Differentiation of Benign and Malignant Pulmonary Nodules by Volatile Organic Compounds in Human Exhaled Breath

Inclusion Criteria: * 18-80 years old; * Pulmonary nodules were detected through low-dose spiral CT, chest CT conventional scan, or high-resolution thin-layer CT examination, with a maximum diameter of 5-30 mm, including solid nodules and ground glass nodules; * Patients require pulmonary nodule resection to define the type of nodule pathology; * The Patients have not yet used any drugs for tumor treatment; * Patients and/or family members are able to understand the research protocol and are willing to participate in this study, providing written informed consent. Exclusion Criteria: * The maximum diameter of pulmonary nodules is greater than 30 mm; * Patients are unable to determine the pathological diagnosis of pulmonary nodules after surgical resection or biopsy; * Patients with recurrent lung cancer; * Patients who have undergone lung transplantation or lobectomy; * Individuals who currently or have a history of malignant tumors; * Patients in the acute phase of inflammation or in need of intensive care in the above selected disease groups; * Individuals with severe liver and kidney dysfunction; * Mental illness patients (such as severe dementia, schizophrenia, severe depression, manic depressive psychosis, etc.); * Confirmed HIV patients; * Pregnant or lactating women; * Patients or family members are unable to understand the conditions and objectives of this study. * The patient is unwilling or unable to personally sign the informed consent form.