Summary of the invention
In order to address the above problem, the invention provides a kind of target image system organization texture preprocess method more careful, ultrasonic signal clearly and system of getting of making.
Accordingly, the preprocess method of a kind of ultrasonic signal of the present invention, said method comprising the steps of:
S1, receive N bar echo-signal, randomly draw echo-signal described in M bar and process from echo-signal described in the N bar receiving, to calculate system function, wherein, M is less than N;
S2, echo-signal described in the N bar receiving is carried out to linear interpolation calculating, so that N bar echo-signal is increased to P bar echo-signal, wherein, P is greater than N;
S3, take the system function that calculates and P bar echo-signal as basis, carry out deconvolution processing;
S4, obtain target image.
As a further improvement on the present invention, described step S1 specifically comprises: receive N bar echo-signal, randomly draw echo-signal described in M bar from echo-signal described in the N bar receiving, and adopt two spectrum identification processing to process, to calculate system function, wherein, M is less than N.
As a further improvement on the present invention, described deconvolution is treated to the long-pending processing of Fourier-small echo regular deconvolution.
As a further improvement on the present invention, described step S3 specifically comprises: remove the noise in described echo-signal.
As a further improvement on the present invention, " removing the noise in described echo-signal " step comprises: echo-signal described in employing Fourier-Tikhonov shrink process, and to weaken the noise in described echo-signal.
As a further improvement on the present invention, " removing the noise in described echo-signal " step also comprises: echo-signal described in employing small echo hard-threshold shrink process, again decompose described echo-signal, and described echo-signal secondary is removed to noise.
As a further improvement on the present invention, step also comprises " to remove the noise in described echo-signal ": adopt Wavelet Domain Wiener Filtering to process described echo-signal.
Accordingly, the pretreatment system of a kind of ultrasonic signal of the present invention, described system comprises:
Communication unit, for receiving N bar echo-signal;
Processing unit, randomly draws echo-signal described in M bar for echo-signal described in the N bar from receiving and processes, and to calculate system function, wherein, M is less than N;
Echo-signal described in the N bar receiving is carried out to linear interpolation calculating, and so that N bar echo-signal is increased to P bar echo-signal, wherein, P is greater than N;
Take the system function that calculates and P bar echo-signal as basis, carry out deconvolution processing;
Obtain target image.
As a further improvement on the present invention, described processing unit is also for receiving N bar echo-signal, randomly draws echo-signal described in M bar from echo-signal described in the N bar receiving, and adopt two spectrum identification processing to process, to calculate system function, wherein, M is less than N.
As a further improvement on the present invention, described deconvolution is treated to the long-pending processing of Fourier-small echo regular deconvolution.
As a further improvement on the present invention, described processing unit is also for removing the noise of described echo-signal.
As a further improvement on the present invention, described processing unit is also for adopting echo-signal described in Fourier-Tikhonov shrink process, to weaken the noise in described echo-signal; Echo-signal described in employing small echo hard-threshold shrink process, decomposes described echo-signal again, and described echo-signal secondary is removed to noise; Adopt Wavelet Domain Wiener Filtering to process described echo-signal.
Compared with prior art, the preprocess method of ultrasonic signal of the present invention and system, before obtaining target image, adopt deconvolution to process described echo-signal, remove the noise in described echo-signal, and at utmost retain original described echo-signal, the target image contrast of finally obtaining is significantly strengthened, and then promoted the resolution of target image, make the tissue texture of the target image obtaining also more careful, clear simultaneously.
The specific embodiment
Describe the present invention below with reference to embodiment shown in the drawings.But embodiment does not limit the present invention, the conversion in structure, method or function that those of ordinary skill in the art makes according to these embodiments is all included in protection scope of the present invention.
As shown in Figure 1, the processing method of ultrasonic signal in prior art, the method mainly comprises the following steps:
M1, launch scanning linear scan destination organization by Ultrasound Instrument, so that original image is sampled;
M2, receive described echo-signal;
M3, complete ultra sonic imaging according to described echo-signal, obtain target image;
M4, finally to described destination organization estimating system function, so that described target image is done to further processing.
