JP2005080869A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic apparatus which can improve quality of an image of a range located in a deeper part than a boundary with a large reflectance. <P>SOLUTION: The ultrasonic diagnostic apparatus is equipped with an ultrasonic wave transmitting and receiving means 10 which transmits an ultrasonic beam to a subject to be examined and receives an ultrasonic echo reflected by the subject to be examined to generate a detection signal, a signal processing means 20 which corrects an intensity change of the detection signal attributable to a position where the ultrasonic signal is reflected in the subject to be examined based on a correction controlling signal, and a correction controlling means 21 which determines a boundary range corresponding to a boundary between soft tissues and hard tissues in the subject to be examined based on the detection signal and generates the correction controlling signal to control the intensity of the detection signal in the boundary range. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic diagnostic apparatus that performs imaging of an organ or bone in a living body by transmitting and receiving ultrasonic waves to generate image data used for diagnosis.

  In an ultrasonic imaging apparatus used for medical use, an ultrasonic probe (probe) including a plurality of ultrasonic transducers having an ultrasonic transmission / reception function is usually used. By using such an ultrasonic probe, by scanning an object with an ultrasonic beam formed by combining a plurality of ultrasonic waves and receiving an ultrasonic echo reflected inside the object Based on the intensity of the ultrasonic echo, image information relating to the subject is obtained. Furthermore, an ultrasonic image in a two-dimensional or three-dimensional region of the subject is reproduced based on this image information.

  The intensity of the ultrasonic wave transmitted from the ultrasonic transducer decreases with the depth inside the subject due to the influence of ultrasonic energy absorption in the subject and the refraction and scattering of the ultrasonic beam. Therefore, the intensity of the ultrasonic echo received at the ultrasonic transducer attenuates with the depth of the reflection position. In order to correct such attenuation of the intensity of the ultrasonic echo, depending on the time (corresponding to the depth of the reflection position) required from the transmission of the ultrasonic wave to the reception of the ultrasonic echo, the amplifier of the receiving circuit A technique for changing the gain has been conventionally used. Such a method is called STC (sensitivity time control) or TGC (time gain compensation).

  However, when there is a boundary having a high reflectance, the intensity of the ultrasonic echo reflected at the boundary becomes extremely large, so the boundary in the ultrasonic image generated by the STC is displayed with high brightness, and the vicinity of the boundary. In this case, the visibility of the image is reduced. In particular, as shown in FIG. 7, in an ultrasonic image obtained by transmitting an ultrasonic beam from an ultrasonic transducer array to a human body, as shown in FIG. 8, a soft tissue such as a muscle and a hard part such as a bone. Since the amplitude of the ultrasonic echo reflected at the boundary with the tissue becomes extremely large, for example, the boundary between the muscle and the bone is displayed with high luminance. On the other hand, since the ultrasonic echoes from inside and behind the bone are weak, it is extremely difficult to visually recognize the image inside and behind the bone located deeper than the boundary between the muscle and the bone.

  As a related technique, the following Patent Document 1 discloses a control method for an ultrasonic diagnostic apparatus that automatically controls a gain of a reception analog circuit or a TGC gain so as to maintain an appropriate value, and a function that implements the control method. An ultrasound diagnostic apparatus is described.

  According to this control method, the image can be divided into a plurality of partial areas, and the gain in each partial area can be automatically adjusted based on the representative value of the frame data corresponding to each partial area. However, Patent Document 1 is intended to improve the overall image quality of an ultrasonic image, and does not attempt to improve the image quality of an image in a region located deeper than a boundary having a large reflectance.

  Further, in Patent Document 2 below, accurate STC correction can be automatically performed even when the state of an ultrasonic probe, a diagnostic site, a subject, or the like changes, and an optimal tomographic image can always be obtained. An ultrasound diagnostic apparatus is described.

