Chest radiograph - Abnormalities. 1  A pulmonary nodule is a discrete opacity in the lung which may be caused by... 2  Neoplasm: benign or malignant. 3  Granuloma: tuberculosis. 4  Infection: roundish pneumonia. 5  Vascular: infarct, varix, granulomatosis with polyangiitis, rheumatoid arthritis.
Helium is used for purposes that require some of its unique properties: its low density, low solubility, and high thermal conductivity. 7,000 tons, or 22%, of the total helium used involves the cooling of superconducting magnets in medical magnetic resonance imaging (MRI) scanners.
Helium's other industrial usesâas a pressurizing and purge gas, as a protective atmosphere for arc welding and in processes such as growing crystals to make silicon wafersâaccount for half of the gas produced. A well-known but minor use is as a lifting gas in balloons and airships.