JP2009210271A - Ultrasonic imaging device and ultrasonic imaging program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic imaging device and an ultrasonic imaging program can high-speed synthetic aperture process, even when a distance to an object is long and a round-trip propagation time is required. <P>SOLUTION: According to this ultrasonic imaging device, a transmission time interval t is defined in a range wherein a transmission ultrasonic wave from each piezoelectric element does not interfere with each other even when being reflected by an imaging domain A and returned, and wherein the transmission ultrasonic wave does not directly interfere with a reception ultrasonic wave, by using the maximum distance and the minimum distance between each piezoelectric element T<SB>NN</SB>constituting an ultrasonic probe and the imaging domain by the ultrasonic wave. The device transmits the ultrasonic wave by using the defined transmission time interval t, and executes aperture synthetic processing by using the obtained reflected wave. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic image processing apparatus that generates ultrasonic images using ultrasonic waves reflected from a target object, and an ultrasonic image. Related to the program.

  Since radio waves are not sufficiently transmitted in the sea, sonar using a sound wave is used to image the position and shape of an object having a distance greater than transparency. It is known that when ultrasonic waves having a high frequency are used among sonars, the wavelength is reduced and the image resolution is improved. That is, the resolution of an imaging apparatus using such ultrasonic reflection is proportional to the wavelength of the ultrasonic wave, but at the same time is proportional to the distance to the target object and inversely proportional to the size (aperture length) of the transducer. Therefore, in order to improve the image resolution of an object with a long distance, it is conceivable to increase the aperture length by using synthetic waves using the reflected waves of a plurality of ultrasonic transducers.

  However, the propagation speed of ultrasonic waves in the sea is approximately 1500 m per second. For example, in order to receive a reflected wave of an object at a distance of 100 m, it takes about 0.13 seconds of round-trip propagation time after transmission. Become. Accordingly, when the next combination of transmission and reception is sequentially performed after the transmission and reception of one set of ultrasonic transducers is completed as in the single-around method, the number of times of transmission and reception at the synthetic aperture × the round-trip propagation time is required. Become.

In addition, as a well-known document relevant to this application, there exist the following, for example.
JP-A-4-206588 JP-A-3-174098

  In this way, an imaging device (ultrasonic imaging device) using ultrasonic reflection whose propagation speed is slower than that of light or the like requires a round-trip propagation time to an object, and consists of a combination of a large number of transmissions and receptions. When the synthetic aperture method is used, it takes time to synthesize an image, and there are problems such as a decrease in imaging accuracy of a moving object and a failure to create a moving image.

  The present invention has been made in view of the above, and an ultrasonic imaging apparatus and an ultrasonic image that enable high-speed synthetic aperture processing even when the distance to an object is long and a round-trip propagation time is required Or to provide a program.

  In order to achieve the above object, the present invention takes the following measures.

  According to the first aspect of the present invention, there is provided an ultrasonic probe having a plurality of piezoelectric elements each of which transmits an ultrasonic wave in response to a supplied drive signal and receives an ultrasonic wave to generate an electric signal; From the maximum distance and the minimum distance between each piezoelectric element and the imaging area to be imaged, ultrasonic waves transmitted from any of the plurality of piezoelectric elements are reflected by the imaging area, and Calculating means for calculating the shortest time and the longest time until reception by any one of the piezoelectric elements, and determining the ultrasonic transmission time interval based on the shortest time and the longest time, and the transmission time interval According to the control means for controlling the supply timing of the drive signal to the plurality of piezoelectric elements, and the reflected waves of the ultrasonic waves transmitted according to the transmission time interval, thereby receiving the electric signals generated by the plurality of piezoelectric elements. Trust Using an ultrasonic imaging apparatus characterized by comprising an image generating device which generates an ultrasound image.