According to this ultrasonic diagnostic apparatus, in addition to the gain control circuit, a smoothing circuit, a differentiation circuit, a threshold setting circuit, a first integration circuit, a second A / D (analog to digital) converter, a second Since the STC circuit is configured by the integration circuit, the memory, and the second D / A (digital to analog) converter, the echo-free portion is not extremely amplified. An STC curve can be obtained even in a portion that is displayed brighter than the surroundings, such as a tumor that is present inside, without significantly reducing the gain and making it difficult to distinguish from surrounding tissues. . However, Patent Document 2 also aims to improve the overall image quality of an ultrasound image, and does not attempt to improve the image quality of an image in a region located deeper than a boundary having a high reflectance.
Japanese Patent Laid-Open No. 7-236637 (pages 3, 5 and 4) JP-A-7-323032 (pages 1, 5, 6 and FIG. 1)

  Therefore, in view of the above points, an object of the present invention is to provide an ultrasonic diagnostic apparatus capable of improving the image quality of an image in a region located deeper than a boundary having a large reflectance.

  In order to solve the above problem, an ultrasonic diagnostic apparatus according to a first aspect of the present invention transmits an ultrasonic beam to a subject and generates a detection signal by receiving an ultrasonic echo reflected from the subject. An ultrasonic transmission / reception means, a signal processing means for correcting an intensity change of the detection signal due to a position where the ultrasonic signal is reflected in the subject in accordance with the correction control signal, and a soft tissue in the subject based on the detection signal And a correction control means for determining a boundary region corresponding to the boundary between the tissue and the hard tissue and generating a correction control signal so as to suppress the intensity of the detection signal in the boundary region.

  The ultrasonic diagnostic apparatus according to the second aspect of the present invention transmits an ultrasonic beam to a subject and receives an ultrasonic echo reflected from the subject to generate a detection signal. And a signal processing means for correcting a change in intensity of the detection signal due to a position where the ultrasonic signal is reflected in the subject according to the correction control signal, and an intensity profile representing a spatial distribution of the detection signal and the sound pressure intensity. A boundary corresponding to the boundary between the soft tissue and the hard tissue in the subject based on the reflectance estimation means for obtaining a value relating to the reflectance in the subject, and the value relating to the reflectance obtained by the reflectance estimation means Correction control means for determining a region and generating a correction control signal so as to suppress the intensity of the detection signal in the boundary region.

  According to the present invention, the boundary region corresponding to the boundary between the soft tissue and the hard tissue in the subject is determined, and the intensity of the detection signal in the boundary region is suppressed. It is possible to improve the image quality of the image located in the deep part.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus according to the first embodiment of the present invention. The ultrasonic diagnostic apparatus according to the present embodiment includes an ultrasonic probe 10, a scanning control unit 11, a transmission delay pattern storage unit 12, a transmission control unit 13, and a drive signal generation unit 14. .

  The ultrasonic probe 10 used in contact with a subject includes a plurality of ultrasonic transducers 10a constituting a one-dimensional or two-dimensional transducer array. These ultrasonic transducers 10a transmit an ultrasonic beam based on an applied drive signal, receive a propagating ultrasonic echo, and output a detection signal.

  Each ultrasonic transducer is, for example, a piezoelectric ceramic represented by PZT (Pb (lead) zirconate titanate), a polymer piezoelectric element represented by PVDF (polyvinylidene difluoride), or the like. It is comprised with the vibrator | oscillator which formed the electrode in the both ends of the material (piezoelectric element) which has the piezoelectricity of. When a pulsed electric signal or a continuous wave electric signal is applied to the electrodes of such a vibrator and a voltage is applied, the piezoelectric element expands and contracts. By this expansion and contraction, pulsed or continuous ultrasonic waves are generated from the respective vibrators, and an ultrasonic beam is formed by synthesizing these ultrasonic waves. Each vibrator expands and contracts by receiving propagating ultrasonic waves and generates an electrical signal. These electric signals are output as ultrasonic detection signals.

  Alternatively, a plurality of types of elements having different ultrasonic conversion methods may be used as the ultrasonic transducer. For example, the above-described vibrator is used as an element that transmits ultrasonic waves, and a photodetection type ultrasonic transducer is used as an element that receives ultrasonic waves. The photodetection type ultrasonic transducer converts an ultrasonic signal into an optical signal and detects it, and is constituted by, for example, a Fabry-Perot resonator or a fiber Bragg grating.

