What is the half-life of Ir-192 approximately?

The half-life of Iridium-192 (Ir-192) is approximately 74 days. This means that after 74 days, half of the original quantity of Ir-192 will have decayed into other isotopes, primarily into platinum-192. This property is significant in applications such as radiographic testing and cancer treatment, where Ir-192 is utilized as a source of gamma radiation. Understanding the half-life helps professionals calculate the amount of Ir-192 available for use over time, ensuring effective and safe application in various practices.

The other options reflect incorrect half-lives for Ir-192. For instance, a half-life of 30 days would not correspond to Ir-192's decay characteristics and could mislead professionals regarding the isotope's behavior over time in a radiological context. Similarly, a half-life of 100 days or 365 days would also misrepresent the rate of decay, which is critical in relevant applications like radiographic imaging and therapy planning. Understanding the correct half-life ensures accurate dosimetry and effective use of the isotope in medical and industrial applications.