JP2001161686A - Ultrasonic imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic imaging apparatus simplified by adaptively controlling the phase between transmitted/received signal channels to automatically focus an ultrasonic beam on a part to be examined and limiting the precision of the structure of synthesizing an ultrasonic beam to an actually required one, and a method of imaging using the apparatus. SOLUTION: The apparatus comprises an ROI setting part 8, a contrast sampling/ setting part 7, and a correlated processing amplitude precision setting part 9. The precision of operation is adjusted to the amplitude of the echo of a subject organ as a standard signal for adaptive processing, and the brightness for the phase detection in an adaptive phase control part 5 is specified within the contrast range of the subject organ. Even when the wave surface of the echo from the part to be truly examined is disturbed by the existence of irregularity of the acoustic properties of the organism from the body surface to the part to be examined, the bit precision is specifically adjusted to the brightness of the contrast range of the subject organ to execute the signal processing operation and the focus is automatically adjusted to the part to be examined. Because of such simple structure as mentioned, the apparatus and the method for focusing the beam on the part to be examined effectively and speedily can be achieved easily at a reasonable price.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of adapting the phase of a transmission / reception signal of an array of fine ultrasonic transducers to a diagnostic part of a subject by utilizing ultrasonic waves by adapting the acoustic characteristics of a living body.
An ultrasonic beam is formed and scanned by controlling circuit characteristics electronically so that the phase of the received signal between elements in the array of echoes from the same reflector matches each other. Distribution of acoustic impedance by structure,
The present invention relates to an ultrasonic imaging apparatus that visualizes such a time change and the like, and in particular, a unit or procedure for adaptively focusing an ultrasonic beam in accordance with the image brightness of a target organ and receiving signals from the organ with high sensitivity. The present invention relates to an ultrasonic imaging apparatus including:

[0002]

2. Description of the Related Art A conventional adaptive image reproducing type ultrasonic imaging apparatus comprises:
The phase of the transmission / reception signal of the array of the fine ultrasonic transducers is aimed at a high intensity echo signal from a living body,
An ultrasonic beam is formed and scanned by electronically controlling the circuit characteristics so that the phases of the echo signal waveforms received by the adjacent elements of the array coincide with each other. And visualized the distribution of body fluids, the distribution of body fluid velocity and the movement of organs, or their temporal changes.

[0003] In FIG. 4, an array probe 1 composed of an array of N natural number of micro-vibrators generates an N beam generated by a transmission circuit 21 of an ultrasonic circuit section 2 so that a beam is slightly converged.
Probe switching scanning unit 23 according to a burst waveform of which the amplitude and phase are controlled for the natural number m channels included in
Converted to ultrasonic waves by each element selected in step
Propagate.

The probe 1 reversely converts the echo signal reflected back in the living body into an electric signal by each element thereof, and passes through a probe switching scanning section 23 and a transmission / reception separating circuit 22 to receive a reception signal. Is output to the receiving circuit 24.

The probe switching and scanning section 23 selects m elements from N elements and forms an aperture for an ultrasonic transmission / reception beam, while performing translational scanning such as linear or convex.

The transmission / reception separation circuit 22 efficiently transmits the transmission signal power output from the transmission circuit 21 to the probe 1 through the probe switching scanning unit 23, and controls the transmission signal power flowing into the reception circuit 24. Preamplifier at its front end
(241-1 to 241-m in FIG. 2), and efficiently transmits the echo signal received by the probe 1 and input through the scanning circuit 2 to the preamplifier.

[0007] The preamplifier (241-1 to 241-m)
Each of the echo signals of the channels is controlled and amplified for each depth, and the levels of the echo signals are adapted to the input range of an ADC (analog-to-digital converter) (242-1 to 242-m). A
These echo signals digitally converted by DC (242-1 to 242-m) are phase-compensated (243-1 to 243) to make the phases of the reception signals for each channel different for each element according to the distance to the focus point. -m), the phase is adjusted for each depth (the phase between the channels is made uniform), and the adder 244 synthesizes the waveform of the ultrasonic beam focused on the diagnosis site.

Here, the phase compensation can be realized by a circuit which is also realized as a time delay circuit, or is realized by changing a memory address for reading or writing. The degree of phase compensation (243-1 to 243-m)
It is controlled by data in the beam focus deflection phase data memory 6.

In the combined beam waveform, the distribution of the echo intensity of the fundamental frequency is detected and logarithmically compressed by the AM detection and video signal processing 25, and the distribution of the echo from the structure and the distribution of the sideband component are obtained. Is FM detection and Doppler signal processing 2
The filter is extracted by 6 and all are converted into images such as tomographic images by the scan converter 31 of the DSC unit 3,
It is displayed on the image display unit 4.

The control circuit 32 controls the ultrasonic circuit section 2 to operate in a coordinated manner according to the operation of the DSC section 3. In order to adaptively compensate for the phase error between channels due to non-uniform sound velocity in the living body, for example, the reception circuit 24 includes a correlation processing unit 245-1.
The adaptive phase control unit 5 monitors the phase difference between adjacent channels, corrects the beam focus deflection phase data, and controls the phase compensation 243-1 to 243-m.

[0011]

However, in ultrasound images, echoes at diagnostic sites are generally moderate or rather low in intensity, so that the part desired by the examiner or the diagnostician is focused on. Often not. In this case, the ultrasonic beam is synthesized by adaptively controlling the phase between the transmission and reception signal channels so as to automatically focus on a part to be truly inspected.

However, a mechanism for comparing phases between transmission and reception signal channels generally requires a configuration equivalent to the original beam forming mechanism, and there is a drawback that the scale of a circuit or a program therefor becomes excessive. .

