JP5559993B2 - Ultrasonic diagnostic apparatus and image processing method thereof - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus for displaying a tomographic image and a 3D image created from a plurality of tomographic images for an imaging target site in a subject using ultrasonic waves.

A conventional ultrasonic diagnostic apparatus includes a probe that transmits / receives ultrasonic waves to / from a subject, an ultrasonic transmission / reception unit that generates ultrasonic waves by driving the probe, and processes received echo signals. A tomographic image generating circuit for inputting a reflected echo signal from the ultrasonic transmission / reception unit and digitizing it to generate a tomographic image of a diagnostic region, and converting the image data from the tomographic image generating circuit into an analog signal for image display An image display unit and a control circuit for controlling each of the constituent elements are included.
In recent years, the probe is driven by a mechanical method to receive reflected echo signals for multiple tomographic images (frames) in the subject, and digitize the reflected echo signals for several frames to create a 3D image of the diagnostic site. A method for displaying image data created by a 3D image creation circuit is disclosed in Patent Document 1.

JP 2000-5166 A

However, in the method disclosed in Patent Document 1, since scanning is performed while the probe is moved mechanically, scanning is not performed on a vertical plane, and a tomographic image is distorted. is there.
Accordingly, an object of the present invention is to correct distortion of a tomographic plane due to driving of a probe using a plurality of frame data such as one frame before in addition to current frame data.

  In order to solve the above-described problems, the present invention is configured as follows.

The image processing method of the present invention acquires frame data for a plurality of sheets while mechanically moving an ultrasonic probe in which a plurality of transducer elements are arranged in the long axis direction in a direction perpendicular to the long axis direction. In the image processing method of the ultrasonic diagnostic apparatus that creates a tomographic image or a 3D image from the frame data, the method includes a step of correcting the reception position of the frame data accompanying the mechanical movement of the ultrasonic probe.
The step of correcting the reception position of the frame data includes obtaining the scan data (A) of the current frame and the scan data (B) of the previous or next frame for each transducer element; The distance (LA) between the reference position perpendicular to the moving direction of the acoustic probe and the scan position of the current frame, and the distance (LB) between the reference position and the scan position of the previous or next frame A step of obtaining, scan data (A) of the current frame, scan data of the previous or next (B), distance (LA) between the reference position and the scan position of the current frame, and the reference position And obtaining data at the reference position by interpolation based on the distance (LB) between the scan position of the previous frame and the next frame.
The reference position may be the position of the transducer element at the start of frame data acquisition for the current frame, or the scan position of the transducer element at the center of the ultrasonic probe.

  The program according to the present invention causes the procedure of the image processing method to be executed.

The ultrasonic diagnostic apparatus of the present invention includes an ultrasonic probe in which a plurality of transducer elements are arranged in the long axis direction, and transmits and receives ultrasonic waves to and from a subject, and ultrasonic image data received from the ultrasonic probe. A plurality of sheets while mechanically moving the ultrasonic probe in a direction perpendicular to the major axis direction. In an ultrasonic diagnostic apparatus that obtains frame data for a minute and creates a tomographic image or a 3D image from the frame data, the image construction unit determines the reception position of the frame data associated with the mechanical movement of the ultrasonic probe. A means for correcting is provided.
The means for correcting the reception position of the frame data includes, for each transducer element, a scan data acquisition unit that acquires scan data (A) of the current frame and scan data (B) of the previous or next frame. , The distance (LA) between the reference position perpendicular to the moving direction of the ultrasonic probe and the scan position of the current frame, and the distance between the reference position and the scan position of the previous or next frame ( LB), a distance calculation unit for obtaining the current frame scan data (A), the previous or next scan data (B), a distance (LA) between the reference position and the current frame scan position, And a data interpolation unit that obtains data at the reference position by interpolation based on the distance (LB) between the reference position and the scan position of the previous or next frame. .
The reference position may be the position of the transducer element at the start of frame data acquisition of the current frame, or the scan position of the transducer element at the center of the ultrasonic probe.

   As described above, according to the present invention, it is possible to correct the reception position of the frame data associated with the driving of the ultrasonic probe, and to eliminate the distortion of the rendering image.

