JP2007082733A - Acoustic image imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the diameters of a cable even when the number of ultrasonic vibrators constituting an ultrasonic vibrator array is increased by reducing the number of wiring drawn out from an ultrasonic transducer. <P>SOLUTION: Each piezoelectric elements 1a of a piezoelectric element array 1 is electrically connected to each charge storage section 2a constituting a charge-coupled device 2. The piezoelectric element array 1 is provided with acoustic lenses 6. An ultrasonic transmission means 7 composed of an ultrasonic emitting section 8 and a drive section 9 emits ultrasound on the basis of a drive signal from the drive section 9. Echoes reflected at positions having differences in acoustic impedance fall on the piezoelectric element array 1. Signal charges stored in the charge storage section 2a of the charge-coupled device 2 are transmitted to a transmission section, and image signals are outputted to an image signal processing circuit 4 via a cable 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sound image imaging apparatus used for acquiring information related to a body tissue of a subject.

  2. Description of the Related Art An endoscope and an ultrasonic diagnostic device are available as devices for inserting into a subject's body and performing examinations and diagnoses. The endoscope includes an insertion portion that is inserted into the body, and an endoscope observation means that includes an illumination portion and an observation portion is provided at the distal end of the insertion portion. Therefore, the in-vivo image by the observation unit can be acquired by inserting the insertion unit into the body and illuminating the body cavity with the illumination light from the illumination unit.

  The ultrasonic diagnostic apparatus also has an ultrasonic transducer, transmits an ultrasonic pulse from the ultrasonic transducer toward the body, receives a reflected echo from a tomographic part of the body tissue, and performs predetermined signal processing. By doing so, an ultrasound image is constructed. This ultrasonic transmission / reception is performed from the outer skin of the body, and the one inserted into the body to transmit / receive ultrasonic waves from the body wall is also used. In the case of insertion into the body, an insertion portion into the body is provided as in the case of an endoscope, but this insertion portion is inserted into the body alone or using an endoscope or other device as guide means.

In order to construct an ultrasonic image over a predetermined range, ultrasonic scanning is performed by an ultrasonic transducer, and there are a mechanical scanning type and an electronic scanning type as scanning methods. As disclosed in, for example, Patent Document 1, an electronic scanning ultrasonic transducer constitutes an ultrasonic transducer array by arranging a large number of ultrasonic transducers in a line or plane. Each of these ultrasonic transducers is individually driven, or a plurality of ultrasonic transducers are driven simultaneously or with a predetermined time difference. Accordingly, wiring is individually connected to each ultrasonic transducer constituting the ultrasonic transducer that performs electronic scanning, and a delay circuit is connected to each.
JP 2002-238906 A

  By the way, as described above, when wiring is connected to each ultrasonic transducer constituting the ultrasonic transducer array of the ultrasonic transducer, a large number of wirings are required, and the ultrasonic wave obtained by operating this ultrasonic transducer is obtained. In order to improve the resolution of the sound image, an extremely large number of ultrasonic transducers must be arranged. For this reason, the number of wirings connected to the ultrasonic transducer becomes enormous. These wirings are integrated into one cable, but as the number of wirings increases, the cable diameter increases accordingly. In an ultrasonic diagnostic apparatus that performs ultrasonic scanning from the outer skin, even if the cable becomes thick, there is no particular problem in operation unless the cable becomes extremely thick. However, in an intracorporeal ultrasonic diagnostic apparatus configured to provide an ultrasonic transducer at the distal end of an insertion portion to be inserted into the body, when the diameter of the cable is increased, the operability of the insertion operation of the insertion portion is reduced. Not only will it worsen, it will cause pain to the subject, and if the cable becomes too thick, it may not be able to be inserted into the body. Therefore, the number of ultrasonic transducers constituting the ultrasonic transducer array is limited in the ultrasonic transducers attached to the insertion portion, and the resolution of the ultrasonic image must be sacrificed to some extent. is there.

