JP2010194085A - Ultrasonographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonographic apparatus capable of configuring an ultrasonic image by using small piezoelectric elements, even its small size, however, at low cost. <P>SOLUTION: One piezoelectric element as an ultrasonic transmitting element and one piezoelectric element as an ultrasonic receiving element are combined and used, and thus the area of the position having the probability of the presence of a reflection source R is acquired as a relative position of each piezoelectric element. Furthermore, a plurality of combinations of transmitting and receiving piezoelectric elements are adopted, and the position of each combination is acquired within the area having the probability of the presence of the reflection source R likewise, and hence the position where the reflection source R is present, and furthermore the shape of the reflection source R are calculated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a small ultrasonic diagnostic apparatus that transmits an ultrasonic signal into a subject and constructs an ultrasonic image in the subject based on the reflected ultrasonic signal.

  The ultrasonic diagnostic apparatus scans the inside of a subject to be diagnosed with an ultrasonic signal, receives a reflected wave, obtains image data corresponding to the intensity of the reflected wave, and thereby obtains a two-dimensional section called a B-mode image. An image (ultrasonic image) is generated. Generally, it is used in hospitals and the like, and is widely used and widely known in medical institutions. However, it is not assumed that general consumers use it in any place or situation. However, with the widespread use of information terminal equipment, it is becoming common for consumers to carry advanced information equipment personally and use it in any location or situation, so it has been used in medical institutions in the past. Even if it is an ultrasonic diagnostic apparatus, if a consumer can carry it personally and use it in arbitrary places and situations, the convenience will be remarkably improved.

  There exists a small-sized ultrasonic diagnostic apparatus proposed for such a purpose (for example, refer patent document 1). In the technique shown in Patent Document 1, an operator manually scans an ultrasonic probe with respect to a subject, detects an inclination angle and a moving direction of the ultrasonic probe with a sensor, and detects reflected waves. An ultrasonic surface image is reconstructed in combination with the received signal. Since the number of piezoelectric elements that transmit and receive ultrasonic signals is very small, there is a merit of scale for the ultrasonic probe, leading to miniaturization of the ultrasonic probe and the ultrasonic diagnostic apparatus.

JP 2008-229245 A

  In the technique described in Patent Document 1, since the number of piezoelectric elements is small, the image quality of the ultrasonic image is inevitably lowered. Further, in order to obtain the angle and position from the output of the sensor, an expensive sensor, a very complicated electronic circuit, and an advanced coordinate reconstruction algorithm are required, which is expensive.

  An object of the present invention is to provide an ultrasonic diagnostic apparatus that can construct an ultrasonic image at low cost while using a small number of piezoelectric elements.

  The above object is achieved by the invention described below.

1. A transmission means having a plurality of transmission elements capable of transmitting an ultrasonic signal into the subject, and transmitting one ultrasonic signal by selecting one transmission element from the plurality of transmission elements; ,
The first ultrasonic wave having a plurality of receiving elements capable of receiving an ultrasonic signal, selecting one receiving element from the plurality of receiving elements, and transmitting the selected transmitting element Receiving means for receiving a second ultrasonic signal generated by reflecting a signal from a reflection source in the subject;
After the selected transmission element transmits the first ultrasonic signal, the time until the selected reception element receives the second ultrasonic signal is measured, and the selected transmission element is selected. Calculating means for calculating a relative position having a probability that the reflection source is present with respect to the received element;
Control means for controlling the transmission means, the reception means, and the calculation means;
The control means performs an operation of selecting one each from the plurality of transmitting elements and the plurality of receiving elements and causing the calculation means to calculate a relative position having a probability that the reflection source exists. A position that is implemented with respect to a predetermined combination of a plurality of transmitting elements and a plurality of receiving elements and has a high probability that the reflection source exists based on a calculation result of all relative positions having the probability that the reflection source exists. An ultrasonic diagnostic apparatus characterized by calculating

2. A transmission means having a plurality of transmission elements capable of transmitting an ultrasonic signal into the subject, and transmitting a first ultrasonic signal by selecting a plurality of transmission elements from the plurality of transmission elements; ,
The first ultrasonic wave having a plurality of receiving elements capable of receiving an ultrasonic signal, selecting one receiving element from the plurality of receiving elements, and transmitting the selected transmitting element Receiving means for receiving a second ultrasonic signal generated by reflecting a signal from a reflection source in the subject;
The virtual transmission element that combines the plurality of selected transmission elements transmits the first ultrasonic signal and then measures the time until the selected reception element receives the second ultrasonic signal. Calculating means for calculating a relative position having a probability that the reflection source is present with respect to the virtual transmitting element and the selected receiving element;
Control means for controlling the transmission means, the reception means, and the calculation means;
The control means performs an operation of selecting one from each of the virtual transmission element and the plurality of reception elements and causing the calculation means to calculate a relative position having a probability that the reflection source exists. It implements for a predetermined combination of a trusted element and the plurality of receiving elements, and calculates a position where the probability that the reflection source exists is high based on calculation results of all relative positions where the reflection source exists. An ultrasonic diagnostic apparatus.

