A "breathing technique" is used to advantage when performing a lateral projection of which portion of the spine?

The use of a "breathing technique" during a lateral projection of the thoracic spine is advantageous because it helps to blur the outlines of the ribs and lungs, allowing for better visualization of the spine itself. When patients are instructed to take slow, deep breaths and hold them, this technique reduces motion artifacts caused by normal respiration, which can obscure the details of the vertebrae.

In the case of the thoracic spine, the ribs are closely situated and can overlap the vertebral bodies on a standard lateral radiograph. By employing a breathing technique, the radiographer can effectively minimize these overlapping structures. The improvement in the clarity of the thoracic spine typically outweighs any potential motion from the lungs during the exposure.

While similar techniques might be applied to other regions of the spine, the anatomical positioning and the nature of overlapping structures make the thoracic spine a particularly suitable candidate for such an approach.