ASNT Industrial Radiography Radiation Safety Practice Test

Which material is commonly used as an exit port for X-radiation in most X-ray tubes?

1. Aluminum

2. Lead

3. Beryllium

4. Copper

The correct answer is: Beryllium

The material commonly used as an exit port for X-radiation in most X-ray tubes is beryllium. This is because beryllium has several advantageous properties that make it well-suited for this application. It has a low atomic number, which minimizes the attenuation of X-rays as they pass through the material, allowing for better transmission of the radiation needed for imaging. Furthermore, beryllium is lightweight and has good thermal conductivity, which helps in managing the heat generated during X-ray production. While aluminum is also used in certain parts of X-ray apparatus due to its ability to filter low-energy X-rays and its relative safety, it does not provide the same level of transmission of high-energy X-rays compared to beryllium. Lead is known for its effective shielding properties against radiation and is commonly used for protective barriers, but it is not utilized as an exit port material because of its high atomic number and density, which would significantly attenuate the X-rays. Copper, while used in some components of X-ray tubes due to its electrical conductivity, does not share the same benefits for an exit port as beryllium does. Thus, beryllium's characteristics make it the preferred choice for an exit port in X