JP3268831B2 - Ultrasound diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus, and more particularly, to a method of projecting an ultrasonic pulse onto a living body,
The present invention relates to an ultrasonic diagnostic apparatus which receives the ultrasonic echo and obtains an ultrasonic image.

[0002]

2. Description of the Related Art In recent years, ultrasonic diagnostic techniques for radiating ultrasonic waves into a body, drawing the state of the body from the echo signals, and finding and diagnosing lesions have become widespread. Above all, the method of endoscopically inserting an ultrasonic probe into the body and irradiating the lesion with ultrasonic waves from inside the body has a smaller attenuation of ultrasonic waves and a higher frequency than the method of irradiating ultrasonic waves from outside the body. Attention has been paid to the fact that an ultrasonic image can be obtained with high resolution because ultrasonic waves can be used.

In such an in-body-cavity ultrasonic diagnostic apparatus, a so-called radial scan in which an ultrasonic transducer is rotated around a lumen axis in a body and an ultrasonic beam is radially scanned to obtain a sectional image of the lumen. The method is the most effective for diagnosis. Attempts have also been made to improve the diagnostic performance by moving the ultrasonic transducer in the axial direction of the probe while performing radial scan, capturing a plurality of cross-sectional images, and performing image processing to construct a three-dimensional image. .

An ultrasonic diagnostic apparatus of the mechanical radial scan type generally transmits a rotation provided by a flexible shaft or the like to a motor provided in a drive unit provided outside the body and an ultrasonic vibrator at the tip of a probe inserted into the body. They are connected by a member, and the outer periphery is covered with a cylindrical resin sheath. Further, a rotation detecting means such as a rotary encoder is provided in the drive unit, and by obtaining rotation information of the vibrator, a stable and accurate radial scan cross-sectional image can be drawn. In addition, the cross-sectional image drawing position is set at one position of the vibrator from the rotary encoder.
It is determined based on an image start position signal that outputs one pulse per rotation.

In order to perform a three-dimensional scan, a drive mechanism for moving the flexible shaft back and forth in the axial direction of the probe is provided, and a radial scan and a linear scan are performed in combination.

[0006]

However, in a normal ultrasonic probe, the rotation detecting means for detecting the rotation of the ultrasonic vibrator is provided in a drive unit on the hand side. The ultrasonic transducer provided at the tip of the probe is connected by a rotating member such as a flexible shaft. For this reason, the rotation detecting means in the drive unit does not always accurately reflect the rotation of the ultrasonic transducer. In particular, when the probe sheath is curved, the frictional force generated between the inner surface of the probe sheath and the flexible shaft changes, causing uneven rotation of the ultrasonic transducer and physical rotation of the probe tip. The position and the positional relationship between the ultrasonic image drawing start position signal output by the rotary encoder changes,
The phenomenon that the image is rotated as a result of the change of the image drawing position occurs. When a normal radial scan is performed under such a condition, each time the probe bends, the displayed image is rotated and it is very difficult to give a diagnostic orientation. Further, when performing a three-dimensional scan, there is a problem that the image is twisted when constructing a three-dimensional image. In order to eliminate such inconveniences, it has been considered to arrange a rotation detecting means in the immediate vicinity of the ultrasonic vibrator. However, especially in the case of an intracavity ultrasonic probe, the outer diameter of the insertion portion is limited, and it is very difficult to provide a rotary encoder or the like at the tip of the probe. In addition, if a rotary encoder is provided at the tip of the probe, a cable for transmitting the rotation information signal detected by the rotary encoder is separately required, which increases the outer diameter of the probe sheath and increases the cost. The present invention has been made in view of such a problem, and there is no need to change the outer diameter of the ultrasonic probe, no need to add a dedicated signal line, and stable ultrasonic waves without rotation. The present invention relates to an ultrasonic diagnostic apparatus capable of obtaining an image.