3. The transmission means includes drive encoded pulse forming means for generating a first ultrasonic signal that is a drive encoded pulse,
3. The ultrasonic diagnostic apparatus according to 1 or 2, wherein the reception unit includes a decoding unit that decodes the second ultrasonic signal.

  It is possible to provide an ultrasonic diagnostic apparatus that can construct an ultrasonic image at low cost while using a small number of piezoelectric elements.

It is a figure which shows the external appearance structure of an ultrasonic diagnosing device. It is a block diagram which shows the electrical structure of an ultrasonic diagnosing device. It is a three-plane figure which shows the outline | summary of an ultrasonic probe. It is the schematic which removed the acoustic separation part 24, the common electrode, and the acoustic matching layer 27, and observed the ultrasonic probe 2 from the diagonal direction. It is sectional drawing which observed the ultrasonic probe 2 from the side surface. FIG. 5 is a schematic diagram of a method for determining the position of a reflection source R using a piezoelectric element that is one ultrasonic transmission element and a piezoelectric element that is an ultrasonic reception element. It is a schematic diagram of a method for obtaining a position having a probability that a reflection source R exists when a plurality of combinations of a piezoelectric element that is an ultrasonic transmission element and two piezoelectric elements that are an ultrasonic reception element are prepared. . FIG. 5 is a schematic diagram illustrating a plurality of reflection source ellipses assuming that the reflection source R2 is a set of minute reflection sources. It is a measurement flowchart which measures the shape of the reflection source which reflects the 1st ultrasonic signal in a subject. It is a two-dimensional object that reflects the first ultrasonic signal. It is the result of calculating the shape of a reflection source ellipse that is a set of positions having a probability that a reflection source exists. It is a calculation result of phantom. 1 is a schematic diagram of a configuration of an ultrasonic diagnostic apparatus using a personal computer P. FIG. It is a block diagram which shows the electrical structure of the ultrasonic diagnosing device S at the time of using the personal computer P. FIG. It is a figure explaining the outline | summary of the encoding transmission / reception method. It is a schematic diagram showing an example of a 13-bit Barker code. It is a schematic diagram showing a state of an ultrasonic wave front when ultrasonic signals are transmitted to piezoelectric elements a to e as a plurality of point sound sources at predetermined time intervals in this order. It is a schematic diagram showing a state of a wavefront in which a single assumed point sound source is formed at a position F by collecting first ultrasonic signals transmitted from a plurality of point sound sources at one point at a predetermined time.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the embodiments described below. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

  An ultrasonic diagnostic apparatus will be described with reference to FIGS. FIG. 1 is a diagram illustrating an external configuration of an ultrasonic diagnostic apparatus according to an embodiment. FIG. 2 is a block diagram illustrating an electrical configuration of the ultrasonic diagnostic apparatus according to the embodiment.

  As shown in FIG. 1, the ultrasonic diagnostic apparatus S transmits an ultrasonic wave (also referred to as a first ultrasonic signal) to a subject H (not shown) and reflects the ultrasonic signal reflected by the subject H. An ultrasonic probe 2 that receives a wave (also referred to as a second ultrasonic signal), is connected to the ultrasonic probe 2 via a cable 3, and is connected to the ultrasonic probe 2 via a cable 3. , The ultrasonic probe 2 transmits the first ultrasonic signal to the subject H, and the second supersonic wave from the subject H received by the ultrasonic probe 2 is transmitted. The ultrasonic diagnostic apparatus main body 1 is configured to image an internal state of the subject H as an ultrasonic image based on a reception signal generated by the ultrasonic probe 2 in accordance with the sound wave signal.

  The ultrasonic probe 2 includes a plurality of piezoelectric elements. For example, as shown in FIG. 2, the ultrasonic probe 2 includes five piezoelectric elements a, b, c, d, and e. Among the piezoelectric elements a, b, c, d, and e, the piezoelectric elements b and d have a function of transmitting and receiving ultrasonic waves, and the piezoelectric elements a, c, and e have only a function of transmitting ultrasonic waves. A protection circuit 29 for protecting the circuit from an excessive electric signal or the like is connected to the piezoelectric elements b and d that receive the ultrasonic signal.

  For example, as shown in FIG. 2, the ultrasonic diagnostic apparatus main body 1 includes an operation input unit 11 for inputting a command for instructing diagnosis and data such as personal information of the subject H, and a cable to the ultrasonic probe 2. A transmission unit 12 that is a transmission unit that drives the ultrasonic probe 2 to generate a first ultrasonic signal by supplying a transmission signal of an electrical signal via the signal 3, and a cable 3 from the ultrasonic probe 2. A receiving unit 13 that is a receiving means for receiving a received signal via the signal, a signal processing unit 17 that performs signal processing based on the received signal received by the receiving unit 13, and a subject based on the output of the signal processing unit 17 An image processing unit 14 that generates an internal state image (ultrasonic image) in H, a storage unit 18 that stores the results obtained by the signal processing unit 17 and the image processing unit 14, and the image processing unit 14 The image of the internal state in the subject H The display unit 15 to be operated and the operation input unit 11, the transmission unit 12, the reception unit 13, the image processing unit 14, the display unit 15, the signal processing unit 17, and the storage unit 18 are controlled according to the function, thereby ultrasonic waves. And a control unit 16 that performs overall control of the diagnostic apparatus S.

