Patent Publication Number: US-2010121193-A1

Title: Ultrasonsographic device

Description:
TECHNICAL FIELD 
     The present invention relates to an ultrasonographic device using complementary coding transmission and reception. 
     BACKGROUND ART 
     A conventional ultrasonographic device is configured such that as shown in  FIG. 7 , an output of a coded waveform generation unit  103  is supplied to a transmission unit  102  which drives a prove  101  in accordance with an output of a complementary code generator  110 ; a reference waveform storage unit  107  stores the output of the coded waveform generation unit  103 ; a reception amplification unit  106  amplifies a received signal from the prove  101 ; a correlator  108  performs a correlation calculation between an output of the reference waveform storage unit  107  and an output of the reception amplification unit  106 ; addition means  109  adds the outputs of the correlator  108 ; a display  111  displays an output of the addition means  109 ; and a synchronous timing generation unit TG controls the timings of the complementary code generator  110 , the reference waveform storage unit  107  and the like, and the correlation between the output of the reception amplification unit  106  and the output of the reference waveform storage unit  107  is calculated by the correlator  108 , and the calculated results are sequentially stored by using, for example, a shift register and the like, and also the waveform after a previous correlation process is outputted in synchronization with the waveform after the current correlation process. 
     As a result, the signal outputted by the addition means  109  becomes the signal whose range side lobe is improved (for example, refer to the following patent document 1). 
     Patent Document 1: Japanese Patent Application Publication after Examination 7-81993 (Page 6-7, FIG. 9) 
     However, in the conventional ultrasonographic device, when such as a tissue of a living body, a test body is in motion, it is difficult to output the reception waveform after the correlation process based on a previous transmission, synchronously with the received signal after the correlation process based on a current transmission. As a result, there was a problem that the range side lobe of the signal outputted by the addition means was not improved. 
     DISCLOSURE OF THE INVENTION 
     The present invention is proposed in order to solve the conventional problems. Therefore, its object is to provide an ultrasonographic device that can improve the range side lobe of the complementary coded transmission and reception method even for the moving test body such as the living body. 
     The ultrasonographic device of the present invention comprises: transmission and reception means for carrying out transmission and reception of a modulated waveform signal obtained by modulating by a complementary code, and transmission and reception of a normal waveform signal that is not modulated; velocity detection means for detecting a velocity of a motion of an interest region of a test body from a received signal received by the transmission and reception means; and switching means for carrying out a switching between the transmission and reception of the modulation waveform signal that is carried out by the transmission and reception means in accordance with the velocity detected by the velocity detection means and the transmission and reception of the normal waveform signal. 
     This configuration reduces the range side lobe by using the complementary code transmission and reception method even if the test body is in motion. 
     Also, the ultrasonographic device of the present invention comprises: transmission and reception means for carrying out transmission and reception of a modulated waveform signal obtained by modulating by a complementary code, and transmission and reception of a normal waveform signal that is not modulated; velocity detection means for detecting a velocity of a motion of an interest region of a test body from the received signal received by the transmission and reception means; and delay process means for changing a delay time of the modulated waveform signal that is received by the transmission and reception means correspondingly to the velocity detected by the velocity detection means. 
     This configuration reduces the range side lobe by using the complementary code transmission and reception method even if the test body is in motion. 
     Moreover, the ultrasonographic device of the present invention comprises: transmission and reception means for carrying out transmission and reception of a modulated waveform signal obtained by modulating by a complementary code, and transmission and reception of a normal waveform signal that is not modulated; heartbeat information detecting means for detecting a heartbeat information of a test body; and switching means for carrying out switching between transmission and reception of the modulated waveform signal that is carried out by the transmission and reception means in accordance with the heartbeat information detected by the heartbeat information detecting means and the transmission and reception of the normal waveform signal. 
     This configuration reduces the range side lobe by using the complementary code transmission and reception method even if the test body is in motion. 
     Moreover, the ultrasonographic device of the present invention comprises: transmission and reception means for carrying out transmission and reception of a modulation waveform signal obtained by modulating by a complementary code, and transmission and reception of a normal waveform signal that is not modulated; velocity detection means for detecting a velocity of a motion of an interest region of a test body from a received signal received by the transmission and reception means; and changing means for changing the code length of the complementary code of the transmission and reception means correspondingly to the velocity detected by the velocity detection means. This configuration reduces the range side lobe by using the complementary code transmission and reception method even if the test body is in motion. 
