This week's #xrayoftheweek is one for non-radiologists - there is airspace opacification on this chest x-ray (the shadowing in the right lung).
The questions for you are:
1. which lobe is it in?
2. how can you tell?
1. The airspace opacification (due to pneumonia) is in the right UPPER lobe.
2. The shadowing is sharply limited on its inferior aspect, approximately half way down the lung. This is the horizontal fissure, locating the opacification to the right UPPER lobe. This sagittal CT image shows the opacification and the fissures of the right lung:
The arrow points to the horizontal fissure which separates the right UPPER from the middle and lower lobes. The oblique fissure lies between the middle and lower lobes. Sometimes pleural fluid can be present within these fissures ("encysted pleural effusions") - knowing the position of the fissures can help identify these effusions.
Learning point: knowing where the fissures lie can help identify which lobe a pathological process is located in.