  The transmission unit 12 includes, for example, a function generator 12a that generates a transmission signal having a predetermined signal waveform, a linear amplifier 12b that amplifies the generated transmission signal, and a piezoelectric element that constitutes the ultrasonic probe 2. , A channel switching circuit 12c for applying transmission signals sequentially in time series is provided.

  The receiving unit 13 receives a second ultrasonic signal generated by reflection from the subject H, and amplifies an electric signal converted by the piezoelectric elements b and d constituting the ultrasonic probe 2, and a preamplifier 13a. An AD converter 13b that converts the amplified electrical signal from an analog value to a digital value is provided.

  Next, the form of the ultrasonic probe 2 will be described with reference to FIGS. FIG. 3 is a trihedral view showing an outline of the ultrasonic probe 2. 3A is a front view of the ultrasound probe 2, FIG. 3B is a top view of the ultrasound probe 2, and FIG. 3C is a side view of the ultrasound probe 2. FIG.

  In the front view of the ultrasonic probe 2 in FIG. 3A and the side view of the ultrasonic probe 2 in FIG. 3C, the acoustic braking member 23 and the acoustic separation are sequentially arranged from the lower side to the upper side in the figure. The unit 24, the common electrode 25, and the acoustic matching layer 27 are stacked in this order. The individual electrode 28 is individually provided in each of a plurality of piezoelectric elements (described later) provided in the ultrasonic probe 2, and a signal line (not shown) for transmitting and receiving an electric signal is connected to each piezoelectric element. It is an electrode for doing.

  In the top view of the ultrasonic probe 2 in FIG. 3B, the individual electrode 28 is exposed from the side surface of the acoustic braking member 23.

  Next, the positional relationship of the piezoelectric elements in the ultrasonic probe 2 will be described. FIG. 4 is a schematic view of the ultrasonic probe 2 observed from an oblique direction with the acoustic separator 24, the common electrode 25, and the acoustic matching layer 27 removed. Five piezoelectric elements a, b, c, d, e are arranged on the upper part of the acoustic braking member 23, and an individual electrode 28 is provided on the lower part of each piezoelectric element. In order to simplify the explanation, the number of piezoelectric elements is five. However, the larger the number of piezoelectric elements, the better the resolution of the ultrasonic image is improved. At least two piezoelectric elements and individual electrodes 28 are prepared. Piezoelectric elements convert signals between electrical signals and ultrasonic signals by utilizing piezoelectric phenomena.

  The piezoelectric element includes an inorganic piezoelectric material or an organic piezoelectric material as a component. For example, PZT (lead zirconate titanate) can be used as the inorganic piezoelectric material. As the organic piezoelectric material, for example, a polymer of vinylidene fluoride can be used. Further, for example, a vinylidene fluoride (VDF) copolymer can be used as the organic piezoelectric material.

  FIG. 5 is a cross-sectional view of the ultrasonic probe 2 observed from the side. FIG. 5A is a cross-sectional view of the AA ′ cross section in FIG. 3B observed from the side, and FIG. 5B is a cross-sectional view of the BB ′ cross section in FIG.

  FIG. 5A is a cross-sectional view of the ultrasonic probe 2 including a cross-sectional view of a piezoelectric element. The piezoelectric element includes an individual electrode 28 and a common electrode 25 on upper and lower surfaces. The common electrode 25 is formed in common on the upper surface of each piezoelectric element so as to conduct in common with each piezoelectric element. FIG. 5B is a cross-sectional view of the ultrasonic probe 2 that does not include a cross-sectional view of the piezoelectric element, and the acoustic separation unit 24 is formed so as to fill between the piezoelectric elements.

  The acoustic braking member 23 is made of a material that absorbs an ultrasonic signal, and absorbs the ultrasonic signal radiated from the plurality of piezoelectric elements toward the acoustic braking member 23.

  Electrical signals are input from the transmission unit 12 to the piezoelectric elements a to e from the cable 3. This electric signal is input between the individual electrode 28 and the common electrode 25 of the piezoelectric element. The plurality of piezoelectric elements transmit the first ultrasonic signal by converting the electric signal into the first ultrasonic signal.

  The acoustic separation unit 24 is composed of a low acoustic impedance resin whose value is greatly different from the acoustic impedance of the piezoelectric element, and acts as an acoustic separation material due to the great difference in acoustic impedance, thereby reducing mutual interference between the piezoelectric elements. It has the function to do. The acoustic separator 24 can reduce crosstalk between the piezoelectric elements.