  The present invention has been made in view of the above points, and an object of the present invention is to provide wiring drawn from an ultrasonic transducer even if the number of ultrasonic transducers constituting the ultrasonic transducer array is increased. This is to reduce the diameter of the cable.

  In order to achieve the above-described object, the present invention provides a piezoelectric element array in which a plurality of piezoelectric elements are two-dimensionally arranged, and an image of a sound generated from a sound source object or reflected on a boundary having a difference in acoustic impedance. An acoustic lens that forms an image on the piezoelectric element array, a charge coupled element in which a charge storage unit is electrically connected to each piezoelectric element constituting the piezoelectric element array, and a signal acquired by the charge coupled element It is characterized by comprising signal processing means for imaging.

  Each piezoelectric element constituting the piezoelectric element array receives a sound wave generated by a target object that forms a sound image and converts it into an electrical signal. This electric signal is taken into the charge coupled device and transferred to the signal processing means. Here, the charge-coupled device has the same configuration as a solid-state image sensor that constitutes imaging means such as a TV camera, and each charge storage unit is two-dimensionally arranged in the same manner as a piezoelectric element. The unit constitutes each pixel in the imaging process. A transfer unit is connected to the charge storage unit, and a transfer method using the transfer unit includes a frame transfer method and an interline transfer method, and any transfer method can be adopted. As many wirings as necessary to supply drive signals to the charge coupled devices and read out the signal charges from the solid-state imaging device are connected. Even if the number of piezoelectric elements constituting the piezoelectric element array is increased, exceptional wiring is provided. The number will not increase.

  The piezoelectric element array is dedicated for reception, and it is necessary to transmit sound waves toward the piezoelectric element array. If the object has a sound source, the sound generated from the sound source can be received by the piezoelectric element array to obtain a sound image. However, if the object to be detected does not have a sound source, the ultrasonic transmission means is used. Try to provide it. Sound is generated intermittently or continuously from the ultrasonic transmission means, and a reflection echo from a boundary portion of a tissue or the like having a difference in acoustic impedance in the body is received by the piezoelectric element array. Since an acoustic lens is mounted on the piezoelectric element array, a reflected image is incident on the piezoelectric element array via the acoustic lens, whereby a sound image at a predetermined position is formed on the piezoelectric element array. Here, it is also possible to control so that the charge accumulated by inputting the sweep pulse to the charge coupled device can be controlled without being transmitted to the signal processing means. In this way, by setting the charge accumulation and sweep timing, that is, by performing the charge accumulation / sweep control, a sound image at a desired position is acquired. As the sound image, an ultrasonic tomographic image approximately parallel to the piezoelectric element array at a certain depth in the body is obtained.

  When performing ultrasonic electronic scanning over a predetermined range, there is no need for a delay circuit, and the number of wires drawn from the ultrasonic image generating means is only the number necessary for driving the solid-state imaging device. Even if the number of piezoelectric elements constituting the piezoelectric element array is increased in order to improve the resolution of the ultrasonic image, the diameter of the cable connected to the ultrasonic image generating means can be reduced.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 shows a schematic configuration of a sound image imaging apparatus. In the figure, reference numeral 1 denotes a piezoelectric element array. This piezoelectric element array 1 has a two-dimensional planar structure in which a large number of piezoelectric elements 1a are arranged in the XY directions (vertical and horizontal). The piezoelectric element array 1 is connected to a charge coupled device 2. The charge coupled device 2 includes a large number of charge storage units 2a and transfer units (not shown), and signal charges stored in the charge storage units 2a are transferred to the transfer units, and the transfer units transfer image signals from the transfer units. It will be taken out as a signal. Accordingly, each piezoelectric element 1 a in the piezoelectric element array 1 is electrically connected to each charge storage portion 2 a constituting the charge coupled device 2. Here, the signal charge accumulated in each charge accumulating unit 2a constituting the charge coupled device 2 is based on a signal relating to the sound pressure level of the reflected echo received by each piezoelectric element 1a. Each of the piezoelectric elements 1a is transmitted to the corresponding charge storage unit 2a.