  According to a fourth aspect of the present invention, there is provided an ultrasonic imaging apparatus having a plurality of piezoelectric elements, each of which transmits an ultrasonic wave in response to a supplied drive signal and receives the ultrasonic wave to generate an electric signal. From the maximum distance and the minimum distance between each piezoelectric element and the imaging area, the ultrasonic waves transmitted from any of the plurality of piezoelectric elements are reflected on the imaging area and transmitted to the computer. Based on the calculation function for calculating the shortest time and the longest time until reception at any of the elements, and the shortest time and the longest time, an ultrasonic transmission time interval is determined, and according to the transmission time interval, Each of the electric power generated by the plurality of piezoelectric elements is received by receiving a control function for controlling the supply timing of the drive signal to the plurality of piezoelectric elements and a reflected wave of the ultrasonic wave transmitted according to the transmission time interval. With No. is an ultrasound imaging program characterized by realizing an image generating function of generating an ultrasonic image.

  As described above, according to the present invention, it is possible to realize an ultrasonic imaging apparatus and an ultrasonic image or a program that enable high-speed synthetic aperture processing even when the distance to an object is long and a round-trip propagation time is required. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

  FIG. 1 is a block diagram of an ultrasonic image processing apparatus 1 according to this embodiment. As shown in the figure, the ultrasonic image processing apparatus 1 includes an ultrasonic probe 10, an amplifier 12, an A / D converter 14, a distance signal calculation circuit 16, an image generation circuit 18, a transmitter 20, a switching circuit 22, A transmission control unit 24, a display control unit 26, a display unit 28, and an operation unit 30 are provided.

The ultrasonic probe 10 has a plurality of piezoelectric elements T ₁₁ , T ₂₁ ,..., T _NN arranged in a matrix. Each piezoelectric element generates an ultrasonic wave based on the supplied drive signal, and receives the ultrasonic wave to generate an electric signal having a predetermined waveform.

  The amplifier 12 amplifies the received ultrasonic wave generated by each piezoelectric element and sends it to the A / D converter 14.

  The A / D converter 14 performs A / D conversion (analog / digital conversion) on the amplified received signal received from the amplifier 12.

  The distance signal calculation circuit 16 calculates the distance between the object to be imaged and each piezoelectric element based on the received signal after A / D conversion.

The image generation circuit 18 generates an ultrasonic image of the object for each piezoelectric element (each channel) based on the positional information of each piezoelectric element and the calculated distance between the object to be imaged and each piezoelectric element. Generate. Here, the channel means a receiving system including an amplifier 12, an A / D converter 14, a distance signal calculation circuit 16, and an image generation circuit 18 provided for each piezoelectric element _TNN .

  The transmitter 20 repeatedly generates a drive signal for forming a transmission ultrasonic wave at a predetermined rate frequency fr Hz (period: 1 / fr second).

  The switching circuit 22 switches the switch according to the control signal from the transmission control unit 24, and supplies the drive signal from the transmitter 20 to a predetermined piezoelectric element at a predetermined timing.

  The transmission control unit 24 performs selection of a piezoelectric element that supplies a drive signal from the transmitter 20, control related to supply timing (supply interval), and reception timing control of reflected ultrasonic waves by each piezoelectric element. In particular, the transmission control unit 24 supplies a drive signal to each piezoelectric element (that is, ultrasonic transmission from each piezoelectric element) and reflects by each piezoelectric element in accordance with an aperture synthesis function using the maximum / minimum distance described later. Control the timing of ultrasonic reception.

  The display control unit 26 combines the ultrasonic images for each channel generated by the image generation circuit 18 and generates an ultrasonic image indicating the shape, internal structure, and the like of the imaging target.

  The display unit 28 displays the ultrasonic image generated by the display control unit 26 in a predetermined form.

  The operation unit 30 includes various switches, buttons, a trackball 13s, a mouse 13c, a keyboard 13d, and the like for incorporating various instructions, condition setting instructions, various image quality condition setting instructions, and the like from the operator into the apparatus main body 1. ing.

(Aperture synthesis function using maximum / minimum distance)
Next, the aperture synthesis function using the maximum / minimum distance of the ultrasonic imaging apparatus 1 will be described. This function is to perform aperture synthesis using the maximum distance and the minimum distance among the distances between the piezoelectric elements _TNN constituting the ultrasonic probe 10 and the ultrasonic imaging region.