  The common ground electrode 25 is made of a conductive material, and is grounded by an unillustrated wiring.

  The acoustic matching layer 27 is a member that matches the acoustic impedance of the piezoelectric element and the acoustic impedance of the subject H. The acoustic matching layer 27 has a shape bulging in an arc shape, and has a function of an acoustic lens that converges the first ultrasonic signal transmitted toward the subject H.

  In the ultrasonic diagnostic apparatus S having such a configuration, for example, when an instruction to start diagnosis is input from the operation input unit 11, a transmission signal of an electrical signal is generated by the transmission unit 12 under the control of the control unit 16.

  The generated transmission signal of the electric signal is supplied to the ultrasonic probe 2 through the cable 3. More specifically, this electrical signal transmission signal is supplied to one of the piezoelectric elements a to e in the ultrasonic probe 2 as will be described later. The electric signal transmission signal is, for example, a voltage pulse repeated at a predetermined cycle. The piezoelectric element supplied with the electrical signal transmission signal expands and contracts in the thickness direction, and is driven so as to vibrate ultrasonically according to the electrical signal transmission signal. Due to this ultrasonic vibration, the piezoelectric element radiates ultrasonic waves through the common ground electrode 25 and the acoustic matching layer 27. When the ultrasonic probe 2 is in contact with the subject H, for example, ultrasonic waves are transmitted from the ultrasonic probe 2 to the subject H.

  The ultrasound probe 2 may be used in contact with the surface of the subject H, or may be inserted into the subject H, for example, inserted into the body cavity of the subject H. May be.

  The ultrasonic wave transmitted to the subject H is reflected at one or a plurality of boundary surfaces having different acoustic impedances inside the subject H, and becomes a reflected wave of the ultrasonic wave.

  The ultrasonic wave of the reflected wave is received by the ultrasonic probe 2. More specifically, the ultrasonic wave of the reflected wave is received by the piezoelectric element through the acoustic matching layer 27, and mechanical vibration is converted into an electric signal as a reception signal by the piezoelectric element and is extracted. The extracted reception signal is received by the receiving unit 13 controlled by the control unit 16 via the cable 3.

  The image processing unit 14 calculates the coordinates of the reflection source present in the subject H from the time from transmission to reception based on the reception signal received by the reception unit 13 as described later. Based on the above, an ultrasonic image is generated.

  The display unit 15 displays an ultrasonic image of the internal state in the subject H generated by the image processing unit 14 under the control of the control unit 16.

  Next, the principle of measuring an ultrasound image inside the subject H will be described with reference to FIG. For simplification, it is assumed that there is a reflection source R having a minute size that reflects the first ultrasonic signal and generates the second ultrasonic signal inside the subject H, and the position of the reflection source R is determined. It will be described as being measured. It is assumed that the field where the ultrasonic signal propagates is two-dimensional.

  FIG. 6 is a schematic diagram of a method for obtaining the position of the reflection source R using a piezoelectric element that is one ultrasonic transmission element and a piezoelectric element that is one ultrasonic reception element.

  A is a piezoelectric element that is an ultrasonic transmission element, and B is a piezoelectric element that is an ultrasonic reception element that is a point sound source. Let L be the distance between the piezoelectric elements A and B.

The pulsed first ultrasonic signal transmitted from the piezoelectric element A is reflected by the reflection source R existing on the xy plane, and is received by the piezoelectric element B at an arbitrary time t. Assuming that the sound velocity in the subject H is c, the first ultrasonic signal has propagated a distance of d = ct. The position of the reflection source R where the reflection occurs is any of the circumference of an ellipse having a minor axis L1 = (d ² −L ² ) ^1/2 and a major axis L2 = d with the positions of the piezoelectric elements A and B as focal points. (This ellipse is also called a reflection source ellipse.)

  Thus, by using a combination of the piezoelectric element A that is one ultrasonic transmission element and the piezoelectric element B that is one ultrasonic reception element, there is a probability that the reflection source R exists. The range of the position can be obtained as a relative position with respect to each of the piezoelectric elements A and B. Accordingly, a plurality of combinations of the transmitting piezoelectric element and the receiving piezoelectric element are adopted, and in each combination, the range of the position having the probability that the reflecting source R exists is obtained in the same manner, whereby the reflecting source R It is possible to narrow down the position where there is. Specifically, the coordinates of a reflection source ellipse obtained by a plurality of combinations of a piezoelectric element that is an ultrasonic transmission element and a piezoelectric element that is an ultrasonic reception element are obtained, and there is a high probability that the reflection source R exists. The position is calculated as an overlapping portion of each reflection source ellipse.

  For example, FIG. 7 shows an example in which two combinations of a piezoelectric element that is an ultrasonic transmission element and a piezoelectric element that is an ultrasonic reception element are prepared.

  FIG. 7 shows a method for obtaining a position having a probability that the reflection source R exists when a plurality of combinations of a piezoelectric element that is an ultrasonic transmission element and two piezoelectric elements that are an ultrasonic reception element are prepared. FIG.

