ASNT Industrial Radiography Radiation Safety Practice Test

For Ir-192, the gamma constant is equal to:

1. 14 R/h

2. 5.3 R/h/Ci

3. 0.5 R/h/Ci

4. 100 R/h

The correct answer is: 5.3 R/h/Ci

For Iridium-192 (Ir-192), the gamma constant is a value that indicates the exposure rate of gamma radiation at a specific distance from a source of radioactivity. The unit of measure for this constant is often expressed in R/h per curie (R/h/Ci). The value of 5.3 R/h/Ci represents how much radiation a person might be exposed to at a distance of one meter from a source containing one curie of Ir-192. This suggests that as the activity of the Ir-192 source increases, the exposure rate at a set distance also increases proportionally. This information is critical in the field of industrial radiography since operators and safety personnel must understand how to evaluate and manage radiation exposure when using various isotopes, including Ir-192. Proper knowledge of the gamma constant allows for better planning in terms of shielding requirements, safety protocols, and establishing safe working distances from a source to minimize radiation exposure to personnel working in or around radiography operations.