CN101273901B - High frame rate ultrasonic imaging method based on single power signal source and switching network thereof - Google Patents

Abstract

The invention relates to a high frame rate (HFR) ultrasonic imaging method based on a single power signal source and a switched network thereof, and the invention can realize the HFR ultrasonic transmission by using only one power signal source and a simple electronic switched network. Compared with the conventional ultrasonic imaging, the high frame rate ultrasonic imaging method uses only one channel of the power signal source and the simple electronic switched network to replace N power signal (source) amplification circuits, thus greatly simplifying the HFR system and reducing the power consumption of the circuit. The high frame rate ultrasonic imaging method approximately uses only a half of ultrasonic array elements for transmitting the signals, so the transmission energy of the device is reduced and the power supply to a future portable medical ultrasonic diagnostic imaging device by using a batter becomes possible. The high frame rate ultrasonic imaging method can be directly realized on a mature commercial machine, thus eliminating a delay circuit with expensive price. The HFR imaging algorithm is further utilized for carrying out the image reconstruction of the received signals and then the image with high quality is output.

Description

High frame rate ultrasonic imaging method based on single power signal source and switching network thereof

Technical field:

The invention belongs to the medical ultrasonic application, (High Frame Rate, HFR) the ultrasound emission system of imaging is for the realization of HFR ultra sonic imaging theory creates favorable conditions based on the high frame per second of non-diffraction ripple.

Background technology:

(High Frame Rate is called for short: HFR) in the imaging system, transmit and adopted limited diffraction ripple array (Array Beam) as transmitting in high frame per second at present.In reality realized, general ultrasonic probe had several emission array element, and each emission array element just needs a power signal source to drive.If ultrasonic probe has N emission array element, then need N power signal source to drive each emission array element respectively, relation between this N power signal source: waveform is the same, but phase place is different with amplitude, therefore in order to pass to each ultrasound emission array element to ultrasonic energy effectively, only the signal that produces with the resistor network dividing potential drop drives ultrasound emission array element and can not meet the demands, must design N ultrasonic power amplifying circuit (being equivalent to N signal source) or adopt N the delay circuit that parameter is different, drive the emission that different ultrasound emission array element could finally realize limited diffraction ripple Array Beam.For the two-dimensional ultrasound B ultrasonic in modern times, N is generally more than 128, and this just means 128 driving power signal sources of needs.And for three-dimension ultrasonic imaging system, if ultrasonic probe is 64 * 64 array elements, then N is 4096, and this will mean 4096 power emission circuit of needs! So because the complexity of emission circuit system and too fat to move huge, circuit power consumption is excessive, has directly limited the realization and the development of this novel ultrasonic image-forming system.

In recent years, the foreign scholar had once proposed a reduction procedure, promptly with two kinds of opposite polarity signal sources as emission pumping signal and electronic switch network, determine the conducting and the closure of electrical switch according to the diffracted wave Array Beam signal of different parameters, sonac emission array element just only needs two kinds of pumping signals of emission like this, produces proximate diffracted wave ArrayBeam sound field.Because this method has been simplified the radiating circuit of HFR greatly, compares with direct emission Array Beam sound field, resulting image quality effect is close to identical.

But,, still need to design two kinds of power signal sources with positive-negative polarity though this scheme is simplified the radiating circuit of HFR system greatly.Electronic switch network has the double-throw function, and its conducting and closure state are subjected to the diffracted wave Array Beam signal controlling of different parameters.The double-throw electronic switch network, each switch has two contacts and connects the positive-negative polarity signal source respectively, ultrasonic array element because of diverse location, when angular spectrum is the Array Beam ripple of high frequency, because the signal phase of adjacent ultrasonic array element emission is opposite, on distance sonac locus far away, the signal amplitude approximately equal of propagation, synergetic result cancels out each other, so angular spectrum is that the Array Beam ripple propagation distance of high frequency is restricted.

