Chest radiograph. A chest radiograph, colloquially called a chest X-ray (CXR), or chest film, is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most common film taken in medicine.
Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among all the elements.he nucleus of the helium-4 atom is identical with an alpha particle. High-energy electron-scattering experiments show its charge to decrease exponentially from a maximum at a central point, exactly as does the charge density of helium's own electron cloud.
Helium is not known to be toxic. Characteristics: Helium is a light, odorless, colorless, inert, monatomic gas. It can form diatomic molecules, but only weakly and at temperatures close to absolute zero. Helium has the lowest melting point of any element and its boiling point is close to absolute zero.elium is also made by nuclear fusion of hydrogen in stars like our own. Image: Gnixon. Helium on earth comes from nuclear fission of radioactive elements such as uranium. Here a radioactive nucleus emits a helium nucleus (also known as an alpha particle).