Ultrasound image generation device and method using nonlinearity of ultrasonic waves

Abstract

The present application relates to an ultrasound image generation device using the nonlinearity of ultrasonic waves, the device comprising: an ultrasound probe for outputting an ultrasonic signal to a region of interest and receiving the ultrasonic signal reflected from the region of interest; and an image generation unit for generating an ultrasound image from the ultrasonic signal received by the ultrasound probe. The ultrasound probe comprises: an ultrasonic wave output unit having a plurality of transducers annularly arranged at regular intervals so as to output, toward the region of interest, a first ultrasonic signal associated with a first frequency, or a second ultrasonic signal associated with a second frequency different from the first frequency; and an ultrasonic wave receiving unit for generating a third ultrasonic signal by using the nonlinearity of the first frequency and the second frequency at a focal point where the first ultrasonic signal and the second ultrasonic signal cross each other, and receiving the third ultrasonic signal reflected from the region of interest.

Description

Ultrasonic image generation device and method using nonlinearity of ultrasound

[0001] The present application relates to an ultrasonic image generation device and method utilizing the nonlinearity of ultrasound, and more particularly, to an ultrasonic probe comprising a plurality of transducers in an annular array, which outputs an ultrasonic signal, facilitates focus formation, and simultaneously enables reception of reflected frequency difference △f ultrasonic signals. In other words, the present application relates to an ultrasonic image generation device and method utilizing the nonlinearity of ultrasound, which can simultaneously implement a conventional 3D ultrasonic image and a nonlinear ultrasonic image using only one type of element.

[0002] [Description of Nationally Supported Research and Development]

[0003] This study was conducted under the supervision of the Korea Institute of Science and Technology (KIST-Industry Bridge Program, Project ID: 1711196539) through the Ministry of Science and ICT's Korea Institute of Science and Technology Research Operation Support Program, the Inter-Ministry Full-Cycle Medical Device Research and Development Program (Development of Capacitive Micro-machined Ultrasound Transducers for MR-Compatible Functional Multimodal Imaging and Therapy, Project ID: 1711174481), and the Inter-Ministry Full-Cycle Medical Device Research and Development Program (Development of Commercialization Technology for Capacitive Micro-machined Ultrasound Transducers Capable of MR-Compatible Ultrasound Diagnosis / Treatment, Project ID: 1711196544).

[0004] Cross-reference to related applications

[0005] This application claims priority to Republic of Korea Patent Application No. 10-2023-0133113, filed October 6, 2023, the entire contents of which are incorporated herein by reference.

[0006] An ultrasonic probe is a device that can measure the round-trip time of an ultrasonic beam by including a transducer that outputs an ultrasonic beam to a region of interest and a receiver that receives the ultrasonic beam reflected from an object within the region of interest. A processing device (e.g., a computer device) connected to the ultrasonic probe generates an image of the region of interest and an object within the region of interest based on the measured round-trip time of the ultrasonic beam. The ultrasonic image thus generated can be provided to a user through a display.

[0007] Elastic ultrasound aims to visualize or quantify the elasticity of an object by providing elasticity images. It maintains the advantages of general medical ultrasound, such as cost-effectiveness, non-invasiveness, and compatibility, and there are techniques that can be overlaid on existing ultrasound images (e.g., B-mode). Furthermore, ultrasound images can provide additional information, such as statistical analysis. However, existing elasticity-based ultrasound images have the disadvantage of being unable to quantify stress when applied. They calculate the elastic modulus by applying stress perpendicular to the surface of the specimen and then calculating the vertical strain. In particular, strain-elastic ultrasound images cannot quantify stress, so they can only calculate relative differences in the elasticity of internal and external tissues under the assumption of a constant stress. Furthermore, because the medical professional conducting the examination must manually apply pressure with a transducer, they lack objectivity and reproducibility. Furthermore, techniques requiring the setting of a region of interest (ROI) (e.g., p-SWE) have subjective and non-standardized ROI setting methods. Existing elastic ultrasound-based ultrasound imaging techniques have struggled to apply stress to deep tissues, making imaging difficult due to insufficient stress. Furthermore, some elastic ultrasound imaging techniques (e.g., acoustic radiation impulse imaging) have been incompatible with existing ultrasound devices. Additionally, several variables and assumptions require further study, such as the assumption of a constant elastic modulus, the assumption that biological tissues are perfectly elastic, and the assumption that tissues are made of a homogeneous material.

