JPS6314985B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electronic scanning ultrasonic diagnostic apparatus, and more particularly to an electronic scanning ultrasonic diagnostic apparatus that can simultaneously observe a wide range of parts of a subject and depict the body surface, making it easy to determine the body part. Ultrasonic testing devices that emit ultrasonic pulses into a subject and obtain tomographic images from the reflected waves have been used for a long time, but electronic scanning is particularly popular as a method for obtaining in-vivo information using this method. Ultrasonic diagnostic equipment is being developed. FIG. 1 is a diagram showing the basic configuration of a linear electronic scanning ultrasonic diagnostic apparatus, which is an example thereof. 1a to 1n are electro-acoustic transducers such as piezoelectric vibrators provided in the ultrasonic probe, which are arranged in a line on the flat surface of the probe main body 11 shown in FIG. These transducers 1a to 1n are hereinafter referred to as a transducer array. These transducer arrays 1a to 1n
are sequentially driven by the pulser 3 via the switching circuits 2a to 2n, thereby causing the ultrasonic beam 4 to move in parallel. The reflected waves of the ultrasound beam 4 from inside the living body are received by the transducer arrays 1a to 1n, and then guided to the wave receiving circuit 5 via the switching circuits 2a to 2n, and then sent to the display 7 through the signal processing circuit 6. will be displayed. These circuits 2a
~2n, 3, 5, 6, and 7 are controlled by a control circuit 8. To actually examine the inside of a living body with this device, the second
As shown in FIG. When the ultrasonic beam is translated in parallel as described above, the inside of the living body 14 is scanned by the ultrasonic beam, so the inside thick frame in FIG. 2b on the display 7 It is possible to obtain ultrasonic tomographic images similar to those shown in the figure. Note that 13 is a cable. However, as shown in FIG.
In the case of an ultrasound probe that directly contacts the surface 31 of the living body, the scanning width is limited to a relatively narrow portion of the living body surface that is in contact with the ultrasound receiving surface 12, and furthermore, the ultrasound probe in the tomographic image is transmitted and received. The wavefront (biological surface) portion is always displayed on the straight line 34'. That is,
Ultrasonic waves can hardly pass through the air, and the ultrasonic wave transmitting/receiving surface 12 is flat, so it is impossible to scan from a part that does not contact the biological surface 31, and the part that is in contact with the biological surface 31 is It becomes flat, and only the part scanned from there can be obtained as a tomographic image. By the way, in the method called manual compound scanning, which is the most popular method in the past, one electro-acoustic transducer 9 is attached to the tip of the angle, as shown in Fig. 3a, and the potentiometers at each fulcrum of the angle are attached. The meters 10a to 10c detect the position of the electro-acoustic transducer 9 and the direction of the ultrasonic beam and display a tomographic image on the display, so as to display a tomographic image of the entire examination area as shown in FIG. 3b. Its body surface 3
4 can also be displayed in its natural form. With this method, a tomographic image is taken as a photograph, and when the image is interpreted later, the entire image is depicted, so there is no problem in identifying the body part. However, in the case of linear electronic scanning ultrasound diagnostic equipment, the shape of the upper body surface, which is displayed in a narrow range as described above, is deformed and displayed in a straight line, so it is difficult to view the display while moving the probe yourself. It is easy to determine the region when observing from above, but the disadvantage is that it becomes extremely difficult to determine the region when interpreting a photograph that has just been taken. In many cases, ultrasonic examinations are taken by a laboratory technician and interpreted by a doctor, and the storage of photographic data is indispensable for routine examinations, so it is extremely inconvenient that it is difficult to judge this area. Also,
In the diagnosis of a fetus, etc., it is necessary to simultaneously depict the image of the entire fetus on one screen, and for this purpose, scanning only a narrow portion is insufficient. The present invention was made in view of the above points, and its purpose is to widen the scanning range and obtain a wide range of tomograms at the same time, regardless of the surface shape of the subject, and to produce tomograms with minimal deformation of the body surface. An object of the present invention is to provide an electronic scanning ultrasonic diagnostic device that facilitates the determination of image parts and tomographic images themselves. The present invention will be explained in detail below with reference to Examples. FIG. 4 is a perspective view of a probe portion of an ultrasonic diagnostic apparatus showing one embodiment of the invention, and FIG. 5 is a sectional view of the same embodiment. Note that the same parts as in FIG. 2 are given the same reference numerals. That is, a convex acoustic lens 18 is provided on the side of the ultrasonic wave transmitting/receiving surface 12 made up of the transducer array of the probe body 11. In contact with the surface of the acoustic lens 18, a bag-like membrane body 14, 1 that independently forms a sealed chamber is provided.
