WO2012141520A2 - Apparatus for diagnosing ultrasound image for minimizing image artifact having tooth shape, and method for diagnosing same - Google Patents

Abstract

Disclosed are an apparatus for diagnosing an ultrasound image for minimizing image artifacts having a tooth shape, resulting from a switching movement by a HVMUX, in an ultrasound image, and a method for diagnosing same. The apparatus for diagnosing the ultrasound image, according to one embodiment of the present invention, comprises: a pulse generator unit for generating a pulse in an electric signal; a plurality of transducer elements; a probe for converting the pulse in the electric signal into an ultrasound wave signal and transferring same to an object body through at least one transducer element; a multiplexer (MUX) for sequentially selecting at least one of the plurality of transducer elements, based on different bias voltages which are applied; and a control unit for moving a scan line in accordance with a line density of the transducer elements, and for switching between the different bias voltages every pulse repetition frequency (PRF) when the scan line moves.

Description

Ultrasonic Imaging Device and Minimization Method for Minimizing Tooth-shaped Image Artifact

An embodiment of the present invention relates to an ultrasound imaging apparatus and a diagnostic method thereof. More particularly, the present invention relates to an ultrasound imaging apparatus and a diagnostic method thereof, which can minimize tooth-shaped image artifacts appearing in an ultrasound image due to spike voltage generated during a switching operation with respect to a bias voltage of the HVMUX. .

The contents described in this section merely provide background information on the embodiments of the present invention and do not constitute a prior art.

Recently, the rapid development of electronics and signal processing, especially digital signal processing technology has a significant impact on the field of image diagnostic equipment. The imaging device is a flower of a medical diagnostic device because it can be seen without cutting the inside of the human body.The imaging device includes an X-ray diagnosis device, a magnetic resonance imaging (MRI) diagnosis device, and an ultrasound diagnosis device. Is used, and each has its advantages and disadvantages. Among them, the ultrasonic imaging apparatus has the advantage of being able to make a real-time diagnosis and having a very low price at the expense of resolution. Accordingly, the ultrasound imaging apparatus has become an essential diagnostic device in almost all medical fields such as internal medicine, gynecology, pediatrics, urology, ophthalmology, radiology, and the demand is rapidly increasing.

The frequency of ultrasound, which is mainly used in the ultrasound imaging apparatus, is from several MHz to several tens of MHz. As ultrasound passes through the human body, the speed changes with the medium, and the amount of attenuation also changes. On the other hand, the ultrasound image is basically composed of the reflected wave generated at the interface consisting of different media.

The velocity V of the ultrasonic waves propagating in the human body can be expressed by Equation 1 when the density of the medium is ρ and the volume fraction is B.

[Equation 1]

The ultrasonic velocity in the human body varies depending on the medium, and accordingly, compensation for the variation of the velocity in the human body has been studied.

An important one of the physical properties of ultrasound is the nature of the attenuation as it propagates in the medium. The intensity I of the ultrasonic wave according to the propagation distance z is expressed by Equation 2.

[Equation 2]

I = I _O exp (-2αz)

Where α is the attenuation coefficient. The attenuation coefficient has a large relationship with the frequency, and the attenuation coefficient in the frequency band used in the ultrasound imaging apparatus increases almost linearly with the frequency.

One of the other important properties of ultrasound imaging is reflection. Reflection is related to the characteristic impedance Z of the medium. The characteristic impedance Z of the medium is expressed as the product of the density ρ of the material and the velocity V of the ultrasonic wave as shown in Equation 3.

[Equation 3]

Z = pV

When incident from the material of the characteristic impedance Z _{1 to} the material of Z ₂ , the reflectivity R is expressed by Equation 4 below.

[Equation 4]

1 is a diagram illustrating the basic principle of an ultrasound imaging apparatus. The transducer 110 converts a pulse of the electrical signal generated by the pulse generator 120 into an ultrasonic signal and transmits the pulse to the object, and converts the ultrasonic signal reflected back from the boundary of different media into an electrical signal. Transfer to the signal processor 130. In this case, the signal processor 130 may perform TGC (Time Gain Compensation) amplification, Rx Beamforming, Echo Processing, Spectral Doppler Processor (CDP) / CDP (Regarding the signal received from the transducer 110). After appropriate signal processing such as a color doppler processor (DCP), a digital scan converter (DSC), and the like, the image is displayed on the display 140.

On the other hand, elements of a plurality of transducers are combined to form a probe (probe: probe), the quality of the image varies depending on the number of transducer elements, and also the number of transducer elements Proportional to the circuits for the transmission and reception of ultrasonic waves also increases.

In general, in order to minimize the ultrasonic transmission and reception circuit and to expand the number of elements, the electrical signal is split into: 2 or 1: 3 using a high voltage multiplexer (HVMUX) on a TI interface board of the ultrasound imaging apparatus. do.

In this case, as shown in FIG. 2, a high bias voltage, that is, the first power source V _PP and the second power source V _NN is applied to the _HVMUX , and the first power source V _PP or the second power source is applied. A first switching operation 210 for selecting (V _NN ) and a second switching operation 220 for determining whether to select a channel are performed.

However, the spike voltage according to the charge injection of the internal circuit is generated during the first switching operation, which acts like another pulse instead of the Tx pulse, thereby causing an image artifact in the ultrasound image. There is a problem that generates.

An embodiment of the present invention was devised to solve the above-described problem, and it is possible to minimize the tooth-shaped image artifacts appearing in the ultrasound image due to the spike voltage generated during the switching operation of the bias voltage of the HVMUX. An object of the present invention is to provide an ultrasound imaging apparatus and a diagnostic method thereof.

An example of an ultrasound imaging apparatus according to an embodiment of the present invention for achieving the above object is a pulse generator for generating a pulse of an electrical signal; A probe including a plurality of transducer elements, the probe converting a pulse of an electrical signal into an ultrasonic signal through at least one transducer element and transmitting the pulse to an object; A mux for sequentially selecting at least one of the plurality of transducer elements based on different bias voltages applied; And a control unit configured to move the scan line corresponding to the line density of the transducer element, and to perform switching for different bias voltages at every pulse repitition frequency (PRF) when the scan line is moved. .

Here, the controller may further form a dummy scan line corresponding to the original scan line.

In addition, the controller may perform switching for different bias voltages corresponding to the dummy scan line.

Another example of an ultrasound imaging apparatus according to an embodiment of the present invention for achieving the above object is a pulse generator for generating a pulse of an electrical signal; A probe comprising a plurality of transducer elements, the probe converting a pulse of an electrical signal into an ultrasonic signal through at least one transducer element and delivering the ultrasonic signal to an object; A mux for sequentially selecting at least one of the plurality of transducer elements based on different bias voltages applied; And a control unit which forms a PRF corresponding to the linear density of the transducer element, and performs switching for different bias voltages for each of the formed PRFs.

Ultrasonic imaging method according to an embodiment of the present invention for achieving the above object, generating a pulse of an electrical signal; Forming a PRF corresponding to the linear density for the transducer element, and performing switching of mux different bias voltages for each formed PRF; Sequentially selecting at least one of the plurality of transducer elements; And converting a pulse of the electrical signal into an ultrasonic signal through the selected transducer element and delivering the pulse to the object.

The above-described ultrasound imaging method may further include moving the scan line in response to the formed PRF.

The ultrasound image diagnosis method may further include forming a dummy scan line corresponding to the scan line.

In this case, the aforementioned ultrasound image diagnosis method may additionally perform switching for different bias voltages corresponding to the dummy scan line.

According to an embodiment of the present invention, the spike voltage generated during the switching operation with respect to the bias voltage of the HVMUX may minimize the tooth-shaped image artifacts appearing in the ultrasound image.

1 is a diagram illustrating the basic principle of an ultrasound imaging apparatus.

2 is a diagram illustrating an example of spike voltage generated in HVMUX.

3 is a diagram schematically illustrating an ultrasound imaging apparatus according to an exemplary embodiment of the present invention.

4 is a diagram illustrating an example of a pulse generated by the pulse generator of FIG. 3.

5 is a diagram illustrating an example of image artifacts due to spike voltages generated by muxes.

6 is a diagram illustrating an operation mechanism of the linear density mode.

FIG. 7 illustrates an example of mux control for the probe of FIG. 6.

8 illustrates an example of an ultrasound image from which image artifacts are removed according to an embodiment of the present invention.

9 is a flowchart illustrating an ultrasound imaging method according to an exemplary embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In addition, in describing the component of this invention, terms, such as 1st, 2nd, A, B, (a), (b), can be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. If a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected to or connected to that other component, but there may be another configuration between each component. It is to be understood that the elements may be "connected", "coupled" or "connected".

3 is a diagram schematically illustrating an ultrasound imaging apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the ultrasound imaging apparatus 300 according to the exemplary embodiment of the present invention may include a pulse generator 310, a probe 320, a mux 330, and a controller 340.

The pulse generator 310 generates a pulse of an electrical signal. At this time, the pulse generating unit 310 in order to increase the axial sharpness of the pulse (Axial Resolution), as shown in Figure 4 to shorten the width of the pulse Tp and to increase the S / N (Signal / Noise) ratio size of the pulse Increase V enough to excite the transducer.

The probe 320 is a device for generating and measuring ultrasonic waves and includes a plurality of transducer elements. In this case, the probe 320 converts the pulse of the electrical signal generated by the pulse generator 310 through the at least one transducer element into an ultrasonic wave and transmits the ultrasonic wave to the object. The returned ultrasonic signal is converted into an electrical signal and transmitted to a signal processor (not shown). In the embodiment of the present invention, the signal processing unit amplifies TGC (Time Gain Compensation), Rx Beamforming, Echo Processing, SDP (Spectral Doppler Processor) / CDP (Color Doppler Processor), and DSC (Digital Scan). Signal processing such as a converter) and display of an image through a display are applied. However, since the signal processing unit and the display deviate from the gist of the present invention, the detailed description thereof will be omitted. The probe 320 may be a linear probe, a sector probe, a convex probe, a trapezoidal probe, or the like according to an assembly form of a plurality of transducer elements.

When the ultrasonic signal is emitted to the object by the transducer element, reflection occurs at the interface when acoustic interfaces with different acoustic impedances exist in the propagation medium, and some light is transmitted, and when multiple interfaces exist, the echo is sequentially reflected. Come back. At this time, the returned echo puts stress on the piezoelectric element of the transducer element, and generates an electric field proportional to the echo intensity to convert it into an electrical signal. This ultrasonic pulse emitted to the object generates a pulse echo from each point at various depths (boundary planes) within the object, taking into account the pulse round-trip propagation distance, the echo from the tissue at distance x is equal to the time axis t = It appears at a position of 2x / c (c = 1530m / s: average sound speed). Therefore, the reflection position can be determined inversely from the delay time for this transmission pulse.

The mux 330 selects at least one of the plurality of transducer elements of the probe 320 to form a channel. At this time, different bias voltages are applied to the mux 330, and the mux 330 performs a switching operation on the different voltages to be applied, thereby generating a pulse of the electrical signal generated by the pulse generator 310. It can be delivered to the probe 320 through the selected channel.

The control unit 340 moves the scan line corresponding to the line density of the transducer element of the probe 320, and different bias voltages of the mux 330 at every pulse repitition frequency (PRF) during movement of the scan line. Enable switching on