[0008] To address these issues, various ultrasound imaging technologies have been proposed. U.S. Patent Application Publication No. 2020 / 0237339 demonstrates a method for generating images that utilize tissue elasticity differences compared to conventional linear ultrasound, improving the speckle problem that degrades ultrasound image quality. Furthermore, mechanized scanning enables the extraction of reproducible and objective data. This method allows areas of high elasticity to be brightly colored (red) due to strong frequency-difference ultrasound signals, while areas of low elasticity are darkly colored due to weak frequency-difference ultrasound signals. Compared to conventional elastic ultrasound images, this method eliminates the need for stress, enabling the generation of ultrasound images of deeper tissues. Furthermore, the absence of manual pressure simplifies the problem of stress quantification. However, because the ultrasound output and detection transducers are divided into three, mechanical focus adjustment is required, making it difficult to synchronize focus formation and timing for frequency-difference imaging. In addition, because three individual transducers must be designed and manufactured separately, the number of parts for repair and maintenance increases, making development, maintenance, and repair inconvenient, and there is still the problem of limited compatibility with existing ultrasound imaging techniques such as B-mode due to the use of cylindrical transducers.

[0009] In order to solve the above problems, the ultrasonic probe of the present application, which is composed of a plurality of transducers in a circular array, outputs an ultrasonic signal, facilitates focus formation, and simultaneously enables reception of reflected frequency difference △f ultrasonic signals. In other words, the present invention relates to an ultrasonic image generation device and method utilizing the nonlinearity of ultrasonic waves, which can simultaneously implement a conventional three-dimensional ultrasonic image and a nonlinear ultrasonic image using only one type of element.

[0010] According to one embodiment of the present application, an ultrasound image generation device utilizing nonlinearity of ultrasound may include: an ultrasound probe that outputs an ultrasound signal to a region of interest and receives an ultrasound signal reflected from the region of interest; and an image generation unit that generates an ultrasound image from the ultrasound signal received from the ultrasound probe; wherein the ultrasound probe may include: an ultrasound output unit in which a plurality of transducers are arranged in an annular array at regular intervals, the transducers outputting a first ultrasound signal associated with a first frequency or a second ultrasound signal associated with a second frequency different from the first frequency toward the region of interest; and an ultrasound receiving unit that generates a third ultrasound signal utilizing nonlinearity of the first frequency and the second frequency at a focus where the first ultrasound signal and the second ultrasound signal intersect, and receives the third ultrasound signal reflected from the region of interest.

[0011] In one embodiment, the plurality of transducers arranged in a circular array at regular intervals may be arranged to be divided into four sections and output a first ultrasonic signal or a second ultrasonic signal for each section.

[0012] In one embodiment, the plurality of transducers arranged in a circular array at regular intervals may be arranged to be divided into eight compartments and output a first ultrasonic signal or a second ultrasonic signal for each compartment.

[0013] In one embodiment, the plurality of transducers arranged in a circular array at regular intervals may be arranged sequentially and alternately, each of a transducer outputting a first ultrasonic signal and a transducer outputting a second ultrasonic signal.

[0014] In one embodiment, a plurality of transducers are arranged in an outer ring and an inner ring array at regular intervals, and the plurality of transducers arranged in the inner ring and the outer ring output ultrasonic signals associated with different frequencies, and can generate ultrasonic waves utilizing nonlinearity at one focus.

[0015] In one embodiment, the transducer disposed in the outer annulus may have a function of outputting an ultrasonic signal, and the transducer disposed in the inner annulus may have a function of receiving an ultrasonic signal reflected from the region of interest, or the transducer disposed in the inner annulus may have a function of outputting an ultrasonic signal, and the transducer disposed in the outer annulus may have a function of receiving an ultrasonic signal reflected from the region of interest.

[0016] In one embodiment, the transducer disposed in the inner annulus can output and receive ultrasound waves to generate a three-dimensional image, and the transducer disposed in the outer annulus can output and receive ultrasound waves to generate a frequency difference image.

[0017] In one embodiment, the ultrasonic probe can adjust the direction of an ultrasonic signal output by each of the plurality of transducers arranged in a ring-shaped array using the output delay time of each of the plurality of transducers, and can adjust the direction of the third ultrasonic signal generated at the focus.

[0018] In one embodiment, the region of interest is the brain, bone marrow, or electrolyte of the subject, and the image generating unit can generate an image of the brain, bone marrow, or electrolyte of the subject by allowing the third ultrasound signal generated at the focus to pass through a bone including the skull or a solid material including a battery.

[0019] In one embodiment, the nonlinearity of the first frequency and the second frequency may utilize at least one of a difference frequency, a sum frequency, and harmonics of the first frequency and the second frequency.

[0020] In one embodiment, when using the frequency difference between the first frequency and the second frequency, the third ultrasonic signal received by the ultrasonic probe may be a signal with a lower frequency difference as the material forming the region of interest is a low-elasticity material, and the third ultrasonic signal received by the ultrasonic probe may be a signal with a higher frequency difference as the material forming the region of interest is a high-elasticity material.

