What gas is used in the production of 15O-Gas?

The production of 15O-gas, which is a radioactive isotope of oxygen used in positron emission tomography (PET) imaging, involves the nuclear reaction in which nitrogen-14 is bombarded with protons. This reaction occurs within a cyclotron, where 14N-gas (nitrogen gas enriched with the nitrogen-14 isotope) is the target material.

When protons are directed at the nitrogen-14 nuclei, a nuclear reaction occurs that converts the nitrogen into 15O and releases a proton. This makes 14N-gas the necessary reactant in the synthesis of 15O-gas. The use of nitrogen-14 enables the efficient production of this important tracer for PET scans, as it ultimately leads to the formation of the desired radioactive oxygen isotope, 15O, which is crucial for imaging metabolic processes in the body.

In contrast, while hydrogen gas, nitrogen gas in its elemental form (which includes isotopes besides 14N), and carbon dioxide may play roles in different chemical or biological processes, they are not directly involved in the production of 15O-gas through this specific nuclear interaction. Thus, nitrogen-14 is the correct choice due to its direct involvement in the creation of the radioactive oxygen isotope