Radiography image analysis using cat swarm optimized deep belief networks

: Radiography images are widely utilized in the health sector to recognize the patient health condition. The noise and irrelevant region information minimize the entire disease detection accuracy and computation complexity. Therefore, in this study, statistical Kolmogorov – Smirnov test has been inte - grated with wavelet transform to overcome the de - noising issues. Then the cat swarm - optimized deep belief network is applied to extract the features from the a ﬀ ected region. The optimized deep learning model reduces the feature training cost and time and improves the overall disease detection accuracy. The network learning process is enhanced according to the AdaDelta learning process, which replaces the learning parameter with a delta value. This process minimizes the error rate while recognizing the disease. The e ﬃ ciency of the system evaluated using image retrieval in medical application dataset. This process helps to determine the various diseases such as breast, lung,

The manuscript is arranged as follows: Section 2 discusses the different research works and analyses the medical radiographic images; Section 3 explains the working process of the optimized DL model for retrieving the clinical patterns; Section 4 evaluates the excellence of the introduced system; and Section 5 defines the conclusion.

Related works
Pandya et al. [23] applied DL techniques for analyzing medical images and detecting diseases. This process uses the medical images (computerized tomography (CT), magnetic resonance imaging (MRI), etc.), biomedical signaling (electrocardiogram, electroencephalogram, and omics (DNA, RNA, etc.) to examine the clinical diseases. The captured medical images are processed by different DL models such as deep belief networks (DBNs), long short-term memory, stacked autoencoder, convolution networks, and recurrent networks. In addition to this, deep hybridized approaches such as multidimensional recurrent networks, deep spatiotemporal networks, and recurrent bidirectional networks classify the diseases from the medical images. Thus, the different DL model ensures promising results while analyzing the medical images with a minimum error rate and human efforts.
Debelee et al. [24] created the breast cancer medical images analyzing system using a deep learning approach (DLA). This process obtains the breast images via the magnetic resonance imaging, digital mammography, ultrasound, and breast tomosynthesis. The gathered medical images are processed using the DL model that predicts the breast cancer patterns with minimum involvement of domain experts.
Wuestemann et al. [25] examined the bone scans to diagnose the tumor entities by applying the DLbased neural network algorithm. This study uses the bone scan imaging (BSI) index values to examine the bone radiographic images. The prostate, lung, breast, and hepatocellular carcinoma cancer entities are examined using DL model from the BSI values. This process helps to minimize the working load also to improve the workflow process in the medical department.
Rehman et al. [26] implemented the brain tumor detection system using the transfer learning with deep learning framework (TLDLF), which uses three convolution networks such as VGGNet, GooglLeNet, and AlexNet for analyzing the various brain tumors such as pituitary, glioma, and meningioma. During the analysis, MRI images are examined with the help of freeze and fine-tune transfer learning process. Data augmentation techniques are applied to generalize the MRI slice image, which helps minimize data overfitting and enhance overall brain tumor recognition accuracy.
Sharma et al. [27] segmented brain tumor-affected region from MRI images using the different evaluations with the OTSU method and neural networks. Initially, in the MRI image, global threshold values are estimated to recognize the tumor-affected region. The optimal threshold value is selected according to the introduced algorithm. This process is continuously trained using neural networks, which effectively minimizes the error rate.
Abid et al. [28] identified lung cancer nodules from CT images using multiview convolution recurrent neural networks (MCRNN). This system is used to resolve the cost-intensive and inconsistent results while recognizing lung cancer nodules. The introduced method utilizes the effective learning process, which examines the image size, shape, and cross-slice variations that improve the accuracy of lung cancer identification. The system's performance was evaluated using Lung Image Database Consortium and Image database resource initiative database with the respective performance metrics.
Azizi et al. [29] examined temporal-enhanced ultrasound images for detecting prostate cancer using deep recurrent neural networks (DRNN). The introduced DRNN approach is analyzing the temporal details from ultrasound images. The extracted information is further investigated with long-term neural networks recognizing the benign and malignant with higher accuracy.
Masud et al. [30] diagnosed breast cancer from ultrasound images using convolution neural networks (CNN). Initially, the ultrasound images are trained by eight different fine-tune models that help to identify the test images related to clinical results. This process utilizes the 10-fold cross-validation process to evaluate the excellence of the system. In addition to this, various research studies are summarized in Table 1. According to the above research studies, DL techniques are widely utilized in the medical field to recognize various clinical diseases. The DL models with effective learning techniques and activation functions to identify the disease-affected region. The DL model requires the optimization process to improve the overall clinical analysis process by reducing the cost, labor intensive, and computation complexity. Moreover, the captured radiographic images are having several noises while gathering the images. Then, the de-noising process also played a crucial role while investing the medical images. So, in this article, we applied the optimized techniques to examine the different radiographic images. The detailed working process of cat swarm-optimized DBNs-based radiography image analysis is discussed in the following section.

Radiography image analysis using optimized DBNs
The detailed working process of optimized DBN-based radiography image analysis is explained in this section. The system aims to increase the radiography image analysis accuracy by reducing the time, error rate, and computation complexity. This process uses different steps such as image noise removal, segmentation, feature extraction, and classification process. According to the discussion, the working process is shown in Figure 2.
Radiography image analysis structure is demonstrated in Figure 2. This system uses the two phases: training and testing; each stage has image preprocessing, segmentation, feature extraction, and classification processes. The training phases use effective learning functions while deriving the medical features and classification process. During the training process, labels are provided and stored in the database. With the help of training images, testing has to be performed to identify the new image patterns. The detailed working process of radiography image analysis is discussed in the following section.

Medical image preprocessing
Preprocessing is nothing but improving the image's quality by applying statistical analysis in a comparable and repeatable manner [1,2]. In medical image processing, the noise removal process consists of resampling, intensity normalization, and co-registration methods. These processes are more helpful to improve further radiographic image analysis. The co-registration is the way of mapping the images with respective reference coordinate system; resampling is performing the voxel size of images with the unique voxel resolution. Therefore, the collected radiographic images are resized into 160 × 160 dimension, and the one-row matrix need to be reshaped.
Further, the complexity of the original images has to be reduced by applying the single-level discrete twodimensional wavelet transform approach, which examines the highly discriminative coefficient values from the medical images; the best coefficient values are selected according to the statistical KSt. Initially, the wavelet transform is applied to the image for reducing the dimensionality of the images by examining the image pixel density value. The density values are derived by using high and low pass filters. Here, Haar wavelet function is applied to the image because of the orthogonality property, which effectively examines the image wavelet coefficients. Considering the mother Haar wavelet function is ( ) φ x that is defined by equation (1).
In equation (1) . Then, the elements presented in the orthogonal basis values are computed using equation (2).
Based on equations (1 and 2), image intensity corresponding coefficient values are computed, and coefficient values are estimated. Then best coefficient values are selected according to the statistical KSt. It is one of the nonparametric tests comparing the two coefficients values from the extracted image coefficient values. This section process is performed according to the location and shape of pixels and cumulative distribution value. Then the empirical distribution function ( ) F n is computed from the distributed observations X i , which is computed using equation (3).
In equation (3), n is independent; the indicator function is denoted as I. From the computed ( ) F x n value, KSt is examined using equation (4).
In equation (4), the supremum of set distance is denoted as sup x . From the computed distance D n value, the KSt samples are analyzed using equation (5).
According to the KSt test similarity values, each pixel was examined with the alternative and null hypothesis. If the pixel has an H0 (null) hypothesis, then both pixels have the same distribution, and there is no need to replace or remove the pixel. If the pixel belongs to the alternative (H1) hypothesis, then pixel has a different population that needs to be removed from the image and replaced by using a median value. After removing the medical image's noise, the disease-affected region must be extracted according to the Prewitt kernel operator.

Region of interest (ROI) region segmentation
The next step is to extract the disease-affected region by applying the Prewitt kernel operator. This process examines the medical image regions by investigating the image edge-related features. The medical image edge features are placed a crucial role while predicting the disease-affected region. This process works similar to the Sobel operator, which means it uses the 3 × 3 kernel. With the kernel details, image left-right adjustment points and upper-lower limit pixels are estimated to identify the edge relevant information. This process eliminates the edge information and smoothens the edge information, which causes to improve the overall ROI segmentation process. Here, the edges are investigated according to the horizontal and vertical direction. Therefore, the horizontal  (6).
From the computed magnitude orientation, the edge gradient direction value should be estimated according to equations (7 and 8).
The computed edge gradient direction value, derivatives of gradient, and vector gradient values are estimated as δ . This has been written as Finally, the computed values are examined to predict the gradient direction ( ) According to the Prewitt kernel values, image edge-relevant details are extracted. Similar edge information is grouped. This Prewitt kernel extracted process is applied continuously to the images for extracting the affected regions.

DBN-based feature derivation
The third important step is feature extraction, which is done by applying the cat swarm optimization algorithm-based deep belief network (CSA-DBN). The extracted edge regions are fed as the input to this process, and the meaningful features are derived. The DBN approach works according to the multilayer restricted Boltzmann machine (RBN) approach that extracts the in-depth image features. During this process, the input data and first hidden layers related to the probability distribution value are estimated in the visible layer computed via equation (10).
The joint probability distribution ( ) − h h , n n 1 between visible and hidden layer values is computed from the RBN model's topmost layer. The RBN has two layers: a visible or input layer and a hidden layer, as shown in Figure 3. The RBN has the connection between the entire visible layer and hidden layer but having no connection within the layer and no connection between the invisible and visible layers. Then the probability distribution of hidden and visible layers is defined as ( ) p v h , here; input image features are obtained from the output layer h. According to the discussion, ( ) p v h , is estimated using equation (11a) and (11b).
The ( ) p v h , value is estimated from the network energy function ( ) E v h , and the normalization factor ( ) Z θ , which are derived from equation (11c) and (11d).
Here, h and v denoted as hidden and visible layer units, visible and hidden layer connections are having W weight, ′ c is the hidden layer bias value, and ′ b is the visible layer bias value. After computing the ( ) p v h , value, the network needs to be trained according to the learning parameters such as weight (W) and a bias value. Initially, the RBM network first layer was trained by fixed training parameters, and the output is passed to the next layer (hidden layer) to predict the image features. The last layer of the network utilizes the SoftMax regression function with supervised gradient descent algorithm. According to RBM algorithm, the training process is performed that helps to investigate the new medical images. In the training process, input samples are analyzed by computing the ( ) p v h , value and contrast divergence value of learning parameter that is calculated as follows: Here, W is weight value, the learning rate of contrast divergence process is denoted as ε, and x x , 1 2 is denoted as the input vectors in the training process. The computed values belong to 1. The samples are trained effectively; the learning parameters should be converged. It has to be updated to improve the overall image training process. In the testing process, the last layer's output is fed into the SoftMax regression function to estimate the image's features. During the input vector training process, AdaDelta learning process is utilized to minimize the convergence value. It is worked according to the squared delta's exponential moving average value. The new weight value is estimated by taking the difference between the newly updated weight value and current value. Therefore, the learning parameter values are replaced by the computed delta value. Then the new weight value is estimated using equation (15).
. After computing the AdaDelta value, the RBM network trained again to improve the system's overall performance. Further, the current weight value detection process should be enhanced by applying the cat swarm optimization algorithm (CSA). The CSA algorithm works better than other optimization algorithms and can resolve the optimization problem during input training and classification. This algorithm works according to food searching behavior of cat, such as seeking and tracing mode. Initially, the cat investigates the surroundings and passes to the next position in the seeking mode. In the tracing process mode, the cat chases a specific target by identifying the location. The cat identifies the global solution in the seeking mode and the local solution in the tracking mode from the searching process. The cat has the seeking memory pool, mixed ratio, and dimension change count parameters during the searching process.
In this process, the fitness value is computed for entire candidate points, and the most relevant probability values are chosen as the fitness value. Else, the seeking and tracking probability value is calculated to select the candidate value, which is done by equation (16).
The seeking mode probability value P k is computed from the fitness value, and the velocity of the cat chasing process is estimated in tracking mode using equation (17).
Here, d is the dimension, and position of the prey or weight value is estimated as , . Inertia weight values are denoted as β, the constant acceleration value is c, and r 1 represented as the random value from 0 to 1. The present and global positions are indicated, respectively, as x k d , and x d best, . This process is repeated every time during the image analysis because the right selection and updating of weight value minimize the deviations while extracting features from the image. Then the overall working process of CSA-DBN-based image feature extraction process is illustrated in Figure 4. Figure 4 shows that the region segmented image pixels are transmitted as the input represented as T1, T2, T3 … Tn. The network processes the input pixels, and the output is obtained as The computed output features are compared with the desired characteristics for investigating the error value done according to equation (19).
If the network produces the error value, then the optimized weight values are selected according to the CSA optimization algorithm process. The algorithm fitness value is estimated using equation (20).
The new velocity is computed using equation (17), and the latest weight value is calculated based on the fitness function. The identified weight values are compared with the current weight value defined in equation (15), and the delta value is used to update the process. This process is repeated until the optimized features from the medical images are extracted. The extracted features are further examined by optimized classifiers such as DL techniques or other classifiers to recognize the affected region's condition. This process effectively identifies the radiographic image's deviation due to the effective examination of each image pixel.

Results and discussion
This section examines the effectiveness of the CSA-DBN-based radiographic image analysis process. The discussed system uses the Medical Segmentation Decathlon dataset for evaluating the proficiency of a defined system. The dataset consists of several radiographic images like hepatic vessel, prostate, liver, heart, brain tumor, spleen, pancreas, and colon. For every medical image, the massive number of radiographic details is illustrated in Table 2. These medical images' segmented regions are investigated pixel by pixel in CSA-DBN algorithm for extracting the optimized features. The derived features are utilized to further image analysis by various  postimage processing techniques. The efficiency of the created system is determined using the following performance metrics: Accuracy rate: Precision rate: F-score: In equations (21), (22), and (23), TrNe represents the true-negative rate, TrPo represents the true-positive rate, FaPo indicates a false-positive rate, and the FaNe indicates a false-negative rate.
The medical image's features are examined effectively from the computation of accuracy in equation (21). The CSA-DBN technique obtained results are compared with the existing research studies such as a DLA [24], TLDLF [26], MCRNN [28], and DRNN [30]. The obtained feature extraction accuracy (Acc) value is shown in Figure 5.  introduced CSA-DBN approach derives the disease-related features from the Prewitt kernel-based segmented region. In addition to these metrics, the presented method's precision value should be examined on the different number of images and another type of medical images. The obtained results are illustrated in Figure 6.    Here, the recall values are investigated in terms of the different number of images and the various medical images. The diseaserelated optimized features are selected from the extracted features according to the CSA seeking and tracking mode. The algorithm determines the best features by computing the fitness value-related weight-updating process. Hence, the introduced CSA-DBN approach ensures the high recall (99.41%) value collated with existing methods such as DLA (95.93%), TLDLF (96.23%), MCRNN (97.01%), and DRNN (98.25%). Due to the effective retrieval and selection of features, improves the overall image feature extraction process. Then the obtained F1-score values are illustrated in Table 3. Table 3 clearly shows that the CSA-DBN obtained high feature extraction accuracy (99.32%) compared to existing researchers works DLA (96.48%), TLDLF (97%), MCRNN (97.65%), and DRNN (98.20%). Although these methods attain high accuracy values, the introduced CSA-DBN approach has a minimum deviation value, which means the extracted features are almost the same as the desired image features. This effectiveness is evaluated using the error rate value. The obtained result is illustrated in Figure 8. , which causes to minimize the deviation between predicted and desired image features. Among the several approaches, CSA-DBN attains the minimum error value (0.11) compared to other methods. Thus, the introduced system successfully recognizes the disease-affected region-related features using optimized learning and training parameters.

Conclusion
Thus, the study analyzes the CSA-DBN-based radiographic image analysis process. In this study, the Medical Segmentation Decathlon dataset was utilized for gathering the medical images. The images are decomposed into approximation and detailed coefficient, which helps remove the noise from the image. Then the KSt test has been conducted to determine the similarity between the pixels. According to the value, the deviated pixels are computed and removed from the image. Then the Prewitt kernel operators are applied to identify the disease-affected region fed into the DBN. The DBN approach recognizes image features by utilizing the AdaDelta learning process. Further, the network process improved by updating the new weight value computed according to the cat swarm optimization technique's seeking and tracking mode. This effective process minimizes the deviation and enhances the feature detection accuracy up to 99.32%. In the future, the excellence of the system is enhanced by using meta-heuristic optimization algorithm based postradiographic image analysis.