[0021] In one embodiment, the device may further include a display for outputting the ultrasound image generated by the image generating unit.

[0022] In one embodiment, the plurality of transducers of the ultrasonic probe may be ultrasonic transducers including a piezoelectric effect, capacitive micromachined ultrasonic transducer (CMUT) or piezoelectric micromachined ultrasonic transducer (PMUT).

[0023] A method for generating an ultrasound image using nonlinearity of ultrasound according to one embodiment of the present application may include the steps of: outputting a first ultrasound signal associated with a first frequency or a second ultrasound signal associated with a second frequency different from the first frequency toward a region of interest using an ultrasound probe having a plurality of transducers arranged in an annular array at regular intervals; generating a third ultrasound signal using the nonlinearity of the first frequency and the second frequency at a focus where the first ultrasound signal and the second ultrasound signal intersect; receiving, by the ultrasound probe, the third ultrasound signal reflected from the region of interest; and generating an ultrasound image for the region of interest from the third ultrasound signal received by the ultrasound probe.

[0024] The present application can be implemented as a computer program stored in a computer-readable storage medium for executing a method for generating an ultrasound image using nonlinearity of ultrasound according to one embodiment.

[0025] According to one embodiment of the present application, focus formation is performed reliably and simply by using a symmetrical annular array of transducers.

[0026] Unlike the existing prior art that used a separate transducer for receiving ultrasonic waves reflected by the material of the subject and an ultrasonic output transducer, it is easy to manufacture a miniaturized device with high reliability by integrating it into a single array transducer.

[0027] Electronic beam steering is possible without mechanical modifications using software using a toroidal array of transducers.

[0028] The use of array transducers provides expandability and versatility, allowing for improvements and modifications for other uses simply through software improvements.

[0029] It has high compatibility as it can simultaneously use conventional B-mode ultrasound images and 3D ultrasound images using an array transducer.

[0030] It can be used as an elastic image in various medical fields, such as tissue images such as the cervix and uterine fibroids, tumor images such as cancer or brain tumors, images for diagnosing neurological diseases, and images for diagnosing musculoskeletal diseases, and its application difficulty is low due to its proven stability.

[0031] The effects of the present application are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0032] FIG. 1 is a schematic diagram showing the configuration of an ultrasonic image generation device using nonlinearity of ultrasonic waves according to one embodiment of the present application.

[0033] FIG. 2 shows an example of an operation for focus formation of an ultrasonic image generation device using nonlinearity of ultrasonic waves according to one embodiment of the present application.

[0034] FIG. 3 shows a detailed configuration of an ultrasonic output unit in which a plurality of transducers are arranged in a circular array at regular intervals according to one embodiment of the present application.

[0035] FIG. 4 is an example showing the difference in reflected frequency difference signals depending on the elasticity of a material according to one embodiment of the present application.

[0036] FIGS. 5A to 5B illustrate various examples of multiple transducers arranged in an annular array according to one embodiment of the present application.

[0037] FIGS. 6A to 6C illustrate examples of adjusting the direction of an ultrasonic signal formed at a focus through electronic beam steering according to one embodiment of the present application.

[0038] FIGS. 7a and 7b illustrate examples of simulated operation of ultrasound output using a plurality of transducers arranged in a symmetrical quadrant-shaped annular array of FIG. 5a according to one embodiment of the present application.

[0039] Figures 8a to 8e show the results of forming a focus using nonlinear ultrasound through a ring-shaped array transducer according to an experimental example of the present application.

[0040] Figure 9 shows the results of an agarose phantom target experiment according to one experimental example of the present application.

[0041] Figures 10a to 10d are the results of a bone penetration image acquisition experiment with a large acoustic impedance difference according to an experimental example of the present application.

[0042] Figures 11a and 11b show the results of a compatibility test with an existing linear ultrasound image (B-mode) according to an experimental example of the present application.

[0043] Fig. 12 is a flowchart showing a method for generating an ultrasound image using nonlinearity of ultrasound according to one embodiment of the present application.

[0044] The detailed description of the present application, which follows, refers to the accompanying drawings, which illustrate specific embodiments in which the present application may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present application. It should be understood that the various embodiments of the present application, while different from each other, are not necessarily mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present application. Furthermore, it should be understood that the position or arrangement of individual components within each disclosed embodiment may be modified without departing from the spirit and scope of the present application. Accordingly, the following detailed description is not intended to be limiting, and the scope of the present application is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly described. Like reference numerals in the drawings designate the same or similar functionality throughout the several aspects.

[0045] Hereinafter, embodiments are described in detail with reference to the attached drawings, but the scope of the claims is not limited or restricted by the embodiments.

[0046] FIG. 1 is a schematic diagram showing the configuration of an ultrasonic image generation device using nonlinearity of ultrasonic waves according to one embodiment of the present application.

