Disclosure of Invention
The invention provides a double-source CT scattering correction method and system based on a deep learning model, and mainly aims to solve the problem that X-ray scattering exists in actual imaging of the existing double-source CT system.
In order to achieve the above object, the present invention provides a dual-source CT scatter correction method based on a deep learning model, including:
Acquiring head model double-source CT projection data of a preset head model;
Acquiring comprehensive cross scattering signals of the head model double-source CT projection data;
acquiring forward scattering signals of the head model double-source CT projection data by using a preset adaptive scattering kernel superposition algorithm;
training a neural network model by using the head model double-source CT projection data, the comprehensive cross scatter signals and the forward scatter signals to obtain a double-source CT scatter analysis model;
Carrying out scattering signal estimation on pre-acquired target double-source CT projection data by using the double-source CT scattering analysis model to obtain scattering signals;
and subtracting the scattering signal from the target double-source CT projection data to obtain target double-source CT scattering correction data.
Optionally, the acquiring the integrated cross scatter signal of the head phantom dual-source CT projection data includes:
starting a first ray tube of a preset double-source CT system and a preset second detector;
Acquiring a first cross scatter signal of the first tube with the second detector;
closing the first ray tube and the second detector, and opening the second ray tube and the first detector of a preset dual-source CT system;
acquiring a second cross scatter signal of the second tube with the first detector;
And summarizing the first cross heat dissipation signal and the second cross scattering signal to obtain a comprehensive cross scattering signal.
Optionally, the acquiring the forward scattering signal of the head mode dual-source CT projection data by using a preset adaptive scattering kernel stacking algorithm includes:
Simulating scattering signals of different energy levels emitted by the high-voltage bulb tube under different currents and voltages through preset water modes with different lengths by Monte Carlo simulation to obtain a scattering signal set;
fitting the distribution of each scattering signal in the scattering signal set to obtain scattering signal distribution of the ray bundle passing through water modes with different lengths under different energy levels;
Traversing each pixel of the head model double-source CT projection data according to the scattering signal distribution to obtain the scattering distribution of each ray in the head model double-source CT projection data;
And superposing the scattering distribution of each ray in the head model double-source CT projection data to obtain forward scattering signals of the head model double-source CT projection data.
Optionally, the training a neural network model by using the head model dual-source CT projection data, the integrated cross scatter signal and the forward scatter signal to obtain a dual-source CT scatter analysis model includes:
obtaining projection image signals in the head model double-source CT projection data, and carrying out standardization processing on the projection image signals to obtain standardized projection image signals;
Combining the integrated cross scatter signal with the forward scatter signal to obtain a standard scatter signal;
Carrying out scattering signal analysis according to the standardized projection graph signals by utilizing a neural network model to obtain scattering signal estimation;
calculating a loss value of the scattered signal estimate and the standard scattered signal;
optimizing the loss value by updating weight parameters of the neural network model by using a random gradient descent algorithm;
Updating the learning rate of the neural network model by using a preset stepping learning rate algorithm to obtain an updated learning rate;
when the preset iteration times are reached, selecting a weight parameter corresponding to the minimum loss value in all the iteration times as a final weight parameter;
and inputting the updated learning rate and the final weight parameters into a neural network model to obtain a dual-source CT scattering analysis model.
Optionally, the normalizing the projection image signal to obtain a normalized projection image signal includes:
and carrying out standardization processing on the projection image signal by using the following formula to obtain a standardized projection image signal:
Wherein p is the standardized projection map signal, I is the projection map signal, and I 0 is the bright field projection map signal contained in the head model dual source CT projection data.
Optionally, the calculating the loss value of the scattered signal estimate and the standard scattered signal includes:
the loss value is calculated using the following formula:
Wherein S is the loss value, N is the number of pixels of the first detector and the second detector, I s is the standard scatter signal, I m is the scatter signal estimate, and I p is the normalized projection map signal.
Optionally, updating the learning rate of the neural network model by using a preset step learning rate algorithm to obtain an updated learning rate, including:
updating the learning rate using the following formula:
Wherein lr new is the updated learning rate, lr old is the learning rate, K is the current iteration number, and M is the preset iteration number.
Optionally, the estimating the scattering signal of the pre-acquired target dual-source CT projection data by using the dual-source CT scattering analysis model to obtain a corrected scattering signal includes:
moving a convolution kernel preset in a convolution layer of the double-source CT scattering analysis model on the target double-source CT projection data according to a preset step length, calculating dot products of the convolution kernel and data of a convolution kernel coverage area after each movement, and summing all the dot products to obtain convolution characteristics;
Continuously moving a rectangular window in a pooling layer of the dual-source CT scattering analysis model in the convolution characteristic, calculating the average value of data of a region covered by the rectangular window after each movement, and replacing the data of the region with the calculated average value of each region to obtain the pooling characteristic;
Introducing nonlinear factors into the pooling feature by utilizing an activation function preset in an activation layer of the dual-source CT scattering analysis model to obtain an activation feature;
And obtaining the output of each neuron by utilizing the full-connection layer of the dual-source CT scattering analysis model according to the activation characteristics, and summing the output of each neuron to obtain a corrected scattering signal.
Optionally, subtracting the scatter signal from the target dual-source CT projection data to obtain target dual-source CT scatter correction data includes:
And carrying out scattering correction on the target double-source CT projection data by using the following formula:
Wherein I corr is the target dual-source CT scatter correction data, I total is the target dual-source CT projection data, and I scatter,model is the scatter signal.
In order to solve the above problems, the present invention further provides a dual-source CT scatter correction system based on a deep learning model, the system comprising:
the data acquisition module is used for acquiring head model double-source CT projection data of a preset head model and acquiring comprehensive cross scattering signals of the head model double-source CT projection data;
the scattering estimation module is used for acquiring forward scattering signals of the head model double-source CT projection data by using a preset adaptive scattering kernel superposition algorithm;
the model training module is used for training a neural network model by utilizing the head model double-source CT projection data, the comprehensive cross scattering signals and the forward scattering signals to obtain a double-source CT scattering analysis model;
And the scattering correction module is used for carrying out scattering signal estimation on the pre-acquired target double-source CT projection data by utilizing the double-source CT scattering analysis model to obtain scattering signals, and subtracting the scattering signals from the target double-source CT projection data to obtain target double-source CT scattering correction data.
According to the embodiment of the invention, the comprehensive cross scatter signal of the head model double-source CT projection data is obtained by obtaining the head model double-source CT projection data of the preset head model, the forward scatter signal of the head model double-source CT projection data is obtained by utilizing the preset self-adaptive scatter kernel superposition algorithm, the efficiency of training a double-source CT scatter analysis model is improved, the neural network model is trained by utilizing the head model double-source CT projection data, the comprehensive cross scatter signal and the forward scatter signal, the double-source CT scatter analysis model is obtained, the scatter signal is estimated by utilizing the double-source CT scatter analysis model to the pre-obtained target double-source CT projection data, the scatter signal is obtained by utilizing the target double-source CT projection data to subtract the scatter signal, the target double-source CT scatter correction data is obtained, and the efficiency and the accuracy of scatter correction of the double-source CT projection data are improved. Therefore, the double-source CT scattering correction method and system based on the depth learning model can solve the problem that the existing double-source CT system actually images X-ray scattering.
Detailed Description
It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The embodiment of the application provides a double-source CT scattering correction method based on a deep learning model. The execution main body of the double-source CT scattering correction method based on the deep learning model comprises, but is not limited to, at least one of a server, a terminal and the like which can be configured to execute the method provided by the embodiment of the application. In other words, the dual source CT scatter correction method based on the deep learning model may be performed by software or hardware installed in a terminal device or a server device, and the software may be a blockchain platform. The server side comprises, but is not limited to, a single server, a server cluster, a cloud server or a cloud server cluster and the like. The server may be an independent server, or may be a cloud server that provides cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, content delivery networks (Content Delivery Network, CDN), and basic cloud computing services such as big data and artificial intelligence platforms.
Referring to fig. 1, a flow chart of a dual-source CT scatter correction method based on a deep learning model according to an embodiment of the invention is shown. In this embodiment, the dual-source CT scatter correction method based on the deep learning model includes:
S1, head model double-source CT projection data of a preset head model are obtained.
In the embodiment of the invention, the dual-source CT projection data is projection data obtained by utilizing a dual-source CT system, the dual-source CT system respectively obtains high-energy and low-energy projection attenuation information of an object under various angles by using X-rays with two energies or energy spectrums in a CT scanning process, and then obtains a distribution diagram about the atomic number and electron density of the imaged object by utilizing a dual-source CT image reconstruction algorithm according to the relation between the linear attenuation coefficient of the substance about the X-rays and the ray energy, the atomic number and density of the substance.
In detail, the dual source CT system includes a first tube, a second tube, a first detector, and a second detector.
In detail, the first detector user receives the signal of the first tube and the second detector user receives the signal of the second tube.
In the embodiment of the invention, the head model is a preset head model used for simulating the head of a patient in an actual use situation.
In the embodiment of the invention, the head model dual-source CT projection data of the preset head model is obtained by utilizing the first detector to receive a ray signal that rays emitted by the first ray tube pass through the head model, and utilizing the second detector to receive a ray signal that rays emitted by the first ray tube pass through the head model, and utilizing a dual-source CT image reconstruction algorithm to construct the head model dual-source CT projection data according to two groups of ray signals.
In the embodiment of the invention, the efficiency of subsequently establishing the double-source CT scattering analysis model is improved by acquiring the head model double-source CT projection data of the preset head model.
S2, acquiring comprehensive cross scattering signals of the head model double-source CT projection data.
In the embodiment of the invention, the comprehensive cross scattering signal refers to that in a dual-source CT system, because two ray tubes simultaneously emit X-rays, the rays may cross when passing through a human body, so as to generate the comprehensive cross scattering signal, and the comprehensive cross scattering signal increases noise of an image and reduces definition of the image.
In an embodiment of the present invention, referring to fig. 2, a flowchart of acquiring a comprehensive cross scatter signal is provided for an embodiment of the present invention, where the acquiring the comprehensive cross scatter signal of the head model dual-source CT projection data includes:
S21, starting a first ray tube of a preset dual-source CT system and a preset second detector;
s22, acquiring a first cross scattering signal of the first ray tube by using the second detector;
S23, closing the first ray tube and the second detector, and opening the second ray tube and the first detector of a preset dual-source CT system;
s24, acquiring a second cross scattering signal of the second ray tube by using the first detector;
And S25, summarizing the first cross heat dissipation signal and the second cross scattering signal to obtain a comprehensive cross scattering signal.
In detail, since the second detector is located at the side of the first tube and the first detector is located at the side of the second tube, the first tube and the second detector can be turned on separately, and the second tube and the first detector can be turned on separately, so that a real scattering signal can be obtained.
In the embodiment of the invention, the efficiency of the subsequent training of the double-source CT scattering analysis model is improved by acquiring the comprehensive cross scattering signal of the head model double-source CT projection data.
S3, acquiring forward scattering signals of the head model double-source CT projection data by using a preset self-adaptive scattering kernel superposition algorithm.
In the embodiment of the invention, the forward scattering signal refers to that when the X-ray passes through the inside of human tissue, the X-ray is deviated due to different substances, so that the forward scattering signal is generated.
In the embodiment of the invention, the adaptive scattering kernel superposition algorithm is a technology used for image processing and computer vision, and is particularly used in image segmentation, feature extraction and pattern recognition. Such algorithms enhance the local features of the image by decomposing the image into different scattering components and improve the accuracy of the image analysis.
In an embodiment of the present invention, referring to fig. 3, a schematic flow chart for acquiring a forward scattering signal is provided in an embodiment of the present invention, where the acquiring a forward scattering signal of the head mode dual-source CT projection data by using a preset adaptive scattering kernel superposition algorithm includes:
S31, simulating scattering signals of different energy levels emitted by the high-voltage bulb tube under different currents and voltages through a preset water model with different lengths by Monte Carlo simulation to obtain a scattering signal set;
S32, fitting the distribution of each scattering signal in the scattering signal set to obtain scattering signal distribution of the ray bundle passing through water modes with different lengths under different energy levels;
S33, traversing each pixel of the head model double-source CT projection data according to the scattering signal distribution to obtain the scattering distribution of each ray in the head model double-source CT projection data;
s34, superposing scattering distribution of each ray in the head model double-source CT projection data to obtain forward scattering signals of the head model double-source CT projection data.
In detail, the monte carlo simulation is a random sampling or statistical simulation based method that estimates a numerical solution or probability distribution of a complex problem by repeatedly generating random samples and calculating statistics.
In detail, simulating the scattering signals of the beams of different energy levels emitted by the high-voltage bulb tube under different currents and voltages passing through the preset water modes with different lengths through Monte Carlo simulation means that random current values and voltage values are generated through Monte Carlo simulation, the beams of different energy levels are generated according to the randomly generated current values and voltage values, and the scattering signals of the beams of different energy levels passing through the water modes with different lengths are obtained.
In the embodiment of the invention, the forward scattering signal of the head model double-source CT projection data is obtained by utilizing the preset self-adaptive scattering kernel superposition algorithm, so that the accuracy of the obtained forward scattering signal is improved, and the accuracy of a subsequently established double-source CT scattering analysis model is improved.
And S4, training a neural network model by using the head model double-source CT projection data, the comprehensive cross scattering signals and the forward scattering signals to obtain a double-source CT scattering analysis model.
In the embodiment of the invention, the head model dual-source CT projection data is a data set containing continuous frame projection map information.
In the embodiment of the present invention, the training of the neural network model by using the head-mode dual-source CT projection data, the integrated cross scatter signal, and the forward scatter signal refers to training the neural network model by using the head-mode dual-source CT projection data as training data, and using the integrated cross scatter signal and the forward scatter signal as labels.
In an embodiment of the present invention, the neural network model includes, but is not limited to, a convolutional neural network model and a recurrent neural network model.
In the embodiment of the present invention, training a neural network model by using the head model dual-source CT projection data, the integrated cross scatter signal and the forward scatter signal to obtain a dual-source CT scatter analysis model includes:
obtaining projection image signals in the head model double-source CT projection data, and carrying out standardization processing on the projection image signals to obtain standardized projection image signals;
Combining the integrated cross scatter signal with the forward scatter signal to obtain a standard scatter signal;
Carrying out scattering signal analysis according to the standardized projection graph signals by utilizing a neural network model to obtain scattering signal estimation;
calculating a loss value of the scattered signal estimate and the standard scattered signal;
optimizing the loss value by updating weight parameters of the neural network model by using a random gradient descent algorithm;
Updating the learning rate of the neural network model by using a preset stepping learning rate algorithm to obtain an updated learning rate;
when the preset iteration times are reached, selecting a weight parameter corresponding to the minimum loss value in all the iteration times as a final weight parameter;
and inputting the updated learning rate and the final weight parameters into a neural network model to obtain a dual-source CT scattering analysis model.
In detail, the normalizing the projection image signal to obtain a normalized projection image signal includes:
and carrying out standardization processing on the projection image signal by using the following formula to obtain a standardized projection image signal:
Wherein p is the standardized projection map signal, I is the projection map signal, and I 0 is the bright field projection map signal contained in the head model dual source CT projection data.
In detail, the bright-field projection image signal refers to an X-ray image without attenuation in CT imaging, that is, an image obtained assuming that all X-rays are not absorbed or scattered;
In detail, the calculating the loss value of the scattered signal estimate and the standard scattered signal comprises:
the loss value is calculated using the following formula:
Wherein S is the loss value, N is the number of pixels of the first detector and the second detector, I s is the standard scatter signal, I m is the scatter signal estimate, and I p is the normalized projection map signal.
In detail, the random gradient descent algorithm is used for updating the weight parameters of the neural network model by updating the preset weight parameters through preset weight attenuation coefficients. The preset weight decay factor may be 0.0001 and the preset weight parameter may be 0.9.
In detail, the updating the learning rate of the neural network model by using a preset step learning rate algorithm to obtain an updated learning rate includes:
updating the learning rate using the following formula:
Wherein lr new is the updated learning rate, lr old is the learning rate, K is the current iteration number, and M is the preset iteration number.
In detail, the preset number of iterations may be 300.
In an embodiment of the present invention, the weight parameters are variables of the connected neurons in the neural network model, which determine the strength of interactions between the neurons.
In the embodiment of the invention, the learning rate is an important super-parameter in the training process of the neural network model, and controls the step size of the model to be adjusted during each weight update.
In the embodiment of the invention, before training the dual-source CT scattering analysis model to reach the preset iteration times, if the loss value is smaller than the preset loss value threshold, the dual-source CT scattering analysis model is directly confirmed to be trained, and the dual-source CT scattering analysis model is prevented from being overfitted.
In the embodiment of the invention, the neural network model is trained by utilizing the head model double-source CT projection data, the comprehensive cross scattering signals and the forward scattering signals to obtain the double-source CT scattering analysis model, so that the efficiency of training the double-source CT scattering analysis model is improved.
S5, utilizing the double-source CT scattering analysis model to conduct scattering signal estimation on the pre-acquired target double-source CT projection data, and obtaining corrected scattering signals.
In the embodiment of the present invention, the pre-acquired target dual-source CT projection data may be real dual-source CT data of the patient acquired by using the dual-source CT system in an actual medical work.
In the embodiment of the present invention, the performing scattering signal estimation on pre-acquired target dual-source CT projection data by using the dual-source CT scattering analysis model to obtain corrected scattering signals includes:
moving a convolution kernel preset in a convolution layer of the double-source CT scattering analysis model on the target double-source CT projection data according to a preset step length, calculating dot products of the convolution kernel and data of a convolution kernel coverage area after each movement, and summing all the dot products to obtain convolution characteristics;
Continuously moving a rectangular window in a pooling layer of the dual-source CT scattering analysis model in the convolution characteristic, calculating the average value of data of a region covered by the rectangular window after each movement, and replacing the data of the region with the calculated average value of each region to obtain the pooling characteristic;
Introducing nonlinear factors into the pooling feature by utilizing an activation function preset in an activation layer of the dual-source CT scattering analysis model to obtain an activation feature;
And obtaining the output of each neuron by utilizing the full-connection layer of the dual-source CT scattering analysis model according to the activation characteristics, and summing the output of each neuron to obtain a corrected scattering signal.
In detail, the convolution kernel is a preset square matrix whose scale is much smaller than the target dual-source CT projection data.
In detail, the preset step size determines the amplitude of each movement of the convolution kernel, and the longer step size is, the higher the efficiency of extracting convolution characteristics is, but the information is lost, and the too short step size increases the calculation amount.
In detail, the activation function is a function added to the nodes between the neural network model layers for introducing nonlinear factors, so that the neural network model can learn and process complex problems. Common activation functions include Sigmoid functions, softmax functions, and ReLU functions.
In the embodiment of the invention, the scattering signal is estimated by utilizing the double-source CT scattering analysis model to pre-obtain the target double-source CT projection data, so that the corrected scattering signal is obtained, and the efficiency and accuracy of correcting the double-source CT signal are improved.
And S6, subtracting the corrected scattering signal from the target double-source CT projection data to obtain target double-source CT scattering correction data.
In an embodiment of the present invention, the corrected scatter signal includes a composite cross scatter signal and a forward scatter signal.
In the embodiment of the present invention, subtracting the scatter signal from the target dual-source CT projection data to obtain target dual-source CT scatter correction data includes:
And carrying out scattering correction on the target double-source CT projection data by using the following formula:
Wherein I corr is the target dual-source CT scatter correction data, I total is the target dual-source CT projection data, and I scatter,model is the scatter signal.
In the embodiment of the invention, the correction scattering signal is subtracted by utilizing the target double-source CT projection data to obtain the target double-source CT scattering correction data, so that the correction efficiency of the double-source CT projection data is improved.
FIG. 4 is a functional block diagram of a dual source CT scatter correction system based on a deep learning model according to an embodiment of the present invention.
The dual-source CT scatter correction system 100 based on the deep learning model of the present invention may be installed in an electronic device. Depending on the functionality implemented, the deep learning model-based dual source CT scatter correction system 100 may include a data acquisition module 101, a scatter prediction module 102, a model training module 103, and a scatter correction module 104. The module of the invention, which may also be referred to as a unit, refers to a series of computer program segments, which are stored in the memory of the electronic device, capable of being executed by the processor of the electronic device and of performing a fixed function.
In the present embodiment, the functions concerning the respective modules/units are as follows:
The data acquisition module 101 is configured to acquire head model dual-source CT projection data of a preset head model, and acquire a comprehensive cross scatter signal of the head model dual-source CT projection data;
The scattering estimation module 102 is configured to obtain forward scattering signals of the head-mode dual-source CT projection data by using a preset adaptive scattering kernel superposition algorithm;
the model training module 103 is configured to train a neural network model by using the head model dual-source CT projection data, the integrated cross scatter signal, and the forward scatter signal, to obtain a dual-source CT scatter analysis model;
the scatter correction module 104 is configured to perform scatter signal estimation on pre-acquired target dual-source CT projection data by using the dual-source CT scatter analysis model to obtain a scatter signal, and subtract the scatter signal from the target dual-source CT projection data to obtain target dual-source CT scatter correction data.
In detail, each module in the deep learning model-based dual-source CT scatter correction system 100 in the embodiment of the present invention adopts the same technical means as the deep learning model-based dual-source CT scatter correction method described in fig. 1 to 3, and can produce the same technical effects, which are not described herein.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus, system and method may be implemented in other manners. For example, the system embodiments described above are merely illustrative, e.g., the division of the modules is merely a logical function division, and other manners of division may be implemented in practice.
The modules described as separate components may or may not be physically separate, and components shown as modules may or may not be physical units, may be located in one place, or may be distributed over multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional module in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units can be realized in a form of hardware or a form of hardware and a form of software functional modules.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.
The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference signs in the claims shall not be construed as limiting the claim concerned.
The embodiment of the application can acquire and process the related data based on the artificial intelligence technology. Wherein artificial intelligence (ARTIFICIAL INTELLIGENCE, AI) is the theory, method, technique, and application system that uses a digital computer or a digital computer-controlled machine to simulate, extend, and expand human intelligence, sense the environment, acquire knowledge, and use knowledge to obtain optimal results.
Furthermore, it is evident that the word "comprising" does not exclude other elements or steps, and that the singular does not exclude a plurality. A plurality of units or means recited in the system claims can also be implemented by means of software or hardware by means of one unit or means. The terms first, second, etc. are used to denote a name, but not any particular order.
Finally, it should be noted that the above-mentioned embodiments are merely for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.