American Society for Nondestructive Testing (ASNT) Radiographic Testing Practice Test

Prolonged exposure of a zinc cadmium fluoroscopic screen to bright daylight leads to discoloration and loss of brilliance. This phenomenon occurs because the materials in the screen can undergo chemical changes when exposed to ultraviolet light and heat associated with bright daylight. As a result, the bright light can break down the phosphorescent properties of the zinc cadmium and lead to a degradation in the screen's ability to emit light effectively when stimulated by X-rays.

The discoloration is typically visible as a change in color, and the loss of brilliance refers to a decrease in the intensity of light emitted when the screen is subsequently used in radiographic procedures. Over time, this can significantly impact the quality of the radiographic images produced, as the screen will not convert the X-ray energy into visible light as effectively as it did prior to the exposure.

In contrast, while prolonged exposure to bright daylight might cause concern for enhancement of brilliance, the reality is that the chemical stability of the screen is compromised, reducing its effectiveness. Permanent damage or increased sensitivity to X-rays are not characteristics associated with light exposure; instead, such exposure primarily results in detrimental changes to the screen’s properties. Thus, the most accurate understanding of the effects of prolonged exposure to bright daylight is that it