What above process adopted is post-processing technology, on the basis that obtains target image, further processes, so that the target image finally obtaining is more outstanding; But, owing to adopting said method, when the different target image of medical supersonic instrument scanning, the system function difference of at every turn obtaining.Run counter to " system uniqueness " this basic norm of measurement, and then caused image processing process low speed, poor efficiency.
As shown in Figure 2, the processing method of ultrasonic signal of the present invention, the method mainly comprises the following steps:
P1, launch scanning linear scan destination organization by Ultrasound Instrument, so that original image is sampled;
P2, receive all echo-signals;
P3, described echo-signal is carried out to pretreatment;
P4, complete ultra sonic imaging according to described echo-signal, obtain target image;
The difference part of the ultrasonic signal processing method of ultrasonic signal processing method of the present invention and prior art is: before completing ultra sonic imaging according to described echo-signal, described method also comprises, described ultrasonic signal is carried out to pretreatment, again according to completing ultra sonic imaging through pretreated described echo-signal, obtain target image afterwards.The target image now obtaining is the target image that finally will obtain.And no longer adopt post-processing technology to process to described target image.
As shown in Figure 3, Fig. 3 is the flow chart of the preprocess method of the ultrasonic signal that provides in embodiment of the present invention; Be the concrete introduction of step P3 in Fig. 2, concrete, the preprocess method of a kind of ultrasonic signal of the present invention, said method comprising the steps of:
S1, receive N bar echo-signal, randomly draw echo-signal described in M bar and process from echo-signal described in the N bar receiving, to calculate system function, wherein, M is less than N;
S2, echo-signal described in the N bar receiving is carried out to linear interpolation calculating, so that N bar echo-signal is increased to P bar echo-signal, wherein, P is greater than N;
S3, take the system function that calculates and P bar echo-signal as basis, carry out deconvolution processing;
S4, obtain target image.
Accordingly, in an embodiment of the present invention, because described system function is unknown, therefore, before carrying out described deconvolution processing, first carry out system identification, i.e. blind deconvolution (blind deconvolution).
Concrete, described step S1 specifically comprises: receive N bar echo-signal, randomly draw echo-signal described in M bar, and adopt two spectrum identification processing to process from echo-signal described in the N bar receiving, to calculate system function, wherein, M is less than N.The described system function that adopts this kind of method to calculate, can be according to ambient temperature, and the impact of the extraneous factors such as humidity variation, calculates suitable described system function in real time.
The method of selecting higher-order spectrum to analyze, for gaussian signal, all Higher Order Cumulants are all zero, can eliminate the interference of white Gaussian noise and coloured noise in non-Gaussian Systems, improve signal to noise ratio; In non-minimum phase system, the phase property that higher-order spectrum method can stick signal.
Concrete, adopt the identification of two spectrum to process to calculate system function, its implementation is as follows:
The three rank cumulants of zero average signal y (n) are defined as:
In formula,
it is zero average signal
three rank cumulants, be a constant;
represent assembly average.
Afterwards, successively use (3) (1) (2) step in following formula can estimate system function;
Further, two spectrums of falling are that above formula is done to transform, after getting natural logrithm, then do inverse transformation, obtain:
The cepstrum of note h (n) is:
In formula,
represent two-dimension fourier transform.
By above-mentioned two spectra system identification algorithms that fall, utilize MatLab higher-order spectrum calculation procedure, the described echo-signal receiving is processed, choose optimum described system function by estimation.
Accordingly, step S2 carries out linear interpolation calculating to echo-signal described in the N bar receiving, and so that N bar echo-signal is increased to P bar echo-signal, wherein, P is greater than N.
Adopting the algorithm of linear interpolation that N bar echo-signal is increased to P bar echo-signal, is general knowledge known in this field, is not described in detail at this.
Accordingly, step S3, take the system function that calculates and P bar echo-signal as basis, carries out deconvolution processing; S4, obtain target image.
Concrete, described deconvolution is treated to the long-pending processing of Fourier-small echo regular deconvolution, removes the noise in described echo-signal simultaneously.Fourier-small echo regular deconvolution integration method has very strong robustness, has high resistance and makes performance, can significantly improve the caused resolution degradation phenomenon of convolution, strengthens picture contrast, reduces noise.
Accordingly, adopt echo-signal described in Fourier-Tikhonov shrink process, to weaken the noise in described echo-signal.
The concrete methods of realizing that adopts Fourier-Tikhonov to shrink is as follows:
The mathematical model of ultra sonic imaging is:
In formula: y (n) represents the described echo-signal observing; X (n) represents the signal of tested tissue, is a Gauss, zero average, stable signal; H (n) is and asks in step S1, represents the described system function of Ultrasound Instrument, is that a length is the FIR filter system of M, definite, cause and effect;
represent additive gaussian noise; * represent convolution.
Above formula is done to discrete Fourier transform to be obtained:
Adopt inverse operator to obtain the estimated value of X:
If
, deconvolution becomes morbid state.
In order to solve the problem of ill deconvolution, the impact of the method attenuating noise shrinking with Fourier, will
be multiplied by a contraction
Above step inverse operator and Fourier shrink and carry out simultaneously, are called the long-pending method of Fourier's regular deconvolution.
Wherein, the long-pending constriction coefficient of Fourier's regular deconvolution is:
for regular terms, the regular terms of the different long-pending technology of Fourier's regular deconvolution is different.
If σ
2for noise variance, α is regular parameter (α >0), and the regular terms of Tikhonov deconvolution is
it is the meansigma methods of y;
If get regular parameter
, can obtain signal noisy without inclined to one side estimation;
If get regular parameter
, can suppress noise completely, but also lose the information of former described echo-signal k item simultaneously.
Choose optimum regular parameter, will make the signal that finally estimates and the mean square deviation of former described echo-signal
minimum, due to former described echo-signal the unknown, so MSE cannot directly obtain.
The present invention uses the cost function based on observing to be similar to MSE:
The α that makes above formula value minimum is optimum regular parameter α.
In actual ultrasonic system, noise variance is unknown; Select classical Donoho to ask the method for noise variance herein,, on the fine dimension of wavelet decomposition, the intermediate value of signal wavelet coefficient is divided by 0.6745;
If make the signal after Fourier-Tikhonov shrinks be
, wherein,
fourier transformation.
Shrink after described echo-signal by Fourier Tikhonov, the noise contribution having amplified is cut down greatly, but has also lost a part of signal component simultaneously, and due to the existence on border, signal exists distortion.In order to improve the quality of signal, need be at wavelet field decomposed signal signal is carried out to denoising again.
Accordingly, adopt echo-signal described in small echo hard-threshold shrink process, again decompose described echo-signal, described echo-signal secondary is removed to noise.
The concrete methods of realizing that adopts small echo hard-threshold to shrink is as follows:
Described in employing Fourier-Tikhonov contraction, small echo hard-threshold shrink process, after echo-signal, recycling Wavelet Domain Wiener Filtering obtains final estimated value
Compared with prior art, the preprocess method of ultrasonic signal of the present invention, before obtaining target image, when overcoming the different target image of same Ultrasound Instrument scanning, the system function difference of at every turn obtaining, adopts the identification of two spectrum to process to calculate system function; Afterwards, adopt the described echo-signal of the long-pending processing of Fourier-small echo regular deconvolution, remove the noise in described echo-signal, and at utmost retain original described echo-signal, the target image contrast of finally obtaining is significantly strengthened, and then promoted the resolution of target image, simultaneously, make the tissue texture of the target image obtaining also more careful, clear.
As shown in Figure 4, Fig. 4 is the module diagram of the pretreatment system of ultrasonic signal in an embodiment of the present invention.
Accordingly, described system comprises: communication unit 100, for receiving N bar echo-signal; Processing unit 200, randomly draws echo-signal described in M bar for echo-signal described in the N bar from receiving and processes, and to calculate system function, wherein, M is less than N; Echo-signal described in the N bar receiving is carried out to linear interpolation calculating, and so that N bar echo-signal is increased to P bar echo-signal, wherein, P is greater than N; Take the system function that calculates and P bar echo-signal as basis, carry out deconvolution processing; Obtain target image.
Accordingly, want ultrasonic signal to process to obtain target image, first need to receive echo-signal by communication unit 100, by processing unit 200, described echo-signal is processed again afterwards, to obtain described target image.
Accordingly, in an embodiment of the present invention, because described system function is unknown, therefore, before carrying out described deconvolution processing, first by processing unit 200, system is carried out to identification, i.e. blind deconvolution (blind deconvolution).
Accordingly, described processing unit 200 is for receiving N bar echo-signal, randomly draws echo-signal described in M bar, and adopt two spectrum identification processing to process from echo-signal described in the N bar receiving, and to calculate system function, wherein, M is less than N.The described system function that adopts this kind of method to calculate, can be according to ambient temperature, and the impact of the extraneous factors such as humidity variation, calculates suitable described system function in real time.
The method that described processing unit 200 selects higher-order spectrum to analyze, for gaussian signal, all Higher Order Cumulants are all zero, can eliminate the interference of white Gaussian noise and coloured noise in non-Gaussian Systems, improve signal to noise ratio; In non-minimum phase system, the phase property that higher-order spectrum method can stick signal.
Concrete, described processing unit 200 adopts the identification of two spectrum to process to calculate system function, and its implementation is as follows:
The three rank cumulants of zero average signal y (n) are defined as:
In formula,
being the three rank cumulants of zero average signal x (n), is a constant; E{} represents assembly average.
Afterwards, successively use (3) (1) (2) step in following formula can estimate system function;
Further, two spectrums of falling are that above formula is done to transform, after getting natural logrithm, then do inverse transformation, obtain:
In formula, F[] expression two-dimension fourier transform.
By above-mentioned two spectra system identification algorithms that fall, utilize MatLab higher-order spectrum calculation procedure, the described echo-signal receiving is processed, choose optimum described system function by estimation.
Accordingly, described processing unit 200 also carries out linear interpolation calculating for echo-signal described in the N bar to receiving, and so that N bar echo-signal is increased to P bar echo-signal, wherein, P is greater than N.
Described processing unit 200 adopts the algorithm of linear interpolation that N bar echo-signal is increased to P bar echo-signal, is general knowledge known in this field, is not described in detail at this.
Accordingly, described processing unit 200 also for the system function to calculate and P bar echo-signal as basis, carry out deconvolution processing; Obtain target image.
Concrete, described processing unit 200 adopts the described echo-signal of the long-pending processing of Fourier-small echo regular deconvolution, removes the noise in described echo-signal simultaneously.Fourier-small echo regular deconvolution integration method has very strong robustness, has high resistance and makes performance, can significantly improve the caused resolution degradation phenomenon of convolution, strengthens picture contrast, reduces noise.
Accordingly, described processing unit 200 adopts echo-signal described in Fourier-Tikhonov shrink process, to weaken the noise in described echo-signal.
The concrete methods of realizing that described processing unit 200 adopts Fourier-Tikhonov to shrink is as follows:
The mathematical model of ultra sonic imaging is:
In formula: y (n) represents the described echo-signal observing; X (n) represents the signal of tested tissue, is a Gauss, zero average, stable signal; H (n) is and asks in step S1, represents the described system function of Ultrasound Instrument, is that a length is the FIR filter system of M, definite, cause and effect; γ (n) represents additive gaussian noise; * represent convolution.
Above formula is done to discrete Fourier transform to be obtained:
Adopt inverse operator to obtain the estimated value of X:
Adopt inverse operator to obtain the estimated value of X:
If
, deconvolution becomes morbid state.
In order to solve the problem of ill deconvolution, the impact of the method attenuating noise shrinking with Fourier, will
be multiplied by a constriction coefficient
Above step inverse operator and Fourier shrink and carry out simultaneously, are called the long-pending method of Fourier's regular deconvolution.
Wherein, the long-pending constriction coefficient of Fourier's regular deconvolution is:
for regular terms, the regular terms of the different long-pending technology of Fourier's regular deconvolution is different.
If σ
2for noise variance, α is regular parameter (α >0), and the regular terms of Tikhonov deconvolution is
it is the meansigma methods of y;
If get regular parameter
, can obtain signal noisy without inclined to one side estimation;
If get regular parameter
, can suppress noise completely, but also lose the information of former described echo-signal k item simultaneously.
Choose optimum regular parameter, will make the signal that finally estimates and the mean square deviation of described echo original signal
minimum, due to former described echo-signal the unknown, so MSE cannot directly obtain.