It is a block diagram which shows the whole ultrasonic diagnostic apparatus. It is a block diagram which shows an ultrasonic image structure part. It is the figure which showed the ultrasonic scan of the ultrasonic probe long-axis surface. It is the figure which showed the ultrasonic scan and reciprocation of an ultrasonic probe short-axis surface. It is the figure which showed the ultrasonic scan position during ultrasonic probe movement. It is the figure which showed a mode that position correction was performed on the basis of the starting end element of the ultrasonic probe of Example 1 of this invention. It is the figure which showed the result of having performed the position correction by Example 1 of this invention. It is the figure which showed the flow of the internal processing of this invention. It is the figure which showed the flow of the position shift correction process of Example 1 of this invention. It is a block block diagram for position shift correction of Example 1 of this invention. It is the figure which showed a mode that position correction was performed on the basis of the scanning position of the transducer element of the center of an ultrasonic probe of Example 2 of this invention.

  First, an ultrasonic diagnostic apparatus to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an ultrasonic diagnostic apparatus to which the present invention is applied. The ultrasonic diagnostic apparatus 1 forms and displays a two-dimensional ultrasonic image or a three-dimensional ultrasonic image on a diagnostic region using a reflected echo signal obtained by transmitting and receiving ultrasonic waves in a subject 2. An ultrasonic probe 3 having a transducer element for irradiating and receiving ultrasonic waves to the specimen 2, an ultrasonic transmission / reception unit 4 for transmitting / receiving ultrasonic signals, and a two-dimensional ultrasonic image (B mode) based on the received signals Image) or an ultrasonic image construction unit 5 constituting a three-dimensional ultrasonic image, a display unit 6 for displaying the ultrasonic image constructed in the ultrasonic image construction unit 5, a control unit 7 for controlling each element, And a control panel 8 for giving an instruction to the control unit 7.

  Here, each component is demonstrated concretely. In the ultrasonic probe 3, transducer elements are arranged for 1 to m channels in the long axis direction of the ultrasonic probe. Here, when k pieces are cut in the short axis direction and arranged for 1 to k channels, the short axis is changed by changing the delay time applied to each transducer element (1 to k channels) in the short axis direction. The direction of transmission and reception can also be applied to the direction. Also, transmission weighting is applied by changing the amplitude of the ultrasonic transmission signal applied to each transducer element in the short axis direction, and the amplification level or attenuation level of the ultrasonic reception signal from each transducer element in the short axis direction is set. By changing, receiving weighting can be applied. Further, the aperture control can be performed by turning each transducer element in the short axis direction on and off.

  The ultrasonic probe 3 changes the ultrasonic transmission / reception sensitivity, that is, the electromechanical coupling coefficient, in accordance with the magnitude of the bias voltage applied to be superimposed on the drive signal supplied from the ultrasonic transmission / reception unit 4. For example, cMUT (Capacitive Micromachined Ultrasonic Transducer: IEEE Trans. Ultrason. Ferroelect. Freq. Contr. Vol 45 pp. 678-690 May 1998) can be applied. The cMUT is an ultrafine capacitive ultrasonic transducer manufactured by a semiconductor microfabrication process (for example, LPCVD: Low Pressure Chemical Vapor Deposition).

  The ultrasonic transmission / reception unit 4 supplies a transmission signal to the ultrasonic probe 3 and processes the received reflected echo signal. Inside the ultrasonic transmission / reception unit 4, the ultrasonic probe 3 is controlled to emit an ultrasonic beam. A transmission circuit that receives the reflected echo signal from the subject of the emitted ultrasonic beam and collects biological information, and a control circuit that controls them.

  The ultrasonic image construction unit 5 converts the reflected echo signal processed by the ultrasonic transmission / reception unit 4 into an ultrasonic tomographic image, and a digital scan converter that forms an ultrasonic image based on the sequentially inputted reflected echo signal; , Comprising a magnetic disk device for storing an ultrasonic image and a storage device comprising a RAM, and processing the reflected echo signal received by the ultrasonic transmission / reception unit 4 to process a two-dimensional ultrasonic image, a three-dimensional ultrasonic image, various Convert to Doppler image and output.

  The display unit 6 inputs an image created by the ultrasonic image constructing unit 5 through the display control unit and displays it as an ultrasonic image, and includes, for example, a CRT monitor and a liquid crystal monitor.

  The control unit 7 controls the operation of each of the constituent elements, and is configured by a control computer system having an interface with a user interface circuit. The control unit 7 controls the ultrasonic transmission / reception unit 4 from the user interface included therein and information from the user interface. In addition, the biological information received by the ultrasonic transmission / reception unit 4 is transferred to the ultrasonic image construction unit 5, and the information imaged by the ultrasonic image construction unit 5 is transmitted to the display control unit.

  The case where the ultrasonic image construction unit 5 in FIG. 1 is a 3D image creation circuit will be described. FIG. 2 shows a 3D image creation circuit 5, which includes a frame data acquisition unit 20, a volume data construction unit 21, a coordinate conversion processing unit 22, a rendering processing unit 23, and an RGB conversion unit 24. The processing of this 3D image creation circuit will be described in order. First, the frame data acquisition unit 20 acquires input frame data from the ultrasonic transmission / reception unit 4. Next, the volume data construction unit 21 accumulates the input frame data and creates volume data. The volume data construction unit 21 does not send data to subsequent processes until volume data is created. The correction processing according to the present invention is executed when the volume data is created. The coordinate conversion processing unit 22 performs coordinate conversion processing of digital scan conversion processing on the data created by the volume data construction unit 21. The rendering processing unit 23 performs rendering processing on the coordinate-converted volume data, and the RGB conversion unit 24 performs RGB conversion, and then transmits image data to the display unit 6. The above processing represents the processing of the 3D image creation circuit.

  Next, an embodiment of the present invention will be described. The generation of an ultrasonic wave from the ultrasonic probe 3 in which transducer elements are arranged in m channels in the major axis direction and receiving an ultrasonic reflection echo signal will be referred to as an ultrasonic scan. FIG. 3A shows the long axis surface of the ultrasonic probe 3, and the ultrasonic probe 3 generates ultrasonic waves in the ultrasonic scanning direction 9. Digital data of ultrasonic reflected echo signals for one tomographic image is defined as frame data, and a collection of frame data for a plurality of tomographic images is defined as volume data.

  FIG. 3 (b) shows the short axis surface of the ultrasonic probe 3. The ultrasonic probe 3 is mechanically driven in a direction perpendicular to the long axis direction and reciprocates between C and D in a fan shape. Is repeated (the ultrasonic probe reciprocating direction 10). When the ultrasound probe 3 moves while acquiring frame data from the C side to the D side, volume data can be obtained, and a 3D image can be created based on the volume data. Volume data can be acquired both when the ultrasonic probe 3 moves from the C side to the D side and when the ultrasonic probe 3 moves from the D side to the C side.

  FIG. 4 shows an ultrasonic scan position of the obtained frame data when the ultrasonic probe 3 performs an ultrasonic scan while moving between C and D in the minor axis direction. In the figure, the solid line in the horizontal direction indicates the position of the transducer at the start of frame data acquisition for a certain frame, and the arrow 11 in the vertical direction indicates the moving direction of the ultrasonic probe. The symbol ◎ indicates the actual scanning position of each transducer element arranged in m channels in the major axis direction. Since the ultrasonic probe 3 moves in the ultrasonic probe moving direction 11 from the start of the ultrasonic scan to the end of the scan to obtain certain frame data, the acquired frame data is the ultrasonic probe. The ultrasonic scan position will shift in the direction of movement of the child short axis.

  FIG. 5 illustrates the ultrasonic scan position correction according to the first embodiment of the present invention, and corrects the position of the transducer element at the start of frame data acquisition as a reference position perpendicular to the moving direction of the ultrasonic probe. Is. Take the case of correcting point A as an example. When correcting the ultrasonic scan data at the point A 13 to the position of the point X 15 which is the position at the start of frame data acquisition, the data of the point A 13 and the point B 14 one frame data before are used. The distance LA 16 between the X point 15 and the A point 13 is obtained using the time T from the start of the ultrasonic scan until the ultrasonic scan of the A point 13 is performed and the moving speed ω of the ultrasonic probe 3 ( Formula 1). Next, a distance LB 17 between the X point 15 and the B point 14 is obtained. The LB 17 starts the ultrasonic scan to obtain a certain frame data, and then calculates the LA16 from the distance L that the ultrasonic probe 3 has moved in the time between the start of the ultrasonic scan to obtain another frame data. Subtract to find (Equation 2). Data interpolation at X point 15 uses LA, LB, L, data A at point A 13 and data B at B point 14 (Equation 3). By performing this interpolation processing on all the frame data, the ultrasonic scan position can be corrected to the position of the transducer element at the start of frame data acquisition shown in FIG. 6, and the distortion of the volume data is eliminated. I can do it.

LA = T * ω------(Formula 1)
LB = L-LA------(Formula 2)
X = A * (L-LA) / L + B * (L-LB) / L
= A * LB / L + B * LA / L-----(Formula 3)
T: Time elapsed from the start of ultrasonic scanning to obtain a certain tomographic plane until ultrasonic scanning of point A 13 ω: Moving speed of the ultrasonic probe L: Ultrasonic scanning to obtain a certain tomographic image The distance traveled by the ultrasonic probe from the start of scanning until the start of ultrasonic scanning of another tomographic image The positional deviation correction according to the first embodiment of the present invention is executed by the volume data construction unit 21 of FIG. FIG. 7 shows the flow of the internal processing. In this processing, the input frame data is stored in a calculation buffer (S101), and information on the stored frame data is acquired (S102). The information of the ultrasonic scan position is read from the acquired information, and if the position is the start end in S103, the frame data is stored in the output volume data buffer (S104), and the next frame data is awaited to be input. If the ultrasonic scanned position is not at the starting end, the frame data is read from the calculation buffer, the position deviation correction processing is performed (S105), and stored in the output volume data buffer (S106). Further, if the ultrasonic scan position of the frame data is not the end in S107, it waits for the next frame data to be input, and if it is the end, the volume data is output (S108), and the process proceeds to the next process.

  FIG. 8 shows a flow of the positional deviation correction process (S105) in FIG. In S201, scan data A at point A of the current frame and scan data B at point B of the previous frame are acquired. In S202, the distance LA between the position at the start of frame data acquisition (point X) and the scan position (point A) of the current frame, and the scan position of the previous frame (point B) and the start of frame data acquisition A distance LB from the position (point X) is obtained. Then, using A, B, LA, and LB, data at the position (point X) at the start of frame data acquisition is obtained by interpolation. Then, by performing this process on the data of each transducer element, it is possible to obtain frame data that has been subjected to positional deviation correction.

  FIG. 9 shows a block configuration diagram for position misalignment correction. A data acquisition unit 25 that acquires scan data A at point A in the current frame and scan data B at point B in the previous frame; The distance LA between the position at the start of frame data acquisition (point X) and the current frame scan position (point A), and the previous frame scan position (point B) and the position at the start of frame data acquisition (X A distance calculation unit 26 that calculates a distance LB with respect to a point) and a data interpolation unit 27 that uses A, B, LA, and LB to obtain data at a position (point X) at the start of frame data acquisition by interpolation. Has been.

  FIG. 10 shows a second embodiment of the present invention. The difference from the first embodiment is that correction processing is performed using the front and rear frames, and the position serving as a correction reference is the scan position of the transducer element in the center of the ultrasound probe 3. In this embodiment, since the scanning position of the center transducer element is set as the reference position, the scan data of the current frame and the next frame of the transducer element scanned before the center transducer element are used. Interpolation is performed using scan data, and for transducer elements scanned after the center transducer element, interpolation is performed using scan data of the current frame and scan data of the previous frame. Become. By setting the correction reference to the center of the ultrasonic probe, the distance between the ultrasonic scan position of the data to be corrected and the correction position is shortened, so that the accuracy of the interpolation processing can be improved.

  In general, the present invention acquires a plurality of pieces of frame data while mechanically moving an ultrasonic probe in which a plurality of transducer elements are arranged in the major axis direction in a direction perpendicular to the major axis direction, The present invention can be applied to an ultrasonic diagnostic apparatus that creates a tomographic image or a 3D image based on the frame data. In the harmonic imaging using the reflected echo signal of the contrast agent bubble due to the sound pressure of the ultrasonic wave and the harmonic component of the reflected echo signal, the present invention is applicable to these imaging techniques in order to estimate the reflected echo signal at the scan position. Is possible.

