What are the two primary gamma ray radiation sources used in radiography?

What are the two primary gamma ray radiation sources used in radiography?

• A. Cobalt & Cesium
• B. Cesium & Iridium
• C. Iridium & Cobalt
• D. Lead & Uranium

Answer: (C)

In radiography, the most effective gamma sources are chosen for the balance of penetrating power, source longevity, and practical handling. The two most common choices are Iridium-192 and Cobalt-60. Iridium-192 emits gamma rays with moderate energies that work well for many welds and thinner sections, offering good image quality with manageable shielding. Cobalt-60 produces higher-energy gamma rays (around 1.17 and 1.33 MeV), which penetrate thicker materials effectively and are useful for larger or denser components; its longer half-life means fewer source replacements over time. Together, they cover a wide range of inspection needs, from lighter to very heavy sections. Other options either don't provide the same practical combination of energy and longevity, or are not gamma-radiography sources (for example, shielding materials like lead or other materials not used as standard sources).

In radiography, the most effective gamma sources are chosen for the balance of penetrating power, source longevity, and practical handling. The two most common choices are Iridium-192 and Cobalt-60. Iridium-192 emits gamma rays with moderate energies that work well for many welds and thinner sections, offering good image quality with manageable shielding. Cobalt-60 produces higher-energy gamma rays (around 1.17 and 1.33 MeV), which penetrate thicker materials effectively and are useful for larger or denser components; its longer half-life means fewer source replacements over time. Together, they cover a wide range of inspection needs, from lighter to very heavy sections. Other options either don't provide the same practical combination of energy and longevity, or are not gamma-radiography sources (for example, shielding materials like lead or other materials not used as standard sources).