  A and C are piezoelectric elements (point sound sources) that are ultrasonic transmission elements, and B is a piezoelectric element that is an ultrasonic reception element. The position where the reflection source R is expected to exist by the combination of the piezoelectric element A and the piezoelectric element B is on the circumference of the reflection source ellipse E1. Similarly, the position where the reflection source R is expected to exist by the combination of the piezoelectric element C and the piezoelectric element B is on the circumference of the reflection source ellipse E2. The position where the reflection source R is considered to be present is narrowed down to one of the intersections Q1 and Q2 of the reflection source ellipse E1 and the reflection source ellipse E2.

  The shape of the reflection source R can be obtained not only when the reflection source R is as small as described above but also when the reflection source R has a size that cannot be ignored compared to the wavelength of the first ultrasonic signal. A method for obtaining the shape of the reflection source R will be described with reference to FIG. FIG. 8 is a schematic diagram illustrating a plurality of reflection source ellipses assuming that the reflection source R2 is a set of minute reflection sources. The reflection source R2 is assumed to be a quadrangle. A is a piezoelectric element that is an ultrasonic transmission element, and B is a piezoelectric element that is an ultrasonic reception element that is a point sound source. The first ultrasonic signal transmitted from the piezoelectric element A, which is an ultrasonic transmission element, is reflected by the reflection source R2, and the reflected wave is received by the piezoelectric element B, which is an ultrasonic reception element. Since the reflection source R2 has a quadrangular shape and each part forming the reflection source R2 can be regarded as a minute reflection source, a reflected wave is generated at each part of the reflection source R2. The relative position of each part exists on the circumference of the reflection source ellipse having the piezoelectric elements A and B as focal points as described above.

  Therefore, as shown in FIG. 8, the rectangular reflection source R2 is surrounded by the smallest reflection source ellipse E6 that is in contact with the reflection source R2 and the largest reflection source ellipse E3 that is also in contact with the reflection source R2. It can be said that there is a probability of existing on the circumference of a plurality of reflection source ellipses existing in the ellipse E4, 5).

  Actually, it can be considered that the reflection source that reflects the ultrasonic wave has a size at least equal to the wavelength of the first ultrasonic signal, so that the shape of the reflection source R2 is the same as that of the first ultrasonic signal. It can be considered that there are as many minute reflection sources as the number divided by the size. In FIG. 8, for the sake of simplicity, four reflection source ellipses are drawn. In order to further specify the shape of the reflection source R, as shown in FIG. 7, more piezoelectric elements that are ultrasonic transmission elements and piezoelectric elements that are ultrasonic reception elements are prepared. A plurality of reflection source ellipses are drawn. Then, the shape of the reflection source R2 is determined on the assumption that the portion where the drawn reflection source ellipses have a large overlap is a position where there is a high probability that the required reflection source R2 exists.

  Next, a measurement flow for actually measuring the shape of the reflection source R that reflects the first ultrasonic signal in the subject H will be described with reference to FIG.

  First, in step S1, the control unit 16 selects one transmission piezoelectric element using the channel switching circuit 12c and transmits the electrical signal produced by the function generator 12a and the linear amplifier 12b to the transmission unit 12. Then, the first ultrasonic signal is transmitted.

  Next, in step S2, the control unit 16 causes the reception unit 13 to generate a second ultrasonic signal generated by reflecting the transmitted first ultrasonic signal at the reflection source R in the subject H. The receiving element is selected and received.

  Next, in step S3, the signal processing unit 17 calculates the time from when the second ultrasonic signal is transmitted to when it is received, using the clock provided in the control unit 16 itself.

  Next, in step S <b> 4, the signal processing unit 17 calculates the coordinates of the reflection source ellipse as the relative position between the selected transmission element and the reception element, and stores it in the storage unit 18. Let That is, the control unit 16 functions as a means for calculating the relative position.

  Next, in step S5, the signal processing unit 17 selects another combination of the transmitting piezoelectric element and the receiving piezoelectric element, and proceeds to step S1. When the other combinations reach the predetermined number, the process proceeds to step S6, and the coordinates of each reflection source ellipse obtained for all the combinations of the transmitting piezoelectric element and the receiving piezoelectric element are called from the storage unit 18, and the respective coordinates are obtained. Find the part where there is a lot of overlap. For example, only the coordinates where the overlap has occurred a predetermined number of times are calculated and specified as a part of the coordinates of the reflection source R. This operation is performed for all the reflection source ellipses, the shape of the reflection source R is calculated, and the flow ends.

