriented from liquid to solid when a crystallization nucleus is provided by an actuator, thereby fixing the corresponding orientation.
2. The ultrasonic transducer array (T) according to claim 1, wherein, The transducer element (TE) is arranged in the ultrasonic transducer array (T) at a corresponding tilt angle, which is opposite to the angle at which the transducer element (TE) will be positioned when the transducer array (T) is positioned around the object.
3. An array of ultrasonic transducers (T), formed by the ultrasonic transducer array (T) according to claim 2, wherein, The set of ultrasonic transducer arrays includes: A first ultrasonic transducer array (T) having a first transducer element (TE), the first transducer element (TE) being arranged in the first ultrasonic transducer array (T) at a first corresponding tilt angle; and A second ultrasonic transducer array (T) having second transducer elements (TE) arranged in the second ultrasonic transducer array (T) at second corresponding tilt angles, each of the second corresponding tilt angles exceeding the corresponding one of the first corresponding tilt angles.
4. An ultrasound system (100), the system comprising: The ultrasonic transducer array according to any one of claims 1-2, or the set of ultrasonic transducer arrays according to claim 3; as well as A processor (120) adapted to receive and process ultrasonic signals acquired by the ultrasonic transducer array or from an ultrasonic transducer array selected from the set of transducer arrays.