[0047] Referring to FIG. 1, an ultrasonic image generating device (1) (hereinafter, “ultrasonic image generating device”) utilizing nonlinearity of ultrasonic waves according to one embodiment may be composed of an ultrasonic probe (10) and an image generating unit (20). In one embodiment, the ultrasonic image generating device (1) may further include a display (30). The ultrasonic probe (10) may include an ultrasonic output unit (110) and an ultrasonic receiving unit (120).

[0048] Each component is merely represented as a block for convenience of explanation, and in reality, two or more components may be included in one software and / or hardware device, or one component may be implemented by two or more software and / or hardware devices.

[0049] Below, with reference to the drawings, the functions, roles, and interconnections of each component constituting the ultrasound image generation device according to the embodiment will be described in detail. Additional components, such as circuits and electronic components for powering and controlling the device, have similar structures and principles to those used in typical ultrasound diagnostic devices in the present technical field, and therefore, a detailed description thereof will be omitted.

[0050] An ultrasonic probe (10) is configured to output an ultrasonic signal to a region of interest and receive an ultrasonic signal reflected from the region of interest. The ultrasonic probe (10) is configured to radiate an ultrasonic beam toward the region of interest using, for example, an existing ultrasonic element using a piezoelectric material, a CMUT, a PMUT, an ultrasonic transducer using the photoacoustic effect, or an ultrasonic transducer using electromagnetic force.

[0051] Ultrasonic transducers utilize physical vibrations, such as the piezoelectric effect, to convert AC energy of 20 kHz or higher into mechanical vibrations of the same frequency. The transducer adjusts its output according to the target area and purpose of treatment, outputting ultrasound waves of appropriate intensity. The output ultrasound waves overlap to form an ultrasound beam.

[0052] The formed ultrasound beam is radiated toward the region of interest, and is reflected by an object (e.g., a skeleton, an organ, a tumor, a lesion, etc.) existing within the region of interest and returns toward the ultrasound probe (10). The ultrasound probe (10) is equipped with an ultrasound receiver to detect the reflected ultrasound.

[0053] The above ultrasonic probe (10) may include an ultrasonic output unit (110) in which a plurality of transducers are arranged in a circular array at regular intervals to output a first ultrasonic signal associated with a first frequency or a second ultrasonic signal associated with a second frequency different from the first frequency toward a region of interest, and an ultrasonic receiving unit (120) that generates a third ultrasonic signal by utilizing nonlinearity of the first frequency and the second frequency at a focus where the first ultrasonic signal and the second ultrasonic signal intersect, and receives the third ultrasonic signal reflected from the region of interest.

[0054] Frequency nonlinearity means that when two ultrasonic signals are superimposed, the superimposed signal generates signals not only at the two frequencies of the original signals, but also at the difference in frequency (difference frequency), the sum of frequencies (sum frequency), and multiples of frequencies (harmonics). In particular, in the case of ultrasonic images using the frequency difference, the strength of the signal tends to be strengthened as the product of the pressure of the original ultrasonic signal increases, and the nonlinear coefficient of the medium increases, and the nonlinear coefficient of the medium tends to increase proportionally as the elasticity increases. When two different frequencies are output and superimposed toward the material of interest, the frequency difference signal that is generated is reflected and can be detected. A strong ultrasonic reflection signal indicates high elasticity of the material to be examined.

[0055] The image generation unit (20) generates an ultrasound image from an ultrasound signal received from the ultrasound probe. The image generation unit (20) generates an image from a signal transmitted in real time from the ultrasound probe (10), and can generate an ultrasound image of a region of interest and an object based on a nonlinear ultrasound signal reflected from the region of interest.

[0056] The display (30) outputs the ultrasound image generated by the image generating unit. In one embodiment, a user can monitor a two-dimensional image or a three-dimensional stereoscopic image of the subject being diagnosed in real time through the display screen of a smartphone, tablet PC, or the like connected to the ultrasound image generating device (1).

[0057] FIG. 2 shows an example of an operation for focus formation of an ultrasonic image generation device using nonlinearity of ultrasonic waves according to one embodiment of the present application.

