JP4733988B2 - Body cavity ultrasound system - Google Patents

Description

  The present invention relates to an intracorporeal ultrasound diagnostic system including an ultrasonic endoscope scope equipped with a capacitive ultrasonic transducer.

  An ultrasonic diagnostic method is widely used in which an ultrasonic wave is irradiated toward the inner wall of a body cavity, and an internal state is imaged from the echo signal to make a diagnosis. One of the equipment used for this ultrasonic diagnostic method is an ultrasonic endoscope scope. An ultrasonic endoscope scope has an ultrasonic transducer (ultrasonic transducer) attached to the distal end of an insertion portion to be inserted into a body cavity. This transducer converts an electrical signal into ultrasonic waves and irradiates the body cavity. It also receives ultrasonic waves reflected in the body cavity and converts them into electrical signals.

  Conventionally, in an ultrasonic transducer, a ceramic piezoelectric material PZT (lead zirconate titanate) has been used as a piezoelectric element that converts an electrical signal into an ultrasonic wave, but a silicon semiconductor substrate is processed using silicon micromachining technology. The capacitive ultrasonic transducer (Capacitive Micromachined Ultrasonic Transducer (hereinafter referred to as c-MUT)) has attracted attention. This is one of the elements collectively referred to as a micromachine (MEMS: Micro Electro-Mechanical System).

  The MEMS element is formed as a fine structure on a substrate such as a silicon substrate or a glass substrate, and includes a driver that outputs a mechanical driving force, a driving mechanism that drives the driving body, and a semiconductor integrated circuit that controls the driving mechanism. An element in which a circuit or the like is electrically and further mechanically coupled. The basic feature of a MEMS device is that a drive body configured as a mechanical structure is incorporated in a part of the device, and the drive body is driven by applying Coulomb attractive force between electrodes. It is done electrically.

  In Non-Patent Document 1, a c-MUT as shown in FIG. 14 is disclosed. FIG. 14 (a) shows two sets of top surfaces of a one-dimensional c-MUT array of 64 elements, and FIG. 14 (b) shows one isolated c-MUT element with dummy neighbors. FIG. 14 (c) shows an enlarged view of a c-MUT element composed of 8 × 160 cells connected in parallel.

  The c-MUT element 500 includes a plurality of cells 501, an upper electrode 502 provided on the top of each cell, a ground electrode 502, an electrode 503, a dummy neighbor 505, and a groove (trench) 506. The upper electrode 502 is also electrically connected and connected to the electrodes 502 and 503 at both ends. The dummy neighbor 505 is for preventing crosstalk with adjacent elements. A groove 506 is provided between the electrodes 502 and 503 and the dummy neighbor.

  The upper electrode is supported by the membrane. Although not shown, a lower electrode is provided inside the cell at a position facing the upper electrode 502, and there is a gap (cavity) between the lower electrode and the membrane.

When a voltage is applied to the upper electrode and lower electrode of the element, each cell is driven simultaneously and vibrates all at the same phase. Thereby, ultrasonic waves are emitted.
In Patent Document 1, using the element 500 described above, Lamb waves (A0 mode) of a silicon substrate and Stoneley waves (boundary waves) transmitted through a solid-liquid interface have a significant effect on crosstalk between elements. I have found that.
Xucheng Jin, 3 others, "Characterization of One-Dimensional Capacitive Micromachined Ultrasonic Immonia Transducer Arrays" 48, NO. 3, P750-760, MAY 2001 A. G. Bashford, two others, “Micromachined Ultracapacitance Transducers for Implication Applications, Ultratransactions Ultrasonics, Ferroelectrics. Ferroelectrics. Ferroelectrics. 45, no. 2, March (1996), P367-P375.

  By the way, if the conventional piezoelectric vibrator is operated in the air, it may be destroyed or suddenly deteriorated in characteristics, and the operation in the air has been avoided. Therefore, the conventional ultrasonic endoscope scope can be operated only in a state where it is in contact with the inner wall of the body cavity. Similarly, since an ultrasonic wave cannot be emitted in the air, a noise signal derived only from the vibrator could not be detected.

  Conventionally, since there is a large difference in acoustic impedance between a living body and air, it has been impossible to detect an aerial sound wave with the same structure as a piezoelectric vibrator of a type that is in contact with the inner wall of a body cavity.

For this reason, conventionally, there is no need to detect information regarding the state of the ultrasonic transducer, such as whether the ultrasonic transducer is in contact with the inner wall of the body cavity.
However, when an ultrasonic transducer that can transmit and receive ultrasonic waves (hereinafter referred to as aerial ultrasonic waves) in a state where the ultrasonic transducer is not in contact with the inner wall of the body cavity, the ultrasonic transducer contacts the inner wall of the body cavity. Therefore, it is necessary to detect information regarding the state of the ultrasonic transducer, such as whether or not it is present.

  Conventionally, an ultrasonic diagnostic image obtained when the ultrasonic transducer is brought into contact with the inner wall of the body cavity and an ultrasonic diagnostic image obtained when the ultrasonic transducer is brought into non-contact with the inner wall of the body cavity are used as one type of ultrasonic transducer. There was no intracorporeal ultrasound diagnostic system acquired in.

  Next, as described above, in Non-Patent Document 1, crosstalk between elements is suppressed by providing grooves at both ends of the transducer element. However, the provision of such a groove causes a problem as shown in FIG.

  FIG. 15 shows a vibration wave generated in the membrane 510 when an ultrasonic wave is generated using the c-MUT of FIG. This figure is a cross-sectional view of the element of FIG. When the groove 506 is provided at both ends and the end 511 is clear as in the element 500, the standing wave 512 having the end 511 as a node is generated.

  That is, a standing wave is generated between a pair of spaced walls with a frequency determined by the distance and the sound velocity of the material (silicon in FIG. 15) filling the distance. When considering a pair of adjacent grooves, first, the vibration wave excited on the membrane is transmitted along the membrane surface as a Lamb wave or a Stoneley wave, and the right wall of the left groove and the left wall of the right groove The ultrasonic wave, which is a vibration wave, can be reflected multiple times to form a transverse standing wave. The transverse standing wave is a base having a frequency component with a distance L of 1 / 2λ, and becomes a vibration wave in which the higher-order standing waves overlap. Therefore, a standing wave is generated by the presence of such a pair of walls. The standing wave 512 can be a noise component in transmission / reception of ultrasonic waves.

Therefore, when an element having grooves 506 at both ends is used, there is a problem that noise due to standing waves is generated.
In view of the above problems, in the present invention, an ultrasonic endoscope scope equipped with one type of capacitive ultrasonic transducer is inserted into a body cavity regardless of whether it is in contact with the inner wall of the body cavity. By constructing an ultrasound diagnostic image related to the contour of the body cavity wall and reaching the diagnostic site where it is fixed in contact therewith, an ultrasound diagnostic image regarding the tomography is constructed, and these constructed ultrasound diagnostic images contain noise. Provided is an intracavitary ultrasound diagnostic system in which components have been removed.

According to the first aspect of the present invention, there is provided an ultrasonic endoscope scope provided with a capacitive ultrasonic transducer that transmits and receives ultrasonic waves, and the capacitive type. In accordance with the discrimination result by the vibrator state discriminating means, the vibrator state discriminating means for discriminating the presence or absence of contact of the ultrasonic vibrator, the storage means for storing the sensing information sensed by the capacitive ultrasonic vibrator, Based on the storage control means for storing the sensing information in the storage means corresponding to the determination result, and using at least one of the sensing information stored in the storage means, an arithmetic process is performed. It is achieved by providing an intra-body-cavity ultrasonic diagnostic system comprising: an arithmetic unit that performs an operation; and an image constructing unit that constructs an ultrasonic diagnostic image from the arithmetic result calculated by the arithmetic unit. It can be.

