Assuming the fluid is free to move, what portion of the angles is most likely to contain effusion on upright PA and lateral chest radiograph?

Question

Quizplus · Accepted Answer

The posterior costophrenic angles are the lowest points in the chest cavity when lying down, and are therefore the most dependent areas where fluid accumulation can occur. These areas are easily visible on upright PA and lateral chest radiographs. The other options (lateral and cardiophrenic angles) are less likely to show evidence of effusion.

Assuming the Fluid Is Free to Move, What Portion of the Angles