If a pulmonary metastatic lesion is seen on a right lateral radiograph but not on a left, where is it likely located?

In the scenario where a pulmonary metastatic lesion is visible on a right lateral radiograph but not on a left one, the lesion is most likely located in one of the left lung lobes.

This conclusion is based on the principles of radiographic interpretation. When viewing lateral radiographs, the structures in the thorax are layered, and the side that is closer to the imaging receptor will display the structures with less interference from other anatomical features. Since the lesion is seen on the right lateral view, this suggests that it is positioned in a location that remains obscured when viewing from the left side, specifically pointing to the left lung lobes. Lesions in the right lung lobes would typically still be visible from that lateral orientation, as they are not occluded by other structures.

The other options describe locations in the right lung or do not accurately account for the visibility of the lesion based on the lateral views provided in radiographs. Thus, interpreting the imaging results in this manner logically leads to the conclusion that the lesion is situated in the left lung lobes.