     Moreover, the ultrasonographic device of the present invention comprises a configuration in which the velocity detection means detects the velocity of the motion of the interest region of the test body, by receiving the normal waveform signal from the transmission and reception means. 
     This configuration reduces the range side lobe by using the complementary code transmission and reception method even if the test body is in motion. 
     Moreover, in the ultrasonographic device of the present invention, the transmission and reception means comprises means for changing a reception sensibility in accordance with the code length of the complementary code of the modulation waveform signal to be transmitted and received. This configuration can decrease the reception sensibility and reduce the noise level when the length of the code becomes long. For example, when the length of the code is N, the reception sensibility may be decreased to ½N. 
     Moreover, in the ultrasonographic device of the present invention, the transmission and reception means comprises a configuration for changing a central frequency of an ultrasonic to be transmitted and received in accordance with the code length of the complementary code of the modulation waveform signal to be transmitted and received. With this configuration, when the code becomes longer, the sensibility becomes higher, which can make the central frequency higher and make a resolution higher. 
     Moreover, in the ultrasonographic device of the present invention, the velocity detection means comprises a function for detecting the dispersion of the velocities of the motions of the interest region. This configuration reduces the range side lobe by using the complementary code transmission and reception method even if the test body is in motion. 
     Moreover, the ultrasonographic device of the present invention has a configuration that further has comprises for adding information with regard to the code length of the complementary code that is transmitted and received by the transmission and reception means to a diagnostic picture and can check the length of the code when the picture is obtained from the picture information. 
     Moreover, the ultrasonographic device of the present invention has a configuration that further comprises display means for displaying information with regard to the code length of the complementary code that is transmitted and received by the transmission and reception means and can check the length of the code from the picture. 
     The present invention can provide the ultrasonographic device having the effect of reducing the range side lobe by using the complementary code transmission and reception method even if the test body is in motion, because as for the transmission and reception unit, the switching between the transmission and reception of the modulation waveform signal that is modulated with the complementary code and the transmission and reception of the normal waveform signal that is not modulated, or the change of the length of the complementary code is possible, and as for the means for detecting the velocity of the motion of the interest region of the test body, the switching between the transmission and reception of the modulation waveform signal that is modulated with the complementary code in accordance with the velocity and the transmission and reception of the normal waveform signal, or the change of the length of the complementary code is carried out. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an ultrasonographic device according to a first embodiment of the present invention. 
         FIG. 2A  is a view showing an output signal example of a correlator according to the first embodiment of the present invention. 
         FIG. 2B  is a view showing an output signal example of the correlator according to the first embodiment of the present invention. 
         FIG. 2C  is a view showing an output signal example of addition means according to the first embodiment of the present invention. 
         FIG. 3A  is a view showing an output signal example of a transmission unit corresponding to a usual transmission and reception according to the first embodiment of the present invention. 
         FIG. 3B  is a view showing an example of a complementary code corresponding to the usual transmission and reception according to the first embodiment of the present invention. 
         FIG. 3C  is a view showing an output signal example of a transmission unit corresponding to transmission and reception of complementary codes according to the first embodiment of the present invention. 
         FIG. 4  is a detailed block diagram of a correlator  7  according to the first embodiment of the present invention. 
         FIG. 5  is a block diagram of an ultrasonographic device according to a second embodiment of the present invention. 
         FIG. 6  is a block diagram of an ultrasonographic device according to a third embodiment of the present invention. 
         FIG. 7  is the block diagram of the conventional ultrasonographic device. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinbelow, description will be given about the ultrasonographic device according to the embodiments of the present invention by using the drawings. 
       FIG. 1  shows the ultrasonographic device according to the first embodiment of the present invention. 
     In  FIG. 1 , an output of a coded waveform generation unit  3  is supplied to the transmission unit  2  for driving a prove  1 , in accordance with an output of a complementary code generator  4 , and a reception amplification unit  6  amplifies a received signal from the prove  1 , and an output of the reception amplification unit  6  is inputted to velocity detection means  8 , and an output of the velocity detection means  8  is inputted to the complementary code generator  4 , and a correlator  7  performs a correlation calculation between an output of the complementary code generator  4  and an output of the reception amplification unit  6 , and a memory  9  stores an output of the correlator  7 , and addition means  13  adds the outputs of the correlator  7  and the memory  9 , and an output of the addition means  13  is processed by a signal procession unit  14 , and a display  15  displays an output of the signal procession unit  14 , and a synchronous timing generation unit TG controls the timings of the complementary code generator  4  and the like. 
