Chest Radiology > Technique > Technically Adequate > Penatration

Technically adequate



Adequate penetration of the patient by radiation is also required for a good film. On a good PA film, the thoracic spine disc spaces should be barely visible through the heart but bony details of the spine are not usually seen. On the other hand penetration is sufficient that bronchovascular structures can usually be seen through the heart. 


On the lateral view, you can look for proper penetration and inspiration by observing that the spine appears to be darken as you move caudally. This is due to more air in lung in the lower lobes and less chest wall. The sternum should be seen edge on and posteriorly you should see two sets of ribs.



Left, an example of a normal PA film that is underpenetrated.  Right, an overpenetrated PA film.


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