  A drive control circuit 3 is connected to the charge coupled device 2, and an ultrasonic image signal processing circuit 4 is connected. A drive control signal is input to the charge coupled device 2 from the drive control circuit 3. The drive control signal includes a transfer signal from the charge storage unit 2a to the transfer unit, a sweeping signal for the accumulated charge, a transfer signal from the horizontal transfer unit, and the like. Then, the image signal transmitted from the charge coupled device 2 is transmitted to the ultrasonic image signal processing circuit 4, and signal processing is performed by the ultrasonic image signal processing circuit 4, which is imaged as an ultrasonic image. It is displayed on the display device 5.

  Further, an acoustic lens 6 is disposed opposite to the surface opposite to the mounting side of the charge coupled device 2 of the piezoelectric element array 1, that is, the reception surface of the ultrasonic reflection echo. Is formed on the piezoelectric element array 1.

  Furthermore, 7 is an ultrasonic transmission means, and this ultrasonic transmission means 7 is composed of an ultrasonic emission part 8 and a drive part 9. The ultrasonic wave emitting unit 8 is made of, for example, a piezoelectric element, and emits ultrasonic waves based on a driving signal from the driving unit 9. Here, the drive unit 9 is controlled so as to emit ultrasonic waves intermittently or as a continuous wave from the ultrasonic wave emission unit 8. Therefore, the ultrasonic transmission signal transmitted from the ultrasonic transmission means 7 is transmitted toward the body and propagates while diffusing into the body. Then, a reflected echo is generated in a tomographic part of the body tissue, that is, in a portion having a difference in acoustic impedance, and this reflected echo is incident on the piezoelectric element array 1. Since the acoustic lens 6 is provided on the incident surface of the piezoelectric element array 1, tissue sectional information at a predetermined depth position in the body can be obtained by the acoustic lens 6.

  Although the sound image imaging apparatus is configured as described above, the sound image imaging apparatus is inserted into the body of a subject and used as an in-body insertion type ultrasonic diagnostic apparatus for acquiring information related to a body tissue. For this purpose, as shown in FIG. 2, at least an ultrasonic wave emission unit 8 constituting an ultrasonic wave transmission unit, an ultrasonic image generation unit 10 including an acoustic lens 6, a piezoelectric element array 1, and a charge coupled device 2, Is attached to the insertion portion 11 to be inserted into the body cavity of the subject. The ultrasonic image generating means 10 has a lens barrel 12 on which an acoustic lens 6 is mounted, and the piezoelectric element array 1 and the charge coupled element 2 are provided in the axial direction of the insertion portion 11. Therefore, the sound image incident from the acoustic lens 6 is formed on the piezoelectric element array 1. Further, in the lens barrel 12, an ultrasonic transmission medium such as liquid paraffin is sealed in the space between the acoustic lenses 6 having two lenses and the space up to the piezoelectric element array 1, for example. While the reflected echo signal from the body is received by the piezoelectric element array 1, the attenuation of this signal is suppressed. Here, the unit composed of the piezoelectric element array 1 and the charge coupled device 2 can be arranged in the axial direction of the insertion portion 11 as shown in FIG. In this case, the signal relating to the sound image incident from the acoustic lens 6 is reflected by the reflecting surface 13 provided at the end of the lens barrel 12 and then taken into the charge coupled device 2.

  A driving unit 9 that inputs a driving signal to the ultrasonic wave emitting unit 8, and an ultrasonic wave that transmits a driving signal to the charge coupled device 2 and reads the signal from the charge coupled device 2 to generate an ultrasonic image signal. The image signal processing circuit 4 and the like are located outside the subject's body. Accordingly, the cable 14 is inserted into the insertion portion 11, and signals are transmitted / received through the cable 14.

  Here, in order to increase the resolution of the ultrasonic image displayed on the image display means, it is necessary to increase the number of arrangements of the piezoelectric elements 1 a constituting the piezoelectric element array 1. Wiring is not directly drawn out from each piezoelectric element 1 a constituting this piezoelectric element array 1, and each piezoelectric element 1 a is connected to a charge storage portion 2 a in the charge coupled element 2. As is apparent from FIG. 1, the charge coupled device 2 is connected to the number of wires 15 a necessary for driving it, the wire 15 b for transmitting an output signal from the charge coupled device 2, and the ultrasonic transmission means 7. The wiring 15c between the ultrasonic wave emission part 8 and the drive part 9 which comprise is provided. These wirings 15 a to 15 c constitute the cable 14.

  Accordingly, although the piezoelectric element array 1 is basically subjected to electronic scanning, it does not transmit ultrasonic waves from the piezoelectric element array 1 as in normal electronic scanning, so that the piezoelectric element array 1 is configured. It is not necessary to connect a delay circuit or the like to each piezoelectric element 1a, and the piezoelectric element 1a is directly connected to the charge storage portion 2a of the charge coupled element 2, thereby simplifying the configuration. Further, in order to improve the image quality of the ultrasonic image, even if the number of piezoelectric elements 1a constituting the piezoelectric element array 1 is increased, the cable 14 does not have a particularly large diameter, and the insertion portion 11 can be reduced in diameter. It becomes. For this reason, the operation of inserting the insertion portion 11 into the body cavity of the subject becomes easy, and the pain of the subject is reduced.

  By using a sound image imaging apparatus configured as an in-body type ultrasonic diagnostic apparatus, an ultrasonic tomographic image at a predetermined depth position in the body can be acquired by the procedure shown in FIG. That is, an ultrasonic pulse is transmitted from the ultrasonic wave emitting unit 8 of the ultrasonic wave transmission means 7 toward the body of the subject (step 1), and the ultrasonic wave thus transmitted toward the internal body is the tissue in the body. The reflected echo is received by each piezoelectric element 1a constituting the piezoelectric element array 1 to generate a voltage. As a result, charges are accumulated in the charge accumulating portion 2a connected to each piezoelectric element 1a in the charge coupled device 2.

  Then, when a predetermined time has elapsed, a sweep pulse is transmitted from the drive control circuit 3 to the charge coupled device 2 (step 2). As a result, the signal charge once accumulated in the charge coupled device 2 is discharged to the drain. After that, each piezoelectric element 1a in the piezoelectric element array 1 receives a reflected echo from the body tissue tomographic section, and an electric signal corresponding to the magnitude of the reflected echo is obtained. This signal is stored in each charge storage unit 2 a in the charge coupled device 2. In this way, by applying the sweep control signal to the charge coupled device 2, the position of the tomographic plane from which the information on the body tissue is acquired is set.

  Thereafter, when a predetermined time elapses, a transfer control signal is input to the charge coupled device 2 (step 3). As a result, the signal charge accumulated in each charge accumulating unit 2a of the charge coupled device 2 is transferred to the horizontal transfer unit (step 4), and a signal from this horizontal transfer unit is read out to perform ultrasonic image signal processing. It is transmitted to the circuit 4. Here, the thickness to be observed in the body is controlled by setting the timing until the transfer signal is input after the sweep pulse in the charge coupled device 2 is applied. If the time interval between them is shortened, the distance resolution is increased accordingly, but the dynamic range is lowered. On the other hand, if the time from the application of the sweep pulse to the input of the transfer signal is lengthened, the distance resolution decreases, but the signal S / N ratio increases.

  The output signal from the charge coupled device 2 taken into the ultrasonic image signal processing circuit 4 is signal amplified (step 5), converted into a luminance signal according to the voltage value (step 6), and further an ultrasonic image is generated. Signal processing necessary for this is performed, and an ultrasonic tomographic image is displayed on the image display device 5 (step 7). The ultrasonic image displayed on the image display device 5 in this way is a tissue tomographic image at a distance D (see FIG. 1) from the acoustic lens 6. This distance D depends on the time from when the ultrasonic pulse is transmitted to when the reading of the signal charge is started.

  By repeating this operation as one cycle, the display image in the image display device 5 is updated. Note that it is desirable that the operation cycle for acquiring the ultrasonic image is synchronized with the video rate at the time of image generation of the charge coupled device 2.

  Although an ultrasonic pulse is transmitted from the ultrasonic wave emission unit 8 of the ultrasonic wave transmission means 7, continuous wave ultrasonic waves may be transmitted. As described above, when a continuous wave ultrasonic wave is transmitted, a superimposed signal is received in the visual field direction, that is, in the depth direction in the body, but the acoustic lens 6 has a predetermined focal length. Since the reflected echo from the focal position of the acoustic lens 6 and the vicinity thereof is the strongest, a rough tomographic image of the focal position of the acoustic lens 6 is formed on the piezoelectric element array 1 depending on the signal processing. Therefore, a sound image centered on the focal position of the acoustic lens 6 can also be acquired by transmitting continuous wave ultrasonic waves. When the operation cycle from the reception of the ultrasonic wave to the transfer of the signal is repeated, the operation of the organ, blood vessel, and the like at a predetermined depth position in the body can be monitored.

  Further, for example, blood flow can be detected by injecting a transvenous ultrasound contrast agent from the terminal vein of the subject, and a wider spatial resolution can be obtained as compared with the color Doppler method. Here, the transvenous ultrasound contrast agent is composed of microbubbles in which air is enclosed, and injects a number of microbubbles into the bloodstream so as to pass through the region where the ultrasound is transmitted. Then, a reflection echo is generated in the ultrasonic wave by the microvalve. The difference in acoustic impedance between blood and body tissue and the air inside the microvalve is very significant. Therefore, since extremely high acoustic energy of reflected echo can be obtained, clearer information on blood flow can be acquired.

1 is a configuration explanatory diagram of a sound image imaging apparatus showing an embodiment of the present invention. FIG. 2 is a configuration explanatory diagram of a distal end portion in an insertion portion when the sound image imaging apparatus of FIG. 1 is configured as an intracorporeal insertion type ultrasonic diagnostic apparatus. FIG. 2 is a configuration explanatory diagram of a sound image imaging apparatus having a structure in which units each including a piezoelectric element array and a charge coupled device are arranged in an axial direction of an insertion portion. It is a flowchart figure which shows the procedure which acquires the ultrasonic tomogram in a body by the sound image imaging apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric element array 1a Piezoelectric element 2 Charge coupling element 2a Charge storage part 3 Drive control circuit 4 Ultrasonic image signal processing circuit 5 Image display apparatus 6 Acoustic lens 7 Ultrasonic transmission / reception means 8 Ultrasonic light emission part 9 Drive part 10 Ultrasonic image Generation means 11 Insertion section 14 Cable

Claims (3)

A piezoelectric element array in which a plurality of piezoelectric elements are two-dimensionally arranged;
An acoustic lens that forms an image of a sound generated from a sound source object or reflected on a boundary portion having a difference in acoustic impedance on the piezoelectric element array;
A charge coupled device in which a charge storage unit is electrically connected to each of the piezoelectric elements constituting the piezoelectric element array;
A sound image imaging apparatus comprising: signal processing means for performing image processing on a signal acquired by the charge coupled device. The sound image imaging apparatus according to claim 1, further comprising an ultrasonic transmission unit configured to transmit an ultrasonic wave in order to reflect sound at the boundary. The acoustic lens and the piezoelectric element array are built in via an ultrasonic transmission medium, and the piezoelectric element array is electrically connected to the solid-state imaging unit between each piezoelectric element and each charge storage unit. 2. The sound image imaging apparatus according to claim 1, wherein the ultrasonic image generating means is provided by mounting the ultrasonic image generating means, and the ultrasonic image generating means and the ultrasonic transmitting means are attached to the distal end of the insertion portion. .

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