What are the two most commonly used isotopes for radiography?

The two most commonly used isotopes for radiography are indeed Iridium-192 and Cobalt-60.

Iridium-192 is favored in industrial radiography due to its ideal gamma-ray energy and half-life, which makes it effective for penetrating various materials while also allowing for a reasonable safety profile and handling characteristics. It emits gamma rays that are well-suited for imaging the internal structures of objects, which is essential in welding inspections and manufacturing processes.

Cobalt-60 is also widely used in radiography, particularly in medical applications and food irradiation, due to its stronger radioactive emissions and the ability to produce high-quality images. Its longer half-life makes it useful in a more extensive range of applications while ensuring consistent performance over time.

These isotopes provide properties that are beneficial for achieving high-resolution images while minimizing exposure and ensuring safety for both the operators and the environment.