DESCRIPTION OF SYMBOLS 1 ... Ultrasound diagnostic apparatus 2 ... Subject 3 ... Ultrasonic probe 4 ... Ultrasonic transmission / reception part 5 ... Ultrasound image structure part 6 ... Display part 7 ... Control part 8 ... Control panel 9 ... Ultrasonic scanning direction 10 ... Ultrasonic probe reciprocating direction 11 ... Ultrasonic probe moving direction 12 ... Frame data acquisition start position 13 ... Ultrasonic scan position A point 14 ... Ultrasonic scan position B point 15 ... Correction position X point 16 ... Correction position Distance 17 between point X and point A ... Distance between corrected position X and point 18 ... Data 19 obtained by ultrasonic scanning of the starting element of the ultrasonic probe 19 Data 20 obtained by ultrasonic scanning of the central element of the ultrasonic probe ... frame data acquisition unit 21 ... volume data construction unit 22 ... coordinate conversion processing unit 23 ... rendering processing unit 24 ... RGB conversion unit 25 ... data acquisition unit 26 for point A and B ... distance calculation unit 27 for LA and LB ... data Interpolator.

Claims (4)

An ultrasonic probe in which a plurality of transducer elements are arranged in the longitudinal direction, and the subject is irradiated with ultrasonic waves and received;
Means for transmitting and receiving ultrasonic signals while mechanically moving the ultrasonic probe in a direction perpendicular to the major axis direction;
Based on the ultrasound received by the ultrasound probe, an image constructing unit that obtains a plurality of frame data and creates a tomographic image or a 3D image from the frame data;
A display unit for displaying the tomographic image or the 3D image;
The image constructing unit comprises means for correcting the reception position of the frame data accompanying the mechanical movement of the ultrasonic probe;
Means for correcting the reception position of the frame data;
For each transducer element, a scan data acquisition unit that acquires scan data (A) of the current frame and scan data (B) of the previous or next frame;
For each transducer element, the distance (LA) between the reference position perpendicular to the moving direction of the ultrasonic probe and the scan position of the current frame, and the scan of the frame immediately before or after the reference position A distance calculation unit for obtaining a distance (LB) to the position;
For each transducer element, the current frame scan data (A), the previous or next scan data (B), the distance (LA) between the reference position and the current frame scan position, and A data interpolation unit that obtains data at the reference position by interpolation based on the distance (LB) between the reference position and the scan position of the previous or next frame,
The reference position is a scan position of a transducer element in the center of the ultrasonic probe;
For the transducer element scanned before the central transducer element, interpolation is performed using the scan data of the current frame and the scan data of the next frame, and the scan is performed after the central transducer element. An ultrasonic diagnostic apparatus characterized by performing interpolation using the scan data of the current frame and the scan data of the previous frame for the transducer element to be performed. The ultrasonic diagnostic apparatus according to claim 1 ,
The ultrasonic diagnostic apparatus, wherein the ultrasonic probe has a plurality of transducer elements arranged in the short axis direction. While mechanically moving an ultrasonic probe in which a plurality of transducer elements are arranged in the long axis direction in a direction perpendicular to the long axis direction, frame data for a plurality of sheets is acquired, and a tomographic image is obtained from the frame data. Alternatively, in an image processing method of an ultrasonic diagnostic apparatus that creates a 3D image,
Correcting the reception position of the frame data accompanying the mechanical movement of the ultrasonic probe,
Correcting the reception position of the frame data,
For each transducer element, obtaining scan data (A) for the current frame and scan data (B) for the previous or next frame;
For each transducer element, the distance (LA) between the reference position perpendicular to the moving direction of the ultrasonic probe and the scan position of the current frame, and the scan of the frame immediately before or after the reference position Obtaining a distance (LB) from the position;
For each transducer element, the current frame scan data (A), the previous or next scan data (B), the distance (LA) between the reference position and the current frame scan position, and Obtaining data at the reference position by interpolation based on a distance (LB) between the reference position and the scan position of the previous or next frame, and
The reference position is a scan position of a transducer element in the center of the ultrasonic probe;
For the transducer element scanned before the central transducer element, interpolation is performed using the scan data of the current frame and the scan data of the next frame, and the scan is performed after the central transducer element. An image processing method for an ultrasonic diagnostic apparatus, wherein the transducer element is interpolated using scan data of the current frame and scan data of the previous frame. The image processing method of the ultrasonic diagnostic apparatus according to claim 3 ,
An image processing method of an ultrasonic diagnostic apparatus, wherein the ultrasonic probe includes a plurality of transducer elements arranged in a short axis direction.

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