[0007]

In order to solve the above-mentioned problems, an ultrasonic diagnostic apparatus according to the present invention provides an ultrasonic probe which performs a radial scan by mechanically rotating an ultrasonic transducer disposed in a probe sheath. In an ultrasonic diagnostic apparatus that forms an ultrasonic image by detecting reflection echo of an ultrasonic pulse projected from the ultrasonic transducer, a part of the probe sheath in a circumferential direction includes a material of the probe sheath. Is provided with different material portions having different acoustic impedances, and provided with signal identification means for distinguishing an ultrasonic echo signal reflected from the different material portion and an ultrasonic echo signal reflected from the probe sheath material, An ultrasonic image writing start signal is generated based on the signal identified by the means.

[0008]

As described above, in the ultrasonic diagnostic apparatus of the present invention, since a different material portion having an acoustic impedance different from that of the probe sheath material is provided on a part of the circumference of the probe sheath, the different material portion is provided. It is detected that the signal level of the ultrasonic echo signal reflected by the probe is different from the signal level of the ultrasonic echo signal reflected by the probe sheath, and based on this detection signal, the image drawing position signal (Z
Phase signal) to generate an ultrasonic image based on the image drawing position signal, so that the physical rotational position of the ultrasonic radiation portion always coincides with the image position, It is possible to prevent the rotation of the image that occurs when the probe sheath is bent or the like.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a probe tip of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. An ultrasonic vibrator 2 is disposed at the tip of a flexible shaft 1 connected to a drive unit (not shown) on the hand side. The flexible shaft 1 and the ultrasonic vibrator 2 are connected to a probe sheath 3 made of a material such as polyethylene. It is inserted inside. The probe sheath 3 is filled with a flowing medium 4 such as water, for example, and the flowing medium 4 functions as a lubricant and an ultrasonic transmission medium.

A dissimilar material portion 5 is provided on a part of the circumference of the probe sheath 3. FIG. 2 is a cross-sectional view taken along line AA of the probe tip shown in FIG. The dissimilar material portion 5 is made of aluminum foil cut to a width of about 1 mm,
As shown in FIG. 2, the probe sheath 3 is sandwiched between double polyethylene tubes, heat-molded, and processed so as to be disposed within the thickness of the probe sheath 2.

FIG. 3 shows an image drawing position signal (hereinafter "Z").
FIG. 3 is a block diagram illustrating a configuration of a detection circuit). The ultrasonic transducer 2 is connected to a preamplifier circuit 11 via a coaxial cable 10 extending into the flexible shaft 1, and the output of the preamplifier circuit 11 is a general ultrasonic wave for forming and displaying an ultrasonic tomographic image. Signal processing circuit 1
2 and output to the display device 14 via the display control circuit 13. The output of the preamplifier circuit 11 is supplied to a voltage comparator 16 via a buffer amplifier 15.
Is output to the positive input of The output of the comparison voltage generation circuit 17 is connected to the negative input terminal of the voltage comparator 16, and the output of the voltage comparator 16 is supplied to the time gate circuit 18. On the other hand, an output from a gate signal generation circuit 19 for generating a gate signal for an arbitrary time determined from a trigger signal output each time the ultrasonic transducer 2 is driven is supplied to a time gate circuit 18. . The output of the time gate circuit 18 is connected to an A-phase synchronizing circuit 20, generates a Z-phase signal via a multiple occurrence prevention circuit 21, and guides the Z-phase signal to the display control circuit 13. I have.