9 is provided. A fluid substance 15 that transmits ultrasonic waves is enclosed in the bag-like membrane bodies 14 and 19. As mentioned above, the acoustic impedance of the fluid substance 15 should be close to that of the biological surface, and should be 1.5 to 1.
1.6×10 ⁶ [Kg/m ²・s] is selected, but
By using an acoustic lens 18 made of silicone rubber having approximately the same acoustic impedance as this, reflections at the boundary between this lens 18 and the fluid substance 15 can be reduced. Since this acoustic lens 18 is a convex lens in order to have a convergence effect as shown by the broken line A, even if air bubbles enter the sealed chamber formed by the membrane 14, the surface will be convex. This allows the air sacs to escape laterally, which is advantageous. Furthermore, since silicone rubber generally allows fluid substances, particularly water, to pass through it slightly, the thin film 19 is used to protect the interior of the acoustic lens 18 and the probe. When attempting to observe, for example, a cross-section of the abdomen of a human body using this ultrasonic probe, see Figure 6a.
The membrane body 14 is brought into contact with the abdominal surface of the living body 31 as shown in FIG. In this case, the membrane body 14 deforms according to the shape of the abdominal surface as shown in the figure, but in this state, the contact surface between the membrane body 14 and the abdominal surface is the ultrasonic wave transmitting/receiving surface 1.
It spreads more than 2. This can be achieved by appropriately selecting the size of the membrane 14, the amount of the fluid substance 15, etc. As a result, the entire surface of the ultrasound transmitting/receiving surface 12 and the abdominal surface are acoustically coupled via the membrane 14 and the fluid substance 15. Therefore, the ultrasonic pulses emitted from the ultrasonic wave transmitting/receiving surface 12 are transmitted into the abdomen without being reflected by an air layer, etc., and the ultrasonic pulses reflected within the abdomen also pass through the air layer on the ultrasonic wave transmitting/receiving surface 12. The ultrasonic beam reaches the target without being reflected by the transducer array, and the ultrasonic beam can be effectively manipulated for the entire transducer array, allowing tomographic images over a wide range to be observed simultaneously. FIG. 6b shows a tomographic image obtained as a result, in which a wide area of the abdominal surface 34 and internal organs 33 are simultaneously depicted on the CRT as one tomographic image. That is, when a conventional ultrasonic probe is used, the ultrasonic wave transmitting/receiving surface 12 as shown in FIG.
The tomographic image 32' is only in a narrow range of the area in contact with the body surface, and the body surface is always depicted as a straight line 34', but if the ultrasonic probe of the present invention is used, the tomographic image 32' will be drawn as shown in FIG. 6b. A wide range tomographic image 32 covering the entire transducer array is depicted as a single tomographic image with the body surface 34 not deformed much and in an almost natural state. Therefore, it is possible to simultaneously describe a single tomographic image over a wide area necessary for diagnosis of a fetus, etc., and it becomes extremely easy to read the tomographic image and determine the region by photographing. In addition, in the ultrasonic probe of the present invention, the membrane body 1
4 is to reduce reflection and absorption of ultrasonic waves,
It must be made of a material that is as thin and durable as possible. Furthermore, in order to reduce the reflection of ultrasonic waves, the membrane body 14 is preferably made of a material that has an acoustic impedance approximately equal to that of the surface of the living body that is the subject. For example, the acoustic impedance of the surface of the abdomen is approximately 1.6×10 [Kg/m·s], and materials that have approximately the same acoustic impedance include natural rubber and synthetic rubber. On the other hand, as for the fluid substance 15, it is desirable that the reflection and absorption of ultrasonic waves is small, and that the acoustic impedance is approximately equal to the acoustic impedance of the biological surface or in-vivo tissue and the membrane body 14. For example, water is Impedance is 1.5×10 [Kg/
m·s], water may be used, but for the abdomen, etc., a substance with a slightly higher acoustic impedance than pure water is suitable; for example, a fluid substance containing saline is preferable. Salt water has a higher sound speed and density than pure water, so its product, the acoustic impedance, is larger than that of water. Moreover, saline can be easily obtained anywhere at the required concentration, and it does not come into contact with the rubber or organic substances that are the material of the membrane 14, so if the membrane 14 is damaged and comes into direct contact with living organisms. It has the characteristic that even if something happens, it will not cause any harm to living organisms. The reason why the acoustic impedance of the membrane body 14 and the fluid substance 15 is made approximately equal to that of the biological surface is as follows. In other words, when these acoustic impedances differ, multiple reflections of ultrasound waves occur, creating a virtual image at a distance that is an integral multiple of the distance between the ultrasound transmission/reception wave surface 12 of the probe body 11 and the biological surface. . For example, as shown in FIG.
