Patients who agree to receive pneumonectomy will be arranged to measure the distance from the incisors to the corresponding anatomical landmarks, including the cardia, the inferior pulmonary vein, the carina, the azygos vein, the lower edge of the aortic arch, the upper edge of the aortic arch, and the cupula of pleura through " fiber measurement method within nasogastric tube " . After building regression equations with the above data, the distance from the incisors to these corresponding anatomical landmarks could be inferred by means of indexes including height and so on.

Inclusion Criteria:

• Patients undergoing thoracic operation(such as radical lung cancer resection, pulmonary lobectomy, pulmonary segmentectomy, etc.) under endotracheal anesthesia ,which can expose the corresponding anatomical landmarks;
• Patients undergoing nasogastric intubation due to their condition.

Exclusion Criteria:

• Patients with diseased or deformed esophagus;
• Patients with obvious thoracic deformity, spinal deformity or dysplasia;
• Patients whose thoracic anatomical landmarks can not be exposed or exposed clearly during operation;
• Patients who do not agree to be measured.

Patient from Department of Thoracic Surgery, Southern Hospital of Southern Medical University.

The results of distance measurement of each individual participant.