JP2000116654A - Ultrasonic image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily select a right unit image and to display an accurate three- dimensional display on processing for making three-dimension from a no. of two-dimensional ultrasonic images obtd. by a two-dimensional ultrasonic image forming means even when speed of movement of an ultrasonic oscillator is changed on every scanning stroke of the ultrasonic oscillator by a simple constitution. SOLUTION: No. of unit images set by a unit image no. setting part 41 is taken in an arithmetic part 42 and no. of sheets of two-dimensional radial ultrasonic images is read. In addition, a pitch interval Ps for taking the unit image is obtd. from the no. of the unit images and the total no. of the two-dimensional radial ultrasonic images and on every counting of a no. corresponding to this pitch interval Ps, a gate in a gate circuit 51 is opened and only the unit images are extracted and taken in the three-dimensional ultrasonic image forming apparatus 50 and other ultrasonic images are thinned-out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for acquiring a large number of two-dimensional radial ultrasonic images in a predetermined direction while operating an ultrasonic transducer in a helical manner, and constructing a three-dimensional image from these two-dimensional radial ultrasonic images. Unit images necessary for performing the three-dimensional processing to be performed, and other unnecessary images,
The present invention relates to an ultrasonic image generation device that takes only unit images into a three-dimensional processing unit and performs three-dimensional processing.

[0002]

2. Description of the Related Art In an ultrasonic examination, an ultrasonic signal is transmitted into a patient's body using an ultrasonic transducer, a reflected echo from a tomographic portion of a body tissue is received, and a received signal of the reflected echo is converted into a predetermined signal. By performing the processing, the tomographic information of the body tissue is displayed as an ultrasonic image on the monitor screen. When ultrasonic scanning is performed over a predetermined range in the body, a two-dimensional ultrasonic image of this scanning range, that is, a B-mode ultrasonic image is obtained. There is known a method of converting these two-dimensional ultrasonic images into three-dimensional images and displaying them by image processing after acquisition. When the two-dimensional ultrasonic image is three-dimensionally displayed on the monitor screen in this manner, the structure of the body tissue can be easily grasped, so that the accuracy of the ultrasonic diagnosis is improved.

[0003] A two-dimensional ultrasonic image is expressed on two axes orthogonal to X and Y. When a large number of two-dimensional ultrasonic images are arranged at predetermined pitch intervals in a predetermined direction, this two-dimensional ultrasonic image is obtained. Coordinate axes (X, Y,
Z) A spatial expression having a predetermined spread on the top becomes possible. Ultrasound images show the tissue structure in the body in shades based on the difference in brightness.For example, if linear interpolation is performed based on the brightness of the two-dimensional ultrasound images before and after, the tissue structure in the body is three-dimensional. Can be displayed. Further, even if the space on the three-dimensional coordinate axis is converted into voxels and the grayscale information of each voxel is displayed, the tissue structure in the body can be displayed three-dimensionally. If predetermined image processing is performed based on these three-dimensional image signals, it becomes possible to extract and display an organ structure of interest, a tissue structure in a body cavity, and the like.

[0004] Ultrasonic probes having a flexible cord with an ultrasonic vibrator attached to the tip thereof have been widely known for acquiring an ultrasonic image of a body cavity. There is also a configuration in which a treatment tool insertion channel of an endoscope or the like is used as guide means for guiding an ultrasonic probe into a body cavity. Regardless of whether or not the guide means is used, the ultrasonic probe is provided by connecting a distal end cap constituting an ultrasonic scanning unit to the distal end of the flexible tube, and an ultrasonic transducer is provided in the distal end cap. . When performing ultrasonic scanning while moving the ultrasonic vibrator straight in the axial direction of the tip cap, the ultrasonic vibrator can be remotely operated by connecting the push-pull operation means to the ultrasonic vibrator or the like. Make it move. On the other hand, if the ultrasonic vibrator is driven to rotate in the tip cap, ultrasonic scanning in the rotational direction becomes possible. The scanning of these ultrasonic transducers is a linear scanning and a radial scanning, respectively. Therefore, the ultrasonic images obtained by each scanning are a linear ultrasonic image and a radial ultrasonic image, respectively, and these are two-dimensional. It is an ultrasonic image.