4 and the fluid substance 15 are both Z1, the biological surface 31 is Z2, and the ultrasonic wave transmitting/receiving surface 12 is Z0, then the nth reflected wave for the first reflected wave from the biological surface 31 is Assuming that there is no attenuation within the fluid material 14, the strength is |Z0−Z1/Z0+Z1・Z2−Z1/Z2+Z1| ⁿ . Z0 is determined by the acoustic impedance of the piezoelectric vibrator and the coating material on its surface, and is a relatively large value, but as mentioned above, Z0
By selecting Z1 such that 2=Z1, the influence of multiple reflections can be reduced from the above equation. For example, Z0=5×10 [Kg/m・s], Z2=1.6×10
Assuming [Kg/m・s], the intensity of multiple reflections when the value of Z1 is varied is as shown in the table below. From this, it can be seen that by bringing Z1 closer to Z2, the influence of multiple reflections is reduced. I know where I'm going.

【table】

Claims (1)

[Claims] 1. An ultrasonic probe, a drive circuit for driving a plurality of electro-acoustic transducers provided in the probe, and an ultrasonic wave incident on the electro-acoustic transducers. In the electronic scanning ultrasound diagnostic apparatus, the electronic scanning ultrasound diagnostic apparatus is equipped with a wave receiving circuit for receiving waves, a processing circuit for processing the received wave signals of this circuit, and a display for displaying the output of this processing circuit. The sonic probe is
An ultrasonic probe body, a plurality of electro-acoustic transducers arranged in a line on the probe body for transmitting and receiving ultrasonic waves, and provided in front of the ultrasonic transmitting and receiving wave surfaces of these transducers, An acoustic lens that converges an ultrasonic beam in a direction perpendicular to the scanning plane, a flexible bag-like membrane body that is provided in contact with the surface of the acoustic lens and forms a sealed chamber by itself, and this bag-like membrane. The ultrasonic wave transmitting/receiving surface is filled with a fluid substance that is filled into a sealed chamber formed by the ultrasonic body and acoustically couples the wave transmitting/receiving surface and the subject surface, and the contact surface between the membrane body and the subject surface is wider than the ultrasonic wave transmitting/receiving surface. An electronic scanning ultrasonic diagnostic device characterized by being configured as follows. 2. The electronic scanning ultrasonic diagnostic apparatus according to claim 1, wherein the membrane has approximately the same acoustic impedance as the surface of the subject. 3. The electronic scanning ultrasonic diagnostic apparatus according to claim 1, wherein the membrane body has a tube for taking in and out the fluid substance. 4. The electronic scanning type ultrasonic probe according to claim 1, wherein the membrane body is configured to independently form the sealed chamber, and is detachably attached to the probe body. Sonic diagnostic equipment. 5. A patent characterized in that the amount of the fluid substance filled in the sealed chamber is set to be smaller than the maximum volume that can be occupied in the sealed chamber when the tension of the membrane body is approximately zero. An electronic scanning ultrasonic diagnostic apparatus according to claim 1. 6. The electronic scanning ultrasonic diagnostic apparatus according to claim 1, wherein the fluid substance is a liquid whose acoustic impedance is higher than that of water. 7. The electronic scanning ultrasound diagnostic apparatus according to claim 6, wherein saline is used as the liquid.