In order further to simplify radiating circuit, the present invention is proposed.

Summary of the invention:

At the present situation of prior art, the present invention proposes only to realize needed radiating circuit in the HFR system with a power signal source and electronic switch network.Among the application transmitting power signal source number among the HFR and ultrasonic power radiating circuit number thereof have been reduced to the limit, promptly a power signal source and simple electronic switch network just can be realized the ultrasound emission of HFR.

High frame per second (HFR) ultrasonic imaging technique of single power signal source excitation is characterised in that with single to have an one pole two-value periodic function control power signal source, the ultrasonic probe that has N array element through the driving of many single-pole single-throws electronic switch network.Institute's art one pole two-value periodic function signal source is the control that is subjected to limited diffraction array ripple (Array Beam).Ultrasonic probe has N array element, and wherein N is the positive integer greater than 1.Described one pole two-value periodic function, wherein ' two-value ' can get ' 0 or 1 '; ' 0 or-1 '.When one pole two-value periodic function was one of them state, array element in the corresponding ultrasonic probe and exciting power signal source disconnected; When one pole two-value periodic function was another state, then array element in the Dui Ying ultrasonic probe and exciting power signal source were connected.

Implementation of the present invention: by an one pole two-value of the determined construction of function of Array Beam periodic function, value is ' 0 or 1 ' or ' 0 or-1 '.This function is a sonac array element function of spatial position.Signal source whether encourage sonac array element just thus the value of function decide.If functional value equals 1, then exciting signal source and sonac array element are joined, and promptly launch pumping signal.If functional value equals at 0 o'clock, then exciting signal source and sonac array element disconnect, and promptly do not have the pumping signal emission.Certainly functional value ' 1/0 ' or ' 0/1 ' or ' 0/-1 ' or ' 1/0 ' transposition still can be protected the state of being switched on or switched off.Equaling at 1 o'clock with one pole two-value periodic function is example, and the sonac array element emission ultrasound wave that is connected with exciting signal source after its echo-signal is received, passes through relevant pretreatment, and can obtain the image of object by the HFR imaging algorithm.

Though the present invention only uses a power signal source, the image quality of the HFR system of its image quality and N signal source of employing does not almost have any difference.Therefore the present invention has further simplified the HFR imaging system greatly, for a new basis has been established in the realization of HFR ultra sonic imaging theory.

The present invention is significant in the HFR ultrasonic image-forming system: first only uses the power signal source of a passage and simple (many single-pole single-throws) electronic switch network to replace N road power signal (source) amplifying circuit or delay line, and the HFR system is simplified greatly; Second because power signal source is compressed to one, the circuit power consumption of HFR imager reduces greatly, be the ArrayBeam ripple of high frequency in addition for angular spectrum, because approximate have only the ultrasonic array element of half (being that functional value is) to transmit at 1 o'clock, and second half (functional value is 0 o'clock) do not work, thereby the emitted energy of instrument further reduces, and this will make following portable medical ultrasonic diagnostic imaging instrument adopt battery powered to become possibility; Each array element of the 3rd the present invention or do not launch ultrasound wave, or the identical ultrasound wave of transmitter, phase, so the energy of acoustic irradiation can be propagated far; Used ultrasonic imaging device on the 4th modern commerce, major part are ultrasonic probe array element and electrical switch to be combined constitute the emission oscillating circuit, and when electrical switch was connected, circuit produced the deamplification in several cycles and launched by ultrasonic probe array element.Obviously the present invention can directly realize on this sophisticated business machine, and has saved expensive delay line parts.Utilize the HFR imaging algorithm to carry out the imaging that image reconstruction gets final product outputting high quality to received signal again.