If the ultrasonic vibrator is driven linearly and rotationally driven, a two-dimensional ultrasonic image that can be expressed on two axes orthogonal to X and Y, that is, a two-dimensional radial ultrasonic image is directed in the linear direction. Can be obtained by lining up at a constant pitch interval. However, if the ultrasonic transducer is intermittently fed at a predetermined pitch interval and is rotated while stopped, control becomes extremely difficult and troublesome. For this,
Generally, the ultrasonic vibrator is continuously rotated while continuously rotating. Accordingly, the moving trajectory of the ultrasonic transducer becomes a helical movement obtained by combining these movements.

In order to operate the ultrasonic vibrator by helical operation by remote control, an operation unit is connected to the base end of the ultrasonic probe, and a flexible shaft composed of a close contact coil or the like is connected to the ultrasonic vibrator. The flexible shaft is inserted into the flexible tube so as to be guided into the operation section. Then, a rotation drive means such as a motor is provided in the operation unit, and is connected to the base end of the flexible shaft. Further, there is provided a straight drive means for moving the entire unit including the flexible shaft and the rotary drive means in the axial direction of the flexible tube. In this case, the linear drive means reciprocates the unit described above,
The reciprocating stroke is set in a predetermined range in advance.

[0007] When the ultrasonic vibrator is operated in a helical manner as described above, the linear motion (Z
(Axial direction). Therefore, the actually obtained radial ultrasonic image is not an ultrasonic image in a direction exactly perpendicular to the Z axis, that is, an ultrasonic image on two axes perpendicular to the X and Y axes. A radial ultrasonic image having a certain width is obtained. In short, the radial ultrasonic image is a pseudo two-dimensional ultrasonic image on two axes orthogonal to X and Y, but the starting position and the ending position of the radial ultrasonic image are shifted in the Z-axis direction. Therefore, it is not a complete two-dimensional ultrasound image. Therefore, in order to minimize the displacement of the joint portion at the origin position (the start end position and the end position in the rotation direction) in the radial image, it is necessary to rotationally drive the ultrasonic transducer as fast as possible. Then, the number of two-dimensional ultrasonic images acquired when moving between all the strokes of the straight-line operation becomes enormous. Performing three-dimensional processing using all of these two-dimensional ultrasonic images requires an extremely large amount of signal processing and extremely complicated signal processing. Requires a lot of time.

As described above, a unit image to be subjected to three-dimensional processing is selected from a large number of obtained two-dimensional ultrasonic images at predetermined pitch intervals, and other unnecessary images are thinned out. In this case, signal processing can be simplified. Several schemes have been proposed for selecting which image is a unit image for performing the three-dimensional processing and decimating which image is unnecessary. Most commonly, a unit image is a radial ultrasonic image obtained at predetermined time intervals from the start of the movement of the ultrasonic vibrator in the rectilinear direction. In addition, in order to distinguish a unit image from other images, there is a configuration in which a marker is attached to a unit image when an ultrasonic image is generated so as to be distinguished from an unnecessary image.

[0009]

As described above, as the ultrasonic probe, as described above, the moving of the ultrasonic transducer in the rotation direction and the straight traveling direction is performed by a flexible shaft inserted through the flexible tube. However, the ultrasonic probe is bent along the insertion path,
Further, particularly when the treatment tool insertion channel of the endoscope or the like is used as the guide means, the ultrasonic transducer may be driven in a state where the angle portion forming the insertion portion of the endoscope is operated to bend. In such a case, a load may act on the linear drive means due to sliding resistance between the flexible shaft and the flexible tube, and the movement in the linear direction may be slowed down. Therefore, if the unit image is divided into the unit image and the other images by time management, if the moving speed in the linear direction changes, the interval in the Z axis direction between the preceding and following unit images changes, and from these unit images, The generated three-dimensional ultrasonic image is elongated or contracted from the actual one. On the other hand, each time a two-dimensional ultrasonic image is acquired, it is determined whether or not it is a unit image, and a marker or the like is added to an image selected as a unit image. Because of the necessity of means and the like, there is a problem that the configuration of a signal processing device for generating an ultrasonic image becomes complicated and signal processing becomes complicated.

