The Chang Gung Pneumothorax Detection Software is a medical software that can automatically detect whether there is a pneumothorax in Chest X-Ray. The purpose of this study is to verify whether the Chang Gung Pneumothorax Detection Software can correctly identify patients with pneumothorax in Chest X-Ray. The results of the software analysis will be used for the performance of the software on the primary and secondary outcomes.

This clinical trial is a retrospective study. DICOM images of de-identified Chest X-Ray were collected from 6 hospitals of Chang Gung Memorial Hospital from January 1, 2006 to December 31, 2020. The test set of 5,347 items was established, and total of 344 cases will be sampled by simple random stratification, including 172 cases with pneumothorax and 172 cases without pneumothorax. The image must be in DICOM format.

Follow-up by three specialist physicians to interpret the presence or absence of pneumothorax, the result will be the standard of this test (Reference). After confirming the correct standard of each Chest X-Ray, the Chest X-Ray will be put into Chang Gung Pneumothorax Detection Software, and analyzed by the primary and secondary outcomes.

Inclusion Criteria:

• The case were over 20 years old and under 100 years old.
• DICOM format.
• Brand model of Canon.
• DICOM resolution length range (700-3400 pixels), width range (490-3600 pixels).
• poster-anterior view(PA-view) of chest X-ray

Exclusion Criteria:

• The chest X-ray contains items that affect interpretation, such as chest tubes, endotracheal tubes, and heart rhythm regulators, but does not include patches and circuits used in electrocardiograms.
• The chest X-ray that are difficult to interpret due to poor image quality.

This is a retrospective study, and the data comes from the Chang Gung Medical Research Database(CGRD) which was an database form 6 hospitals of Chang Gung Memorial hospital. According to inclusion and exclusion criteria, Chest X-ray data from the database during 2006.01.01~2020.12.31 was collected.