Under country nature fund assistance from proposing a kind of function aspect theoretical and the experiment two by force and high frame per second (High Frame Rate, HFR) 3 D medical ultra sonic imaging model and system thereof that structure is more simplified.This system is reconstructed image frequency spectrum in the angular spectrum territory at first, and is synthetic by frequency spectrum, forms the broader frequency spectrum of a width of cloth complete image, obtains image by the Fourier conversion then.This system can provide per second 3750 two field pictures (imaging depth is 200mm) in theory, has very high temporal resolution and spatial resolution.

Description of drawings:

Fig. 1 is the population structure block diagram: can be divided into three parts: I, be input circuit, comprising: power signal source [1], switching network [2], and wherein 2a is many single-pole single-throws electrical switch, 2b is switch controller (being waveform generator).II, it is the signal transmitting and receiving change-over circuit, comprise: the linear probe of medical supersonic [3] (is called for short: ultrasonic probe [3]), it has N ultrasonic array element [3a], N is the positive integer greater than 1, tested human body [4] and signal front-end processing device [5], and comprise three parts (not drawing among the figure) in this device the inside: ultrasonic signal receives permutator [5a] and high frequency amplifier [5b] and modulus (being A/D) transducer [5c].III, the date processing imaging circuit, comprise: data pretreatment [6], wherein 6a is the data minus musical instruments used in a Buddhist or Taoist mass, Fourier transformer [7]), variable converting member [8] and reconstructed image unit [9] 6b is that data storage, fast Fourier transform (FFT) device [7] (are called for short:.

Fig. 2 is the logic connection diagram between input circuit [I] and the ultrasonic probe [3].

The incentive program that Fig. 3 takes for input circuit in the background technology, wherein: 10 for positive negative bipolar exciting signal source, 11 is multitool commutator network, the 12nd, has the on-off control waveform of positive-negative polarity.

Fig. 4 is that the comparison of imaging results: 4a is the imaging diagrammatic sketch with N (as 128 etc.) exciting signal source; 4b is the positive and negative exciting signal source imaging of a up-to-date external employing diagrammatic sketch; 4c is that the present invention adopts single exciting signal source imaging sketch map.

The specific embodiment:

Below in conjunction with accompanying drawing the specific embodiment of the invention is done a step explanation.

Present once conventional ultrasound imaging motivation status at first is described:

For clarity sake, only provide the radiating circuit of the one-dimensional linear array element in the ultrasonic probe, its principle can directly expand to the radiating circuit of two-dimentional array element

For the ultrasonic linear probe of one dimension, emission parameter is

The expression formula of Array Beam be:

${\mathrm{\φ}}_{\mathrm{array}}(x,z)=A\left(k\right)e^{j(k_x^{t}x+k_z^{t}z)}---\left(1.1\right)$

${\mathrm{\φ}}_{\mathrm{array}}(x,z)=A\left(k\right)e^{j(-k_x^{t}x+k_z^{t}z)}---(1.2)$

Here A (k) is the expression formula of frequency spectrum on wave number k of signal source α (t), k=ω/c wherein, and c is the spread speed of ultrasound wave in human body.

With Between relation be

$k^2={\left(k_x^t\right)}^2+{\left(k_z^t\right)}^2---\left(2\right)$

If directly adopt (1) formula to transmit, establish pick off z=0 (x, y) on the plane, then the pumping signal that applies of each pick off array element is ${\mathrm{\φ}}_{\mathrm{array}}\left(x\right)=A\left(k\right)e^{j{k}_x^{t}x}$ Or ${\mathrm{\φ}}_{\mathrm{array}}\left(x\right)=A\left(k\right)e^{-j{k}_x^{t}x},$ Here x is the coordinate position of sonac array element.Because the required pumping signal difference of each array element, for the sonac that N array element is arranged, will need N power signal amplifier (source) or with the delay line of the individual different delay parameters that cost an arm and a leg of N as N exciting signal source.

Be the specific embodiment of the invention below.The present invention adopts the radiating circuit pattern of single power signal source [1], set waveform by power signal source [1] output, be connected with the ultrasonic probe of selecting [3] through switching network [2], by switch] conducting and the disconnection of controller [2b] control many single-pole single-throws electrical switch [2a], electrical switch has S1S2 ... Si ... Sn hilted broadsword contact.Switch controller [2b] is at first constructed the pulse signal of two kinds of monodromes in order to produce the condition of control electrical switch [2a] conducting and disconnection $f_1\left(k_x^{t}x\right)$ With $f_2\left(k_x^{t}x\right)$

$f_1\left(k_x^{t}x\right)$ Value is as follows:

$\left\{\begin{array}{cc}{f}_1\left(k_x^{t}x\right)=1& \cos k_x^{t}x>\mathrm{cons}\tan t\\ f_1\left(k_x^{t}x\right)=0& \cos k_x^{t}x\≤\mathrm{cons}\tan t\end{array}\right.---\left(3\right)$

$f_2\left(k_x^{t}x\right)$ Value is as follows:

$\left\{\begin{array}{cc}{f}_2\left(k_x^{t}x\right)=1& \sin k_x^{t}x>\mathrm{cons}\tan t\\ f_2\left(k_x^{t}x\right)=0& \sin k_x^{t}x\≤\mathrm{cons}\tan t\end{array}\right.---\left(4\right)$

If x=x _i, then that expression is S _iThe coordinate of switch corresponding sensor array element [3a].Constant is a constant, gets 0 here, so the pulse signal of monodrome

With

Peak-peak value is 0 and 1 square-wave signal.

With

Between phase contrast be 90 the degree.

Switch controller [2b] decision electrical switch [2a] S _iThe condition of individual switch closure or disconnection is as follows: if square-wave signal

Or

Functional value is 0, and the pick off array element [3a] on the then corresponding coordinate position does not transmit, and corresponding switch disconnects.And be that pick off array element [3a] on 1 the coordinate position transmits corresponding switches Si closure at functional value.

In imaging process, transmit main the branch following two steps:

The first step, all switches in the switching network [2]: S1S2 ... Si ... Sn is all closed, the power signal that produces by power signal source [1] directly and each the ultrasonic array element [3a] in all ultrasonic linear pop one's head in [3] be connected.Ultrasonic array element [3a] the emission ultrasonic signal that is energized in the ultrasonic probe [3], the Pulse Plane Wave of the signal of being launched this moment for propagating along the z axle.Ultrasonic signal is propagated in tested human body [4] and the tissue in tested human body [4] reflection, and this reflected signal amplifies and is converted to digital signal y through signal front-end processing device [5] ₀(x, t), x is the coordinate of ultrasonic array element [3a] in the ultrasonic probe [3].Said digital signal y ₀(x, t) temporary by data storage part [6b], this digital signal y ₀(x t) is the echo-signal of the Pulse Plane Wave propagated along the z axle with respect to transmitting.

Second step, then

Get non-0 value, switch controller [2b] produces switch controlling signal according to above-mentioned relation (formula (3) or (4)) and gives electrical switch [2a], closure and the disconnection of the respective switch Si in the control electrical switch [2a].The power signal that produced of power signal source [1] is connected with ultrasonic array element [3a] in the ultrasonic linear probe [3] selectively like this.Ultrasonic array element [3a] the emission ultrasonic signal that in ultrasonic probe [3], is energized, this ultrasonic signal is propagated in tested human body [4] and is reflected by the tissue in the tested human body [4], reflected signal obtains the signal y corresponding to formula (3) and (4) respectively after FEP [5] amplifies and passes through analog digital conversion _Cos(x, t) and y _Sin(x, t).

In image reconstruction process, data pretreatment [6] is at first carried out pretreatment to data.From data storage part [6b], take out the echo-signal y of the Pulse Plane Wave of propagating along the z axle with respect to transmitting ₀(x, t), and get its amplitude half with For non-0 when value correspondence received signal y _Cos(x, t) and y _Sin(x, the t) processing that subtracts, that is:

$\left\{\begin{array}{c}{y}_{\cos }^{\′}(x,t)=y_{\cos }(x,t)-0.5y_0(x,t)\\ y_{\sin }^{\′}(x,t)=y_{\sin }(x,t)-0.5y_0(x,t)\end{array}\right.---\left(5\right)$

The gained difference constitutes complex function:

$r_{k_x^t,k_y^t}(x,t)=y_{\cos }^{\′}(x,t)+i{y}_{\sin }^{\′}(x,t)---\left(6.1\right)$

$r_{{-k}_x^t,k_y^t}(x,t)=y_{\cos }^{\′}(x,t)-i{y}_{\sin }^{\′}(x,t)---\left(6.2\right)$

Just can utilize the HFR imaging algorithm to carry out imaging then.Its process is as follows:

Fourier transformer [7] obtains the frequency spectrum designation formula of formula (6) by quick Fourier transformation:

$R_{k_x^t}(k_x,k)=F\left[r_{k_x^t}(x,t)\right]---\left(7.1\right)$

$R_{-k_x^t}(k_x,k)=F\left[r_{{-k}_x^t}(x,t)\right]---\left(7.2\right)$

Here F () expression Fourier conversion.

Variable converting member [8] utilizes relational expression (2) and following relational expression

$\left\{\begin{array}{c}{k}_x^{\′}=k_x^t+k_x\\ k_z^{\′}=k_z^t+\sqrt{k^2-k_x^2}\end{array}\right.---\left(8\right)$

Be converted to

Be converted to

Promptly

$R_{k_x^t}(k_x^{\′},k_z^{\′})=R_{k_x^t}(k_x,k)---\left(9.1\right)$

$R_{-k_x^t}(k_x^{\′},k_z^{\′})=R_{-k_x^t}(k_x,k)---\left(9.2\right)$

Handle in the reconstructed image unit [9]

With

Synthesize the frequency spectrum of last image:

$R(k_x^{\′},k_z^{\′})=R_{k_x^t}(k_x^{\′},k_z^{\′})+R_{-k_x^t}(k_x^{\′},k_z^{\′})---\left(10\right)$

And carry out the Fourier inverse transformation and export ultra sonic imaging

$y(x,z)=F^{-1}\left[R(k_x^{\′},k_z^{\′})\right]---\left(11\right)$

Here F ^-1() expression Fourier inverse transformation

Also can utilize Foureir conversion handle in reconstructed image unit [9] as can be seen

Or Be converted to two two field pictures respectively.

Accompanying drawing 4 is in 2 dimension spaces (x, imaging results z).Display gray scale is a logarithmic scale, and the normalization value is-40～0dB.Wherein, Fig. 4 a is for being N the resulting imaging of exciting signal source with transmitting; Fig. 4 b is that correlation technique adopts the resulting imaging of positive negative bipolar exciting signal source; Fig. 4 c is the resultant imaging of single exciting signal source for the present invention adopts.As can be seen, image quality almost is consistent, but the circuit-mode that transmits involved in the present invention is very simple.

It is to be noted that the position of data pretreatment [6] and Fourier transformer [7] can be moved mutually according to the characteristics of linear system.If data pretreatment [6] is in the back of Fourier transform [7], at this moment data storage part [6b] institute canned data is y ₀(x, frequency spectrum t).

Claims (1)

1. high frame rate ultrasonic imaging method based on single power signal source and switching network thereof, it is characterized in that with one pole two-value periodic function control power signal source, the ultrasonic probe that has a plurality of array elements through multitool single-throw switch network-driven, one pole two-value periodic function is the function of spatial position of sonac array element, described one pole two-value periodic function signal source is controlled by limited diffraction array ripple, " opening " or " pass " of 1 or 0 control multitool single-throw switch network of functional value is switched on or switched off corresponding array element and exciting power signal source in the ultrasonic probe.

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