  Next, calculation results for performing shape measurement on a predetermined object to be measured in the subject H using the principle of measuring the shape according to the present embodiment will be described. FIG. 10 shows a predetermined object to be measured which is a measurement target. FIG. 10 is a two-dimensional object (also referred to as a phantom) that reflects the first ultrasonic signal. The phantom is an area surrounded by a white line, and the white line part reflects the first ultrasonic signal. The ultrasonic probe shown in FIG. 3 is used as the ultrasonic probe used for the calculation. The piezoelectric elements b and d are piezoelectric elements that transmit the first ultrasonic signal and receive the second ultrasonic signal, and the piezoelectric elements a, c, and e are piezoelectric elements that only transmit the first ultrasonic signal. And For each of the combinations of the transmission and reception piezoelectric elements, the reflection source ellipse shape, which is a set of positions having the probability that the reflection source R exists as described above, is obtained, and the obtained 10 reflection source ellipse shapes are obtained. The shape of the phantom is obtained by specifying a portion where the shape overlaps frequently.

  FIG. 11 shows the result of calculating the shape of the reflection source ellipse, which is a set of positions having the probability that the reflection source R exists in each combination. In FIGS. 9A to 9E, the piezoelectric element b is common to the receiving piezoelectric elements, and in the order of FIGS. 9A to 9E, the transmitting piezoelectric elements are a to e. In FIGS. 5F to 5J, the piezoelectric element d is common to the receiving piezoelectric element, and in the order of FIGS. 5F to 10J, the transmitting piezoelectric element is a to e.

  Thus, different calculation results of the phantom can be obtained for each combination of the transmitting piezoelectric element and the receiving piezoelectric element. Each calculation result is a calculation result with a predetermined position in the ultrasound probe 2 as a reference position. If these calculation results are calculated based on a predetermined reference position and the coordinates are combined to obtain a large pixel value, the result shown in FIG. 12 is obtained. FIG. 12 shows the calculation result of the phantom. In FIG. 12, the portion where the overlapping of the shape of the reflection source ellipse is large is displayed so as to be black. As shown in the figure, the portion having the same shape as the phantom is displayed in black, and it is proved that the principle of measuring the shape of the predetermined object in the subject H according to this embodiment is effective. It was.

  In the present embodiment, when an ultrasonic signal is transmitted to one piezoelectric element as described above, the piezoelectric element itself becomes a point sound source, but the point sound source is composed of a plurality of point sound sources. An assumed point sound source can also be used. This will be described below with reference to FIGS. FIG. 17 is a schematic diagram showing the state of an ultrasonic wavefront when ultrasonic signals are transmitted at predetermined time intervals in this order from piezoelectric elements a to e which are a plurality of point sound sources. The ultrasonic signals transmitted from the piezoelectric elements a to e form a plane wave, and the transmission direction of the plane wave can be arbitrarily changed by setting the time interval. By forming a plane wave, when there is an obstacle when the first ultrasonic signal is transmitted to the subject H, the first ultrasonic signal can be transmitted while avoiding the obstacle. Such a plane wave can be considered as a spherical wave propagated from a point sound source existing at infinity, but can also be treated as a spherical wave transmitted from a point sound source existing at a predetermined position at a predetermined time. For example, in FIG. 17, the position of the reflection source R can be obtained as described above, assuming that the assumed point sound source transmits the first ultrasonic signal to the position F at the timing when the plane wave passes through the piezoelectric element C. . The position F is a position where an assumed point sound source where a plane wave passing through the piezoelectric element C exists is present. The relative position between the assumed point sound source and the piezoelectric element A can be obtained as described above from the time when the plane wave passes through the assumed point sound source and the time when the second ultrasonic signal is reflected on the piezoelectric element A, for example.

  The assumed point sound source may exist on a plane wave, or one point sound source may be created from a plurality of point sound sources as shown in FIG. FIG. 18 is a schematic diagram showing a state of a wavefront in which one assumed point sound source is formed at a position F by collecting first ultrasonic signals transmitted from a plurality of point sound sources at one point at a predetermined time. is there. In FIG. 18, the ultrasonic signal transmitted from the piezoelectric elements a to e reaches the position F at a predetermined time. Waves that arrive at the same position at a predetermined time have the same phase, so it can be considered that an assumed point sound source exists at that position.

  Accordingly, assuming that the assumed point sound source has transmitted the first ultrasonic signal to the position F, the time at which the ultrasonic signal is transmitted to the assumed point sound source, and the time at which the second ultrasonic signal is reflected on the piezoelectric element A, for example. As described above, the relative position between the assumed point sound source and the piezoelectric element A can be obtained. In this way, by providing the assumed point sound source at a position where no actual piezoelectric element exists, the inside of the subject H can be diagnosed even when an obstacle exists.

  The ultrasonic diagnostic apparatus S may be configured as shown in FIG. 1, or an external general-purpose computer may serve as the control unit 16, the display unit 15, and the operation input unit 11. As the general-purpose computer, for example, a personal computer (personal computer) can be used. By using a personal computer, a small and low cost ultrasonic diagnostic apparatus S can be provided. FIG. 13 shows a schematic diagram of a configuration of an ultrasonic diagnostic apparatus using the personal computer P. The personal computer P includes a personal computer main body P1, a keyboard P2, and a display P3 such as a liquid crystal display. The main body P1 corresponds to the control unit 16, the keyboard P2 corresponds to the operation input unit 11, and the display P3 corresponds to the display unit 15. FIG. 14 is a block diagram showing an electrical configuration of the ultrasonic diagnostic apparatus S when the personal computer P is used. A control unit 16, a display unit 15, and an operation input unit 11 are arranged on a personal computer P outside the ultrasonic diagnostic apparatus S. In this way, when performing ultrasonic diagnosis using a general-purpose personal computer, ultrasonic diagnostic software necessary for ultrasonic diagnosis is installed in advance. The ultrasonic diagnostic software has a function of performing ultrasonic diagnosis using the function of a personal computer. The ultrasound diagnostic software also has a function of showing the procedure for performing the ultrasound diagnosis to the operator. Specifically, the procedure for operating the ultrasonic diagnostic apparatus is displayed on the display unit as the surgeon inputs in order using a keyboard or a mouse (not shown). A detailed explanation book by the help function, a specific handling explanation diagram, and a model example of the diagnostic operation example (video shooting operation example) are prepared by the ultrasonic diagnostic apparatus S, and a diagnostic image can be obtained even by a complete amateur. It is preferable that the explanation is prepared as described. This is because the ultrasonic diagnosis is non-invasive, so that a major problem does not occur even if it takes some time for failure or diagnosis. Further, it is preferable that the connection with the personal computer can be made by a USB cable or the like which is a commercially available connection function.

  The ultrasonic diagnostic software has a function of determining whether the function of the ultrasonic probe 2 is maintained normally. For example, the transmitting piezoelectric element can transmit a first ultrasonic signal having a predetermined intensity, or the receiving piezoelectric element has a predetermined intensity with respect to a second ultrasonic signal having a predetermined intensity. It is determined whether or not it can be converted into an electric signal. The determination may be performed for each piezoelectric element in order, or may be performed for a plurality of piezoelectric elements at once. Specifically, regarding the determination of the transmitting piezoelectric element, one transmitting piezoelectric element is driven, the first ultrasonic signal is received by the receiving piezoelectric element located in the vicinity thereof, and a predetermined intensity is obtained. It is determined whether the first ultrasonic signal is transmitted. Also, regarding the determination of the receiving piezoelectric element, the first ultrasonic signal is transmitted to one receiving piezoelectric element by the transmitting piezoelectric element located in the vicinity thereof, and a predetermined electric signal is output. Determine whether or not. These operations are performed on all the transmitting piezoelectric elements and the receiving piezoelectric elements.

  In the present embodiment, regarding the signal processing in the signal processing unit 17, in order to specify the coordinates of the reflection source R located at a deeper location in the subject H, the second ultrasonic signal is converted into the converted electrical signal. Less electrical noise is desired. Therefore, an encoded transmission / reception method is adopted. The encoded transmission / reception method refers to a method in which the strength of a received signal can be increased by encoding a signal to be transmitted. The outline | summary of the encoding transmission / reception method is demonstrated using FIG. FIG. 15A shows a case where the transmission waveform is not encoded, and FIG. 15B shows a case where the transmission waveform is encoded. As shown in FIG. 15A, when the transmission waveform is not encoded, when the ultrasonic probe 2 is driven with the drive pulse a1 using a function generator (not shown), it is converted into a first ultrasonic signal. In the process, an ultrasonic pulse having a waveform b 1 is generated by the transfer function of the ultrasonic probe 2 and transmitted toward the subject H. When this is reflected by the reflection source R in the subject H and returned as a second ultrasonic signal, it is received by the ultrasonic probe 2 and converted into an electric signal, and converted into a digital signal by the AD converter 21. Is output. At this time, since it is again deformed by the transfer function, the received signal has a waveform c1. The amplitude obtained in this way is the signal strength. In the ultrasonic image, since the distance from the time until the pulse returns to the reflection source R is obtained, the distance resolution is about the width of the waveform c1 which is the pulse-like waveform, and in the case of the figure, the wavelength is about 3 times. Become.

  On the other hand, in the case of the encoded transmission / reception method, as shown in FIG. 15 (b), a drive encoded pulse a2 that is produced using a predetermined drive encoded pulse forming means (not shown) and that is elongated in the time axis direction is used. Use. When the ultrasonic probe 2 is driven by the drive encoded pulse a2, the first ultrasonic signal having the waveform b2 is transmitted from the ultrasonic probe 2 into the subject H, and is reflected by the reflection source R in the subject H. It is reflected and returned as a second ultrasonic signal. When it is converted again into an electrical signal by the ultrasonic probe 2, a waveform c2 is obtained. Then, processing corresponding to the drive encoded pulse a2 is performed by using the decoding filter 20 which is a drive encoded pulse decoding means to shorten the waveform c2 on the time axis by the length of the drive signal. As a result, compared to the waveform c1, the decoded waveform d2 has the same distance resolution and a high signal strength. Thus, the transmission energy can be increased without increasing the amplitude in the subject H. According to the encoded transmission / reception method, the reflected ultrasonic wave that has passed through the subject H is converted into an electrical signal by the ultrasonic probe, and then received by compressing in the time axis direction while maintaining the signal energy. The signal is converted into a pulse signal having a large peak value.

  When the encoded transmission / reception method is employed in the ultrasonic diagnostic apparatus S, a drive encoded pulse forming unit and a drive encoded pulse decoding unit are provided in the electric circuit of the ultrasonic diagnostic apparatus S.

  Specifically, in the block diagram showing the electrical configuration of the ultrasonic diagnostic apparatus S shown in FIG. 2, the function generator 12a in the transmission unit 12 is used as drive coding pulse forming means, and drive coding is performed in the signal processing unit 17. What is necessary is just to provide the function of the decoding filter 20 which is a pulse decoding means.

  As an example of the encoded transmission waveform, there is a Barker code composed of pulses having amplitude values of +1 and −1 and different phases. FIG. 16 is a schematic diagram showing an example of a 13-bit Barker code. In FIG. 16, the horizontal axis represents time, and the vertical axis represents the amplitude value.

  As described above, according to the present embodiment, by adopting a new principle for measuring the shape of the reflection source R in the subject H, an ultrasonic image can be obtained at low cost with a small number of piezoelectric elements. Can be provided.

  Further, according to the present embodiment, by providing the assumed point sound source at a position that does not exist in the actual piezoelectric element, the inside of the subject H can be diagnosed even when an obstacle exists.

  Further, according to the present embodiment, by adopting an encoded transmission / reception method for transmission / reception of an ultrasonic signal, the second ultrasonic signal can be converted into an electric signal with little electric noise, and the coordinates of the reflection source R can be changed. It is possible to easily identify a deeper place in the specimen H.

DESCRIPTION OF SYMBOLS 1 Ultrasonic diagnostic apparatus main body 2 Ultrasonic probe 3 Cable 11 Operation input part 12 Transmission part 13 Reception part 14 Image processing part 15 Display part 16 Control part 17 Signal processing part 18 Memory | storage part 20 Decoding filter 21 AD converter 23 Acoustic braking Member 24 Acoustic separation unit 25 Common ground electrode 27 Acoustic matching layer 28 Individual electrode 29 Protection circuit A, a, B, b, C, c, d, e Piezoelectric element R, R2 Reflection source S Ultrasonic diagnostic apparatus

Claims (3)

A transmission means having a plurality of transmission elements capable of transmitting an ultrasonic signal into the subject, and transmitting one ultrasonic signal by selecting one transmission element from the plurality of transmission elements; ,
The first ultrasonic wave having a plurality of receiving elements capable of receiving an ultrasonic signal, selecting one receiving element from the plurality of receiving elements, and transmitting the selected transmitting element Receiving means for receiving a second ultrasonic signal generated by reflecting a signal from a reflection source in the subject;
After the selected transmission element transmits the first ultrasonic signal, the time until the selected reception element receives the second ultrasonic signal is measured, and the selected transmission element is selected. Calculating means for calculating a relative position having a probability that the reflection source is present with respect to the received element;
Control means for controlling the transmission means, the reception means, and the calculation means;
The control means performs an operation of selecting one each from the plurality of transmitting elements and the plurality of receiving elements and causing the calculation means to calculate a relative position having a probability that the reflection source exists. A position that is implemented with respect to a predetermined combination of a plurality of transmitting elements and a plurality of receiving elements and has a high probability that the reflection source exists based on a calculation result of all relative positions having the probability that the reflection source exists. An ultrasonic diagnostic apparatus characterized by calculating A transmission means having a plurality of transmission elements capable of transmitting an ultrasonic signal into the subject, and transmitting a first ultrasonic signal by selecting a plurality of transmission elements from the plurality of transmission elements; ,
The first ultrasonic wave having a plurality of receiving elements capable of receiving an ultrasonic signal, selecting one receiving element from the plurality of receiving elements, and transmitting the selected transmitting element Receiving means for receiving a second ultrasonic signal generated by reflecting a signal from a reflection source in the subject;
The virtual transmission element that combines the plurality of selected transmission elements transmits the first ultrasonic signal and then measures the time until the selected reception element receives the second ultrasonic signal. Calculating means for calculating a relative position having a probability that the reflection source is present with respect to the virtual transmitting element and the selected receiving element;
Control means for controlling the transmission means, the reception means, and the calculation means;
The control means performs an operation of selecting one from each of the virtual transmission element and the plurality of reception elements and causing the calculation means to calculate a relative position having a probability that the reflection source exists. It implements for a predetermined combination of a trusted element and the plurality of receiving elements, and calculates a position where the probability that the reflection source exists is high based on calculation results of all relative positions where the reflection source exists. An ultrasonic diagnostic apparatus. The transmission means includes drive encoded pulse forming means for generating a first ultrasonic signal that is a drive encoded pulse,
The ultrasonic diagnostic apparatus according to claim 1, wherein the reception unit includes a decoding unit that decodes the second ultrasonic signal.