The present invention has been made in view of the above points, and an object of the present invention is to use a simple structure to convert a large number of two-dimensional ultrasonic images obtained by a two-dimensional ultrasonic image generating means into a three-dimensional ultrasonic image. The unit image to perform the normalization process can be easily selected, and even if the moving speed of the ultrasonic transducer in the linear direction changes, a unit image capable of displaying an accurate three-dimensional ultrasonic image can be obtained. Is to do.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a helical operation for reciprocating a predetermined stroke in a rectilinear direction while rotating an ultrasonic vibrator by remote control. A two-dimensional ultrasonic image generating means for acquiring a two-dimensional radial ultrasonic image for each rotation of the ultrasonic transducer, and a two-dimensional radial ultrasonic image acquired by the two-dimensional ultrasonic image generating means is regularly arranged. A unit image selecting unit for selecting and acquiring a unit image at every pitch interval, and a three-dimensional processing unit for generating a three-dimensional ultrasonic image signal from these unit images, Means for counting the total number of two-dimensional radial ultrasonic images obtained from the start position to the end position of the straight-line stroke of the ultrasonic vibrator; and a two-dimensional unit to be taken into the three-dimensional processing unit. A unit image number setting unit for setting the number of digital ultrasonic images, and an unnecessary image based on a ratio between the total number of two-dimensional radial ultrasonic images acquired by the counting unit and the number of images set by the unit image number setting unit And an image extracting unit for extracting a unit image.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. First, FIGS. 1 and 2 show an ultrasonic inspection apparatus which is inserted endoscopically as an example of a two-dimensional ultrasonic image generating means.

In FIG. 1, reference numeral 1 denotes an endoscope. The endoscope 1 has a main body operation section 1a and an insertion section 1b inserted into a body cavity. The endoscope 1 has a main body operation unit 1
a to the tip of the insertion portion 1b
A treatment tool insertion channel 2 for inserting a treatment tool such as forceps is provided, and the treatment tool insertion channel 2 is inserted into the insertion portion 1b.
It is open at the tip. 3 is an ultrasonic probe,
The ultrasonic probe 3 is formed by connecting a flexible catheter 5 inserted into the treatment instrument insertion channel 2 to the operation section 4. The operation section 4 includes an ultrasonic observation device 6. A cable 7 detachably connected is drawn out.

As shown in FIG. 2, the catheter 5 has a flexible tube 8 having a closed distal end, and a flexible shaft 9 made of a tight coil is inserted into the flexible tube 8. A rigid tip cap 8a is connected to the distal end of the flexible tube 8, and an ultrasonic vibrator 10 made of a single plate is provided inside the distal end cap 8a. It is installed in. The distal end of the flexible shaft 9 is provided to be connected to the mounting member 11 in the distal end cap 8a. Therefore, the portion of the distal end cap 8a constitutes an ultrasonic scanning unit, and the movement of the ultrasonic transducer 10 in the distal end cap 8a reciprocates by a predetermined stroke in the axial direction while rotating. The so-called helical operation is performed.

The operating portion 4 connected to the proximal end of the catheter 5 has a rotary shaft 12 provided inside the casing, and the rotary shaft 12 is provided on the casing with bearings 13 and 1.
3 support it so that it can rotate and move in the axial direction. The distal end of the rotary shaft 12 extends into the base end of the flexible tube 8 via the seal member 14, and is connected to the flexible shaft 9 at this position. A drive unit 15 is connected to a base end of the rotating shaft 12. The drive unit 15 is provided so as to be non-rotatable in the operation unit 4 and movable in the axial direction of the rotary shaft 12, and a pulley 16 is connected to a position of the rotary shaft 12 in the drive unit 15. . A radial drive motor 17 provided with an encoder 17 a is mounted in the drive unit 15, and the radial drive motor 17 has a pulley 1 as a transmission member for rotating and driving the pulley 16.
8 is connected, and a timing belt 19 is wound between the pulleys 16 and 18. Further, a rotary connector 20 is connected to the base end of the rotating shaft 12. A signal cable (not shown) connected to the ultrasonic vibrator 10 and rotated together with the flexible shaft 9 is connected via the rotary connector 20. The cable 21 is connected to a non-rotating cable 21.