Calculation of minimum path _{L 1} and the maximum path _{L 2]}
FIG. 2 is a diagram showing a positional relationship between each piezoelectric element _TNN and the imaging region A. The imaging area A is an area to be imaged with ultrasound. In the example shown in FIG. 2, the imaging region A is a distance from the center of the surface where the piezoelectric elements _TNN of the ultrasonic probe 10 are arranged in a matrix (that is, the ultrasonic transmission / reception surface) to the center of the imaging region A. H ₀ is defined as a rectangular parallelepiped region having a depth of 2ΔH, a width of 2W, and a height of 2H in a form orthogonal to the irradiation surface of the ultrasonic probe.

In such a positional relationship, an orthogonal coordinate system orthogonal to the irradiation surface of the ultrasonic probe 10 is set, and the maximum distance and the minimum distance between the piezoelectric element _TNN and the ultrasonic imaging region are calculated.

FIG. 3 shows the minimum distance L ₁ between the imaging region A set in FIG. 2 and each piezoelectric element _TNN of the ultrasonic probe 10. As shown in the figure, if the directly opposite as the imaging region A and the matrix ultrasonic probe 10 Togazu 3, the minimum distance L ₁ can be expressed by the following equation (1).

L ₁ = 2 (H ₀ −ΔH) (1)
FIG. 3 shows the maximum distance L ₂ between the imaging region A set in FIG. 2 and each piezoelectric element _TNN of the ultrasonic probe 10. The maximum distance L ₂ is somewhat different depending originating from any piezoelectric element. For example, when facing each other as shown in FIG. 4, in the case of transmitting from the piezoelectric element in the center of the irradiation surface of the ultrasonic probe 10, the distance to the end point of the imaging region A farthest from the transmitting piezoelectric element and L _21, the sum of the distance L ₂₂ from the end point of the previous image region a to a piezoelectric element located on the irradiated surface of the diagonal opposite the ultrasonic probe 10 becomes maximum distance.

That is, when the center of the ultrasonic probe 10 and the center of the imaging region are arranged at the minimum distance H ₀ as shown in FIG. 2 and the transmitting piezoelectric element is at the center of the ultrasonic probe 10, L ₂₁ , L ₂₂ and L ₂ are given by the following equations, respectively.

L ₂₁ = (H ₀ + ΔH) ² + D ² + W ² ) ^0.5 (2)
L ₂₂ = (H ₀ + ΔH) ² + (D + d) ² + (W + d) ² ) ^0.5 (3)
L ₂ = L ₂₁ + L ₂₂ (4)
Here, d indicates half of the length of one side of the ultrasonic irradiation surface formed by the piezoelectric element of the ultrasonic probe 10 shown in FIG.

In the example of FIGS. 2 to 4 described above, the minimum distance L ₁ and the maximum distance L ₂ are defined by an orthogonal coordinate system in which the imaging region A is a rectangular parallelepiped region and the ultrasonic irradiation surface of the ultrasonic probe 10 is a reference. And defined. However, this expression is merely an example, and the technical idea of the present invention is not limited to this example. For example, the minimum distance L ₁ and the maximum distance L ₂ may be defined by another expression such as a cylindrical coordinate system (radius and height) or a spherical coordinate system (distance from the center).

In particular, since the ultrasonic wave transmitted from the piezoelectric element is generally transmitted with a beam shape having a certain width, for example, the transmitted ultrasonic wave is transmitted to the range of the truncated cone having the transmission position as the apex. Therefore, it is a preferable example to define the imaging region A as a truncated cone region. In such a case, the minimum distance L ₁ and the maximum distance L ₂ can be calculated as follows.

FIG. 5 is a diagram showing the positional relationship between each piezoelectric element _TNN and the imaging area A as a truncated cone area. As shown in the figure, the length to the innermost part of the imaging area A is D, and the radius of the truncated cone in D is R. At this time, if the depth length of the image region and H, the minimum distance L ₁ can be obtained by the following equation (5).