     A test body  20  is brought into contact with the prove  1 .  FIG. 2A ,  FIG. 2B  and  FIG. 2C  are the waveform views describing the principle of the complementary code transmission and reception, and  FIG. 3A ,  FIG. 3B  and  FIG. 3C  are the outputs of the transmission unit  2  in the usual transmission and reception and the coded transmission and reception.  FIG. 4  is the detailed block diagram of the correlator  7 , and the output of the reception amplification unit  6  is inputted to delay circuits  71 ,  72  and  73 . The output of the reception amplification unit  6  is inputted to multipliers  74 ,  75 ,  76  and  77  and multiplied by complementary codes k( 1 ), k( 2 ), k( 3 ) and k( 4 ) generated by the complementary code generator  4  and added in an adder  78 . 
     The operations of the above-configured ultrasonographic device will be described below by using  FIG. 1 ,  FIG. 2A ,  FIG. 2B ,  FIG. 2C ,  FIG. 3A ,  FIG. 3B ,  FIG. 3C  and  FIG. 4 . 
     Firstly, the complementary code is described. 
     The complementary code has the following features. For example, a 2  and b 2  of the following equation are the complementary codes of a length N=2̂m (m=1, ̂ represents a power). 
         a 2=[+1,+1]  (1) 
         b 2=[+1,−1]  (2) 
     an autocorrelation c 2  of a 2  and an autocorrelation d 2  of b 2  are represented by the following equation. 
         c 2=[+1,+2,+1]  (3) 
         d 2=[−1,+2,−1]  (4) 
     A sum e 2  of the autocorrelation c 2  and the autocorrelation d 2  becomes: 
         e 2=[0,+4,0]  (5) 
     Then, at the peak of the center of a sequence, the value becomes 2N=4, and before and after the peak, namely, the range side lobe becomes zero. 
     The complementary code of N=2̂m (m=2) is obtained from a procedure that in accordance with the complementary code of the length N, an item in which b 2  is linked after a 2  is defined as a 4 , and an item in which the code of b 2  is inverted and linked after a 2  is defined as b 4 . 
         a 4=[+1,+1,+1,−1]  (6) 
         b 4=[+1,+1,−1,+1]  (7) 
       FIG. 2A  and  FIG. 2B  are the views showing the autocorrelation of the complementary code of N=2̂m (m=3), and  FIG. 2C  is the view showing the sum of the autocorrelations. Then, at the peak of the center of the sequence, the value is 2N=16, and before and after the peak, namely, the value of the range side lobe is zero. 
     In this way, when the length of the complementary code becomes N, the peak value of a received signal becomes 2N times. Thus, when the complementary code becomes long, for example, in the signal procession unit  14 , a reception sensibility can be decreased, which can relatively reduce the noise level included in the received signal. For example, when the length of the complementary code is N, the reception sensibility may be set to ½N. Reversely, when the length of the complementary code becomes short, the reception sensibility may be increased. 
       FIG. 3A  is the view showing an impulse that is the output waveform of the transmission unit  2  in the usual transmission and reception,  FIG. 3B  is the view showing an example of the complementary code outputted by the complementary code generator  4 , and  FIG. 3C  is the view showing the output waveform of the transmission unit  2  that corresponds to the complementary code in  FIG. 3B . The complementary code in  FIG. 3B  corresponds to the equations (6), (7). The pulse widths of impulses T 1 , T 2  of the transmission unit  2  in the usual transmission and reception shown in  FIG. 3A  are δT 1 . The output waveform of the transmission unit  2  that corresponds to the complementary code shown in  FIG. 3C  is the waveform equal to the impulse T 1  when the value of the complementary code in  FIG. 3B  is +1, and when the value of the complementary code is −1, it is the waveform in which the impulse T 1  is inverted. 