The rotary shaft 1 is driven by a radial drive motor 17.
The ultrasonic vibrator 10 is driven to rotate via the second shaft 2 and the flexible shaft 9 sequentially, and the ultrasonic vibrator 10 is further moved in the axial direction of the distal end cap 8a within a finite range within the distal end cap 8a. It has been made possible. For this purpose, the rotating shaft 12 is provided with an interlocking member 22.
The interlocking member 22 includes a ball nut portion 22a, and a screw shaft 23 is inserted through the ball nut portion 22a. Therefore, when the screw shaft 23 is rotated, the interlocking member 22 moves straight, and the rotary shaft 12 and the drive unit 15 move forward and backward. In order to rotationally drive the screw shaft 23, a straight-forward motor 24 that can rotate forward and reverse is connected. As a result, the ultrasonic transducer 10 can move straight, and therefore the ball nut 2
An interlocking member 22 having 2a, a screw shaft 23, and a linear motor 24 as a rotation driving device of the screw shaft 23 constitute a linear driving unit.

A pair of limit switches 25a and 25b are provided for regulating the stroke end position of the ultrasonic vibrator 10 in the rectilinear direction, and when the ultrasonic vibrator 10 reaches the forward stroke end, an interlocking member is provided. When the limit switch 25a is turned on by the switch 22, and the end position of the reverse stroke is reached, the interlocking member 22 turns on the limit switch 25b. Therefore, when either of the limit switches 25a, 25b is turned on, control is performed so that the operation direction of the straight-ahead motor 24 is reversed.

The ultrasonic probe 3 having the above configuration is
By simultaneously operating the radial drive motor 17 and the straight-ahead motor 24, the ultrasonic vibrator 10 is operated in a helical manner. However, the ultrasonic scanning is performed in the rotational direction, so that the radial scanning is performed. This is why the encoder 17a in the rotational direction is provided, and the ultrasonic transducer 10 travels straight while rotating. Therefore, although pseudo, a large number of two-dimensional radial ultrasonic images are provided between the stroke ends in the linear direction. A signal is obtained.

FIG. 3 shows a circuit configuration of the signal processing section 6a of the ultrasonic observation device 6 constituting the ultrasonic probe 3. As shown in FIG. The signal processing unit 6a has a two-dimensional ultrasonic image signal processing unit 30, and the two-dimensional ultrasonic image signal processing unit 30
Is an ultrasonic transmission / reception circuit 31, a transducer driving circuit 32,
It comprises a position detection circuit 33, an ultrasonic scanning control circuit 34, and an ultrasonic signal processing circuit 35.

The ultrasonic transmitting / receiving circuit 31 includes the ultrasonic vibrator 1
The ultrasonic transmission / reception circuit 31 is for controlling transmission / reception of ultrasonic waves at 0. The ultrasonic transmission / reception circuit 31 switches between a transmission mode and a reception mode alternately. In the transmission mode, a trigger signal is input to the ultrasonic vibrator 10, and an ultrasonic pulse signal is transmitted from the ultrasonic vibrator 10 toward the body based on the trigger signal. When the ultrasonic pulse signal is transmitted,
The ultrasonic transmission / reception circuit 31 switches to the reception mode. In the ultrasonic pulse signal transmitted toward the inside of the body, a reflected echo is generated at a tomographic portion of a body tissue having a different acoustic impedance, and the reflected echo is received by the ultrasonic vibrator 10 and converted into an electric signal. Then, this signal is transmitted to the ultrasonic transmission / reception circuit 31.

