1. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University Boramae Medical Center, Seoul Metropolitan Government, Seoul, Republic of Korea
2. Department of Respiratory Medicine, Konkuk University Hospital, Seoul, Republic of Korea
3. Department of Radiology, Seoul National University College of Medicine, Seoul, Republic of Korea
4. Center for Lung Cancer, National Cancer Center, Goyang, Gyeonggi-do, Republic of Korea
5. Division of Pulmonary and Critical Care Medicine and Lung Institute, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
6. Department of Social and Preventive Medicine, School of Medicine, Inha University, Inchon, Republic of Korea