In general, the charge injection spike voltage generated when switching to the different bias voltages of the mux 330 is a major cause of image artifacts, and especially in the line density mode The effect of the image artifacts is prominent since Tx / Rx is performed two to four times per producer element. That is, assuming that the probe 320 uses 128 transducer elements and operates in the linear density mode 2 as shown in FIG. 5, the probe 320 may have the same effect as using the 256 transducer elements. . In this case, the probe 320 virtually divides one transducer element into four quadrants to make a delay curve when the first # 1 Tx / Rx and the second # 2 Tx / Rx are different, and thus the Tx / Rx. This allows you to adjust the resolution. In this case, since the switching of HVMUX occurs only on the first # 1 Tx / Rx of each transducer element during scan line movement, the image artifacts of scan lines # 1 and # 2 for one transducer element are significantly different. I will. Similarly, even when the linear density mode is 0 to 5, the image artifacts are markedly different by this operation mechanism. As described above, in the linear density mode, switching of HVMUX occurs only in the first Tx / Rx due to the characteristics of HVMUX used after the scan line movement for each PRF, charge injection spike voltage occurs according to switching of HVMUX, and 2-4 th Tx / Since the HVMUX does not switch at Rx, the ultrasonic image shows a tooth-shaped image artifact as shown in FIG. 6.

The control unit 340 of the ultrasound imaging apparatus 300 according to an embodiment of the present invention performs an operation for minimizing the tooth-shaped artifacts appearing in the ultrasound image by the switching operation of the HVMUX.

To this end, the controller 340 forms a PRF corresponding to the linear density of the transducer element of the probe 320, and performs switching on different bias voltages of the mux 330 for each formed PRF. In this case, as illustrated in FIG. 7, the controller 340 may transmit a pulse signal EMIF_INT for executing the movement of the scan line in response to the linear density of the transducer element of the probe 320. When moving, a PRF signal having the same period as that of the pulse signal EMIF_INT may be formed and transmitted. At this time, it is preferable that the pulse of the PRF signal precedes the pulse of the EMIF_INT signal. The controller 340 for such an operation may be implemented by a field programmable gate array (FPGA). FPGAs are semiconductor devices that include programmable logic elements and programmable internals. Programmable logic elements can be programmed by duplicating basic logic gate functions such as AND, OR, XOR, NOT, more complex decoders, or combinations of computational functions. Most FPGAs include programmable logic elements (also called logical blocks) that contain memory elements that are either simple flip-flops or more complete memory blocks. Programmable internal hierarchies allow the logic blocks in the FPGA to be interconnected as required by the system designer. These logic blocks and internal lines can be programmed by the consumer / designer after the manufacturing process to perform any logic function required. For this reason, it is called "on-site programmable gate array." FPGAs are generally slower than ASIC replacements, cannot be applied to complex designs, and consume more power. However, the development time is short, the error can be corrected on-site, and the initial development cost is low.

Meanwhile, when the moved scan line is an original scan line, the controller 340 further forms a dummy scan line corresponding to the original scan line. Here, the dummy scan line is not an actual scan line executed by the probe 320, but a virtual scan line for forcibly executing switching to the different bias voltages of the mux 330. That is, the controller 340 transmits a switching command to the mux 330 on the assumption that there is a dummy scan line in advance of the original scan line (in the drawing, the switching command corresponding to the original scan line is represented by IDEX, and the dummy scan line is shown in FIG. The switching command corresponding to DUMMY). In this case, even though the mux 330 is designed to switch to different bias voltages only at the first scan of each transducer element, the scan according to the linear density is performed by the dummy scan line formed by the controller 340. It is determined that there is a line, and thus switching between different bias voltages corresponding to Tx and Rx is possible for each PRF. Although one dummy scan line is formed in front of the original scan line in the drawing, the number of dummy scan lines formed may vary depending on the linear density mode. For example, when the linear density mode is 3, two dummy scan lines may be formed in front of the original scan line to perform switching for different bias voltages of the mux 330 at every PRF. In addition, although the dummy scan line is formed in front of the original scan line in the drawing, in some cases, the dummy scan line may be formed behind the original scan line, or may be formed together with the front and back of the original scan line.

As such, by controlling switching of the different bias voltages of the mux 330 at every PRF, tooth-shaped image artifacts can be eliminated as shown in FIG.

9 is a flowchart illustrating an ultrasound imaging method according to an exemplary embodiment of the present invention.