The vibrator driving circuit 32 includes the ultrasonic vibrator 10
ON of the radial drive motor 17 for rotationally driving the
The position detection circuit 33 controls the OFF control and the rotation speed thereof to be constant, and the position detection circuit 33 controls the position of the ultrasonic transducer 10 in the rotation direction, that is, the rotation angle, and both stroke end positions in the rectilinear direction. Is to be detected. Therefore,
The position detection circuit 33 receives signals from an encoder 17a for detecting the rotation angle of the ultrasonic transducer 10 and signals from limit switches 25a and 25b for detecting the start position and the end position of the straight stroke. It has become. In addition, the start end position and the end position of the straight travel stroke may be detected by, for example, an encoder or the like in addition to the above.

The ultrasonic scanning control circuit 34 controls the ultrasonic transmission / reception circuit 31 to generate a trigger signal based on a position detection signal in the rotational direction of the ultrasonic transducer 10 output from the position detection circuit 33. . Further, the ultrasonic reflected echo signal is taken into the ultrasonic signal processing circuit 35 via the ultrasonic transmitting / receiving circuit 31, and the encoder 17a outputs the ultrasonic reflected echo signal as a signal related to the position in the rotational direction of the ultrasonic reflected echo signal. Will be taken into.

Here, when performing radial scanning, it is necessary to detect the absolute position of the ultrasonic transducer 10 or to detect the scanning start and end positions. An absolute encoder can be used as the encoder 17a for detecting the rotation angle. However, when an incremental encoder having a simple structure is used, the encoder 17a is provided with a reference position display section, and the ultrasonic transducer 10a is provided.
In addition to the angle signal, a reference position signal based on the reference position display section is also generated. Accordingly, one radial ultrasonic image is formed from the ultrasonic reflected echo signal when the reference position signal is obtained to the ultrasonic reflected echo signal immediately before the next reference position signal is output.

As described above, the ultrasonic signal processing circuit 35 receives the ultrasonic reflected echo signal from the ultrasonic transmitting / receiving circuit 31 and outputs the radial scanning reference position signal and the angle signal from the position detecting circuit 33. The ultrasonic signal processing circuit 35 has a scan converter because it is taken in and generates a two-dimensional radial ultrasonic image signal.

The ultrasonic transducer 10 is driven so as to go straight while rotating continuously, and performs a helical operation. Therefore, the ultrasonic transducer 10 outputs an ultrasonic reflected echo signal almost continuously. . The reference position signal in the encoder 17a is used as the origin position of the two-dimensional radial ultrasonic image signal. At the same time, the ultrasonic scanning control circuit 3
4 is taken into the ultrasonic signal processing circuit 35, and a vertical synchronizing signal (VD) and a horizontal synchronizing signal (HD) in the ultrasonic image signal are generated. Therefore, every time the ultrasonic transducer 10 makes one rotation, the ultrasonic signal processing circuit 35
Output a one-dimensional two-dimensional radial ultrasonic image signal, which is sequentially loaded into the image memory 36.

Further, of the output signals from the encoder 17a, the reference position signal is taken into a counter 37, and the counter 37 is connected to the limit switch 25.
It is reset every time a or 25b is turned on, and the number of reference position signals of the encoder 17a is counted from that time. Accordingly, the total number of two-dimensional radial ultrasonic images obtained from one stroke end position to the other stroke end position in the straight traveling direction of the ultrasonic transducer 10 is the counter 3
7 will be counted. Each time the limit switch 25a or 25b is turned on, this counter 3
At step 7, the signal relating to the count value is taken into the image memory 36. Accordingly, the image memory 36 stores a certain number of two-dimensional radial ultrasonic image signals acquired from one stroke end position to the other stroke end position in the straight traveling direction of the ultrasonic transducer 10 and the total number thereof. Is done. Here, the image memory 36 is, for example, an internal memory of a personal computer, a magnetic disk,
It can be composed of a recording medium such as a TR (video tape recorder) or the like.

With the above configuration, the image memory 36 stores data on a large number of two-dimensional ultrasonic images, and a three-dimensional ultrasonic image generating apparatus performs three-dimensional processing from these data. Various methods such as voxel data conversion have been developed as a method of three-dimensional processing. For example, a three-dimensional ultrasonic image including a cut plane as shown in FIG. 4 can be displayed. To generate the three-dimensional ultrasonic image, first, unit images for performing the three-dimensional processing are selected, and a three-dimensional ultrasonic image is constructed from these unit images. FIG. 5 shows a circuit configuration for acquiring a unit image and performing three-dimensional processing.

In FIG. 3, reference numeral 40 denotes a unit image selection unit for selecting a unit image used for performing three-dimensional processing from a large number of two-dimensional radial ultrasonic images recorded in the image memory 36. A three-dimensional image generating apparatus 50 extracts a predetermined number of unit images at predetermined pitch intervals from a large number of two-dimensional ultrasonic images read from the image memory 36 by the unit image selecting unit 40 and thins out other units. Is controlled so as to be taken in. A gate circuit 51 is provided at an input unit of the three-dimensional image generation device 50,
When the gate circuit 51 is turned on and off, the timing of taking in the ultrasonic image signal from the image memory 36 is set.

The unit image selection section 40 is a unit image number setting section 4
The unit image number setting unit 41 determines how many two-dimensional radial ultrasonic images are to be subjected to three-dimensional processing,
That is, it is for setting the number of unit images. This set value may be fixed, but it is desirable that the operator or the like can appropriately set the set value from the viewpoint of the purpose of the three-dimensional processing.

The number of unit images set by the number-of-unit-images setting section 41 is fetched by the calculating section 42, and the calculating section 42
Sets the unit image capture pitch interval. For this purpose, the arithmetic unit 42 receives data on the number of two-dimensional radial ultrasonic images stored in the image memory 36, and stores the number of unit images (Ns) and the total number of two-dimensional radial ultrasonic images (Nt). ) And (Nt / Ns)
Is calculated, the pitch interval of the two-dimensional ultrasonic image data read from the image memory 36 is determined as a unit image. Here, (Nt / N
As a result of executing the calculation of s), the unit image capture pitch interval Ps is obtained.

The pitch interval Ps obtained by the operation unit 42 is taken into the unit image number extraction command unit 43. The unit image number extraction command unit 43 is configured to take in only the vertical synchronizing signal (VD) among the output signals from the image memory 36, count this vertical synchronizing signal, and obtain a number corresponding to the pitch interval Ps. The gate in the gate circuit 51 is opened each time one ultrasonic image signal is output each time the count is counted, and only the unit image is extracted and taken in by the three-dimensional ultrasonic image generation device 50. Sonic images are thinned out.

As described above, of the ultrasonic image signals from the image memory 36, unit images of the set number (Ns) are sequentially fetched, and a tertiary image is obtained based on these two-dimensional radial ultrasonic image signals. The three-dimensional processing is performed by the original ultrasonic image generation device 50.

The three-dimensional ultrasonic image generating apparatus 50 includes a coordinate conversion circuit 52, and a unit image is taken into the coordinate conversion circuit 52 at every predetermined pitch interval Ps. When the unit image is taken into the coordinate conversion circuit 52, the three-dimensional coordinate axes (X, Y,
The coordinates are converted so as to be displayed as Z). And
Each unit image thus coordinate-converted is stored in the memory 53.
Are sequentially stored, and predetermined signal processing is performed by the three-dimensional processing circuit 54, and a three-dimensional display is performed on the monitor 55. Here, the three-dimensional processing circuit 54 generates a three-dimensional original image in the form of a cylindrical surface, displays it on the monitor 55, and displays only the outer surface of the cylindrical surface. The three-dimensional original image is also recorded in the memory 53.

A three-dimensional image display control circuit 56 is connected to the three-dimensional processing circuit 54, and the three-dimensional image display control circuit 56 is connected to a cut plane input means 57 such as a mouse. When the cut plane is designated by the cut plane input means 57, the three-dimensional display control circuit 56 determines what position and what cut is made with respect to the three-dimensional original image displayed on the monitor 55. It is set whether to insert a surface. The three-dimensional processing circuit 54 reads out data on the cut plane from the memory 53 based on this signal, and performs the hidden plane processing by pasting the cut plane and inserting the cut plane into the three-dimensional original image. By doing so, as is apparent from FIG.
A three-dimensional ultrasonic image I including a cut plane having two cut planes C1, C2, and C3 is displayed on the monitor 54.

Here, when displaying the three-dimensional image exemplified as the three-dimensional ultrasonic image including the cut surface, it is necessary to change the number of unit images to be acquired depending on the resolution of the three-dimensional ultrasonic image. The number of unit images can be set to an arbitrary number by the unit image number setting unit 41. Therefore, when a close examination of the affected part is required, a large number of unit images are acquired, and when a special close examination is not required, the number of acquired unit images is reduced to speed up signal processing. So that

As described above, when acquiring the unit image selected for performing the three-dimensional processing, the two-dimensional radial ultrasonic wave obtained by the ultrasonic probe 3 constituting the two-dimensional ultrasonic image generating means is obtained. Total number of images, that is, limit switch 2
Limit switch 2 from when 5a or 25b is turned on
By calculating the number of required unit images from the number of two-dimensional radial ultrasonic images obtained until 5b or 25a is turned on, the pitch interval of the obtained unit images is set.

The ultrasonic vibrator 10 performs a helical operation in the tip cap 8a.
Is not constant depending on the state of the ultrasonic probe 3. For example, in a state where the ultrasonic probe 3 is substantially straight,
When the ultrasonic transducer 10 moves straight without resistance, and when the ultrasonic probe 3 is bent, the resistance to the movement of the flexible shaft 9 in the axial direction increases, and the load on the motor 24 for linear movement increases, and the ultrasonic wave In the state where the movement of the transducer 10 in the rectilinear direction is slow, the number of ultrasonic images acquired in one rectilinear stroke changes. For example, when the ultrasonic vibrator 10 moves straight without resistance, the ultrasonic vibrator 10 rotates 400 times in one straight stroke, but the ultrasonic probe 3 is bent in a complicated manner, and the flexible probe 8 It is assumed that one straight stroke requires twice as much time because the shaft 9 has a great resistance to the movement in the axial direction. Then, assuming that the rotation speed of the flexible shaft 9 is constant during both scans, the ultrasonic transducer 10 rotates 800 times.

In the above state, if the unit image is taken every time a predetermined time elapses, when the ultrasonic vibrator 10 moves straight ahead at a low speed, it is half of when moving straight ahead at a high speed. An ultrasonic image obtained only from the distance is three-dimensionally processed as a unit image obtained from the entire length of one straight stroke. Therefore, an ultrasonic image that is greatly extended from the actual state in the body cavity is obtained, and only half of the set range information is displayed. Therefore, the division (Ns / Nt) of the number of unit images (Ns) and the total number of two-dimensional radial ultrasonic images (Nt) is calculated.
For example, assuming that the number of unit images (Ns) is 20, a three-dimensional unit image is formed as a unit image every 20 images when the ultrasonic transducer 10 rotates 400 times in one straight stroke and every 40 images when the ultrasonic transducer 10 rotates 800 times. Even when the time required for one straight stroke changes, the ultrasound image at a position where the length of one straight stroke is almost equally divided is always taken as a unit image because the ultrasound image is captured by the sound image generating device 50. During that time, the ultrasonic images are thinned out. Of course, not only the linear movement but also the rotation speed of the flexible shaft 9 may be changed by the effect of sliding on the inner surface of the flexible tube 8. The ultrasonic image at the position thus set is selected as a unit image.

In order to simplify the signal processing, Ns /
As a result of the operation of Nt, it is desirable to round off fractions below the decimal point. However, when the ratio between the number of acquired two-dimensional radial ultrasonic images and the number of unit images is small, and if the fractional part is truncated, when signal processing is performed to form a three-dimensional ultrasonic image, of the total length of the straight stroke, The portion that does not form the three-dimensional ultrasonic image may have a length that cannot be ignored. In this case, the above-described calculation is performed up to one digit after the decimal point, and when the numerical value after the decimal point is n, the trigger signal output to the gate circuit 51 is n / 10
What is necessary is just to set so that the capture timing may be changed by delaying one time each time.