FIG. 4 is a timing chart of each signal in the Z-phase signal detection circuit shown in FIG. Below, FIG.
The operation of the present embodiment will be described with reference to FIG. When the ultrasonic transducer 2 starts the radial scan, FIG.
As shown in the waveform of the echo signal in (a), the echo from the interface of the probe sheath 3 returns after the large amplitude waveform at the time of driving. When the ultrasonic transducer 2 emits an ultrasonic beam in the direction of the dissimilar material portion 5, a normal probe sheath 3
Since the reflection intensity of the ultrasonic wave is higher than that of the signal returning from the boundary surface, the echo level is higher in this portion. The setting of the comparison voltage in the comparison voltage generation circuit 17 is
By setting the peak voltage of the reflected echo from the boundary surface of the sheath 3 to the peak voltage of the reflected echo from the dissimilar material portion 5, the ultrasonic vibrator 2 moves the ultrasonic beam toward the dissimilar material portion 5. The voltage comparator 16 responds only when is emitted (FIG. 4B). Actually, the voltage comparator 1 is caused by a noise component such as a large amplitude waveform during driving.
6 responds, so the gate is applied by the time gate circuit 18. In this case, since the distance from the surface of the ultrasonic transducer 2 to the probe sheath 3 is always constant, the signal generation timing of the gate signal generation circuit 19 is changed from the generation of the trigger signal (FIG. 4D) to the probe sheath. The setting is made in accordance with the time until the echo arrives from near the boundary surface (FIG. 4C). In this manner, the response signal from which the noise component has been removed by the time gate circuit 18 is converted into an A-phase signal (FIG. 4 (e),
The pulse is output to the multiple occurrence prevention circuit 21 in synchronization with the A-phase synchronization circuit 20. Since the dissimilar material portion 5 has a certain width, the response of the voltage comparator 16 is not limited to one time (one sound ray) during one rotation scan. The multiple occurrence prevention circuit 21 is configured to ignore the response of the voltage comparator 16 by a specific number of sound rays from the first response of the voltage comparator 16 by counter control, and the output of the time gate circuit 18 As a result, a Z-phase signal generated only once per rotation of the ultrasonic transducer 2 is formed (FIG. 4F). This Z-phase signal is input to the display control circuit 13, where it is used as an image signal of an ultrasonic tomographic image.

As described above, in the ultrasonic diagnostic apparatus according to the present invention, the physical position of the dissimilar material portion 5 and the drawing point of the ultrasonic tomographic image can be matched, so that the rotation transmission of the flexible shaft 1 is performed. An ultrasonic tomographic image in a stable direction can always be obtained without being affected by the performance at all.

In the above-described embodiment, a metal foil is used for the dissimilar material portion 5 so that the echo level reflected on the dissimilar material portion is higher than the echo level reflected on the boundary surface of the probe sheath. Conversely, the different material portion 5 may be made of a material having a high ultrasonic wave transmittance so that the echo level is reduced, and the portion where the echo level is reduced may be detected.

FIGS. 5 to 7 show the configuration of a second embodiment of the present invention. In the first embodiment described above, the ultrasonic transducer 2 is configured to perform a radial scan, but in the present embodiment, a three-dimensional scan is performed by combining a radial scan and a linear scan.

As shown in FIG. 5, the flexible shaft 1 constituting the ultrasonic probe is connected to the rotating shaft of the DC motor 30. The rotation of the DC motor 30 is one-to-one.
The gear ratio is transmitted to the rotary encoder 32 via the gear 31 meshing with the gear ratio, and the rotary encoder 32 outputs a rotational position signal of the ultrasonic transducer 2. These D
The radial rotating unit 33 including the C motor 30, the gear 31, and the rotary encoder 32 is entirely connected to a linear driving unit 34. The linear drive unit 34 is fitted to a ball screw 35, and the rear end of the ball screw 35 is connected to a rotation shaft of a stepping motor 36.

FIG. 6 is a block diagram of a control circuit of the ultrasonic probe according to the second embodiment. FIG. 5 and FIG.
The operation of this embodiment will be described with reference to FIG. When the radial control switch 40 is turned on and the rotation of the DC motor 30 starts, the rotary encoder 32 outputs the DC motor 3
A rotation position signal (A-phase signal) of 256 pulses is output per one rotation of 0. The A-phase signal is supplied to the radial control circuit 44
A so-called DC servo operation for controlling the supply voltage to the DC motor 30 in accordance with the frequency of the A-phase signal, which is input to an F / V converter (not shown) inside, performs stable radial rotation.

On the other hand, when the linear control switch 42 is turned on, the linear control circuit 45
, A stepping motor 36 is driven to rotate. The rotation of the stepping motor 36 is transmitted to the ball screw 35 to move the radial rotating unit 33 connected to the linear driving member 34 in the linear direction. Actually, this linear motion is controlled so as to reciprocate within a specific section, but a detailed description thereof is omitted here.