  The scanning control unit 11 sequentially sets the transmission direction of the ultrasonic beam and the reception direction of the ultrasonic echo. The transmission delay pattern storage unit 12 stores a plurality of transmission delay patterns used when forming an ultrasonic beam.

  The transmission control unit 13 selects a predetermined pattern from a plurality of delay patterns stored in the transmission delay pattern storage unit 12 according to the transmission direction set in the scanning control unit 11, and based on the pattern The delay times given to the drive signals of the plurality of ultrasonic transducers 10a are set.

  For example, the drive signal generator 14 includes a plurality of pulsars respectively corresponding to the plurality of ultrasonic transducers 10a. These pulsers generate drive signals based on the delay time set in the transmission control unit 13.

  Furthermore, the ultrasonic diagnostic apparatus according to the present embodiment includes a signal processing unit 20, an STC control unit 21, a primary storage unit 22, a reception delay pattern storage unit 23, a reception control unit 24, and a secondary storage unit. 25, an image data generation unit 26, a tertiary storage unit 27, an image processing unit 28, a display unit 29, an operation console 30, and a control unit 31.

  The signal processing unit 20 includes a plurality of amplifiers 20a, a plurality of STC amplifiers 20b, and a plurality of A / D converters 20c corresponding to the plurality of ultrasonic transducers 10a. The detection signal output from the ultrasonic transducer 10a is amplified by the amplifier 20a and the STC amplifier 20b, and the levels of these detection signals are matched with the input signal level of the A / D converter 20c.

  The analog signals output from the STC amplifier 20b are converted into digital signals by the A / D converter 20c. The sampling frequency of the A / D converter needs to be at least about 10 times the frequency of the ultrasonic wave, and is preferably 16 times or more the frequency of the ultrasonic wave. The resolution of the A / D converter is preferably 10 bits or more.

  Here, the STC amplifier 20b corrects attenuation by distance according to the depth of the reflection position of the ultrasonic wave, and outputs a detection signal with a gain suitable for each detection signal under the control of the STC control unit 20. Amplify. In the present embodiment, the STC control unit 21 performs soft tissue and hard tissue (bone, tendon, ligament, etc., hereinafter referred to as “hard part” based on the detection signal converted into a digital signal by the A / D converter 20c. The STC control signal for controlling the gain of each detection signal in the next frame is generated based on the result.

  The STC control unit 21 includes a gain setting unit 21a, a gain storage unit 21b, and a D / A converter 21c. The gain setting unit 21a determines the boundary in the subject by determining whether or not the luminance value of the detection signal converted into the digital signal by the A / D converter 20c is larger than a preset threshold value. The gain of the STC amplifier 20b in the next frame is set, and gain data relating to the set gain is output.

  The gain storage unit 21b stores the gain data output from the gain setting unit 21a. The D / A converter 21c converts the gain data stored in the gain storage unit 21b into an analog signal, and outputs the analog signal to the STC amplifier 20b as an STC control signal. By using a mixed LSI in which a D / A converter 21c is arranged together with a CPU corresponding to the control unit 31, and realizing the gain setting unit 21a with a CPU and software, the overall circuit configuration can be reduced in size, and , Can reduce the cost.

  The primary storage unit 22 stores the respective detection signals converted into digital signals by the A / D converter 20c in time series for each ultrasonic transducer. The reception delay pattern storage unit 23 stores a plurality of reception delay patterns used when receiving focus processing is performed on a plurality of detection signals output from the plurality of ultrasonic transducers 10a.

  The reception control unit 24 selects a predetermined pattern from a plurality of reception delay patterns stored in the reception delay pattern storage unit 23 based on the reception direction set in the scanning control unit 11, and based on the pattern. The reception focus processing is performed by adding a delay to the plurality of detection signals. By this reception focus processing, sound ray data in which the focus of the ultrasonic echo is narrowed down is formed. The reception focus process may be performed before A / D conversion by the A / D converter 20c or before amplification by the STC amplifier 20b.

  The secondary storage unit 25 stores the sound ray data formed in the reception control unit 24. The image data generation unit 26 calculates image data based on the sound ray data stored in the secondary storage unit 25. The tertiary storage unit 27 stores the image data calculated by the image data generation unit 26.