[0058] Referring to FIG. 2, the ultrasonic probe (10) includes an ultrasonic output unit (110) in which a plurality of transducers are arranged in an annular array at regular intervals to output a first ultrasonic signal associated with a first frequency (f1) or a second ultrasonic signal associated with a second frequency (f2) different from the first frequency toward a region of interest, and a third ultrasonic signal can be generated by utilizing the nonlinearity of the first frequency and the second frequency at a focus (F) where the first ultrasonic signal and the second ultrasonic signal intersect. The nonlinearity of the frequency can utilize at least one of a frequency difference, a frequency sum, and a frequency multiple of the first frequency and the second frequency. When the frequency sum and the frequency multiple are utilized, the frequency may increase, which may increase the attenuation of the reflected signal, but when the frequency difference is utilized, since it is lower than the first and second frequencies, the attenuation of the signal is small, and there are many cases where the intensity of the reflected signal remains, which is an advantage. That is, when the frequency difference is utilized, the intensity of the reflected ultrasonic signal increases, which may enable the features of the material to be better expressed in the image due to the short wavelength. In the example of Figure 2, the frequency difference is f1 (7.81 MHz) - f2 (6.25 MHz) = △f (1.56 MHz), and a third ultrasonic signal of 1.56 MHz was generated at the focus (F).

[0059] FIG. 3 shows a detailed configuration of an ultrasonic output unit in which a plurality of transducers are arranged in a circular array at regular intervals according to one embodiment of the present application.

[0060] Referring to Fig. 3, the plurality of transducers of the ultrasonic probe (10) may be ultrasonic transducers including a piezoelectric effect, capacitive micromachined ultrasonic transducers (CMUTs) or piezoelectric micromachined ultrasonic transducers (PMUTs). In order to apply voltage to the ultrasonic elements, there are two terminals including a bottom electrode and a top electrode. The ultrasonic producer (ultrasonic transducer element) can individually control the ultrasonic output, and can control the frequency difference image and focus for each position by varying the frequency or controlling the intensity of the signal and the generation of the ultrasonic signal.

[0061] In one embodiment, a plurality of transducers may be arranged in an array of an outer ring and an inner ring at regular intervals, and the transducers arranged in the inner ring and the outer ring may apply different frequencies to generate frequency-differential ultrasound at one focus. In one example, the transducer arranged in the inner ring may output a first ultrasound signal associated with a first frequency or a second ultrasound signal associated with a second frequency different from the first frequency toward the region of interest, and the transducer arranged in the outer ring may output a third ultrasound signal and a fourth ultrasound signal associated with a third frequency and a fourth frequency different from the first frequency and the second frequency.

[0062] In another embodiment, the transducer arranged in the outer annulus may output ultrasound, and the transducer arranged in the inner annulus may receive the reflected frequency difference ultrasound. Conversely, the transducer arranged in the inner annulus may output ultrasound, and the transducer arranged in the outer annulus may receive the reflected frequency difference ultrasound. In addition, the transducer arranged in the inner annulus may output and receive ultrasound for generating a three-dimensional image using conventional linear ultrasound, and the transducer arranged in the outer annulus may output and receive ultrasound for generating a frequency difference image. This has the advantage of being able to simultaneously display a quantitative frequency difference image along with the conventional ultrasound image.

[0063] FIG. 4 is an example showing the difference in reflected frequency difference signals depending on the elasticity of a material according to one embodiment of the present application.

[0064] Referring to FIG. 4, when using the frequency difference (△f) between the first frequency (f1) and the second frequency (f2), the lower the elasticity of the material forming the region of interest, the lower the frequency difference signal of the third ultrasonic signal received by the ultrasonic probe (10), and the higher the elasticity of the material forming the region of interest, the higher the frequency difference signal of the third ultrasonic signal received by the ultrasonic probe (10). In other words, a strong ultrasonic reflection signal means high elasticity of the test object.

[0065] FIGS. 5A to 5C illustrate various examples of multiple transducers arranged in an annular array according to one embodiment of the present application.

[0066] Referring to FIG. 5a, a plurality of transducers arranged in a circular array at regular intervals can be divided into four sections and arranged to output a first ultrasonic signal or a second ultrasonic signal for each section.

[0067] Referring to FIG. 5b, the plurality of transducers arranged in a circular array at regular intervals can be divided into eight sections and arranged to output a first ultrasonic signal or a second ultrasonic signal for each section.

[0068] Referring to FIG. 5c, the plurality of transducers arranged in a circular array at regular intervals may be arranged sequentially and alternately, with each transducer outputting a first ultrasonic signal and each transducer outputting a second ultrasonic signal.

[0069] The ultrasonic probe (10) divides the annular array elements into a plurality of sections and outputs first and second frequencies that are symmetrical left and right and up and down, respectively, and the image generation section (20) can generate a nonlinear ultrasonic image using the frequency difference. Through this, the present application has the advantage of excellent expandability because it is possible to output the array transducer in various ways and with different frequencies only by replacing the software without hardware improvement. Each section area can be arbitrarily set and can be changed only with simple software modification. In one embodiment, all 120 annular array elements on the outside and inside are usable and can provide output independently.

[0070] FIGS. 6A to 6C illustrate examples of adjusting the direction of an ultrasonic signal formed at a focus through electronic beam steering according to one embodiment of the present application.