L ₁ = D−H (5)
FIG. 6 shows the maximum distance L ₂ between the imaging region A set in FIG. 5 and each piezoelectric element _TNN of the ultrasonic probe 10. As shown in the figure, the distance L ₂₁ from the transmitting piezoelectric element to the end point of the imaging region A is on the irradiation surface of the ultrasonic probe 10 diagonally opposite from the end point of the previous imaging region A. the sum of the distance L ₂₂ to the piezoelectric element becomes the maximum distance.

That is, when the center of the ultrasonic probe 10 and the center of the imaging region are arranged at the minimum distance H0 as shown in FIG. 2 and the transmitting piezoelectric element is at the center of the ultrasonic probe 10, L ₂₁ , L ₂₂ , L ₂ are given by the following equations, respectively.

L ₂₁ = (R ² + D ² ) ^0.5 (6)
L ₂₂ = (d ² + (R + d) ² + D ² ) ^0.5 (7)
L ₂ = L ₂₁ + L ₂₂ (8)
Further, when the imaging region A is a truncated cone region and transmission / reception from each piezoelectric element of the ultrasonic probe 10 is considered in this way, the imaging region A overlaps the truncated cone regions corresponding to the piezoelectric elements. It becomes an area.

FIG. 7 and FIG. 8 are diagrams conceptually showing an imaging area A defined by overlapping the truncated cone areas corresponding to the piezoelectric elements. As shown in each figure, the hatched area a (the area shown by hatching) at the depth D is an imaging area A obtained by superimposing all the truncated cone areas corresponding to the piezoelectric elements. In this case, the minimum distance L ₁ is defined by the following equation (9).

L ₁ = D−H (9)
On the other hand, the maximum distance L _2, the region b where the beam transmitted from the piezoelectric element existing at the end of the ultrasonic probe 10 reaches in depth D includes a shaded region a. In this case, the maximum distance L ₂ may be obtained by the following calculation.

L ₂₁ = (R ² + D ² ) ^0.5 (10)
L ₂₂ = (d ² + (R + D) ² + D ² ) ^0.5 (11)
L ₂ = L ₂₁ + L ₂₂ (12)
Thus, if the position of each piezoelectric element of the ultrasonic probe 10 and the imaging region A are set, the transmission piezoelectric element is included depending on which piezoelectric element on the ultrasonic probe 10 is transmitted. in case of receiving a piezoelectric element of the ultrasonic probe 10, the minimum path of the ultrasonic wave reflected in the image region a comes back to the ultrasonic probe 10 L ₁ and the maximum path L ₂ is specified. In the ultrasonic imaging apparatus 1, the minimum path L ₁ based on the spatial information of the imaging area A set in advance (that is, the center position, H ₀ , D, W, ΔH in the example of FIG. 2). And the maximum path L ₂ is calculated in the distance signal calculation circuit 16.

[Calculation of transmission time interval and reception time interval]
Outgoing call control part 24 uses the minimum path L ₁ and the maximum path L ₂ of each of the piezoelectric elements are calculated as described above, the drive signal of the transmission time interval (transmitter 20 of the ultrasonic example, as follows The transmission time interval, the supply time interval of the drive signal to each piezoelectric element) and the ultrasonic reception time interval are calculated.

If the speed of sound in the medium is C, it takes a minimum of L ₁ / C and a maximum of L ₂ / C until it is reflected by the imaging area A and returns after transmission. That is, since the reflected wave does not return from the imaging area A unless the time of L ₁ / C elapses at the minimum, even if the next ultrasonic wave is transmitted at an interval equal to or less than L ₁ / C, interference occurs on the receiving side. There is nothing. On the contrary, since the reflected wave from the imaging region A returns between L ₁ / C and L ₂ / C in the time after transmission, it is transmitted at a time interval of (L ₂ −L ₁ ) / C or less. The received ultrasonic waves have overlapping reception times.