3 and 9, the pulse generator 310 generates a pulse of an electrical signal (S910). At this time, the pulse generating unit 310 in order to increase the axial sharpness of the pulse (Axial Resolution), as shown in Figure 4 to shorten the width of the pulse Tp and to increase the S / N (Signal / Noise) ratio size of the pulse Increase V enough to excite the transducer.

The controller 340 forms a PRF corresponding to the linear density of the transducer element of the probe 320, and performs switching of different bias voltages of the mux 330 for each formed PRF (S920). In this case, as shown in FIG. 7, the controller 340 may transmit a pulse signal EMIF_INT for executing the movement of the scan line in response to the linear density of the transducer element of the probe 320 (S930). In response to the movement of the scan line, a dummy scan line may be further formed (S940). In this case, the number of dummy scan lines may be adjusted differently according to the linear density mode.

The mux 330 selects at least one of the plurality of transducer elements of the probe 320 to form a channel (S950). The selection of such transducer elements is made sequentially, thereby scanning the plurality of transducer elements of the probe 320.

The probe 320 converts the pulse of the electrical signal generated by the pulse generator 310 through the at least one transducer element into an ultrasonic wave and transmits the ultrasonic wave to the object. The probe 320 reflects back from the boundary of different media of the object and returns back to the object. The ultrasonic signal is converted into an electrical signal and transmitted to the signal processor. Since the function and operation of the probe 320 are well known techniques, detailed description thereof will be omitted.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application claims priority pursuant to Article 119 (a) (35 USC § 119 (a)) of the US Patent Act No. 10-2011-0035235, filed April 15, 2011, with the Republic of Korea. All content is incorporated by reference in this patent application. In addition, if this patent application claims priority to a country other than the United States for the same reason, all its contents are incorporated into this patent application by reference.

Claims (8)

1. In the ultrasound imaging apparatus,

   A pulse generator for generating a pulse of an electrical signal;

   A probe comprising a plurality of transducer elements, the probe converting a pulse of the electrical signal into an ultrasonic signal through at least one of the transducer elements and transmitting the ultrasound signal to an object;

   A mux for sequentially selecting at least one of the plurality of transducer elements based on different bias voltages applied; And

   A control unit configured to move a scan line corresponding to a line density of the transducer element, and to perform switching on the different bias voltages at every pulse repitition frequency (PRF) during movement of the scan line

   Ultrasonic imaging apparatus comprising a.
2. The method of claim 1,

   The control unit,

   Ultrasonic imaging apparatus, characterized in that to form a dummy scan line (Dummy scan line) in addition to the original scan line (Original scan line).
3. The method of claim 2,

   The control unit,

   And performing switching to the different bias voltages corresponding to the dummy scan line.
4. In the ultrasound imaging apparatus,

   A pulse generator for generating a pulse of an electrical signal;

   A probe including a plurality of transducer elements, the probe converting a pulse of the electrical signal into an ultrasonic signal through at least one of the transducer elements and delivering the ultrasonic signal to an object;

   A mux for sequentially selecting at least one of the plurality of transducer elements based on different bias voltages applied; And

   A control unit which forms a PRF corresponding to the linear density of the transducer element, and performs switching of the different bias voltages for each of the formed PRFs

   Ultrasonic imaging apparatus comprising a.
5. In the ultrasound imaging method,

   Generating a pulse of an electrical signal;

   Forming a PRF corresponding to the linear density for the transducer element, and performing switching of mux different bias voltages for each of the formed PRFs;

   Sequentially selecting at least one of a plurality of said transducer elements; And

   Converting a pulse of the electrical signal into an ultrasonic signal through the selected transducer element and delivering the ultrasonic signal to an object

   Ultrasound imaging method characterized in that it comprises a.
6. The method of claim 5,

   Moving a scan line in response to the formed PRF

   Ultrasound imaging method characterized in that it further comprises.
7. The method of claim 6,

   Further forming a dummy scan line corresponding to the scan line

   Ultrasound imaging method characterized in that it further comprises.
8. The method of claim 7, wherein

   And performing switching to the different bias voltages corresponding to the dummy scan line.

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