The present invention uses the cost function based on observing to be similar to MSE:
The α that makes above formula value minimum is optimum regular parameter α.
In actual ultrasonic system, noise variance is unknown; Select classical Donoho to ask the method for noise variance herein,, on the fine dimension of wavelet decomposition, the intermediate value of signal wavelet coefficient is divided by 0.6745;
If make the signal after Fourier-Tikhonov shrinks be
?
, wherein,
fourier transformation.
Described processing unit 200 shrinks after described echo-signal by Fourier Tikhonov, and the noise contribution having amplified is cut down greatly, but also lost a part of signal component simultaneously, and due to the existence on border, signal exists distortion.In order to improve the quality of signal, need be at wavelet field decomposed signal signal is carried out to denoising again.
Accordingly, described processing unit 200 adopts echo-signal described in small echo hard-threshold shrink process, again decomposes described echo-signal, and described echo-signal secondary is removed to noise.
The concrete methods of realizing that described processing unit 200 adopts small echo hard-threshold to shrink is as follows:
Described processing unit 200 adopts that Fourier-Tikhonov shrinks, described in small echo hard-threshold shrink process after echo-signal, recycling Wavelet Domain Wiener Filtering obtains final estimated value
;
Compared with prior art, the preprocess method of ultrasonic signal of the present invention and system, before obtaining target image, when overcoming the different target image of same Ultrasound Instrument scanning, the system function difference of at every turn obtaining; Adopt the identification of two spectrum to process to calculate system function; Afterwards, adopt the described echo-signal of the long-pending processing of Fourier-small echo regular deconvolution, remove the noise in described echo-signal, and at utmost retain former described beginning echo-signal, the target image contrast of finally obtaining is significantly strengthened, and then promoted the resolution of target image, simultaneously, make the tissue texture of the target image obtaining also more careful, clear.
For convenience of description, while describing above device, being divided into various modules with function describes respectively.Certainly, in the time implementing the application, the function of each module can be realized in same or multiple software and/or hardware.
As seen through the above description of the embodiments, those skilled in the art can be well understood to the mode that the application can add essential general hardware platform by software and realizes.Based on such understanding, the part that the application's technical scheme contributes to prior art in essence in other words can embody with the form of software product, this computer software product can be kept in Protector, as ROM/RAM, magnetic disc, CD etc., comprise that some instructions (can be personal computers in order to make a computer equipment, Information Push Server, or the network equipment etc.) carry out the method described in some part of each embodiment of the application or embodiment.
Device embodiments described above is only schematic, the wherein said module as separating component explanation can or can not be also physically to separate, the parts that show as module can be or can not be also physical modules, can be positioned at a place, or also can be distributed on multiple mixed-media network modules mixed-medias.Can select according to the actual needs some or all of module wherein to realize the object of present embodiment scheme.Those of ordinary skills, in the situation that not paying creative work, are appreciated that and implement.
The application can be used in numerous general or special purpose computingasystem environment or configuration.For example: personal computer, Information Push Server computer, handheld device or portable set, plate equipment, multi-processing module system, system, set top box, programmable consumer-elcetronics devices, network PC, minicomputer, mainframe computer based on micro treatment module, comprise distributed computing environment of above any system or equipment etc.
The application can describe in the general context of the computer executable instructions of being carried out by computer, for example program module.Usually, program module comprises and carries out particular task or realize routine, program, object, assembly, data structure of particular abstract data type etc.Also can in distributed computing environment, put into practice the application, in these distributed computing environment, be executed the task by the teleprocessing equipment being connected by communication network.In distributed computing environment, program module can be arranged in the local and remote computer Protector including preservation equipment.
Be to be understood that, although this description is described according to embodiment, but be not that each embodiment only comprises an independently technical scheme, this narrating mode of description is only for clarity sake, those skilled in the art should make description as a whole, technical scheme in each embodiment also can, through appropriately combined, form other embodiments that it will be appreciated by those skilled in the art that.
Listed a series of detailed description is above only illustrating for feasibility embodiment of the present invention; they are not in order to limit the scope of the invention, all do not depart from the equivalent embodiment that skill spirit of the present invention does or change and all should be included in protection scope of the present invention within.