The output of the radial control switch 40 and the output of the linear control switch 41 are supplied to the input terminal of an AND gate 46, and the output of the AND gate 46 is input to the selector 43. A motor clock serving as a reference for the rotation of the stepping motor 36 is selected by the selector 43.
That is, the selector 43 includes the rotary encoder 32.
Supplies an A-phase signal, and a clock signal from the clock generator 42. When the radial control switch 40 is turned on, the linear control switch 41 is turned on, and a three-dimensional scan is set, the output of the AND gate 46 becomes low, and the selector 43 outputs the signal A supplied from the rotary encoder 32. In order to select the phase signal, the stepping motor 36 rotates in synchronization with the rotation in the radial direction. In other words, the movement speed in the linear direction changes in accordance with the change in the rotation speed in the radial direction. As a result, a constant movement width in the linear direction is always obtained for one rotation in the radial direction. , The slice interval of the ultrasonic tomographic image can be kept constant.

On the other hand, the radial control switch 40 is turned off.
When only the linear control switch 41 is ON, the output of the AND gate 46 becomes high level, the clock signal supplied from the clock generator 42 is selected by the selector 43, and the linear scan at the optimum speed is performed. Will be

As described above, the radial control switch 40
And the linear control switch 41 can be set completely independently of each other. Therefore, the radial scan, the linear scan, and the three-dimensional scan can be individually realized by one ultrasonic probe. FIG. 7 shows an image of each scan. By disposing the dissimilar material portion 5 on the probe sheath of the ultrasonic probe configured as described above, even when a three-dimensional scan is performed, the drawing position of the ultrasonic image and the physical rotational position of the ultrasonic radiation portion And can be matched.

[0022]

As described above, according to the present invention, the ultrasonic transducer has a simple structure without changing the outer diameter of the ultrasonic probe and without adding a dedicated signal line. , A Z-phase signal faithfully reflecting the physical rotation position of the ultrasonic image can be obtained, and rotation of the ultrasonic image can be prevented. Further, by adopting the configuration as described in the second embodiment, radial scanning with one ultrasonic probe,
The linear scan and the three-dimensional scan can be realized independently, and the Z-phase signal reflecting the rotational position of the ultrasonic transducer can be obtained even when performing not only the radial scan but also the three-dimensional scan. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view of the ultrasonic probe shown in FIG. 1 taken along line AA.

FIG. 3 is a block diagram illustrating a configuration of a Z-phase signal detection circuit.

FIG. 4 is a waveform diagram of each signal in a Z-phase signal detection circuit.

FIG. 5 is a diagram showing a configuration of a second embodiment of the present invention.

FIG. 6 is a block diagram of a control circuit of a supersonic probe according to a second embodiment of the present invention.

FIG. 7 shows an image of each scan in a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible shaft 2 Ultrasonic transducer 3 Probe sheath 4 Fluid medium 5 Dissimilar material part 10 Coaxial cable 11 Preamplifier circuit 12 Ultrasonic signal processing circuit 13 Display control circuit 14 Display device 16 Voltage comparator 17 Comparison voltage generation circuit 18 Time gate circuit 19 Gate signal generation circuit 20 A-phase synchronization circuit 21 Multiple occurrence prevention circuit 30 DC motor 31 Gear 32 Rotary encoder 33 Radial rotating unit 34 Linear driving member 35 Ball screw 36 Stepping motor 40 Radial control switch 41 Linear control switch 42 Clock generator 43 Selector 44 Radial control circuit 45 Linear control circuit 46 AND gate

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) A61B 8/00-8/15

Claims (1)

(57) [Claims] An ultrasonic probe for mechanically rotating an ultrasonic transducer disposed in a probe sheath to perform a radial scan, and detecting a reflection echo of an ultrasonic pulse projected from the ultrasonic transducer. In an ultrasonic diagnostic apparatus that forms an ultrasonic image by using a probe, a dissimilar material portion having an acoustic impedance different from that of the material of the probe sheath is provided in a part of the probe sheath in a circumferential direction, and the Providing signal identification means for identifying the echo signal and the ultrasonic echo signal reflected from the probe sheath material, so as to generate an ultrasonic image writing start signal based on the signal identified by the signal identification means. An ultrasonic diagnostic apparatus, comprising: