JP2012040312A - Ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy in obtaining three-dimensional information of an object to be measured.SOLUTION: First and second ultrasonic vibrators 34A and 34B are arranged so as to sandwich the object to be measured between them. A ultrasonic wave is transmitted by the first ultrasonic vibrator 34A. A reflected wave reflected on the object is received and a receiving signal is stored in a storing part 76 as reflected wave information 76a of a first side. In the second ultrasonic vibrator 34B, the reflected wave is similarly received and a receiving signal is stored in the storing part 76 as reflected wave information 76b of a second side. A three-dimensional model of the object is formed from the reflected wave information of the first and second sides and relative positions of the two ultrasonic vibrators.

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to acquisition of three-dimensional information in an ultrasonic diagnostic apparatus.

  2. Description of the Related Art There is known an ultrasonic diagnostic apparatus that performs diagnosis based on information obtained by transmitting ultrasonic waves from an ultrasonic transducer to a measurement target such as an organ or bone in a living body and receiving the reflected waves. Usually, an ultrasonic wave is transmitted from one direction to the measurement object, and a reflected wave from the entire measurement object is received. An apparatus that performs diagnosis based on an ultrasonic wave that has passed through a measurement object is also known. In the following Patent Document 1, a pair of ultrasonic transducers are arranged with a footpad interposed therebetween, and ultrasonic waves transmitted from one ultrasonic transducer are received by the other ultrasonic transducer, For example, a bone density measuring device that measures the amount of attenuation in the ribs is described.

JP-A-7-204205

  The device described in Patent Document 1 has a pair of ultrasonic transducers, one of which is used for transmission and the other is used for reception. Therefore, although information on the attenuation amount of the ultrasonic beam of the measurement object (for example, ribs) can be obtained, the three-dimensional (three-dimensional) tissue structure, shape, etc. of the measurement object could not be grasped. . Although one ultrasonic transducer can send and receive ultrasonic waves and grasp the structure, shape, etc. of the measurement object from the reflected wave information, the side of the measurement object on which the ultrasonic transducer is placed The information from the opposite side has a problem that attenuation is large and it is difficult to obtain detailed information.

  An object of this invention is to provide the three-dimensional information of a measurement object.

  The ultrasonic diagnostic apparatus according to the present invention includes two ultrasonic transducers capable of two-dimensional scanning, and these are arranged at positions sandwiching a measurement object. The two ultrasonic transducers are driven by a transmission / reception unit provided corresponding to them. The ultrasonic wave is transmitted / received by one ultrasonic transducer, and the reflected wave information of the measurement object on the side where the ultrasonic transducer is arranged is acquired based on the received ultrasonic wave. Similarly, the reflected wave information of the measurement object on the side on which the other ultrasonic transducer side is arranged is acquired in the other ultrasonic transducer. Based on the relative positions of the two ultrasonic transducers grasped in advance, a three-dimensional model of the measurement object is formed based on the reflected wave information obtained by each ultrasonic transducer.

  The three-dimensional model is, for example, a three-dimensional shape of the surface of the measurement object.

  A highly accurate three-dimensional model can be acquired by obtaining reflected wave information with two ultrasonic transducers arranged so as to sandwich the measurement object.

It is a perspective view which shows the external appearance of the ultrasonic bone evaluation apparatus of this embodiment. It is a perspective view which shows the external appearance of the ultrasonic bone evaluation apparatus of this embodiment. It is an expansion perspective view which shows the external appearance of a footrest and a vibrator unit. It is an expanded sectional view which shows the positional relationship of a footrest, a vibrator | oscillator unit, and a leg. It is a schematic sectional drawing of a vibrator | oscillator unit. It is a perspective view which shows the shape of the front side member of a matching material bag. It is a perspective view which shows the shape of the front side member of a matching material bag. It is a perspective view which shows the shape of the front side member of a matching material bag. It is a perspective view which shows the outline of the mechanism for moving an ultrasonic transducer | vibrator. It is a figure which shows the scanning range of an ultrasonic beam. It is a functional block diagram of the ultrasonic bone evaluation apparatus of this embodiment. It is explanatory drawing which concerns on the signal processing of a received signal. It is a figure which shows the example of the three-dimensional display of a measuring object. It is a figure which shows the example of the range which calculates | requires a volume.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, an ultrasonic diagnostic apparatus using a rib as a measurement object, particularly an ultrasonic bone evaluation apparatus capable of evaluating bone such as bone density will be described, but the measurement object is not limited to this. Regarding the bones and other organs other than the ribs, it is possible to achieve the purpose of the present invention by appropriately changing the configuration of the apparatus according to the shape, characteristics, etc. of the bones, organs, and tissues around these objects. Those who are skilled in the art can easily assume this.

  FIG. 1 and FIG. 2 are perspective views showing an appearance of an ultrasonic bone evaluation apparatus 10 that uses a rib as an evaluation target. A footrest 14 is disposed on the upper part of the apparatus main body 12. The footrest 14 is a base having a substantially L-shaped placement surface, and places the foot F as shown by the chain line in FIG. 2 for positioning. The foot is positioned by aligning the heel with the L-shaped corner of the footrest 14. Two transducer units 16A and 16B including ultrasonic transducers are arranged on the left and right sides of the footrest 14 so as to sandwich the heel portion. The left and right vibrator units 16A and 16B have a symmetric structure, and when it is not particularly necessary to distinguish between left and right, they are simply referred to as the vibrator unit 16 and will be described below. In addition, regarding the elements constituting the left and right vibrator units 16A and 16B, A and B are added to the reference signs when it is necessary to distinguish between the left and right, and only the numerical signs are used when the distinction is not necessary. It explains using. The transducer unit 16 has an acoustic matching unit in order to achieve acoustic matching between the heel portion and the ultrasonic transducer. The acoustic matching portion is deformable and deforms to adhere to the heel portion, eliminating the air layer therebetween. In this ultrasonic bone evaluation apparatus 10, the acoustic matching unit includes an acoustic matching material such as water and a matching material bag 18 containing the water and the like. When the foot is placed on the footrest 14, the matching material bag 18 is brought into contact with the heel portion of the foot, thereby matching the acoustic impedance between the ultrasonic transducer and the heel portion.

  3 and 4 are enlarged views of the footrest 14 and the vibrator unit 16. In FIGS. 3 and 4, one side, that is, a portion on the right side for the subject when the subject puts his / her foot on the footrest 14 is shown by being broken at the median surface of the footrest 14. Yes. The footrest 14 is substantially L-shaped, and the angle formed between the bottom surface 20 constituting the two sides of the L-shape and the contact surface 22 is substantially a right angle. The subject places the sole of the foot on the bottom surface 20 with the rear end surface of the footpad contacting the contact surface 22. At this time, the alignment material bag 18 is disposed so as to abut on the position of the foot heel, particularly the position of the rib and the surrounding position. The flange portion of the matching material bag 18 and the surface in contact with the periphery thereof have a shape of a substantially spherical surface surrounded by a surface orthogonal to one diameter and two surfaces parallel to this diameter and orthogonal to each other. ing. When the foot is placed on the footrest 14, the alignment material bag 18 comes into contact with the heel portion and the left and right sides around the heel portion, and the alignment material bag 18 is deformed so as to follow the surface of the heel portion, thereby eliminating the presence of an air layer. .

