What sign indicates overpenetration on a chest radiograph?

• A. Excessively dark lungs with diminished detail of mediastinal structures.
• B. Elevated diaphragms with reduced lung markings.
• C. Prominent cardiac silhouette due to underpenetration.
• D. Increased chest wall thickness causing image blur.

Answer: (A)

Overpenetration happens when the exposure is too high, so the x-ray beam passes through the chest more than intended. This makes the lungs appear excessively dark on the image and reduces the ability to see details in central structures like the mediastinum. The loss of contrast in the mediastinal area is the hallmark, so excessively dark lungs with diminished mediastinal detail best indicates overpenetration. The other signs point to other issues, such as poor inspiration or underpenetration, which would not produce the same combination of extreme darkness and reduced central detail.