  The image processing unit 28 performs various types of image processing on the image data stored in the tertiary storage unit 27. The display unit 29 includes, for example, a display device such as a CRT or LCD, and displays an ultrasonic image based on the image data subjected to image processing in the image processing unit 28.

  The console 30 outputs, to the control unit 31, control signals indicating the acquisition of the moving image (freeze release state) and the stop of the moving image acquisition (freeze state) based on the operation of the operator. In the frozen state, ultrasonic imaging is stopped and a stationary ultrasonic image is displayed on the display unit 29. The control unit 31 controls the scanning control unit 11 and the gain setting unit 21a based on a control signal input from the console 30, and outputs information related to the initial value of the gain set in the gain setting unit 21a.

  Next, the operation of the STC control unit in the ultrasonic diagnostic apparatus according to the present embodiment will be described with reference to FIG. FIG. 2 is a flowchart showing the operation of the STC control unit in the ultrasonic diagnostic apparatus according to the present embodiment.

  When the freeze state is canceled by the operator operating the console 30, first, the gain setting unit 21a sets the initial value S0 of the boundary determination threshold value S in step S1. The boundary determination threshold S is a threshold set with respect to the intensity or amplitude of the detection signal amplified by the STC amplifier 20b. The initial value S0 may be set in advance or may be input by the operator using the console 30.

  Further, the gain setting unit 21 a performs initial setting of the gain G (f, m, n) based on the information regarding the initial value of the gain supplied from the control unit 31. Here, f represents a frame number, m represents a line number, and n represents a sampling number, where 0 ≦ m ≦ M and 0 ≦ n ≦ N. The gain setting unit 21a sets the initial gain value G (0, m, n) as f = 0, and then sets m = n = 0.

  FIG. 3 is a diagram for explaining the line number m and the sampling number n. In FIG. 3, the scanning directions of the plurality of ultrasonic beams in the tomographic ultrasonic image are indicated by arrows. As shown in FIG. 3, the line number m is a number that represents a specific ultrasonic beam in a plurality of ultrasonic beams. On the other hand, the sampling number n is a number representing a specific sampling point at a plurality of sampling points along each ultrasonic beam.

  Since the sampling number n corresponds to the depth in the subject, in step S1 shown in FIG. 2, in order to correct the attenuation due to the distance of the ultrasonic echo, G (f, m, n) increases as n increases. Is set to be large. In this embodiment, in the m-th line, the value of n is incremented by 1 to perform ultrasonic imaging for one line, and further, the value of m is incremented by 1 to increase the values of all lines. By performing ultrasonic imaging, a tomographic ultrasound image of one frame is generated.

Referring to FIG. 2 again, the gain setting unit 21a reads the intensity Sig (f, m, n) of the detection signal output from the A / D converter 20c in step S2, and in step S3, the following equation (1) ) Is used to calculate the boundary determination threshold value S.
S = S0 × G (f, m, n) / G (0, m, n) (1)
Thereby, the boundary determination threshold value S can be set with respect to the intensity of the detection signal in which the attenuation due to the distance is corrected. When the number of detection signals per frame (M × N) is large and it takes time to calculate the boundary determination threshold value S, the calculated boundary determination threshold value S (f, m, n) is stored as a gain. It may be stored in the unit 21b, or a frame memory for storing the boundary determination threshold value S (f, m, n) may be provided separately.

  In step S4, the gain setting unit 21a determines whether or not the intensity Sig (f, m, n) of the detection signal is greater than or equal to the boundary determination threshold value S. That is, based on the intensity of the detection signal indicating reflection at the depth corresponding to the sampling number n, it is determined whether or not the boundary between the soft tissue and the bone exists at the depth corresponding to the sampling number n. Here, when the intensity Sig (f, m, n) of the detection signal is greater than or equal to the boundary determination threshold S, the process proceeds to step S5, where the intensity Sig (f, m, n) of the detection signal is the boundary determination threshold S. If smaller than this, the process proceeds to step S6.