  FIG. 5 is a cross-sectional view of the vibrator unit 16. The matching material bag 18 is formed by fixing a back side member 26 opposite to the front side member 24 on the foot side, which is a target living body, to an annular ring frame 28. The front side member 24 is sandwiched between the ring frame 28 and a first fixing ring 30 located inside the ring frame 28, and is fixed to the ring frame 28. Further, the rear side member 26 is sandwiched between the first fixing ring 30 and the second fixing ring 32 and indirectly fixed to the ring frame 28. The back side member 26 is bent in a bellows shape, and the central portion is coupled to the outer peripheral portion of the ultrasonic transducer 34. On the further back side of the back side member 26, a support plate 36 that restricts and supports the back side member 26 so as not to bulge to the back side is disposed. The support plate 36 includes a plurality of annular plate-like support plates 38a, 38b, 38c, and 38d, and the outermost support plate 38a further has a cylindrical portion at the outer peripheral edge portion. It is fixed to. The innermost support plate 38 d is fixed to the outer periphery of the ultrasonic transducer 34. The back-side member 26 is fixed to the ultrasonic transducer 34 by being sandwiched between a flange 40 provided on the outer peripheral portion of the ultrasonic transducer 34 and an innermost support plate 38d. The support plates 38a, 38b, 38c, and 38d are slidable with respect to each other, and allow movement of the ultrasonic probe 34, which will be described later, in a direction perpendicular to the probe axis.

  FIGS. 6-8 is a perspective view which shows the shape of the front side member 24 of a matching material bag. The front member 24 has a circular base portion 41, and a bulging portion 42 that bulges toward the heel portion on the footrest 14 and each of the pair of vibrator units 16 </ b> A and 16 </ b> B. The communication pipes 44A and 44B communicating with the internal spaces of the matching material bags 18A and 18B, and a calibration block pocket 46 for arranging a calibration block are provided. The left and right communication pipes 44A and 44B are connected at the center, and the internal spaces of the left and right alignment material bags are communicated. By moving the two ultrasonic transducers 34A and 34B to the positions of the communication tubes 44A and 44B and making them face each other, the speed of sound in the alignment material can be measured.

  The shape of the bulging portion 42 is a shape obtained by cutting a spherical surface with a first plane orthogonal to one diameter and second and third planes parallel to the diameter and orthogonal to each other. The diameter is orthogonal to the base portion 41, and the plane formed by the base portion 41 corresponds to the first plane. The second and third planes are surfaces formed by the bottom surface 20 and the contact surface 22 of the footrest 14. The cut surface formed by the second and third planes becomes the first side surface 48 and the second side surface 50. Further, a part of the spherical surface cut out by these first to third planes becomes the living body contact surface 51 that contacts the foot, which is the target portion. Therefore, the first side surface 48 of the bulging portion 42 is along the bottom surface 20 of the footrest and the second side surface 50 is along the contact surface 22. And the side surface of the bulging part 42 formed from the 1st and 2nd side surfaces 48 and 50 is formed in an L shape along the surface which puts the leg of an L-shaped footrest as a whole. In other words, the bulging portion can be seen as a partial dome shape obtained by cutting a dome with a low height by two intersecting planes.

  FIG. 9 is a diagram showing a moving mechanism 52 that moves the ultrasonic transducer 34. The vibrator unit 16 is shown with the support plate 36 omitted, and the bellows-shaped portion of the back member 26 of the alignment material bag 18 appears. The two ultrasonic transducers 34A and 34B are fixed to the tip of a U-shaped or U-shaped support frame 54. The support frame 54 is moved by a drive mechanism 56 in a plane orthogonal to the direction in which the two ultrasonic transducers 34A and 34B face each other (that is, the axial direction of the ultrasonic transducer). Accordingly, the two ultrasonic transducers 34A and 34B do not move in the direction in which they face each other, and the distance from each other does not change. However, the two ultrasonic transducers 34A and 34B can move in either direction in the direction orthogonal to the facing direction. It has become. In this movement, the two ultrasonic transducers 34A and 34B are always maintained in the opposed state. In order to allow the movement of the ultrasonic transducer 34, the back member 26 of the alignment material bag has a bellows structure, and the support board 36 has a configuration having multiple support plates 38a to 38d. The respective support plates 38a to 38d slide on each other to allow the ultrasonic transducer 34 to move.

