What does an underexposed x-ray image look like?

• A. Pale image, dark background, translucent edges
• B. Dark image, dark background, translucent edges
• C. Pale image, pale background, translucent edges
• D. Bright image, light background, sharp edges

Answer: (A)

Exposure controls how dark or light the radiograph appears and how clearly the edges between structures are seen. When a film or detector is underexposed, not enough X-ray photons reach it. The result is a pale image because there isn’t enough density to darken the film. With that low density, contrast is poor, so the boundaries between tissues don’t stand out well and can look translucent. The combination of a pale overall appearance with relatively less defined edges and a darker-looking background matches what an underexposed image looks like. In properly exposed images you’d see appropriate density and sharper edges, while overexposed ones would be too dark with blown-out details.