Accordingly, an object of the present invention is to truly require a mechanism for synthesizing an ultrasonic beam by adaptively controlling the phase between transmission and reception signal channels so as to automatically focus on a site to be inspected. Another object of the present invention is to provide a simplified ultrasonic imaging apparatus by limiting the accuracy of the ultrasonic imaging apparatus.

[0014]

In order to achieve the above object,
In the ultrasonic imaging apparatus according to the present invention, the contrast (brightness) of the received echo signal from the depth near the organ to be diagnosed (ROI) in the ultrasonic beam is extracted and 100 dB (16
bit), a mechanism or procedure to detect the cross-correlation value with sufficient computational accuracy to cover the dynamic range of the scattered echo signal from the target organ within the vast dynamic range of more than A unit or a procedure for adaptively adjusting the phase is provided so that the phase can be adaptively adjusted to the target organ.

In general, the contrast of a target organ is moderate in brightness and contrast, since it is easy to discriminate between a lesion and a healthy part, and an image of a healthy person's organ is displayed in the entire field of view with recognizable brightness and contrast. It is common sense to set the parameters of the device so as to be observed as, and the entire device is also designed to do so. Therefore, the echo from the target organ can be used as the reference signal for performing the adaptive processing by adjusting the calculation accuracy to the amplitude of the echo of the target organ.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic configuration of an ultrasonic imaging apparatus according to an embodiment of the present invention.

As a mechanism for detecting a contrast of a target organ, for example, R
An OI setting unit 8, a contrast extraction / setting unit 7, and a correlation processing amplitude accuracy setting 9 are provided.
, The luminance for phase detection is specified within the contrast range of the target organ.

Here, the receiving circuit 24 extracts and detects a signal bit within the contrast range designated by the correlation processing amplitude accuracy setting 9 from the received signal.

As shown in FIG. 2, the adaptive phase control unit 5
The phase correction value calculation unit 51 is a ROI contrast extraction setting unit 7
Using the peak time difference of the correlation of the echo signals in the luminance range according to the ROI contrast data as the phase correction value, the phase compensation data generation unit 52 corrects the beam focus deflection phase data to obtain the phase compensation 243-1 to 243-m Control. RO
The correction in I can be realized by obtaining a phase compensation value for each scanning line in the ROI and correcting the focus / deflection phase data of the beam in the ROI or the entire screen. Or R
ROI is a phase compensation value detected by one scanning line in OI.
It can also be realized by correcting the focus / deflection phase data of the beam within or on the entire screen. As a result, it becomes possible to efficiently focus the ultrasonic beam on a part necessary for diagnosis.

Instead of the adder 244 for synthesizing the waveform of one ultrasonic beam focused on the diagnosis site, a plurality of beams in a range according to the transmission / reception directivity angle of the element and the inspection depth are generated as shown in FIG. It is also effective to provide an all-beam memory 246 that performs the operation. Phase compensation 243-1 to 243-m and later include quadrature modulation
If all the beams are stored as two orthogonal components in a two-system processing system and passed to the scan converter 31 as multiple beam data, the scan converter 31 can perform parallel arithmetic processing to obtain the ultimate resolution. be able to. By performing the correlation processing 245-1 to 245-m / 2 after the addition 247-1 to 247-m processing, it becomes a correlation processing between the averages of two adjacent channels, and the resistance to noise can be increased.

Although the method of detecting the phase correction value has been described above as a method of determining the phase difference of the received signal between adjacent elements by the correlation process, the method is not limited to this method alone.

[0023]

According to the present invention, even when the acoustic wave characteristic of the living body is uneven from the body surface to the relevant part, the wavefront of the echo from the part to be truly inspected is disturbed.
In particular, since the signal processing operation is performed by adjusting the bit precision to the brightness of the contrast range of the target organ and the focus is automatically focused on the target part, the focus can be efficiently and quickly focused on that part. Simple apparatus and method can be easily realized at a reasonable price.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an ultrasonic imaging apparatus according to the present invention.

FIG. 2 is a block diagram illustrating an internal configuration of a wave receiving circuit in the ultrasonic circuit unit.

FIG. 3 is a block diagram showing another embodiment of the wave receiving circuit in the ultrasonic circuit unit.

FIG. 4 is a block diagram showing a conventional ultrasonic imaging apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Probe 2 ... Ultrasonic circuit part 3 ... DSC part 4 ... Image display part 5 ... Adaptive phase control part 6 ... Beam / focus deflection phase data memory 7 ... Contrast extraction / setting part 8 ... ROI setting part 9 ... Correlation processing amplitude accuracy setting 21 ... Transmission circuit 22 ... Transmission / reception separation circuit 23 ... Sensor switching scanning unit 24 ... Reception circuit 25 ... Detection / video signal processing 31 ... Scan converter 32 ... Control circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4C301 AA02 BB01 BB12 BB23 EE15 HH26 HH27 HH33 HH37 HH38 HH42 JB17 JB28 JB50 KK26 KK30 5B057 AA07 BA05 BA17 CH04 DA07 DC22 DC34 DC36 5C054 AA01 AA05 CA08

Claims (2)

[Claims] 1. An ultrasonic imaging apparatus characterized in that correlation processing of signals between channels is performed on an image of an organ having an appropriate contrast, and an image is adaptively reconstructed. 2. A mechanism for setting and displaying an ROI on a target organ in an image in order to detect the appropriate contrast.
And a mechanism for detecting a luminance range of a signal in the ROI, and a mechanism for matching a signal phase difference between channels by focusing only on signals in the luminance range, and adaptively reconstructing an image. Ultrasound imaging device characterized by doing.