  FIG. 10 is a diagram showing the footrest 14 and the foot F placed thereon. A meandering arrow Y indicates a scanning path of the ultrasonic transducer 34. A range R surrounding the locus of the arrow Y is an ultrasonic beam scanning range. The ultrasonic transducer 34 is scanned in a range R including the rib C to obtain transmitted ultrasonic data. Based on this received data, bones, particularly ribs are evaluated.

  FIG. 11 is a block diagram showing a functional configuration of the ultrasonic bone evaluation apparatus 10. The structures of the transducer units 16A and 16B and the moving mechanism 52 are as already described. The ultrasonic transducers of the transducer units 16A and 16B are connected to the reception circuit 68 and the transmission circuit 70 via the transmission / reception switching circuit 66. Through the transmission / reception switching circuit 66, the direction of ultrasonic transmission or the ultrasonic transducer for transmission can be switched. Further, it is possible to connect so that the ultrasonic wave transmitted from one ultrasonic transducer is reflected by the target and the reflected wave is received by the same ultrasonic transducer. By performing this connection, the distance from the ultrasonic transducer to the bulging portion 42 of the matching material bag can be measured.

  The control unit 72 controls the reception circuit 68 and the transmission circuit 70 to obtain an ultrasonic reception signal that has passed through the living body. The control unit 72 controls the switching operation of the transmission / reception switching circuit 66 described above. The control unit 72 also controls the operation of the moving mechanism 52 to move the ultrasonic transducer 34 as indicated by an arrow Y in FIG. 10, for example, and further transmit and receive ultrasonic waves at a predetermined value while moving. Control is performed to obtain an ultrasonic reception signal at a predetermined point within the scanning range R (that is, a measurement range; measurement range). The received signal is processed by the reception data processing unit 74 and stored in the storage unit 76 as reception data. The stored reception data includes a reception waveform, that is, sound pressure data that changes with time.

  The ultrasonic bone evaluation apparatus 10 includes a calculation unit 78 that performs a calculation process on the received waveform. The calculation process of the calculation unit will be described later. Furthermore, the ultrasonic bone evaluation apparatus 10 includes an operation panel unit 80 for an operator to instruct operation of the apparatus and a display unit 82 for displaying a result. A so-called touch panel display in which the functions of the operation panel unit 80 and the display unit 82 are integrated may be employed.

  The formation of a three-dimensional model will be described. Here, an example of a three-dimensional model will be described using a three-dimensional shape of a rib. As described above, the ultrasonic bone evaluation apparatus 10 has a function of receiving, with the same ultrasonic transducer, a reflected wave that is reflected from an object by an ultrasonic wave transmitted from one ultrasonic transducer. That is, the ultrasonic wave is transmitted and received between the ultrasonic transducer 34A belonging to the transducer unit 16A and the ultrasonic transducer 34B belonging to the transducer unit 16B, and the reception signal of the reflected wave is acquired. The reception signal received by the first ultrasonic transducer 34A is stored in the storage unit 76 as reflected wave information (echo data) 76a on the first side. Similarly, the reception signal received by the second ultrasonic transducer 34B is stored in the storage unit 76 as second-side reflected wave information (echo data) 76b.

  The received signal includes a reflected wave from the body surface (and the matching material bag), and is removed by the computing unit 78 as necessary (body surface removing unit 78a). By this removal, the reflected wave at the rib portion can be extracted. FIG. 12 shows the waveform of the received signal. FIG. 12A shows the received signal waveform itself, where the first peak is the reflected wave S from the body surface, and the next peak represents the reflected wave T from the rib surface. The reflected wave S from the body surface is easy to detect because no conspicuous reflected wave is generated before it. When the reflected wave S from the body surface is detected, the weighting function W is set based on this. The weighting function W rises from 0 to 1 after a predetermined time has elapsed after the reflected wave S from the body surface is detected, as shown by the one-dot chain line in FIG. Function. Further, since the distance between the body surface and the rib surface is empirically known, the weighting function W eliminates the peak of the reflected wave from the body surface and maintains the peak of the reflected wave from the rib surface as it is. Is set to A signal waveform obtained by multiplying the received signal shown in FIG. 12A by the weighting function W is represented by a solid line in FIG. In FIG. 12B, the received signal before the weighting process is also indicated by a broken line. By this weighting process, the reflected wave from the body surface can be eliminated.

  Based on the consultation signal from which the reflected wave from the body surface is removed, luminance modulation data is generated (luminance modulation data generation unit 78b). That is, the luminance value for each distance (depth) from the ultrasonic transducer is calculated based on the voltage value of the received signal. A three-dimensional model of the rib is formed from the luminance modulation data for each measurement point obtained by two-dimensional scanning of the ultrasonic transducers 34A and 34B (three-dimensional model forming unit 78c). At this time, a half three-dimensional model of the rib on the first ultrasonic transducer 34A side is obtained from the luminance modulation data based on the reflected wave information 76a on the first side, and the reflected wave information 76b on the second side is obtained. A half three-dimensional model on the second ultrasonic transducer 34B side is obtained from the luminance modulation data based thereon. In other words, the luminance modulation data obtained by the corresponding ultrasonic transducers are created on the respective sides at the middle point between the two ultrasonic transducers 34A and 34B, and these are combined to obtain the three-dimensional of the entire rib. Get the model. For this combination, information relating to the positional relationship between the two ultrasonic transducers 34A and 34B is necessary, and is stored in advance in the storage unit 76, for example. In this ultrasonic bone evaluation apparatus 10, the two ultrasonic transducers 34A and 34B are fixed to a U-shaped support frame 54 and move in parallel during scanning, so that the distance is always constant. Kept. Therefore, in this ultrasonic bone evaluation apparatus 10, the information related to the positional relationship between the ultrasonic transducers is the interval between the two ultrasonic transducers. Since the luminance modulation data has distance information (depth) from the corresponding ultrasonic transducer, the relative luminance modulation data on the first side and the second side is determined from the interval between the two ultrasonic transducers. A specific positional relationship can be determined, and a three-dimensional model can be formed.

  The three-dimensional model includes data on the rib surface, and a three-dimensional shape of the rib surface can be obtained based on the data. Since the bone surface strongly reflects ultrasonic waves, the luminance value is high in the luminance modulation data. In the received waveform shown in FIG. 12, the peak that appears next to the body surface corresponds to the bone surface. By using any of these features, the three-dimensional shape of the rib surface can be extracted.

  For example, as shown in FIG. 13, the three-dimensional shape is displayed on the display unit 82 in a three-dimensional display (a two-dimensional display with a sense of depth). This three-dimensional shape is a shape as if the ribs were cut out in the scanning region R of the ultrasonic transducer, and the upper and left side planes in FIG. It is not the surface of bone.

  Further, the calculation unit 78 calculates the volume of a predetermined portion of the rib from the three-dimensional shape of the rib obtained as described above (volume calculation unit 78d). The range for which the volume is to be calculated can be determined based on the characteristic part of the contour shape of the rib. For example, the volume calculation range G shown in FIG. 14 is determined, and the volume of the rib within this range is calculated. The volume calculation range G can be determined as follows. A substantially arc-shaped portion H of the rib corresponding to the tip of the rib (downward in the figure) is approximated by a circular arc, and four planes that are separated from the center P of the circular arc by a predetermined distance in the vertical and horizontal directions are determined. These four planes correspond to the sides of the square of the volume calculation range G in FIG. The volume of the portion surrounded by these four planes and the front rib surface and the rear rib surface in the direction penetrating the paper surface in FIG. 14 is calculated.

  For each measurement point in the volume calculation range G, the attenuation amount of the ultrasonic wave at the measurement point is divided by the calculated volume, and the calculated values of the measurement points in the range G are integrated. This value is the amount of ultrasonic attenuation per volume, and is correlated with bone density.