If the intensity Sig (f, m, n) of the detection signal is greater than or equal to the boundary determination threshold S, it is determined that the position (m, n) of the frame number f is the boundary region between the soft tissue and the bone, and step 5, the gain G (f + 1, m, n) at the same position (m, n) of the next frame is calculated based on the following equation (2).
G (f + 1, m, n) = G (0, m, n) × k1 (2)
However, k1 <1. The value of the coefficient k1 may be set in advance or may be input by the operator using the console 30. As described above, the flag F (n) is set to “1” for the sampling point obtained by multiplying the gain by k1.

  Since the boundary region between the soft tissue and the bone is displayed with high brightness as it is, the visibility of the image in the vicinity thereof is lowered. Therefore, in the present embodiment, when the intensity Sig (f, m, n) of the detection signal is equal to or greater than the boundary determination threshold S, the position (m, n) at the frame number f is the boundary between the soft tissue and the bone. By determining that the region is a region and setting the same position (m, n) in the frame number (f + 1) to be small, the boundary region between the soft tissue and the bone is prevented from becoming high luminance.

  The set gain G (f + 1, m, n) is stored in the gain storage unit 21b. Since the gain multiplied by k1 using Expression (2) is compared with the boundary determination threshold value corrected using Expression (1), a detection signal whose intensity is larger than the corrected boundary determination threshold value is input. While being performed, the gain can be continuously multiplied by k1.

On the other hand, when the intensity Sig (f, m, n) of the detection signal is smaller than the boundary determination threshold S, it is determined that the position (m, n) of the frame number f is not a boundary region between the soft tissue and the bone. In step S6, the gain G (f + 1, m, n) at the same pixel position (m, n) in the next frame is set based on the following equation (3).
G (f + 1, m, n) = G (0, m, m) (3)
The set gain G (f + 1, m, n) is stored in the gain storage unit 21b.

  In step S <b> 7, the gain setting unit 21 a determines whether or not the frozen state is set by the operator operating the console 30. Here, when the freeze state is set, the imaging is stopped, and when the freeze state is not set, the process proceeds to step S8.

  In step S8, the gain setting unit 21a increments the sampling number n to (n + 1). In step S9, the gain setting unit 21a determines whether the sampling number n is greater than N. As a result, it is determined whether or not the gain setting has been completed at all sampling points in one line. If the gain setting has not been completed at all sampling points in one line (n ≦ N), steps S2 to S9 are repeated. On the other hand, when all the gain settings for one line have been completed (n> N), the process proceeds to step S10.

In step S10, the gain setting unit 21a sets a gain deeper than the boundary region between the soft tissue and the bone. That is, the gain setting unit 21a extracts the sampling number _{n B} the flag F (n) is set to "1", the sampling point of the sampling number _{n = (n B +1) ~} (n B + p), If the flag F (n) is not 1, the gain G (f + 1, m, n) at the same position (m, n) of the next frame is calculated.
G (f + 1, m, n) = G (0, m, n) × k2 (4)
However, k2> 1. The value of the coefficient k2 may be set in advance or may be input by the operator using the console 30. The set gain G (f + 1, m, n) is stored in the gain storage unit 21b, and the flag F (n) is reset.

  That is, since the intensity of the detection signal in or behind the bone located deeper than the boundary region between the soft tissue and the bone is small, the gain of the detection signal at that position is increased. Here, the value p representing the sampling range in the depth direction for amplifying the luminance of the pixel may be set in advance, or may be input by the operator using the console 30. When the operator inputs the coefficient k2 and the value p using the console 30, it is possible to adjust the luminance of the ultrasonic image in a desired range deeper than the boundary region according to the operator's preference. .

  In step S11, the gain setting unit 21a increments the line number m to (m + 1). In step S12, the gain setting unit 21a determines whether or not the line number m is larger than M. Thus, it is determined whether or not all gain settings in one frame have been completed. If setting of all gains in one frame has not been completed, n = 0 and steps S2 to S12 are repeated. On the other hand, when all gain settings in one frame are completed, the process proceeds to step S13. In step S13, the gain setting unit 21a increments f to (f + 1), sets m = n = 0, and proceeds to step S2.

  Therefore, according to the ultrasonic diagnostic apparatus having the configuration according to the present embodiment, as shown in FIG. 4A, a detection signal having no high intensity portion is shown in FIG. Thus, it is sufficient to use only a gain for correcting attenuation by distance, and the corrected detection signal is as shown in FIG.

  On the other hand, as shown in FIG. 5 (A), in addition to the gain for correcting attenuation due to distance, as shown in FIG. The gain in the period of high intensity corresponding to the reflection from the boundary region between the soft tissue and the bone is multiplied by k1, and the gain in the predetermined period T corresponding to reflection from the deeper part than the boundary region is further multiplied by k2. Therefore, the corrected detection signal is as shown in FIG. As a result, in the ultrasonic image, it is possible to suppress the high luminance near the boundary between the soft tissue and the bone, and to improve the low luminance in the deeper portion than the boundary.

  In the above, at least one of the initial value S0 of the boundary determination threshold S, the coefficients k1 and k2 multiplied by the gain, and the predetermined period T may be set for each assumed boundary type. good. For example, when the operator inputs using the console 30 that the boundary displayed in the ultrasonic image is a boundary between muscles and bones, the control unit 31 shown in FIG. Therefore, a predetermined initial value S0, coefficients k1 and k2, and a period T are set.

  Note that the intensity of the detection signal, specifically, the peak-to-peak value (pp value) or the effective value (RMS value) of the detection signal is used to determine the boundary in the ultrasonic diagnostic apparatus according to the present embodiment. However, the phase shift amount of the detection signal may be used.

  Next, an ultrasonic diagnostic apparatus according to the second embodiment of the present invention will be described. FIG. 6 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to the second embodiment of the present invention. The ultrasonic diagnostic apparatus according to the present embodiment includes a gain setting unit 40 instead of the gain setting unit 21a, and a detection signal converted into a digital signal by the A / D converter 20c in the previous stage of the gain setting unit 40. Is input, and further includes an intensity profile storage unit 42 that stores a plurality of different sound pressure intensity profiles (also simply referred to as intensity profiles or profiles). Other configurations are the same as those of the ultrasonic diagnostic apparatus shown in FIG.

  In the ultrasonic diagnostic apparatus shown in FIG. 1, the gain setting unit 21a determines the boundary region between the soft tissue and the bone based on the intensity of the detection signal converted into a digital signal by the A / D converter 20c. It was. On the other hand, in the present embodiment, the reflectance estimation unit 41 calculates based on the detection signal converted into a digital signal by the A / D converter 20c and the intensity profile stored in the intensity profile storage unit 42. Based on the detection signal in which the component is suppressed, the reflectance of the ultrasonic wave in each part in the subject is obtained, and the gain setting unit 40 determines the boundary region between the soft tissue and the bone based on the reflectance.

  The intensity profile represents the sound pressure intensity or the sound pressure intensity ratio in a plurality of regions included in a surface that arrives after a predetermined time has elapsed since the ultrasonic beam was transmitted in a plurality of different directions. Here, a surface that arrives after a predetermined time has elapsed since the transmission of the ultrasonic beam is referred to as an isochronous surface. In a plurality of regions included in the isochronous plane, the distance from the transmission position of the ultrasonic beam is considered to be substantially equal. The intensity profile is represented by a function of the position (direction) of a plurality of regions included in the isochronal plane and the sound pressure intensity or the sound pressure intensity ratio.

  The plurality of intensity profiles stored in the intensity profile storage unit 42 are based on the transmission direction of the ultrasonic beam and the reception focus processing of the ultrasonic echo, that is, based on the reception direction and the depth of the reception focus. Is set. Alternatively, the elements for setting the sound pressure intensity profile include the number of ultrasonic transducers 10a to be used, the pitch of the ultrasonic transducers 10a, the opening diameter of the ultrasonic transducers 10a to be used, and the weights in the openings. At least one of the opening conditions may be included. The intensity profile can be obtained by simulating a sound field based on the above opening conditions, transmission conditions including a transmission delay pattern, and reception conditions including a reception delay pattern. Alternatively, an intensity profile may be obtained by transmitting and receiving an ultrasonic beam to / from the scattering phantom based on these conditions and using an intensity ratio of ultrasonic echoes obtained by measurement.

