Improved deep convolutional neural networks using chimp optimization algorithm for Covid19 diagnosis from the X-ray images

Abstract

Applying Deep Learning (DL) in radiological images (i.e., chest X-rays) is emerging because of the necessity of having accurate and fast COVID-19 detectors. Deep Convolutional Neural Networks (DCNN) have been typically used as robust COVID-19 positive case detectors in these approaches. Such DCCNs tend to utilize Gradient Descent-Based (GDB) algorithms as the last fully-connected layers' trainers. Although GDB training algorithms have simple structures and fast convergence rates for cases with large training samples, they suffer from the manual tuning of numerous parameters, getting stuck in local minima, large training samples set requirements, and inherently sequential procedures. It is exceedingly challenging to parallelize them with Graphics Processing Units (GPU). Consequently, the Chimp Optimization Algorithm (ChOA) is presented for training the DCNN's fully connected layers in light of the scarcity of a big COVID-19 training dataset and for the purpose of developing a fast COVID-19 detector with the capability of parallel implementation. In addition, two publicly accessible datasets termed COVID-Xray-5 k and COVIDetectioNet are used to benchmark the proposed detector known as DCCN-Chimp. In order to make a fair comparison, two structures are proposed: i-6c-2 s-12c-2 s and i-8c-2 s-16c-2 s, all of which have had their hyperparameters fine-tuned. The outcomes are evaluated in comparison to standard DCNN, Hybrid DCNN plus Genetic Algorithm (DCNN-GA), and Matched Subspace classifier with Adaptive Dictionaries (MSAD). Due to the large variation in results, we employ a weighted average of the ensemble of ten trained DCNN-ChOA, with the validation accuracy of the weights being used to determine the final weights. The validation accuracy for the mixed ensemble DCNN-ChOA is 99.11%. LeNet-5 DCNN's ensemble detection accuracy on COVID-19 is 84.58%. Comparatively, the suggested DCNN-ChOA yields over 99.11% accurate detection with a false alarm rate of less than 0.89%. The outcomes show that the DCCN-Chimp can deliver noticeably superior results than the comparable detectors. The Class Activation Map (CAM) is another tool used in this study to identify probable COVID-19-infected areas. Results show that highlighted regions are completely connected with clinical outcomes, which has been verified by experts.

Keywords: COVID-19 diagnosis; Chest X-rays; Chimp Optimization Algorithm; Convolutional neural networks; Deep learning; Machine learning.

Fig. 1

Typical Chest X-ray images, showing ground-glass opacification (blue rectangles) as well as lobar and patchy consolidation (red ellipses).

Fig. 2

Allocating the parameters of DCNN as the chimps (candid solutions) of ChOA.

Fig. 3

The flowchart for the DCNN-ChOA.

Fig. 4

Precision-recall and ROC curves.

Fig. 5

Accuracy and STD for the i-2 s-6c-2 s-12c structure.

Fig. 6

Computation time for the i-2 s-6c-2 s-12c structure.

Fig. 7

Accuracy and STD for the i-2 s-8c-2 s-16c structure.

Fig. 8

Computation time for the i-2 s-8c-2 s-16c structure.

Fig. 9

An illustration of a feature map, (a) COVID19 and (b) Non-COVID19.

Fig. 10

Typical example of masked images.

Fig. 11

The CAM demonstration for COVID19.

Fig. 12

The CAM demonstration for Non-COVID19.