  The outline of the measurement flow is described below. The subject's feet are placed on the footrest 14 and the operator instructs the start of measurement from the operation panel unit 80. The control unit 72 controls the moving mechanism 52 to start scanning measurement of the heel portion on the determined scanning line. At each measurement point, the control unit 72 first sets the transmission / reception switching circuit 66 so that ultrasonic waves are transmitted / received by the first ultrasonic transducer 34A, transmits / receives by the transmission circuit 70 and the reception circuit 68, and receives signals. Get a signal. The received signal is sent to the storage unit 76 via the reception data processing unit 74 and stored therein as the reflected wave information 76a on the first side. At the same measurement point, the control unit 72 sets the transmission / reception switching circuit 66 so that ultrasonic waves are transmitted / received by the second ultrasonic transducer 34B, transmits / receives by the transmission circuit 70 and the reception circuit 68, and receives signals. Get a signal. The received signal is sent to the storage unit 76 via the reception data processing unit 74 and stored therein as the reflected wave information 76b on the second side. This is repeated at each measurement point. Further, at each measurement point, it is also possible to transmit an ultrasonic wave with one ultrasonic transducer, receive an ultrasonic wave that has passed through the eyelid with the other ultrasonic transducer, and obtain an obtained reception signal. When the acquisition of information is completed in the entire range of the scanning region, the subject's foot can be lowered from the footrest 14.

  From the acquired received signal, reflection on the body surface is removed, and information on a bone part such as a rib is extracted. This extraction is performed by weighting the received signal. A cross-sectional image in a predetermined plane is created based on the signal after this weighting processing. This plane can be adjusted to the scanning direction of the ultrasonic transducer. As shown in FIG. 10, if the horizontal scanning is repeated at different heights, the cross section is preferably a horizontal plane. If these cross-sectional images are laminated, a three-dimensional model can be obtained. Based on this information, a three-dimensional image can be created by a method such as volume rendering.

  In the above-described embodiment, the two-dimensional scanning is performed by moving the ultrasonic transducer that forms a linear ultrasonic beam vertically and horizontally, but a linear or convex one-dimensional array ultrasonic transducer is used. Also, two-dimensional scanning can be realized by performing electronic scanning in the first direction and performing scanning by mechanically moving the transducer in a second direction orthogonal to the first direction. Also, two-dimensional scanning can be performed by electronic scanning using a two-dimensional array ultrasonic transducer.

  Further, in the present embodiment, the paired ultrasonic transducers are arranged so as to face each other on the same straight line, but are arranged so as to operate the ultrasonic waves respectively on the opposite side surfaces of the measurement object. be able to. At this time, the relative positional relationship between the ultrasonic transducers needs to be determined.

  DESCRIPTION OF SYMBOLS 10 Ultrasonic bone evaluation apparatus, 16, 16A, 16B transducer unit, 34, 34A, 34B ultrasonic transducer, 66 transmission / reception switching circuit (transmission / reception unit), 68 reception circuit (transmission / reception unit), 70 transmission circuit (transmission / reception unit) 72 Control unit (transmission / reception unit), 74 Reception data processing unit (transmission / reception unit), 78 Calculation unit (three-dimensional reflected wave information providing means).

Claims (2)

First and second ultrasonic transducers arranged across a measurement object and capable of two-dimensional scanning;
A transmission / reception unit provided corresponding to the first and second ultrasonic transducers and controlling these ultrasonic transducers;
Reflected wave information on the first ultrasonic transducer side of the measurement object acquired by the first ultrasonic transducer, and reflection on the second ultrasonic transducer side of the measurement target acquired by the second ultrasonic transducer. Three-dimensional model forming means for forming a three-dimensional model of the measurement object based on the wave information and the relative positions of the first ultrasonic transducer and the second ultrasonic transducer;
An ultrasonic diagnostic apparatus.   2. The ultrasonic diagnostic apparatus according to claim 1, wherein the three-dimensional model is a three-dimensional shape of a measurement object surface.