  According to the second aspect of the present invention, the capacitive ultrasonic transducer is composed of a plurality of capacitive ultrasonic transducer elements, and is formed on a cylindrical outer peripheral surface. The intra-body-cavity ultrasonic diagnostic system according to claim 1, wherein the ultrasonic diagnostic system is a one-dimensional or two-dimensional array-type capacitive ultrasonic transducer in which the plurality of capacitive ultrasonic transducer elements are arranged. Can be achieved by providing.

  According to the third aspect of the present invention, the object according to claim 3 is characterized in that a groove is provided between the adjacent transducer elements. This can be achieved by providing an ultrasound diagnostic system.

  According to the fourth aspect of the present invention, there is provided the intra-body-cavity ultrasonic diagnostic system according to claim 3, wherein a conductive film is formed in the groove. Can be achieved.

  According to the invention described in claim 5 of the present invention, the intracorporeal ultrasound diagnostic system further includes a synthesized ultrasonic beam emitted from the capacitive ultrasonic transducer, It can achieve by providing the intra-body-cavity ultrasonic diagnostic system of Claim 2 provided with the radial scanning control means to carry out radial scanning along the circumferential direction of the said cylinder.

  According to the invention described in claim 6, the radial scanning control means further causes the synthetic ultrasonic beam to perform sector scanning in the long axis direction of the cylinder. This can be achieved by providing the intracorporeal ultrasound diagnostic system according to claim 5.

  According to the seventh aspect of the present invention, the calculation means is configured such that the calculation means includes a sum, a difference, or a difference of at least two of the detection information stored in the storage means, or The calculation for calculating the cross-correlation is performed, and this can be achieved by providing the intra-body-cavity ultrasonic diagnostic system according to claim 1.

  According to an eighth aspect of the present invention, the calculation means performs a calculation for calculating an autocorrelation from one of the sensing information. This can be achieved by providing an intracorporeal ultrasound diagnostic system.

  According to the ninth aspect of the present invention, the vibrator state discriminating unit is configured such that the capacitive ultrasonic transducer reaches the inner wall outside the body and inside the body cavity. A state detection unit that detects whether the state is any one of the status detection unit, and a detection information determination unit that determines the state based on detection information obtained from the state detection unit. This can be achieved by providing the intracorporeal ultrasound diagnostic system according to claim 1.

  According to the invention described in claim 10, the state detection means is an optical sensor provided substantially in the vicinity of the capacitive ultrasonic transducer, and the detection information discrimination The means is based on the output of the optical sensor to determine whether the capacitive ultrasonic transducer is outside the body or inside the body cavity, but is not in contact with the inner wall of the body cavity, or is not in contact with the inner wall of the body cavity. This can be achieved by providing an intra-body-cavity ultrasonic diagnostic system according to claim 9.

  According to the invention described in claim 11, the state detection means is a pressure sensor provided in the vicinity of the capacitive ultrasonic transducer, and the detection information discrimination The means determines, based on the output of the pressure sensor, whether the capacitive ultrasonic transducer is in a body cavity but is not in contact with a body cavity inner wall or in a body cavity inner wall non-contact state. This can be achieved by providing an intracorporeal ultrasound diagnostic system according to claim 9.

  According to a twelfth aspect of the present invention, the state detection means generates the state detection information corresponding to a frequency of an electric signal representing the detection information, and the detection is performed. Based on the state detection information, the information discriminating means determines whether the capacitive ultrasonic transducer is outside the body or inside the body cavity, but is not in contact with the inner wall of the body cavity, or is not in contact with the inner wall of the body cavity. It can achieve by providing the intra-body-cavity ultrasonic diagnostic system of Claim 9 characterized by distinguishing.

  According to the invention described in claim 13, the state detection means is a filter circuit that passes the electric signal when the frequency of the electric signal is equal to or lower than a predetermined threshold value. This can be achieved by providing the intra-body-cavity ultrasound diagnostic system according to claim 12.

  According to the invention described in claim 14, the memory control means is configured such that the capacitive ultrasonic transducer is outside the body, inside the body cavity, but not in contact with the inner wall of the body cavity, and It can achieve by providing the intra-body-cavity ultrasonic diagnostic system according to claim 1, wherein at least one of the sensing information sensed in a contact state is stored in the inner wall of the body cavity.

  According to the fifteenth aspect of the present invention, the sensing information stored in the first storage means of the storage means is under a condition in which the ultrasonic waves are not reflected. 2. The intra-body-cavity ultrasonic diagnostic system according to claim 1, wherein the first ultrasonic detection information is detected by radiating ultrasonic waves to the capacitive ultrasonic transducer. 3. it can.

  According to the invention described in claim 16 of the scope of the invention, the sensing information stored in the second storage means of the storage means is obtained by the capacitive ultrasonic transducer. It is second sensing information sensed by transmitting and receiving the ultrasonic wave in a body cavity but in a non-contact state with the inner wall of the body cavity, and the computing means includes the second sensing information and the first sensing information. The correlation or difference is calculated, and this can be achieved by providing the body cavity ultrasonic diagnostic system according to claim 15.

  According to the invention described in claim 17, the above-mentioned problem is that the capacitive ultrasonic transducer stores the sensing information stored in the third storage unit of the storage unit. Third sensing information sensed by transmitting and receiving the ultrasonic wave in contact with the inner wall of the body cavity, and the calculation means calculates a correlation or difference between the third sensing information and the first sensing information. This can be achieved by providing an intracorporeal ultrasound diagnostic system according to claim 15.

  According to the invention described in claim 18, the above-mentioned problem is that the sensing information stored in the second storage means of the storage means is obtained by the capacitive ultrasonic transducer. The second sensing information sensed by transmitting and receiving the ultrasonic wave in a body cavity but in a non-contact state with the inner wall of the body cavity, and the sensing information stored in the third storage means of the storage means is: Third capacitive information sensed by transmitting and receiving the ultrasonic wave in a state where the capacitive ultrasonic transducer is in contact with an inner wall of the body cavity, and the computing means includes the second sense information and the first sensitive information. A first calculation process for calculating a correlation or difference with the sensing information is performed, a second calculation for calculating a correlation or difference between the third sensing information and the first sensing information is performed, and the first calculation is performed. The result of the processing and the result of the second arithmetic processing are added. It can be achieved by providing a body-cavity diagnostic ultrasound system according to.

  According to the invention described in claim 19 of the claim, the ultrasonic diagnostic image is an image representing the contour of the inner wall surface of the body cavity. This can be achieved by providing an ultrasound diagnostic system.

  According to the invention described in claim 20 of the claim, the ultrasonic diagnostic image is an image representing a tomogram of tissue in the body cavity. This can be achieved by providing an ultrasound diagnostic system.

  According to the invention described in claim 21, the ultrasonic diagnostic image is an image representing an outline of a body cavity inner wall surface and an image representing a tomographic tissue in the body cavity. It can achieve by providing the intra-body-cavity ultrasonic diagnostic system of Claim 18.

  According to the invention described in claim 22, the above-described problem is an intracorporeal ultrasonic wave provided with an ultrasonic endoscope scope provided with a capacitive ultrasonic transducer for transmitting and receiving ultrasonic waves. A noise removing device for removing a noise component from sensing information sensed by the capacitive ultrasonic transducer used in a diagnostic system, wherein the capacitive ultrasonic vibration is performed under a condition in which the ultrasonic wave is not reflected. The first storage means for storing the first sensing information sensed by radiating the ultrasonic wave to the child and the capacitive ultrasonic transducer are in the body cavity but are not in contact with the inner wall of the body cavity A second storage means for storing the second sensing information sensed by transmitting and receiving the ultrasonic wave in a state, and an operation for calculating a correlation or difference between the second sensing information and the first sensing information And a noise removing method comprising: It can be achieved by providing a location.

  According to the invention as set forth in claim 23, the above-described problem is an intracorporeal ultrasonic wave provided with an ultrasonic endoscope scope provided with a capacitive ultrasonic transducer for transmitting and receiving ultrasonic waves. A noise removing device for removing a noise component from sensing information sensed by the capacitive ultrasonic transducer used in a diagnostic system, wherein the capacitive ultrasonic vibration is performed under a condition in which the ultrasonic wave is not reflected. A first storage means for storing the first sensing information sensed by radiating ultrasonic waves to the child; and the ultrasonic waves are transmitted and received while the capacitive ultrasonic transducer is in contact with the inner wall of the body cavity. And a third storage means for storing the third sensed information sensed as a result, and an arithmetic means for calculating a correlation or difference between the third sense information and the first sense information. To provide a noise removing device Thus it can be achieved.

  By using the present invention, an ultrasonic endoscope scope equipped with one type of capacitive ultrasonic transducer is inserted into the body cavity regardless of whether it is in contact with the inner wall of the body cavity or not. By constructing an ultrasonic diagnostic image and reaching a diagnostic site where it is fixed in contact therewith, an ultrasonic diagnostic image relating to a tomogram can be constructed. Further, noise components due to standing waves are removed from these constructed ultrasonic diagnostic images.

<First Embodiment>
In the present embodiment, in addition to being able to obtain a tomographic image by using a radial scanning type capacitive ultrasonic transducer and fixing the contact as in the prior art, it is possible to perform intra-body cavity supervision that enables non-contact diagnosis. The ultrasonic diagnostic system will be described.

  FIG. 1 shows an outline of an intracorporeal ultrasound diagnostic system in the present embodiment. In FIG. 1, the intracorporeal ultrasound diagnostic system 1 includes an ultrasonic endoscope scope unit 2, a signal processing unit 3, an image processing unit 200, and a display unit 4. Although only the reception signal system is shown in FIG. 1, the transmission signal system is omitted from the figure.

  The ultrasonic endoscope scope 2 is mounted with a capacitive ultrasonic transducer 2-1 at its tip. As a main function of the capacitive ultrasonic transducer 2-1, first, the distal end portion of the ultrasonic endoscope scope 2 is inserted into a body cavity, and ultrasonic waves are emitted from the capacitive ultrasonic transducer 2-1. The capacitive ultrasonic transducer 2-1 receives the ultrasonic wave reflected in the body cavity, and converts the received ultrasonic wave into an electrical signal.

  The signal processing unit 3 performs an operation by analyzing an electrical signal obtained by the ultrasonic endoscope scope 2. The signal processing unit 3 includes a storage control unit 3-1, a storage unit 3-2, a calculation unit 3-3, and a vibrator state determination unit 3-5.

  The vibrator state discriminating means 3-5 includes, for example, an electrostatic capacity such as whether the capacitive ultrasonic transducer 2-1 is outside the body, is not in contact with the inner wall of the body cavity in the body cavity, or is in contact with the inner wall of the body cavity. The state of the type ultrasonic transducer is discriminated. The transducer state determination unit 3-5 includes a state detection unit 3-5a and a detection information determination unit 3-5b. The state detection means 3-5a is for detecting the state of the capacitive ultrasonic transducer 2-1. The detection information discriminating means 3-5b is for discriminating the state of the capacitive ultrasonic transducer 2-1, based on the information detected by the state detecting means 3-5a. The transducer state determination unit 3-5 may be included in the ultrasonic endoscope scope 2 or may be included in the signal processing unit 3, depending on the determination method. May be included across.

  The storage means 3-2 is for storing sensing information (received reflected wave, standing wave, etc.) sensed by the capacitive ultrasonic transducer 2-1. There are a plurality of storage means 3-2. Note that there may be a plurality of storage means physically or as a plurality of logical areas (logically securing a plurality of storage areas in one storage device and using each storage area as a storage means). May be present.

  The storage control means 3-1 detects the sensing information sensed by the capacitive ultrasonic transducer 2-1 based on the discrimination result of the vibrator state discrimination means 3-5 and stores the sensing information corresponding to the discrimination result. 2 for memorizing.

  The calculation means is for performing calculation (difference, correlation) based on the sensing information stored in each storage means 3-2. There are a plurality of combinations of operations, and operations can be performed according to individual purposes.

  The image processing unit 200 includes image construction means 200-1. Based on the result calculated by the calculation unit 3-3, the image construction unit 200-1 calculates an ultrasonic diagnostic image (for example, a contour image of a body cavity inner wall, a biological tissue tomographic image, or a combination thereof) from the calculated signal. Image, etc.).

  The display unit 4 is for displaying the ultrasonic diagnostic image generated by the image processing unit 200, and includes, for example, a monitor (display) 4-1. The display means is not limited to the display, and may be an output device such as a printer.

  FIG. 2 shows an external configuration of the ultrasonic endoscope scope 2 in the present embodiment. The ultrasonic endoscope scope 2 includes an operation unit 9 at the proximal end of the elongated insertion unit 5 and a scope connector 11 at one end. A universal cord 10 connected to a light source device (not shown) extends from the side of the operation unit 9. Further, the scope connector 11 is connected to the signal processing unit 3.

  The insertion portion 5 is provided with a capacitance type radial sector scanning array ultrasonic transducer 6, a bendable bending portion 7, and a flexible flexible tube portion 8 that are mounted on the tip portion in order from the tip side. Configured. The operation portion 9 is provided with a bending operation knob 9a, and the bending portion 7 can be bent by operating the bending operation knob 9a. Further, an illumination lens cover that constitutes an illumination optical unit that irradiates illumination light to an observation site (not shown), an observation lens cover that constitutes an observation optical unit that captures an optical image of the observation site, and a treatment tool are provided at the distal end portion. A forceps outlet or the like that is a projecting opening is provided.

  FIG. 3 is a conceptual diagram of a configuration of a capacitive radial sector scanning array ultrasonic transducer 6 (hereinafter referred to as an ultrasonic transducer or transducer) mounted on the distal end portion of the ultrasonic endoscope scope 2 of FIG. Indicates. The ultrasonic transducer 6 includes a two-dimensional array transducer 20, a transmission / reception circuit 21, and a coaxial cable bundle 22. The two-dimensional array transducer 20 is an array of a plurality of transducer elements. The coaxial cable bundle 22 is a bundle of a plurality of cables connected to each transducer element and is inside the insertion portion 5. The transmission / reception circuit 21 is for controlling signals transmitted to and received from the transducer element. In other words, the transmission / reception circuit 21 controls the scanning of the synthesized ultrasonic beam emitted from the ultrasonic transducer 6 and includes not only the scanning 25 (radial scanning ultrasonic beam) along the circumference of the cylinder but also one element. Sector scanning 24 (in the ultrasonic major axis direction) can be performed. Thereby, a three-dimensional ultrasonic image can be constructed.

  FIG. 4 is a cross-sectional perspective view of the two-dimensional array transducer 20 in the present embodiment. The two-dimensional array transducer 20 includes a transducer unit 32 composed of a plurality of transducer elements 33, a control circuit unit 34, and an FPC (flexible printed circuit board) 31 for wiring.

  The plurality of rectangular vibrator units 32 are arranged at equal intervals in the circumferential direction, and form a cylindrical shape. The control circuit unit 34 is provided on the back surface (cylindrical inside) of the vibrator unit 32 and controls transmission / reception of electric signals to the vibrator unit 32. The shape of the vibrator unit 32 is not limited to a rectangle.

  FIG. 5 shows a top view of a single unit of the vibrator unit 32 in the present embodiment. The transducer unit 32 includes a plurality of square transducer elements 33. In the figure, the transducer unit 32 is configured by arranging a plurality of transducer elements 33 in one dimension. A groove 47 is provided between adjacent vibrator units perpendicular to the vibrator unit arrangement direction. In addition, an inter-vibrator element groove 46 is provided between adjacent vibrator elements in each vibrator unit. The shape of the transducer element is not limited to a square.

  FIG. 6 shows a top view of the transducer element 33 alone in the present embodiment. The transducer element 33 includes a trench 47 perpendicular to the transducer unit arrangement direction, a transducer element groove 46, transducer cell electrode interconnect electrodes 40, 48, 49, an upper electrode 41, a sacrificial layer agent removal hole 43, and a lower electrode. The through-hole electrode portion 44 is configured. A cavity is formed on the back surface of the upper electrode 41 (the back side in the direction perpendicular to the drawing), which is represented as a cavity peripheral edge 42.

  The transducer element 33 is composed of a plurality of transducer cells, and the transducer cell is equal to the number of cavities, and is composed of four transducer cells in FIG. Reference numeral 45 denotes a dicing line for dicing.

FIG. 7 is a cross-sectional view taken along Aa-Ab in FIG. The structural unit indicated by 50 is called a transducer cell. The membrane is a film covering the upper part of the transducer cell 50, and is composed of the upper electrode 41, the membrane upper layer 54, and the membrane lower layer 52 in FIG. 7. This membrane is a vibrating membrane fixed by membrane support portions 58 at both ends of each transducer cell 50. A lower electrode 63 is formed on the surface of the silicon substrate 61 (the bottom portion of the recess) between the membrane support portions 58 so as to face the upper electrode 41, and a dielectric film 57 (for example, SiO ₂ , Si ₃ N) is formed thereon. ₄ , Ta ₂ O ₅ , SrTiO ₃ , BaTiO ₃ , ALN, etc.).

  The lower electrode 63 is provided with a lower electrode through-hole electrode portion 44 for electrically connecting the lower electrode 63 and the signal input / output terminal electrode pad 56 provided on the bottom surface of the silicon substrate 61. Specifically, the lower electrode 63 and the signal input / output terminal electrode pad 56 are electrically connected by an interconnect wiring 59 formed on the hole surface of the lower electrode through-hole electrode portion 44.

  The bottom surface of the silicon substrate 61 is coated with a silicon oxide film 62. The upper electrode 41 and the interconnect electrode 40 between the transducer cell electrodes are made of a metal film such as Au, Al, Pt, Ta, Mo, and W. The upper electrode is electrically connected to the metal film formed on the side and bottom surfaces of the groove portions 46 and 47.

The ground electrode pad 55 is a pad for electrically connecting the electrodes formed on the bottom surfaces of the grooves 46 and 47 to the bottom surface of the silicon substrate 61 in order to connect the upper electrode 41 to the GND.
The dielectric film 57 is used to increase the capacitance between the upper electrode 41 and the lower electrode 63 across the cavity. The depletion layer 60 is a layer in which almost no electrons or holes exist, and a reverse bias voltage may be applied to reduce the capacitance of the depletion layer, that is, parasitic capacitance.

The cavity 51 is a space surrounded by the membrane, the membrane support 58, the lower electrode 63, and the dielectric film 57. When the cavity 51 is formed, a sacrificial layer is formed in the cavity part in the manufacturing process. A sacrificial layer agent removal hole 43 for removing the sacrificial layer is provided in the membrane lower layer 54 (Si ₃ N ₄ ), The sacrificial layer is removed therefrom.

In addition, the “contact resistance” between the electrode disposed on the bottom of the grooves 46 and 47 and the ground electrode pad 55 is infinitely small (ohmic contact).
The operation of the transducer cell 50 will be described. When a voltage is applied to the pair of electrodes of the upper electrode 41 and the lower electrode 63, the electrodes are pulled together, and when the voltage is reduced to 0, the original state is restored. As a result of the vibration of the membrane by this vibration operation, ultrasonic waves are generated, and the ultrasonic waves are irradiated upward in the upper electrode 41.

Next, a series of operations of the intracorporeal ultrasound diagnostic system 1 in this embodiment will be described.
FIG. 8 shows an ultrasonic anechoic cell 70 in the present embodiment. As shown in FIG. 8, a cavity is formed inside the ultrasonic anechoic cell 70, and the ultrasonic transducer 6 is inserted through the opening. After inserting the ultrasonic transducer 6, ultrasonic waves are emitted. At this time, since the ultrasonic anechoic cell 70 is composed of a member that absorbs ultrasonic waves (for example, urethane fiber, foamed silicone resin, etc.), the ultrasonic waves do not reflect. Therefore, even if an ultrasonic wave is radiated by the ultrasonic vibrator in the ultrasonic anechoic cell 70, a reflected wave is not received. Therefore, at the time of reception, since the membrane does not originally vibrate, the charge of the upper electrode does not change. However, when unnecessary vibrations such as standing waves occur, the charge on the membrane changes due to the influence, and here, the change in the charge is detected. That is, along with the vibration of the membrane at the time of transmission, unnecessary vibration that is not converted to transmission ultrasonic waves remains as a standing wave, and this vibration is superimposed as a noise signal even when an actual echo signal is received, resulting in a reduction in S / N. Leads to.

  FIG. 9 shows a state in which the ultrasonic transducer 6 is inserted into the body cavity. FIG. 9A shows a state where it is inserted into the mouth, and FIG. 9B shows a state where the ultrasonic transducer 6 is brought into contact with the inner wall of the stomach to transmit / receive ultrasonic waves.

  When transmitting / receiving ultrasonic waves in the ultrasonic anechoic cell 70 (FIG. 8) (hereinafter referred to as “state 1”), it is in the air until it reaches the observation site after being inserted into the body cavity ( When transmitting / receiving without contact with the inner wall of the body cavity (FIG. 9 (a)) (hereinafter referred to as "state 2"), when transmitting and receiving with the ultrasonic transducer in contact with the inner wall of the body cavity (FIG. 9 (b)) (hereinafter referred to as , “State 3”).

  Conventionally, when a piezoelectric vibrator is used, an ultrasonic image can be obtained only by contacting an observation site, but in c-MUT, the acoustic impedance of the ultrasonic transmission / reception surface is not as small as air and not as large as a living body. Since it has impedance, an ultrasonic image can be obtained in the air (in a state where it is not in contact with the inner wall of the body cavity). Accordingly, it is possible to easily receive the reflected wave on the surface of the inner wall of the body cavity, so that the contour of the lumen wall, that is, the uneven surface can be measured while inserting the ultrasonic transducer. The c-MUT can transmit and receive high-frequency ultrasonic waves of several MHz, and can detect surface irregularities with high accuracy.

  FIG. 10 shows an outline of the internal configuration of the intra-body-cavity ultrasound diagnostic system in the present embodiment. The intra-body-cavity ultrasonic diagnostic system includes an ultrasonic endoscope scope 2 and an ultrasonic endoscope observation apparatus 300.

The ultrasonic endoscope scope 2 includes a capacitive ultrasonic transducer 101, an optical sensor 102, a charge amplifier 103, and a pulsar (pulse generation circuit) 104.
The ultrasonic endoscope observation apparatus 300 includes an optical sensor signal processing circuit 105, a switch circuit 106 (selection terminal SW1 (107), selection terminal SW2 (108), selection terminal SW3 (109)), AD converters 110 and 111. 112, storage devices 113, 114, 115, arithmetic processing circuits 116, 117, 118, switch circuit 119 (selection terminal Q1 (120), selection terminal Q2 (121), selection terminal Q3 (122)), operation unit 123, It comprises an image converter (digital scan converter) 124 and a monitor 4-1.

The pulsar 104 is a circuit for generating an electrical signal for driving the capacitive ultrasonic transducer 101.
The charge amplifier 103 has a function of performing impedance conversion (converting from high impedance to low impedance), a function of detecting charge on the electrode surface of the capacitive ultrasonic transducer 101, and a function of an amplifier. . The function of detecting the charge is that when the capacitive ultrasonic transducer 101 receives the reflected wave, the membrane vibrates according to the received intensity of the reflected wave, and the charge on the upper electrode according to the vibration. This means the function of detecting the charge. In the present embodiment, it is assumed that not only electric charges caused by reception of reflected waves but also electric charges caused by unnecessary vibrations such as standing waves are detected. Hereinafter, both of these are referred to as a received signal.

The optical sensor 102 detects the brightness around the capacitive ultrasonic transducer 101.
The optical sensor signal processing circuit 105 discriminates light and dark based on the signal output from the optical sensor 102. That is, a signal based on the amount of light detected by the optical sensor can be analyzed to determine a difference in brightness around the ultrasonic transducer 101.

  For example, before the ultrasonic transducer 101 is inserted into the body cavity, that is, when transmission / reception is performed in the ultrasonic anechoic cell 70 (state 1), the brightness can be detected most among the three states. . Next, until the ultrasound transducer 101 is inserted into the body cavity and reaches the observation site (state 2), it becomes dark so that it can be detected. When the ultrasonic transducer reaches the observation site (state 3), light emitted from a light guide (not shown) provided around the ultrasonic transducer is reflected on the inner wall of the body cavity, and the reflected light is reflected. Therefore, brightness can be detected more than in the case of state 2.

  Accordingly, as the setting of the discrimination information of the optical sensor signal processing circuit 105, it is determined that it is before inserting the ultrasonic transducer 101 into the body cavity (state 1) in the initial state. Then, until the ultrasound transducer 101 is inserted into the body cavity and reaches the observation site (state 2), it becomes dark. Therefore, if the signal from the optical sensor falls below a certain threshold value, the state 2 state is assumed. to decide. After that, when it becomes bright again and the signal from the optical sensor becomes equal to or greater than a certain threshold value, it is determined that the ultrasonic transducer is in contact with the observation site (state 3).

  The switch circuit 106 is for turning ON / OFF the selection terminals SW1, SW2, and SW3 according to the output of the optical sensor signal processing circuit 105. When the optical sensor signal processing circuit 105 determines that it is before insertion into the body cavity (state 1), a signal to that effect is output, and the switch circuit 106 receives the signal and the selection terminal SW1 (107) receives the signal. Turns on. If the optical sensor signal processing circuit 105 determines that the optical sensor signal processing circuit 105 is inserted into the body cavity and is moving to the observation site (state 2), a signal to that effect is output, and the switch circuit 106 receives the signal. The selection terminal SW2 (108) is turned on. If the optical sensor signal processing circuit 105 determines that the observation site has been reached (state 3), a signal to that effect is output, and the switch circuit 106 receives the signal and the selection terminal SW3 (109) receives the signal. Turns on.

  A reception signal based on the charge information detected by the charge amplifier 103 is input to one of the AD converters 110, 111, and 112 based on the switching destination of the switch circuit 106. The AD converters 110, 111, and 112 convert the input analog signal into a digital signal. The converted signals are input to and stored in the storage devices 113, 114, 115 corresponding to the AD converters 110, 111, 112.

  In the arithmetic processing circuits 116, 117, and 118, the noise component obtained in the state 1 is obtained by obtaining a correlation function between the reception signals obtained in the respective states (signals stored in the storage devices 113, 114, and 115). It is possible to remove unnecessary vibration wave components such as standing waves from the received signals of states 2 and 3.

  The correlation function includes a cross correlation function and an autocorrelation function. The case where the cross-correlation function is used will be described. This is a function of the shift amount τ when one of the two signals is delayed by τ, and is defined as the following equation.

[X (t): Waveform based on received signal in state m (m is arbitrary), y (t): Waveform based on received signal in state n (n is arbitrary)]
By using the cross-correlation function R _xy , the similarity between the two signals can be obtained. If the two signals are completely different, the cross-correlation function R _xy approaches zero regardless of τ. As a result, an unnecessary vibration component such as a standing wave can be detected, so that this component can be removed. The cross-correlation function R _xy can be obtained by inverse Fourier transform of the cross spectrum.

  An autocorrelation function can also be used. The autocorrelation function is a function of a shift amount τ using a waveform x (t) and a waveform x (t + τ) obtained by shifting the waveform x (t) by τ, and is defined as follows.

The autocorrelation function R _xx becomes a maximum value when τ = 0, that is, the product of itself, and if the waveform is periodic, the autocorrelation function also shows a peak with the same period. For irregular signals, if the fluctuation is slow, the value becomes high when τ is large, and if it fluctuates finely, a high value is shown when τ is small, and τ is a temporal measure of the fluctuation. As a result, an unnecessary vibration component such as a standing wave can be detected, so that this component can be removed. An autocorrelation function can be obtained by inverse Fourier transform of the power spectrum.

  In addition to using the correlation function, an unnecessary vibration component such as a standing wave is removed by obtaining a difference between the waveform based on the received signal in the state m and the waveform based on the received signal in the state n. Also good.

  The arithmetic processing circuit 116 receives a signal stored in the storage device 113 (received signal in state 1) and a signal stored in the storage device 114 (received signal in state 2). The arithmetic processing circuit 116 removes unnecessary vibration components from the received signal in the state 2 by obtaining a correlation between two signals or obtaining a difference.

  The arithmetic processing circuit 117 receives a signal stored in the storage device 114 (received signal in the state 2) and a signal stored in the storage device 115 (received signal in the state 3). Similarly, the arithmetic processing circuit 117 can remove the reception signal in the state 2 from the reception signal in the state 3 by obtaining the correlation between the two signals or obtaining the difference. Thereby, unnecessary vibration components can be removed at the same time.

  The arithmetic processing circuit 118 calculates the sum of the signals obtained by the arithmetic processing circuits 116 and 117. Thereby, a contour image of the lumen wall (surface unevenness information of the lumen wall) and a tomographic image (information in the depth direction) are obtained at the same time. Note that the correlation of signals obtained by the arithmetic processing circuits 116 and 117 may be obtained using a correlation function.

  The operation unit 123 is for operating switching of the switch circuit 119. By operating the operation unit 123, the switch of the switch circuit 119 can be switched to select an image to be output. That is, when the selection terminal Q1 (120) is selected, the signal that has been subjected to the arithmetic processing by the arithmetic processing circuit 116 can be output to the image converter 124. When the selection terminal Q 2 (121) is selected, a signal that has been subjected to arithmetic processing by the arithmetic processing circuit 118 can be output to the image converter 124. In addition, when the selection terminal Q3 (122) is selected, a signal that has been subjected to arithmetic processing by the arithmetic processing circuit 117 can be output to the image converter 124.

  The signal before being input to the image converter 124 is a time axis signal, but this signal is converted into an image signal via the image converter 124. The image signal obtained in this way is output to the monitor 4-1, and an ultrasonic diagnostic image is displayed on the monitor 4-1.

  As described above, by using the capacitive ultrasonic transducer, the ultrasonic transducer can transmit and receive ultrasonic waves in both a contact state and a non-contact state with respect to the inner wall of the body cavity. By detecting this, it is possible to transmit an ultrasonic reception signal received in each state to a corresponding channel.

  In addition to being able to obtain tomographic images with contact fixation as in the prior art, “non-contact diagnosis” becomes possible. In the “non-contact diagnosis”, the tissue shape information on the surface of the lumen wall can be obtained even during insertion through the body cavity. In other words, it is possible to perform ultrasonic diagnosis that was impossible with conventional ultrasonic diagnosis.

  In addition, by performing signal processing for obtaining a correlation or difference between received signals obtained in each state, a standing wave component (noise component) that is unnecessary vibration can be removed. Therefore, it is possible to obtain an ultrasonic diagnostic image that is clearer than before.

  Further, since unnecessary vibration components such as standing waves that are noise components can be removed from the ultrasonic diagnostic image, a clear image signal can be obtained. Thereby, even when an ultrasound diagnostic image is photographed in a non-contact state on the inner wall of the body cavity, an ultrasound diagnostic image showing a clear contour shape of the inner wall of the body cavity can be obtained.

Further, by performing signal processing by combining the received signals in each state, it is possible to obtain a contour image and a biological tissue tomographic image of the inner wall of the body cavity.
Further, by using detection means such as an optical sensor, it is possible to detect whether or not the ultrasonic transducer is in contact with the body cavity inner wall, so that the state of the ultrasonic transducer can be detected.

  In this embodiment, a radial capacitive ultrasonic transducer is used to obtain a contour image of a body cavity inner wall and a biological tissue tomographic image. However, regarding the removal of unnecessary vibration components such as standing waves, Both types and linear types can be used. In this embodiment, the optical sensor is used to detect the state of the ultrasonic transducer. However, for example, a pressure sensor may be used to detect whether or not the body is in contact with the inner wall of the body cavity. Further, in the present embodiment, in order to detect only unnecessary vibration components such as standing waves with the capacitive vibrator, ultrasonic waves are radiated in the ultrasonic anechoic cell. Any anechoic environment that does not reflect ultrasonic waves may be used.

<Second Embodiment>
In the first embodiment, the optical sensor is used to detect whether the ultrasonic transducer is in contact with the inner wall of the body cavity. However, in this embodiment, the ultrasonic transducer is detected by the difference in the frequency of the received ultrasound. A case where it is detected whether or not it is in contact with the inner wall will be described.

  FIG. 11 is a graph showing frequency characteristics when the ultrasonic transducer according to this embodiment is brought into contact with an object and when it is not brought into contact. The vertical axis of this graph represents relative amplitude (value obtained by dividing (normalized) by the maximum value of the vertical axis), and the horizontal axis represents frequency.

  Reference numeral 130 denotes a frequency characteristic in a state where the ultrasonic transducer is not in contact with the object. Reference numeral 131 denotes a peak frequency (fc_non-contact) in a state where the ultrasonic transducer is not in contact with the object (curve 130). Reference numeral 132 denotes frequency characteristics in a state where the ultrasonic transducer is in contact with the object. Reference numeral 133 denotes a peak frequency (fc_contact) when the ultrasonic transducer is in contact with the object (curve 132).

  From this graph, there is a large difference in the frequency characteristics of ultrasonic waves radiated depending on whether the object is in contact with or not in contact with the organ wall in the body cavity. Such a change in frequency characteristics due to contact / non-contact is described in FIG. 4 of Non-Patent Document 2, for example. According to this Non-Patent Document 2, (1) the difference in acoustic impedance of the acoustic load (water / air) seen from the membrane, (2) the internal pressure of the cavity on the back of the membrane varies depending on the acoustic load (water / air), 3) It is described that frequency characteristics change due to contact / non-contact because high-frequency ultrasonic waves are not easily released into the air.

  Therefore, by providing a threshold value between fc_contact and fc_non-contact, it is possible to determine which state (curve 130 or curve 132) is that threshold.

  FIG. 12 shows an outline of the internal configuration of the intra-body-cavity ultrasonic diagnostic system in the present embodiment. This figure is obtained by removing the optical sensor 102 and the optical sensor signal processing circuit 105 from FIG. 10 and adding a low-pass filter 125 and a detector 126 instead.

  A signal based on the charge information detected by the charge amplifier 103 is input to the low-pass filter 125. The low-pass filter 125 passes a signal having a frequency lower than a preset threshold value. Therefore, the signal that passes through the low-pass filter 125 is a reception signal in a state where the ultrasonic transducer is not in contact with the object, and the signal that cannot pass is a reception signal in a state where the ultrasonic transducer is in contact with the object. Can be determined.

  The detector 126 detects the signal (AC signal) output from the low-pass filter 125 and converts it to a DC signal for driving the switch circuit 106. When the ultrasonic reception signal has a low frequency, it passes through the low-pass filter 125, and the ultrasonic reception signal is input to the detector 126 to perform AC / DC conversion. When the ultrasonic reception signal has a high frequency, the low-pass filter 125 cuts the ultrasonic reception signal. Therefore, the ultrasonic reception signal is not input to the detector 126, and therefore there is no output from the detector 126. Further, in FIG. 8, since the received signal in the ultrasonic anechoic cell 70 is not observed except for the low level noise, there is no output from the detector 126 in this case. Therefore, the output from the detector 126 is zero when the calibration signal is detected (FIG. 8), high level output when inserted into the lumen (FIG. 9A), and when the contact is fixed (FIG. 9B). Becomes a low level output. The switch of the switch circuit 106 is switched from SW1 (107) → SW2 (108) → SW3 (109) according to the difference in the detection output, and the received signals in the above states are transmitted to the AD converters 110, 111, and 112. The subsequent operation is the same as that of the first embodiment.

  As described above, by determining the difference in frequency characteristics, it is possible to detect whether the ultrasonic transducer is outside the body, or whether the ultrasonic transducer is in the body cavity and is in contact with the inner wall or non-contact. Can be detected.

<Third Embodiment>
In the present embodiment, variations of signal processing based on ultrasonic reception signals obtained in each state will be described.

  FIG. 13 shows an arithmetic control circuit 150 that performs signal processing of a plurality of patterns in the present embodiment. The arithmetic control circuit 150 is a circuit group corresponding to the arithmetic processing circuits (116, 117, 118) and the switch circuit 119 of FIG.

  The arithmetic control circuit 150 includes distributors 151, 152, 153, arithmetic processing circuits 154, 155, 156, 157, 158, 159, and a switch circuit 161. The distributors 151, 152, and 153 distribute the signals output from the corresponding storage devices 113, 114, and 115 to the respective arithmetic processing circuits. The arithmetic processing circuits 154 to 159 calculate the correlation, difference, or sum of the two input reception signals.

  In the first or second embodiment, when the switch control signal 141 output from the optical sensor signal processing circuit 105 (FIG. 10) or the detector (FIG. 12) is input to the switch circuit 106, as described above, The switch is switched based on the information of the switch control signal 141.

  Then, a signal (reception signal 140) based on the charge information detected by the charge amplifier 103 is input to any of the AD converters 110, 111, and 112 based on the switching destination of the switch circuit 106. The AD converters 110, 111, and 112 convert the input analog signal into a digital signal. The converted received signal 140 is input to and stored in the storage devices 113, 114, 115 corresponding to the converters 110, 111, 112.

  Thereafter, the operator uses the operation unit 123 to select in what manner the received signal is displayed. Then, a switch control signal 145 is output from the operation unit 123 and input to the switch circuit 161. In the switch circuit 161, based on the switch control signal 145, any of the selection terminals 161a, 161b, 161c, 161d, 161e, 161f, 161g, 161h, 161i is turned on. Then, the arithmetic processing circuit connected to the selection terminal turned on operates.

  Further, storage device control signals 142, 143, and 144 are generated based on signals from the operation unit 123. When the storage device 113 receives the storage device control signal 142, the storage device 113 outputs the stored reception signal of state 1 (hereinafter referred to as S 1) to the distributor 151. When the storage device 114 receives the storage device control signal 143, the storage device 114 outputs the stored reception signal of state 2 (hereinafter referred to as S <b> 2) to the distributor 152. When the storage device 115 receives the storage device control signal 144, the storage device 115 outputs the stored reception signal in the state 3 (hereinafter referred to as S 3) to the distributor 153.

  Then, the signals output from the storage devices 113 to 115 are subjected to arithmetic processing by the arithmetic processing circuit, output as the arithmetic processing signal 146 through the switch circuit 161, and input to the image converter 124. The subsequent steps are the same as in the first embodiment.

Next, each calculation processing when each selection terminal 161 is turned on will be described.
(Case 1) When the selection terminal 161a is turned ON, the signal S1 output from the distributor 151 is output as the arithmetic processing signal 146.

(Case 2) When the selection terminal 161d is turned ON, the signal S2 output from the distributor 152 is output as the arithmetic processing signal 146.
(Case 3) When the selection terminal 161i is turned on, the signal S3 output from the distributor 153 is output as the arithmetic processing signal 146.

  (Case 4) When the selection terminal 161b is turned ON, the signals S1 and S2 output from the distributors 151 and 152 are input to the arithmetic processing circuit 154. The arithmetic processing circuit 154 performs an arithmetic process of S4 = S2-S1 in order to generate the signal S4. Then, the generated signal S4 is output as the arithmetic processing signal 146.

  (Case 5) When the selection terminal 161f is turned ON, the signals S1 and S3 output from the distributors 151 and 153 are input to the arithmetic processing circuit 155. The arithmetic processing circuit 155 performs the arithmetic processing of S5 = S3-S1 in order to generate the signal S5. Then, the generated signal S5 is output as the arithmetic processing signal 146.

  (Case 6) When the selection terminal 161h is turned ON, the signals S2 and S3 output from the distributors 152 and 153 are input to the arithmetic processing circuit 156. The arithmetic processing circuit 156 performs the calculation of S6 = S3−S1 in order to generate the signal S6. Then, the generated signal S6 is output as the arithmetic processing signal 146.

  (Case 7) When the selection terminal 161c is turned ON, the signals S4 and S5 generated by the arithmetic processing circuits 154 and 155 are input to the arithmetic processing circuit 157. The arithmetic processing circuit 157 performs an operation of S7 = S4 + S5 in order to generate the signal S7. Then, the generated signal S7 is output as the arithmetic processing signal 146.

  (Case 8) When the selection terminal 161e is turned ON, the signals S5 and S6 generated by the arithmetic processing circuits 155 and 156 are input to the arithmetic processing circuit 158. The arithmetic processing circuit 158 performs an operation of S8 = S5 + S6 in order to generate the signal S8. Then, the generated signal S8 is output as the arithmetic processing signal 146.

  (Case 9) When the selection terminal 161g is turned ON, the signals S4 and S6 generated by the arithmetic processing circuits 154 and 156 are input to the arithmetic processing circuit 159. The arithmetic processing circuit 159 performs an operation of S9 = S4 + S6 in order to generate the signal S9. Then, the generated signal S9 is output as the arithmetic processing signal 146.

  Here, each calculation process will be described in detail. S1 is, for example, measurement data in the ultrasonic anechoic cell 70 in FIG. 8 (state 1) (this is noise data related to noise and fluctuations derived from transducers (including drive signals) generated with ultrasonic transmission) In the noise derived from the vibrator, a crosstalk vibration wave and a standing wave related to the in-plane transverse wave propagation unique to c-MUT are included.

  S2 is the received ultrasonic data during insertion through the body cavity in FIG. 9A (state 2), and the surface reflection from the lumen wall in the body cavity without contact using the aerial ultrasound. It corresponds to a signal. Among these signals, noise signals related to noise and fluctuations derived from vibrators (including drive signals) are also included. Therefore, this noise signal can be removed by the calculation “S4 = S2−S1”.

  Next, S3 is data including deep diagnostic measurement information when the transducer in FIG. 9B (state 3) is fixed in contact with the surface of the lumen wall, and corresponds to a deep reflection signal. This signal includes signal components S1 and S2. In this case, since the S1 signal is a noise signal, it is necessary to remove the S1 signal. Therefore, the calculation is “S5 = S3−S1”.

  On the other hand, since the noise signal is also included in the S2 signal, the calculation of “S6 = S3−S2” may be performed, but at the same time, the surface reflection signal from the lumen wall included in S3 is also removed. It will be. On the one hand, such signal processing has the disadvantage of losing the tissue information on the surface of the luminal wall of the living body, but on the other hand, it is easier to see the deep diagnostic image by deleting the tissue information on the surface of the luminal wall. There is also an advantage. In this way, whether to use “S5 = S3-S1” or “S6 = S3-S2” is left to the discretion of the operator. For this reason, it leads to improving the freedom degree of a diagnosis.

  Note that “S7 = S4 + S5” is a sum of the surface reflection signal from the lumen wall from which noise has been removed and the deep diagnostic signal from which noise has been removed, thereby enabling diagnosis from the surface to the deep portion without any unevenness. In addition, for “S8 = S5 + S6” and “S9 = S4 + S6”, images having various signal advantages can be obtained.

  By the way, the operator may be interested in how the original signal was, and the arrangement of the switch circuit 161 makes it possible to select and detect the single signals S1, S2, and S3. Become. Although the signal processing subsequent to the arithmetic processing signal 143 is not described in detail in this embodiment, for example, it can be displayed on a monitor screen which is the presentation device 23 in a separate window.

  In the present embodiment, the arithmetic processing devices 154, 155, and 156 calculate the difference between the two input signals. However, as in the first embodiment, a correlation function (cross-correlation, autocorrelation) is used. May be.

Furthermore, the capacitive ultrasonic transducer can cope with Doppler signal control and harmonic imaging, and the ultrasonic diagnostic system according to the present invention can be applied.
As described above, various patterns of signal processing can be performed based on the ultrasonic reception signals obtained in the respective states according to the selection of the operator. As a result, the ultrasonic diagnostic image to be generated can also be provided with features corresponding to the signal processing, so that diagnosis can be performed from multiple aspects.

It is a figure which shows the outline | summary of the intracorporeal ultrasound diagnostic system in 1st Embodiment. It is a figure which shows the external appearance structure of the ultrasonic endoscope scope 2 in this embodiment in 1st Embodiment. It is a figure which shows the structure of the electrostatic capacitance type radial scanning array ultrasonic transducer | vibrator in 1st Embodiment. FIG. 3 is a cross-sectional perspective view of a two-dimensional array transducer 20 in the first embodiment. FIG. 5 is a top view of a single vibrator unit 32 according to the first embodiment. FIG. 5 is a top view of a single transducer element 33 according to the first embodiment. It is sectional drawing about Aa-Ab of FIG. It is a figure which shows the ultrasonic anechoic cell 70 in 1st Embodiment. It is a figure which shows the case where the ultrasonic transducer | vibrator 6 in 1st Embodiment is inserted in the body cavity. It is a figure which shows the outline | summary of the internal structure of the ultrasonic diagnostic system in a body cavity in 1st Embodiment. It is a figure which shows the frequency characteristic when the ultrasonic transducer | vibrator in 2nd Embodiment contacts / non-contacts the target object. It is a figure which shows the outline | summary of the internal structure of the ultrasonic diagnostic system in a body cavity in 2nd Embodiment. It is a figure which shows the arithmetic control circuit 150 which performs the signal processing of the multiple pattern in 3rd Embodiment. It is a figure which shows the conventional c-MUT. It is a figure which shows a mode that the standing wave generate | occur | produced in the membrane when c-MUT of FIG. 14 was used.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Intracorporeal ultrasound diagnostic system 2 Ultrasound endoscope scope 2-1 Capacitive ultrasonic transducer 3 Signal processing unit 3-1 Storage control unit 3-3 Storage unit 3-3 Calculation unit 200 Image processing unit 200 -1 Image construction unit 3-5 Vibrator state determination unit 3-5a State detection unit 3-5b Detection information determination unit 4 Display unit 4-1 Monitor 5 Insertion unit 6 Capacitive radial sector scanning array ultrasonic transducer 7 Bending portion 8 Flexible tube portion 9 Operating portion 10 Universal cord 11 Scope connector 20 Two-dimensional array transducer 21 Transceiver circuit 22 Coaxial cable bundle 31 FPC for wiring
32 vibrator unit 33 vibrator element 34 control circuit unit 40, 48, 49 interconnect electrode between vibrator cell electrodes 41 upper electrode 42 cavity peripheral edge 43 sacrificial layer agent removal hole 44 lower electrode through-hole electrode part 45 dicing line 46 vibrator Inter-element groove 47 Oscillator unit arrangement direction groove 50 cell 51 cavity 52 membrane lower layer 54 membrane upper layer 55 ground electrode pad 56 signal input / output terminal electrode pad 57 dielectric film 58 membrane support 59 interconnect wiring 60 depletion layer 61 silicon substrate 62 silicon Oxide film 63 Lower electrode 70 Ultrasonic anechoic cell 300 Ultrasound endoscope observation apparatus 101 Capacitive ultrasonic transducer 102 Optical sensor 103 Charge amplifier 104 Pulser (pulse generation circuit)
105 Photosensor signal processing circuit 106 Switch circuit 110, 111, 112 AD converter 113, 114, 115 Storage device 116, 117, 118 Arithmetic processing circuit 119 Switch circuit 123 Operation unit 124 Image converter 125 Low-pass filter 126 Detector 150 Operation Control circuit 151, 152, 153 Distributor 154, 155, 156, 157, 158, 159 Arithmetic processing circuit 161 Switch circuit

Claims (23)

An ultrasonic endoscope scope provided with a capacitive ultrasonic transducer for transmitting and receiving ultrasonic waves;
Vibrator state discriminating means for discriminating the presence or absence of contact of the capacitive ultrasonic transducer;
Storage means for storing sensing information sensed by the capacitive ultrasonic transducer;
A storage control unit for storing the sensing information in the storage unit corresponding to the determination result based on the determination result by the vibrator state determination unit;
Arithmetic means for performing arithmetic processing using at least one of the sensing information stored in the storage means;
Image construction means for constructing an ultrasound diagnostic image from the computation result computed by the computation means;
An intra-body-cavity ultrasonic diagnostic system comprising:   The capacitive ultrasonic transducer is composed of a plurality of capacitive ultrasonic transducer elements, and is a one-dimensional or two-dimensional array in which the plurality of capacitive ultrasonic transducer elements are arranged on a cylindrical outer peripheral surface. The intra-body-cavity ultrasonic diagnostic system according to claim 1, wherein the ultrasonic diagnostic system is an array-type capacitive ultrasonic transducer.   The intra-body-cavity ultrasonic diagnostic system according to claim 2, wherein a groove is provided between the adjacent transducer elements.   The intra-body-cavity ultrasonic diagnostic system according to claim 3, wherein a conductive film is formed in the groove. The intracorporeal ultrasound diagnostic system further comprises:
3. The intra-body-cavity superstructure according to claim 2, further comprising: a radial scanning control unit that causes the synthetic ultrasonic beam radiated from the capacitive ultrasonic transducer to perform radial scanning along the circumferential direction of the cylinder. Ultrasonic diagnostic system.   The intra-body-cavity ultrasonic diagnostic system according to claim 5, wherein the radial scanning control unit further causes the synthetic ultrasonic beam to perform sector scanning in the cylindrical major axis direction.   2. The body cavity according to claim 1, wherein the calculation unit performs a calculation to calculate a sum, a difference, or a cross-correlation of at least two pieces of the detection information stored in the storage unit. Internal ultrasound diagnostic system.   The intra-body-cavity ultrasound diagnostic system according to claim 1, wherein the calculation means performs a calculation for calculating an autocorrelation from one of the sensing information. The vibrator state determining means includes
State detecting means for detecting whether the capacitive ultrasonic transducer is in any state of whether it reaches the inner wall outside the body and inside the body cavity;
Based on detection information obtained from the state detection means, detection information determination means for determining the state;
The intra-body-cavity ultrasonic diagnostic system according to claim 1, comprising: The state detection means is an optical sensor provided substantially in the vicinity of the capacitive ultrasonic transducer,
Based on the output of the optical sensor, the detection information discriminating means is in a state in which the capacitive ultrasonic transducer is outside the body or inside the body cavity but is not in contact with the inner wall of the body cavity, or is not in contact with the inner wall of the body cavity It is discriminate | determined whether It is. The intra-body-cavity ultrasonic diagnostic system of Claim 9 characterized by the above-mentioned. The state detection means is a pressure sensor provided substantially in the vicinity of the capacitive ultrasonic transducer,
The detection information discriminating means is in any state of the capacitive ultrasonic transducer in the body cavity but not in contact with the body cavity inner wall or in the body cavity inner wall non-contact based on the output of the pressure sensor. The intra-body-cavity ultrasonic diagnostic system according to claim 9, wherein: The state detection means generates the state detection information corresponding to the frequency of an electrical signal representing the detection information,
The detection information discriminating means is based on the state detection information when the capacitive ultrasonic transducer is outside the body or inside the body cavity, but is not in contact with the inner wall of the body cavity, or is not in contact with the inner wall of the body cavity. It is discriminate | determined. The intra-body-cavity ultrasonic-diagnosis system of Claim 9 characterized by the above-mentioned.   The intra-body-cavity ultrasonic diagnostic system according to claim 12, wherein the state detection means is a filter circuit that allows the electrical signal to pass when the frequency of the electrical signal is equal to or lower than a predetermined threshold.   The storage control means stores at least one of the sensing information sensed when the capacitive ultrasonic transducer is outside the body, inside the body cavity, but not in contact with the inner wall of the body cavity, and in contact with the inner wall of the body cavity. The intra-body-cavity ultrasonic diagnostic system according to claim 1, wherein:   The sensing information stored in the first storage means of the storage means is sensed by emitting ultrasonic waves to the capacitive ultrasonic transducer under conditions where the ultrasonic waves are not reflected. The intra-body-cavity ultrasonic diagnostic system according to claim 1, which is first sensing information. The sensing information stored in the second storage means of the storage means is the transmission and reception of the ultrasonic waves in a state where the capacitive ultrasonic transducer is in the body cavity but not in contact with the inner wall of the body cavity. Second sensing information sensed,
16. The intracorporeal ultrasound diagnostic system according to claim 15, wherein the calculation means calculates a correlation or difference between the second sensing information and the first sensing information. The sensing information stored in the third storage means of the storage means is a third sensing sensed by transmitting and receiving the ultrasound in a state where the capacitive ultrasonic transducer is in contact with the inner wall of the body cavity. Information,
16. The intracorporeal ultrasound diagnostic system according to claim 15, wherein the calculation means calculates a correlation or difference between the third sensing information and the first sensing information. The sensing information stored in the second storage means of the storage means is the transmission and reception of the ultrasonic waves in a state where the capacitive ultrasonic transducer is in the body cavity but not in contact with the inner wall of the body cavity. Second sensing information sensed,
The sensing information stored in the third storage means of the storage means is a third sensing sensed by transmitting and receiving the ultrasound in a state where the capacitive ultrasonic transducer is in contact with the inner wall of the body cavity. Information,
The computing means performs a first computing process for calculating a correlation or difference between the second sensing information and the first sensing information, and correlates the third sensing information with the first sensing information. Or the 2nd calculation which calculates a difference is performed, and the result of a 1st calculation process and the result of a 2nd calculation process are added, The intrabody cavity ultrasonic diagnosis system of Claim 15 characterized by the above-mentioned.   The ultrasonic diagnostic system for body cavity according to claim 16, wherein the ultrasonic diagnostic image is an image representing a contour of a surface of a body cavity inner wall.   The intracorporeal ultrasound diagnostic system according to claim 17, wherein the ultrasonic diagnostic image is an image representing a tomographic tissue in a body cavity.   19. The intra-body-cavity ultrasonic diagnostic system according to claim 18, wherein the ultrasonic diagnostic image is an image that represents an outline of a surface of a body cavity inner wall and an image that represents a tomogram of tissue in the body cavity. From sensing information sensed by the capacitive ultrasonic transducer used in an intracorporeal ultrasound diagnostic system having an ultrasonic endoscope scope provided with a capacitive ultrasonic transducer for transmitting and receiving ultrasonic waves A noise removing device for removing noise components,
First storage means for storing the first sensing information sensed by emitting ultrasonic waves to the capacitive ultrasonic transducer under a condition where the ultrasonic waves are not reflected;
A second storage means for storing the second sensing information sensed by transmitting and receiving the ultrasound in a state where the capacitive ultrasonic transducer is in a body cavity but is not in contact with the inner wall of the body cavity;
An apparatus for removing noise, comprising: an arithmetic means for calculating a correlation or difference between the second sensing information and the first sensing information. From sensing information sensed by the capacitive ultrasonic transducer used in an intracorporeal ultrasound diagnostic system having an ultrasonic endoscope scope provided with a capacitive ultrasonic transducer for transmitting and receiving ultrasonic waves A noise removing device for removing noise components,
First storage means for storing the first sensing information sensed by emitting ultrasonic waves to the capacitive ultrasonic transducer under a condition where the ultrasonic waves are not reflected;
Third storage means for storing third sensing information sensed by transmitting and receiving the ultrasound in a state where the capacitive ultrasonic transducer is in contact with a body cavity inner wall;
A noise removing apparatus comprising: an operation unit that calculates a correlation or difference between the third sensing information and the first sensing information.