As described above, in the three-dimensional ultrasonic image generating apparatus 50, even if the velocity of the ultrasonic transducer 10 in the linear direction and the rotational direction changes, the ultrasonic image at the same position of the linear stroke is always used as a unit. It can be an image. Therefore, when displayed as a three-dimensional ultrasonic image, an accurate display is made, and the interval in the Z-axis direction between the unit images before and after changes due to the movement of the ultrasonic vibrator 10, resulting in an elongated image or a contracted image. It will not be.

[0041]

As described above, according to the present invention, the ratio between the total number of two-dimensional radial ultrasonic images acquired by the two-dimensional ultrasonic image generating means and the number of images set by the unit image number setting unit is set. In order to extract the unit images necessary for performing the three-dimensional processing by thinning out unnecessary images based on the above, the speed of the movement changes with each scanning stroke of the ultrasonic transducer with a simple configuration. However, it is possible to easily select the correct unit image in performing the three-dimensional processing from a large number of two-dimensional ultrasonic images obtained by the two-dimensional ultrasonic image generating means, thereby enabling accurate three-dimensional display. Has the effect of

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing a state in which an ultrasonic probe as a two-dimensional ultrasonic image acquisition device is incorporated in an endoscope.

FIG. 2 is a sectional view of an operation unit in the ultrasonic probe.

FIG. 3 is an explanatory diagram showing a cut plane-containing three-dimensional ultrasonic image as an example of a three-dimensional ultrasonic image generated from a two-dimensional ultrasonic image.

FIG. 4 is a circuit configuration diagram of a signal processing unit of the ultrasonic observation apparatus.

FIG. 5 is an explanatory diagram showing a display mode of a cut-plane three-dimensional ultrasonic image as an example of a three-dimensional ultrasonic image.

[Explanation of symbols]

 REFERENCE SIGNS LIST 3 ultrasonic probe 4 operating unit 5 catheter 7 cable 10 ultrasonic transducer 12 rotary shaft 17 radial drive motor 17a encoder 23 screw shaft 24 linear motor 25a, 25b limit switch 30 two-dimensional ultrasonic image signal processing unit 36 image memory 37 Counter 40 Unit image selection unit 41 Unit image number setting unit 42 Operation unit 43 Synchronization separation circuit 44 Unit image number extraction command unit 50 3D ultrasonic image generation device 51 Gate circuit

Continued on the front page F term (reference) 4C301 BB01 BB03 BB30 BB34 BB40 EE11 FF05 FF09 GA14 GA15 GA16 GB14 GD10 JB32 JC14 JC20 KK17 LL02 5B057 AA07 BA05 BA26 CA08 CA12 CA16 CB08 CB13 CB16 CE08 CH08 CH11

Claims (1)

[Claims] 1. While performing a helical operation of reciprocating a predetermined stroke in a rectilinear direction while rotating an ultrasonic vibrator by remote control, a two-dimensional radial ultrasonic image is generated every rotation of the ultrasonic vibrator. Two-dimensional ultrasonic image generating means for obtaining, and unit image selecting means for selecting a two-dimensional radial ultrasonic image obtained by the two-dimensional ultrasonic image generating means at regular pitch intervals to obtain a unit image And three-dimensional processing means for generating a three-dimensional ultrasonic image signal from these unit images, wherein the unit image selecting means obtains the ultrasonic transducer from the start position to the end position of the straight stroke of the ultrasonic transducer. A counting unit that counts the total number of the obtained two-dimensional radial ultrasonic images, a unit image number setting unit that sets the number of two-dimensional radial ultrasonic images to be taken into the three-dimensional processing unit, A configuration including an image extraction unit that extracts unnecessary images based on the ratio between the total number of two-dimensional radial ultrasonic images acquired by the counting unit and the number of images set by the unit image number setting unit, and extracts a unit image; An ultrasonic image generating apparatus, comprising: