Pulmonary Nodule Recognition Based on Multiple Kernel Learning Support Vector Machine-PSO

Pulmonary nodule recognition is the core module of lung CAD. Te Support Vector Machine (SVM) algorithm has been widely used in pulmonary nodule recognition, and the algorithm of Multiple Kernel Learning Support Vector Machine (MKL-SVM) has achieved good results therein. Based on grid search, however, the MKL-SVM algorithm needs long optimization time in course of parameter optimization; also its identifcation accuracy depends on the fneness of grid. In the paper, swarm intelligence is introduced and the Particle Swarm Optimization (PSO) is combined with MKL-SVM algorithm to be MKL-SVM-PSO algorithm so as to realize global optimization of parameters rapidly. In order to obtain the global optimal solution, diferent inertia weights such as constant inertia weight, linear inertia weight, and nonlinear inertia weight are applied to pulmonary nodules recognition. Te experimental results show that the model training time of the proposed MKL-SVM-PSO algorithm is only 1/7 of the training time of the MKL-SVM grid search algorithm, achieving better recognition efect. Moreover, Euclidean norm of normalized error vector is proposed to measure the proximity between the average ftness curve and the optimal ftness curve afer convergence. Trough statistical analysis of the average of 20 times operation results with diferent inertial weights, it can be seen that the dynamic inertial weight is superior to the constant inertia weight in the MKL-SVM-PSO algorithm. In the dynamic inertial weight algorithm, the parameter optimization time of nonlinear inertia weight is shorter; the average ftness value afer convergence is much closer to the optimal ftness value, which is better than the linear inertial weight. Besides, a better nonlinear inertial weight is verifed.