The supine chest x-ray shows a deep sulcus sign on the right side indicating the presence of a supine pneumothorax. There is a pleural line visible on the right extending all the way up to the apex, further supporting the presence of a pneumothorax.
Deep sulcus sign can be the only finding on the supine chest x-ray in a patient with pneumothorax. It represents abnormal lucency of the lateral costophrenic angle extending towards the hypochondrium.
The nasogastric tube tip should be at least 10 cm beyond the gastro oesophageal junction.
Further reading: https://pubs.rsna.org/doi/10.1148/radiol.2282020524?mobileUi=0 &https://radiopaedia.org/articles/nasogastric-tube-positioning