[0071] Referring to FIGS. 6A to 6C together, the ultrasonic probe (10) can adjust the direction of the ultrasonic signal output by each of the plurality of transducers arranged in an annular array using the output delay time of each of the plurality of transducers, and can adjust the direction of the third ultrasonic signal generated at the focus. Since the speed of propagation of ultrasonic waves is constant, the distance reached varies depending on the time difference. By overlapping using the output delay time, the location of the focus where the ultrasonic waves are focused in each space can be changed. Unlike the existing prior art that divides into three transducers and mechanically scans to adjust the focus, the structure of the plurality of transducers arranged in an annular array of the present application can create a frequency difference image in all three-dimensional spaces. That is, electronic beam steering makes it easy to change the direction of the ultrasonic signal without mechanical movement.

[0072] FIGS. 7a and 7b illustrate examples of simulated operation of ultrasound output using a plurality of transducers arranged in a symmetrical quadrant-shaped annular array of FIG. 5a according to one embodiment of the present application.

[0073] Referring to FIGS. 7A and 7B, a plurality of transducers arranged in an annular array at regular intervals can be arranged to be divided into four sections and output a first ultrasonic signal or a second ultrasonic signal for each section. After outputting a first frequency ultrasonic signal in two symmetrical quadrants, it can be confirmed that a focus is formed, and by outputting a second frequency ultrasonic signal in two other quadrants, it can be confirmed that a focus is similarly formed.

[0074] Figures 8a to 8e show the results of forming a focus using nonlinear ultrasound through a ring-shaped array transducer according to an experimental example of the present application.

[0075] Referring to FIGS. 8a to 8e, the x-axis and y-axis passing through the center of the annular array transducer are defined as the 1st quadrant, the 2nd quadrant, the 3rd quadrant, and the 4th quadrant in a clockwise direction, respectively, and an ultrasonic wave with a frequency f1 (7.81 MHz) is applied to the 1st and 3rd quadrants, and an ultrasonic wave with a frequency f2 (6.25 MHz) is applied to the 2nd and 4th quadrants, thereby evaluating the nonlinear ultrasonic focus formation of the frequency difference. The position of the focus was changed for each depth (23 mm, 25 mm, 33 mm), and the ultrasonic focus formation was adjusted at each desired depth through beam steering to electronically change the focus position, and it was confirmed that the ultrasonic focus was formed in a ring-shaped array at one point in space.

[0076] Figure 9 shows the results of an agarose phantom target experiment according to one experimental example of the present application.

[0077] Referring to Fig. 9, experiments were conducted on 4% agarose and 8% agarose phantoms (by weight) in a tank of DI water, and the elasticity increased in the order of water < 4% agarose phantom < 8% agarose phantom. In the agarose target experiment, it was observed that as the elasticity increased, the intensity of the frequency difference signal (△f) became stronger, but conversely, in the case of the existing frequencies f1 and f2 output from the ultrasonic transducer, such a tendency was not observed, confirming the characteristics of the nonlinear ultrasonic signal using the frequency difference. By imaging this difference in elasticity, a frequency difference ultrasonic elasticity image can be generated.

[0078] Figures 10a to 10d are the results of a bone penetration image acquisition experiment with a large acoustic impedance difference according to an experimental example of the present application.

[0079] Fig. 10a is an image of a chicken bone model taken with a conventional B-mode, 10b is a conventional linear ultrasound image, 10c is a frequency difference ultrasound image generated using an ultrasound image generating device utilizing the nonlinearity of ultrasound of the present application, and 10d is a chicken bone fracture surface image for confirmation of the image of 10c.

[0080] Referring to FIGS. 10A to 10D, it was confirmed that bone marrow images between chicken bones could be realized as frequency difference ultrasound images through chicken bones, and that a nonlinear ultrasound signal could be generated through the difference between the first and second frequencies to penetrate bones with very large acoustic impedance differences and image bone marrow between bones. In other words, the degree of elasticity of the material could be clearly demonstrated.

[0081] In one embodiment, the region of interest is the brain, bone marrow, or electrolyte of the subject, and the image generating unit (20) can generate an image of the brain, bone marrow, or electrolyte of the subject by allowing the third ultrasound signal generated at the focus to pass through a bone including the skull or a solid material including a battery. In other words, an image of the inside of a solid material can be generated by passing through a solid material with a very large difference in acoustic impedance.

[0082] Figures 11a and 11b show the results of a compatibility test with an existing linear ultrasound image (B-mode) according to an experimental example of the present application.

[0083] Referring to FIGS. 11a and 11b, a three-dimensional linear ultrasound image can be obtained through an electrical beam forming method of a single annular array transducer, and imaging of each wire phantom is possible. The above experiment is an experiment that shows that a three-dimensional B-mode image can be expressed in an annular shape and a frequency difference image can be implemented at the same time. If linear ultrasound utilizing a single frequency is used through the same ultrasonic transducer element, a conventional ultrasound image, a B-mode image, can be generated, and if different frequencies are applied to each section of the annular array, a frequency difference ultrasound image can also be generated.

