Inclusion Criteria:  Participants with the clinical diagnosis of lung cancer, pulmonary tuberculosis, and COVID-19. Participants that have signed informed consent. Participants >= 18 years old and < 90 years old. Participants with detailed electronic medical records, image records, pathological records, multi-omics information, and other important clinical diagnostic information. Healthy participants with no clinical diagnosis of lung cancer, pulmonary tuberculosis, and COVID-19.  Exclusion Criteria:  Participants < 18 years old. Participants with primary clinical and pathological data missing. Participants lost to follow-up. Participants with too poor medical image quality to perform segment and mark ROI accurately.