ASRT Practice Exam 2025 – Complete Study Resource

In a 45° left posterior oblique (LPO) position, the left lung field is best displayed due to the overlap and anatomy of the lungs in relation to the thoracic spine and heart. This positioning rotates the left lung posteriorly while moving the right lung anteriorly, allowing for better visualization of the left lung structures such as the left upper lobe and the left bronchial anatomy without significant superimposition from the heart and mediastinal structures.

The right lung, although visible, is more obscured due to anatomical structures like the heart and the thoracic wall obstructing the view. The choice of an AP oblique projection in this position maximizes the clarity for the left lung while providing a similar effect of reducing overlap for the areas of interest within the left lung field, making it ideal for diagnostic imaging purposes.