  In the space where the ultrasonic waves are transmitted and received, the spatial distribution of sound pressure intensity (sound is based on the sound pressure intensity distribution formed by transmitting the ultrasonic beam and the reception focus processing performed in the reception control unit 24. Field) is assumed to be formed. In this embodiment, in order to remove the influence of the side lobe in the detection signal, the reflectance of the ultrasonic wave is obtained using such a spatial distribution of the sound pressure intensity. The gain setting unit 40 compares the ultrasonic reflectance at each part in the subject with a threshold and determines that a boundary region exists when the reflectance is greater than the threshold. The threshold setting method and gain setting method are the same as those in the first embodiment.

  According to the ultrasonic diagnostic apparatus according to the present embodiment, since the boundary region between the soft tissue and the bone is determined based on the reflectance of the ultrasonic wave calculated using the intensity profile, the intensity of the detection signal is not a boundary region. A portion where the value is large is not erroneously determined as a boundary region. As a result, it is possible to eliminate the influence of the crosstalk caused by the side lobe in the multi-beam or the beam spread of the single beam, and it is possible to more accurately determine the boundary region between the soft tissue and the bone.

  As described above, according to the present invention, it is used in an ultrasound diagnostic apparatus that captures an image of an organ, bone, or the like in a living body by transmitting and receiving ultrasound to generate image data used for diagnosis. It is possible.

1 is a block diagram illustrating a configuration of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. It is a flowchart which shows operation | movement of the STC control part in the ultrasound diagnosing device which concerns on this embodiment. It is a figure for demonstrating the line number m and the sampling number n. It is a figure for demonstrating correction | amendment with respect to the detection signal without a large intensity | strength part. It is a figure for demonstrating correction | amendment with respect to the detection signal with a part with a big intensity | strength. It is a block diagram which shows the structure of the ultrasonic diagnosing device which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating the state which transmits an ultrasonic beam from an ultrasonic transducer array to a human body. It is a figure which shows the detection signal of the ultrasonic echo reflected in the boundary of a soft tissue and a hard tissue.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ultrasonic probe 10a Ultrasonic transducer 11 Scan control part 12 Transmission delay pattern memory | storage part 13 Transmission control part 14 Drive signal generation part 20 Signal processing part 20a Amplifier 20b STC amplifier 20c A / D converter 21 STC control part 21a 40 gain setting unit 21b gain storage unit 21c D / A converter 22 primary storage unit 23 reception delay pattern storage unit 24 reception control unit 25 secondary storage unit 26 image data generation unit 27 tertiary storage unit 28 image data processing unit 29 Display unit 30 Console 31 Control unit 41 Reflectance estimation unit

Claims (16)