[0084] By using an array transducer, images that were impossible to achieve with conventional ultrasound techniques can be realized, and these images can be utilized in various applications, such as providing elastic images in the medical field.

[0085] Fig. 12 is a flowchart illustrating a method for generating an ultrasound image using the nonlinearity of ultrasound according to one embodiment of the present application. The method according to one embodiment can be performed by the components of the ultrasound image generating device described above, and redundant descriptions of each component will be omitted.

[0086] Referring to FIG. 12, a method for generating an ultrasound image using the nonlinearity of ultrasound may include a step (S10) of outputting a first ultrasound signal associated with a first frequency or a second ultrasound signal associated with a second frequency different from the first frequency toward a region of interest using an ultrasound probe in which a plurality of transducers are arranged in a circular array at regular intervals.

[0087] Next, the method for generating an ultrasound image may further include a step (S20) of generating a third ultrasound signal by using nonlinearity of the first frequency and the second frequency at a focus where the first ultrasound signal and the second ultrasound signal intersect.

[0088] Next, the method for generating the ultrasound image may further include a step (S30) in which the ultrasound probe receives the third ultrasound signal reflected from the region of interest.

[0089] Next, the method for generating an ultrasound image may further include a step (S40) of generating an ultrasound image for the region of interest from the third ultrasound signal received from the ultrasound probe.

[0090] The ultrasound image generation method according to the embodiment may be implemented as an application or in the form of program commands that can be executed through various computer components and recorded on a computer-readable recording medium. The computer-readable recording medium may include program commands, data files, data structures, etc., either singly or in combination.

[0091] Examples of computer-readable recording media may include magnetic media such as hard disks, floppy disks, and magnetic tape, optical recording media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, and flash memory.

[0092] The ultrasound image generation device and method utilizing the nonlinearity of ultrasound described above utilizes a symmetrical annular array of transducers, enabling reliable and simple focus formation. Unlike existing prior art techniques that utilize separate transducers for outputting ultrasound and receiving ultrasound reflected by the material of the subject, this device integrates the transducer into a single array transducer, resulting in high reliability and mechanical simplicity. The annular array of transducers facilitates electronic beam steering using software. The array transducer allows for expandability and versatility, enabling improvements and modifications for other purposes simply by improving the software. The array transducer allows for simultaneous use of conventional B-mode and 3D ultrasound images, ensuring high compatibility. Its applications include tissue imaging (e.g., cervix and uterine fibroids), tumor imaging (e.g., cancer and brain tumors), neurological disease diagnostic imaging, and musculoskeletal disease diagnostic imaging. This allows for elasticity imaging in a variety of medical fields. Its proven stability makes it easy to apply.

[0093] Although the above has been described with reference to embodiments, it will be understood by those skilled in the art that various modifications and changes can be made to the present application without departing from the spirit and scope of the present application as set forth in the claims below.

[0094] The ultrasonic probe of the present application, which comprises a plurality of transducers in a circular array, outputs an ultrasonic signal, facilitates focus formation, and simultaneously enables reception of reflected frequency difference △f ultrasonic signals. In other words, the present invention relates to an ultrasonic image generation device and method utilizing the nonlinearity of ultrasonic waves, which can simultaneously implement a conventional three-dimensional ultrasonic image and a nonlinear ultrasonic image using only one type of element.

[0095] According to the ultrasonic image generation device and method utilizing the nonlinearity of ultrasonic waves, according to one embodiment of the present application, focus formation is performed reliably and simply by using a symmetrical annular array of transducers. Unlike the existing prior art that used separate transducers for receiving ultrasonic waves reflected by the material of the subject to be examined and for outputting ultrasonic waves, the device is integrated into a single array transducer, thereby ensuring high reliability and facilitating the manufacture of miniaturized devices.

Claims

1. An ultrasonic probe that outputs an ultrasonic signal to a region of interest and receives an ultrasonic signal reflected from the region of interest, and an image generation unit that generates an ultrasonic image from the ultrasonic signal received from the ultrasonic probe; The above ultrasound probe: An ultrasonic output unit having a plurality of transducers arranged in a circular array at regular intervals, outputting a first ultrasonic signal associated with a first frequency or a second ultrasonic signal associated with a second frequency different from the first frequency toward an area of ​​interest; and An ultrasound image generation device utilizing the nonlinearity of ultrasound, comprising: an ultrasound receiving unit that generates a third ultrasound signal using the nonlinearity of the first frequency and the second frequency at a focus where the first ultrasound signal and the second ultrasound signal intersect, and receives the third ultrasound signal reflected from the region of interest; 2. In paragraph 1, An ultrasound image generation device utilizing the nonlinearity of ultrasound, characterized in that the plurality of transducers arranged in a circular array at regular intervals are divided into four sections and arranged to output a first ultrasound signal or a second ultrasound signal for each section.