On the other hand, in order to prevent interference on the receiving side, it is necessary to transmit ultrasonic waves at a time interval larger than (L ₂ −L ₁ ) / C.

FIG. 9 is a diagram for explaining a transmission interval for preventing interference on the receiving side, and shows a case where ultrasonic waves are transmitted in the order of four piezoelectric elements 10a to 10d, for example. In this example, when the transmission time interval t _t is in the range of the following expression (13), even if each transmission ultrasonic wave is reflected back from the imaging region A and does not interfere, It can be seen that the sound wave and the received ultrasonic wave are not mixed directly.

(L ₂ −L ₁ ) / C <t _t <L _t / (3C) (13)
Equation (13) can be generalized as follows, where the number of piezoelectric elements is M. That is, when performing transmission of M ultrasonic waves, in order to finish all transmissions before the first transmission ultrasonic wave returns, the time interval is generally set to L ₁ / {(M−1) C} or less. There is a need. Therefore, in the case of the present embodiment, the transmission time interval can be set as in the following equation (14).

(L ₂ −L ₁ ) / C <t _t <L ₁ / {(M−1) C} (14)
When the above time interval is verified with a real value, it is as follows. That is, as shown in FIG. 2, when the center of the ultrasound probe 10 and the center of the imaging region A are facing each other and 100 m away, the size of the ultrasound probe 10 is d = 0.5 m, and the imaging region A Is W = D = 1 m and ΔH = 0.5 m, the minimum path L ₁ and the maximum path L ₂ are as follows.

L ₁ = 2 × (100−0.5) = 199 m
L ₂ = {(100 + 0.5) ² +1 ² +1 ² } ^0.5
+ {(100 + 0.5) ² + (1 + 0.5) ² + (1 + 0.5) ² } ^0.5
= 100.51 + 100.52 = 201.03m
When the medium is water, the sound speed is approximately 1500 m per second, so the following equation (15) is obtained.

(L ₂ −L ₁ ) / C = (201.3-199) /1500=0.00135 seconds (15)
When the ultrasonic probe 10 is mounted with 8 × 8 = 64 piezoelectric elements and 64 transmissions are performed, the following is performed.

L ₁ /{(M−1)C}=199/(63×1500)=0.0002 seconds Therefore, if 64 ultrasonic waves are transmitted at a time interval of 0.00135 seconds or more and 0.0021 seconds or less, It is possible to receive without interference.

Further, by providing a gate time even at the time of reception, it is possible to specify which piezoelectric element (that is, channel) the received reflected wave corresponds to the ultrasonic wave transmitted by. For example, as shown in FIG. 10, the transmission start time is T ₃ and the transmission end time is T ₄ , and the ultrasonic wave reaches the imaging region A from the transmitted piezoelectric element and is reflected and reflected on the ultrasonic probe 10. If the minimum path until any piezoelectric element returns is L ₃ and the maximum path is L ₄ , the transmission time interval t _t can be taken as in the following expression (16) as in the expression (14). In this case, the received ultrasonic waves from the previous and next transmissions do not overlap.

(L ₄ −L ₃ ) / C <t <L ₃ / {(M−1) C} (16)
Further, since the reflected wave in the imaging region A returns to the time from T ₃ + L ₃ / C to T ₄ + L ₄ / C, all the reflected waves received in this time zone are from a specific piezoelectric element. You can see that it is outgoing. The reception control according to the gate time is used for control of reception timing by the switching circuit 22 or control for specifying a piezoelectric element in the image generation circuit 18.

(Operation)
Next, the operation in the process according to the aperture synthesis function using the maximum / minimum distance of the ultrasonic imaging apparatus 1 (hereinafter simply referred to as “aperture synthesis process”) will be described.

FIG. 11 is a flowchart showing the flow of the aperture synthesis process of the ultrasonic imaging apparatus 1. As shown in the figure, first, position information (center position, depth, height, width) of the imaging region A including the object whose shape is to be detected is input from the operation unit 30 (step S1). The distance signal calculation circuit 16 is configured to input the minimum distance L ₁ between each piezoelectric element and the imaging area A based on the input positional information about the imaging area A and the previously stored position information about each piezoelectric element. calculating the maximum distance _{L 2} (step S2).