An ultrasonic transmission / reception means for transmitting an ultrasonic beam to the subject, receiving an ultrasonic echo reflected from the subject, and generating a detection signal;
According to the correction control signal, signal processing means for correcting the intensity change of the detection signal due to the position where the ultrasonic signal is reflected in the subject; and
Correction control means for determining a boundary region corresponding to the boundary between the soft tissue and the hard tissue in the subject based on the detection signal, and generating a correction control signal so as to suppress the intensity of the detection signal in the boundary region; ,
An ultrasonic diagnostic apparatus comprising:   The ultrasonic diagnostic apparatus according to claim 1, wherein the correction control unit generates a correction control signal for a next frame based on a detection signal output from the signal processing unit.   The correction control means generates the correction control signal so as to increase the intensity of the detection signal in the second region corresponding to a portion deeper than the boundary between the soft tissue and the hard tissue. Ultrasonic diagnostic equipment. The signal processing means is
A variable gain amplifier that amplifies the detection signal according to the correction control signal;
An analog / digital converter for converting the detection signal amplified by the variable gain amplifier into a digital value;
The correction control means includes:
Based on the first threshold relating to the intensity of the detection signal and the initial value and the current value of the gain of the variable gain amplifier corresponding to the plurality of positions in the subject, a plurality of positions corresponding to the plurality of positions in the subject A second threshold value is obtained, and a correction control value for the next frame is generated based on the result of comparing the digital values of the detection signals corresponding to the plurality of positions in the subject with the plurality of second threshold values, respectively. A gain setting section;
A storage unit for storing the correction control value generated by the gain setting unit;
A digital / analog converter for converting the correction control value read from the storage unit into an analog correction control signal;
The ultrasonic diagnostic apparatus of Claim 3 containing this.   When the gain setting unit multiplies the initial value of the gain of the variable gain amplifier by a first coefficient when the digital value of the detection signal is greater than the corresponding second threshold, the corresponding boundary of the next frame A gain for the detection signal in the region is set, and a gain for the detection signal in the second region of the next frame is set by multiplying the initial value of the gain of the variable gain amplifier by a second coefficient. The ultrasonic diagnostic apparatus according to claim 4.   6. The method of claim 5, further comprising setting means used to set at least one of the first threshold value, the first and second coefficients, and the range of the second region. Ultrasonic diagnostic equipment. First setting means used for designating the types of soft tissue and hard tissue in the subject;
A second setting that sets at least one of the first threshold, the first and second coefficients, and the range of the second region according to the specified soft tissue and hard tissue. Means,
The ultrasonic diagnostic apparatus according to claim 6, further comprising: An ultrasonic transmission / reception means for transmitting an ultrasonic beam to the subject, receiving an ultrasonic echo reflected from the subject, and generating a detection signal;
According to the correction control signal, signal processing means for correcting the intensity change of the detection signal due to the position where the ultrasonic signal is reflected in the subject; and
A reflectance estimation means for obtaining a value related to the reflectance in the subject based on the detection signal and an intensity profile representing a spatial distribution of sound pressure intensity;
A boundary region corresponding to the boundary between the soft tissue and the hard tissue in the subject is determined based on the value relating to the reflectance obtained by the reflectance estimation means, and the intensity of the detection signal in the boundary region is suppressed. A correction control means for generating a correction control signal;
An ultrasonic diagnostic apparatus comprising:   The ultrasonic diagnostic apparatus according to claim 8, wherein the correction control unit generates a correction control signal for the next frame based on a detection signal output from the signal processing unit.   10. The correction control signal according to claim 8 or 9, wherein the correction control means generates a correction control signal so as to enhance the intensity of the detection signal in the second region corresponding to a portion deeper than the boundary between the soft tissue and the hard tissue. Ultrasonic diagnostic equipment. The signal processing means is
A variable gain amplifier that amplifies the detection signal according to the correction control signal;
An analog / digital converter for converting the detection signal amplified by the variable gain amplifier into a digital value;
The correction control means includes:
A plurality of second thresholds corresponding to the plurality of positions in the subject based on the first threshold value relating to the reflectance and the initial value and the current value of the gain of the variable gain amplifier corresponding to the plurality of positions in the subject. And a gain setting unit that generates a correction control value for the next frame based on a result of comparing values relating to reflectance corresponding to a plurality of positions in the subject with a plurality of second threshold values, respectively. When,
A storage unit for storing the correction control value generated by the gain setting unit;
A digital / analog converter for converting the correction control value read from the storage unit into an analog correction control signal;
The ultrasonic diagnostic apparatus according to claim 10, comprising:   When the gain setting unit multiplies the initial value of the gain of the variable gain amplifier by the first coefficient when the value related to the reflectance is larger than the corresponding second threshold, the corresponding boundary region of the next frame Setting the gain of the variable gain amplifier for the detection signal at, and multiplying the initial value of the gain of the variable gain amplifier by a second coefficient for the detection signal in the second region of the next frame The ultrasonic diagnostic apparatus according to claim 11, wherein a gain of the variable gain amplifier is set.   13. The method of claim 12, further comprising setting means used to set at least one of the first threshold value, the first and second coefficients, and the range of the second region. Ultrasonic diagnostic equipment. First setting means used for designating the types of soft tissue and hard tissue in the subject;
A second value that sets at least one of the first threshold value, the first and second coefficients, and the range of the second region in accordance with the designated soft tissue and hard tissue. Setting means,
The ultrasonic diagnostic apparatus according to claim 13, further comprising:   The ultrasonic diagnostic apparatus according to any one of claims 4 to 7 and 11 to 14, wherein the gain setting unit is a functional block realized by a CPU and software.   The ultrasonic diagnostic apparatus according to claim 1, wherein the hard tissue includes at least one of a bone, a tendon, and a ligament.

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