3. In paragraph 1, An ultrasound image generation device utilizing the nonlinearity of ultrasound, characterized in that the plurality of transducers arranged in a circular array at regular intervals are divided into eight sections and arranged to output a first ultrasound signal or a second ultrasound signal for each section.

4. In paragraph 1, An ultrasound image generation device utilizing the nonlinearity of ultrasound, characterized in that the plurality of transducers arranged in a circular array at regular intervals are sequentially arranged alternately, each of a transducer outputting a first ultrasound signal and a transducer outputting a second ultrasound signal.

5. In paragraph 1, A plurality of transducers are arranged in an outer ring and an inner ring arrangement at regular intervals, An ultrasound image generation device utilizing nonlinearity of ultrasound, characterized in that a plurality of transducers arranged in the inner and outer rings output ultrasound signals associated with different frequencies and generate ultrasound utilizing nonlinearity at one focus.

6. In paragraph 5, The transducer placed in the outer ring has the function of outputting an ultrasonic signal, and the transducer placed in the inner ring has the function of receiving an ultrasonic signal reflected from the area of ​​interest, or An ultrasound image generation device utilizing the nonlinearity of ultrasound, characterized in that the transducer arranged in the inner ring has a function of outputting an ultrasound signal and the transducer arranged in the outer ring has a function of receiving an ultrasound signal reflected from the region of interest.

7. In paragraph 5, An ultrasonic image generation device utilizing the nonlinearity of ultrasonic waves, characterized in that the transducer arranged in the inner ring outputs and receives ultrasonic waves to generate a three-dimensional image, and the transducer arranged in the outer ring outputs and receives ultrasonic waves to generate a frequency difference image.

8. In paragraph 1, An ultrasonic image generation device utilizing the nonlinearity of ultrasonic waves, characterized in that the ultrasonic probe adjusts the direction of the ultrasonic signal output by each of the plurality of transducers arranged in a ring-shaped array using the output delay time of each of the plurality of transducers, and adjusts the direction of the third ultrasonic signal generated at the focus.

9. In paragraph 1, The above region of interest is the brain, bone marrow, or electrolytes of the subject, An ultrasound image generating device utilizing the nonlinearity of ultrasound, characterized in that the image generating unit generates a brain image based on the third ultrasound signal generated at the focus and reflected from the brain, bone marrow, or electrolyte of the subject by passing through a bone including a skull or a hard material including a battery.

10. In paragraph 1, An ultrasound image generation device utilizing nonlinearity of ultrasound, characterized in that the nonlinearity of the first frequency and the second frequency utilizes at least one of a difference frequency, a sum frequency, and harmonics of the first frequency and the second frequency.

11. In paragraph 10, When using the frequency difference between the first and second frequencies, The more the material forming the region of interest is a low-elasticity material, the lower the frequency difference signal of the third ultrasonic signal received by the ultrasonic probe is. An ultrasonic image generation device utilizing the nonlinearity of ultrasonic waves, characterized in that the third ultrasonic signal received by the ultrasonic probe is a signal with a higher frequency difference as the material forming the area of ​​interest is a highly elastic material.

12. In paragraph 1, An ultrasound image generation device utilizing the nonlinearity of ultrasound, characterized in that it further comprises a display for outputting the ultrasound image generated by the image generation unit.

13. In paragraph 1, An ultrasonic image generation device utilizing the nonlinearity of ultrasonic waves, characterized in that the plurality of transducers of the ultrasonic probe are ultrasonic transducers including a piezoelectric effect, a capacitive micromachined ultrasonic transducer (CMUT) or a piezoelectric micromachined ultrasonic transducer (PMUT).

14. A step of outputting a first ultrasonic signal associated with a first frequency or a second ultrasonic signal associated with a second frequency different from the first frequency toward a region of interest using an ultrasonic probe in which a plurality of transducers are arranged in a circular array at regular intervals; A step of generating a third ultrasonic signal by using the nonlinearity of the first frequency and the second frequency at a focus where the first ultrasonic signal and the second ultrasonic signal intersect; The step of the ultrasonic probe receiving the third ultrasonic signal reflected from the region of interest; and A method for generating an ultrasound image using nonlinearity of ultrasound, comprising: a step of generating an ultrasound image for the region of interest from the third ultrasound signal received from the ultrasound probe; 15. A computer program stored in a computer-readable storage medium for executing a method for generating an ultrasound image using nonlinearity of ultrasound according to Article 14.

Images