Next, the transmission control unit 24 sets (L ₂ −L ₁ ) / C <t _t <L ₁ / C, where C is the sound speed of the medium.
The switching circuit 22 is controlled so that the piezoelectric elements are switched at a transmission time interval t _t that satisfies the above, and control related to ultrasonic transmission is performed (step S3). As a result, the ultrasonic transmission is executed without directly mixing the transmission ultrasonic wave and the reception ultrasonic wave.

Next, each piezoelectric element of the ultrasonic probe 10 receives the reflected wave from the object and generates an electric signal based on the received wave (step S4). The distance signal calculation circuit 16 calculates the distance between the object to be imaged and each piezoelectric element based on the received signal after A / D conversion. For example, the image generation circuit 18 sets the transmission start time of the specific piezoelectric element to T ₃ and the end time to T _4, and sets the shortest distance from the piezoelectric element in the setting space to return to the ultrasonic probe 10 as L ₃ , when the maximum distance was _{L 4,} as the next time T _R, originating the signals received in the _{T 3 + L 3 / C <} T R <T 4 + L 4 / C time from a specific originating sensor Aperture synthesis is performed (step S5). Further, the image generation circuit 18 executes this aperture synthesis for all the piezoelectric elements (step S6).

  The display control unit 26 uses the aperture synthesis result for each channel generated in the image generation circuit 18 to generate an ultrasonic image indicating the shape, internal structure, and the like of the imaging target. The display unit 28 displays the ultrasonic image generated by the display control unit 26 in a predetermined form (step S7).

(effect)
According to the configuration described above, the following effects can be obtained.

According to this ultrasonic imaging apparatus, from each of a plurality of piezoelectric elements, using the maximum distance and the minimum distance between each piezoelectric element _TNN constituting the ultrasonic probe and the ultrasonic imaging region. The shortest time and the longest time until the transmitted ultrasonic wave is reflected by the imaging region and received by any of the plurality of piezoelectric elements are calculated, and the transmitted ultrasonic wave from each piezoelectric element is calculated in the imaging region A. The transmission time interval is defined within a range in which interference does not occur even when reflected and returns, and transmission ultrasonic waves and reception ultrasonic waves are not directly mixed. Therefore, even when the distance between the ultrasonic probe and the target object is long and the propagation time from when the ultrasonic wave is transmitted until it is reflected by the target object is long, multiple piezoelectric elements on the ultrasonic probe are used. Thus, it is possible to shorten the transmission time interval of ultrasonic waves when performing the synthetic aperture processing, and the image resolution can be improved.

Further, in this ultrasonic imaging apparatus, a gate time is provided even at the time of reception by using the maximum distance and the minimum distance between each piezoelectric element _TNN constituting the ultrasonic probe and the ultrasonic imaging area. Thus, it is possible to specify which piezoelectric element (channel) the received reflected wave corresponds to the ultrasonic wave transmitted. Therefore, it is possible to easily specify with a simple device configuration which piezoelectric element the received signal is caused by the ultrasonic wave transmitted from.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. As a specific modification, for example, the function according to the present embodiment can be realized by installing a program for executing the processing in a computer such as a workstation and developing the program on a memory. At this time, a program capable of causing the computer to execute the technique is stored in a recording medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), or a semiconductor memory. It can also be distributed.

  In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  As described above, according to the present invention, it is possible to realize an ultrasonic imaging apparatus and an ultrasonic image or program that enable high-speed synthetic aperture processing even when the distance to an object is long and a round-trip propagation time is required. .

