Development and Performance Evaluation of a Deep Learning Lung Nodule Detection System

Background: Lung cancer is the leading cause of cancer-related deaths throughout the world. In screening and diagnosis of lung cancer, chest computed tomography (CT) is now widely used due to its effectiveness. Radiologists need to identify each small nodule shadow from 3D volume images, which is very burdensome and often results in missed nodules. To address these challenges, we developed a Computer-Aided Detection (CAD) system that automatically detects lung nodules in CT images. Methods: A total of 1,997 chest CT images were collected for algorithm development. The algorithm was designed using deep learning technology. In addition to evaluating detection performance on various public datasets, its robustness to changes in radiation dose was assessed by a phantom study. To investigate the clinical usefulness of the CAD system, a reader study was conducted with 10 doctors, including inexperienced and expert readers. In this study, whether using the CAD as a second reader would prevent nodular lesions in lungs that require follow-up examinations from being overlooked was investigated. Analysis was performed using the Jackknife Free-Response Receiver-Operating Characteristic (JAFROC). Results: The CAD system achieved sensitivity of 0.98/0.96 at 3.1/7.25 false positives per case on two public datasets. Sensitivity did not change within the range of practical doses for a study using a phantom. A second reader study showed that the use of this system significantly improved the detection ability of nodules that could be picked up clinically (p = 0.026). Conclusions: A deep learning-based CAD system that is robust to imaging conditions was developed, and it was found that using this system as a second reader increases detection performance.