     In a waveform T 3 , the impulses T 1  or the waveform-inverted impulses T 1  are arranged at a δT 2  interval. By the way, there is a relation of δT 1 &lt;δT 2 . Also, an interval between the waveform T 3  and a waveform T 4  is ΔT. As for the received signal through the waveform T 3 , by using the complementary code of the equation (6), the correlator  7  performs an autocorrelation process thereon, and as for the received signal through the waveform T 4 , by using the complementary code of the equation (7), the correlator  7  performs the autocorrelation process thereon. Then, after the output of the correlator  7  that corresponds to the waveform T 3  is stored in the memory  9  and delayed by a time ΔT and read out, this is added by the addition means  13 . Consequently, a complementary transmission and reception output is obtained. 
     The process in the correlator  7  is specifically shown by using  FIG. 4 . The correlator  7  shown in  FIG. 4  corresponds to the complementary code of the length N=4 of the equations (6), (7). The output of the reception amplification unit  6  is inputted to the delay circuits  71 ,  72  and  73 , and the delay of the time δT 2  is given to each of them. The δT 2  is the interval of the impulses included in the output waveforms corresponding to the complementary codes in already-described  FIG. 3C . The output of the amplification unit  6  is multiplied by the coefficients k( 1 ), k( 2 ), k( 3 ) and k( 4 ) in the multipliers  74 ,  75 ,  76  and  77 . The coefficient k(j) (1≦j≦4) is the complementary code of the length N=4 of the equations (6), (7). When the output waveform of the transmission unit  2  corresponds to the complementary code of the equation (6), the coefficient k(j) corresponds to the equation (6), and when the output waveform of the transmission unit  2  corresponds to the complementary code of the equation (7), the coefficient k(j) corresponds to the equation (7). In the foregoing description, in order that at the output of the addition means  13 , the range side lobe is zero as indicated by the equation (5), the test body  20  is required to be static. 
     However, when the test body  20  is a living body, its tissue is in motion. In particular, when the received signal from the tissue of a circulatory organ group is processed, it is required not to receive the influence of the pulsation of the tissue. The velocity operation means  8  performs a Doppler operation process on the output signal from the reception amplification unit  6  and detects a movement velocity V of the tissue. 
     When the Doppler operation process is carried out, the output waveform of the transmission unit  2  may use the impulse of the usual transmission and reception. At first, the complementary code generator  4  carries out the output corresponding to the usual transmission and reception. The coded waveform generation unit  3  generates the impulse waveform of  FIG. 3A . The velocity operation means  8  measures the velocity for the interest region of the test body  20 . 
     When the velocity detected by the velocity operation means  8  becomes equal to a constant level or less, the complementary code generator  4  generates the complementary code of the equation (6) at a certain time. Then, the output of the correlator  7  is stored in the memory  9 . After the ΔT time, the complementary code generator  4  generates the complementary code of the equation (7). Then, the output of the correlator  7  and the output read from the memory  9  are added by the addition means  13 . While the complementary code transmission and reception is carried out, the velocity detection of the velocity operation means  8  is carried out through the usual transmission and reception at a proper temporal interval. When the detected velocity V becomes equal to or higher than the constant level, the transmission and reception through only the usual transmission and reception is carried out. 
     Or, on the basis of the velocity detected by the velocity operation means  8 , the length of the complementary code may be changed. For example, as the velocity becomes faster, the complementary code may be shorter. Or, when the code of the complementary code becomes longer, the central frequency of the ultrasonic may be made higher. Moreover, as a result of the Doppler operation process, when the distribution of the velocities is spread even if the average velocity is equal to or less than the constant level, namely, when the velocities are dispersed, the complementary code generator  4  may be designed to generate the complementary code of the equation (6) at a certain time, when the dispersion becomes equal to or less than the constant level. 
     Moreover, the length information of the code of the complementary code may be added to the picture information obtained by the signal procession unit  14 . Moreover, the length information of the code of the complementary code added to the picture information together with the picture of the test body may be displayed on the display  15 . 
     According to the ultrasonographic device according to the first embodiment of the present invention as mentioned above, as for the transmission and reception unit, the switching between the transmission and reception of a modulation waveform signal modulated with the complementary code and the transmission and reception of the normal waveform signal that is not modulated is possible, and as for the means for detecting the velocity of the motion in the interest region of the test body, by carrying out the switching between the transmission and reception of the modulation waveform signal modulated with the complementary code correspondingly to the velocity and the transmission and reception of the normal waveform signal that is not modulated, the accurate complementary code transmission and reception can be carried out in which it is difficult to receive the influence of the motion of the test body. 
     Next, the ultrasonographic device according to the second embodiment of the present invention is shown in  FIG. 5 . 
     In  FIG. 5 , for that having the same action and function as the first embodiment, its description is omitted. In  FIG. 5 , an output of the velocity detection means  8  is connected to delay means  10 . An output of the memory  9  is inputted to the delay means  10 , and an output of the delay means  10  is inputted to the addition means  13 . 
     As for the ultrasonographic device configured as mention above, its operations will be described below by using  FIG. 5 . 
     At first, the velocity detection means  8  detects the velocity V of the motion of the interest region of the test body  20 . The waveform of the coded waveform generation unit  3  in this case may be the waveform corresponding to the usual transmission and reception or may be the waveform corresponding to the coded transmission and reception. Since the motional velocity is V, after the ΔT time that is the interval between the transmissions, the position of the interest region is changed by ΔTL=V·ΔT. 
     With the change of the position of ΔL, an arrival time of an echo from the interest region is changed by ΔΔT=2·ΔL/c (however, c is a sound velocity inside the test body). For this reason, in the interest region, the temporal interval of the corresponding echo is ΔT−ΔΔT. In this way, in the delay means  10 , the delay time of ΔΔT is adjusted for the signal outputted by the memory  9 . Then, the output of the delay means  10  and the output of the correlator  7  are added by the addition means  13 . 
     As mentioned above, according to the ultrasonographic device according to the second embodiment of the present invention, the output of the velocity detection means  8  is connected to the delay means  10 . The output of the memory  9  is inputted to the delay means  10 , and the output of the delay means  10  is inputted to the addition means  13 . Thus, even if the interest region of the test body  20  is in motion, the accurate complementary code transmission and reception can be carried out in which it is difficult to receive the influence of the motion of the test body. 
     Next, the ultrasonographic device according to the third embodiment of the present invention is shown in  FIG. 6 . 
     In  FIG. 5 , for that having the same action and function as the first embodiment, its description is omitted. In the test body  20 , an electrocardiograph  16  for detecting its pulsating is installed. Then, an output of the electrocardiograph  16  is inputted to R-wave trigger delay means  12 , and an output of the R-wave delay means  12  is inputted to the complementary code generator  4 . 
     For the ultrasonographic device configured as mentioned above, its operations will be described below by using  FIG. 6 . 
     At first, the prove  1  is assumed such that a carotid artery wall of the test body  20  serves as the interest region. On the other hand, the electrocardiograph  16  is assumed to observe a cardiac electrograph of a heart of the test body  20 . 
     The contraction and dilation of the heart involves the change in the blood vessel diameter of the carotid artery. However, a timing when, since the carotid artery diameter is maximized or minimized, a carotid artery wall is instantaneously rested has a certain temporal delay from the contraction and dilation of the heart. For this reason, the R-wave trigger delay means  12  for delaying an R-wave trigger outputted by the electrocardiograph  16  estimates a time when the carotid artery diameter is maximized or minimized. Then, at a time when the carotid artery wall is instantaneously rested, the complementary code generator  4  generates the complementary code and carries out the complementary code transmission and reception. 
     As mentioned above, according to the ultrasonographic device according to the third embodiment of the present invention, the electrocardiograph  16  is installed inside the test body  20 , the output of the electrocardiograph  16  is inputted to the R-wave delay means  12 , and the output of the R-wave delay means  12  is inputted to the complementary code generator  4 . Thus, even if the interest region of the test body  20  is in motion, the accurate complementary code transmission and reception can be carried out in which it is difficult to receive the influence of the motion of the test body. 
     By the way, in the foregoing descriptions, the prove  1  may be composed of the transducer of a single element or may be configured such that a plurality of transducers are arrayed. 
     INDUSTRIAL APPLICABILITY 
     As described above, in the ultrasonographic device according to the present invention, as for the transmission and reception unit, the switching between the transmission and reception of the modulation waveform signal modulated with the complementary code and the transmission and reception of the normal waveform signal that is not changed, or the change of the length of the complementary code is possible, and as for the means for detecting the velocity of the motion of the interest region of the test body, the switching between the transmission and reception of the modulation waveform signal modulated with the complementary code correspondingly to the velocity and the transmission and reception of the normal waveform signal, or the change of the length of the complementary code is carried out. Thus, there is an effect that, even if the test body is in motion, the complementary code transmission and reception method is used to reduce the range side lobe, and this is useful as the ultrasonographic device that uses the complementary coded transmission and reception method and the like.