FIG. 1 is a block diagram of an ultrasonic image processing apparatus 1 according to this embodiment. FIG. 2 is a diagram showing a positional relationship between each piezoelectric element _TNN and the imaging region A. FIG. 3 shows the maximum distance L ₁ between the imaging region A set in FIG. 2 and each piezoelectric element _TNN of the ultrasonic probe 10. FIG. 4 shows the minimum distance L ₂ between the imaging region A set in FIG. 2 and each piezoelectric element _TNN of the ultrasonic probe 10. FIG. 5 is a diagram showing the positional relationship between each piezoelectric element _TNN and the imaging area A as a truncated cone area. FIG. 6 shows the maximum distance L ₂ between the imaging region A set in FIG. 5 and each piezoelectric element _TNN of the ultrasonic probe 10. FIG. 7 is a diagram conceptually showing an imaging area A defined by superposition of the truncated cone areas corresponding to the piezoelectric elements. FIG. 8 is a diagram conceptually showing an imaging area A defined by superposition of the truncated cone areas corresponding to the piezoelectric elements. FIG. 9 is a diagram for explaining a transmission interval for preventing interference on the receiving side, and shows a case where ultrasonic waves are transmitted in the order of four piezoelectric elements 10a to 10d, for example. FIG. 10 is a diagram for explaining the gate time at the time of reception. FIG. 11 is a flowchart showing the flow of the aperture synthesis process of the ultrasonic imaging apparatus 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic imaging apparatus, 10 ... Ultrasonic probe, 12 ... Amplifier, 14 ... A / D converter, 16 ... Distance signal arithmetic circuit, 18 ... Image generation circuit, 20 ... Transmitter, 22 ... Switching circuit, 24 ... Transmission control unit, 26 ... Display control unit, 28 ... Display unit, 30 ... Operation unit

Claims (4)

An ultrasonic probe having a plurality of piezoelectric elements each transmitting ultrasonic waves in response to a supplied drive signal, receiving ultrasonic waves and generating electrical signals;
From the maximum distance and the minimum distance between each piezoelectric element and the imaging area to be imaged, ultrasonic waves transmitted from any of the plurality of piezoelectric elements are reflected by the imaging area. A calculation means for calculating a shortest time and a longest time until reception by any one of the plurality of piezoelectric elements;
Control means for determining an ultrasonic transmission time interval based on the shortest time and the longest time, and controlling the supply timing of the drive signal to the plurality of piezoelectric elements according to the transmission time interval;
An image generation means for generating an ultrasonic image using each electrical signal generated by the plurality of piezoelectric elements by receiving reflected ultrasonic waves transmitted according to the transmission time interval;
An ultrasonic imaging apparatus comprising: The calculating means calculates the transmitted ultrasonic wave from the maximum distance and the minimum distance between each piezoelectric element and the imaging region, and the start time and the end time of ultrasonic transmission in each piezoelectric element. Calculating the shortest time and the longest time for each of the piezoelectric elements to be reflected by the conversion region and received by any of the plurality of piezoelectric elements,
The image generation means generates the ultrasonic image using an electrical signal for each of the piezoelectric elements based on the shortest time and the longest time;
The ultrasonic imaging apparatus according to claim 1.   The ultrasonic imaging apparatus according to claim 1, wherein the imaging region is a rectangular parallelepiped region or a truncated cone region. Each of the computers of the ultrasonic imaging apparatus having a plurality of piezoelectric elements that transmit an ultrasonic wave in response to the supplied drive signal and receive the ultrasonic wave to generate an electrical signal,
From the maximum distance and the minimum distance between each of the piezoelectric elements and the imaging area to be imaged, an ultrasonic wave transmitted from any of the plurality of piezoelectric elements is reflected by the imaging area. A calculation function for calculating the shortest time and the longest time until reception at any one of the plurality of piezoelectric elements;
A control function for determining an ultrasonic transmission time interval based on the shortest time and the longest time, and controlling a supply timing of a drive signal to the plurality of piezoelectric elements according to the transmission time interval;
An image generation function for generating an ultrasonic image using each electrical signal generated by the plurality of piezoelectric elements by receiving reflected ultrasonic waves transmitted according to the transmission time interval;
An ultrasonic imaging program characterized by realizing the above.

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