Final answer:
Quiet, shallow breathing is recommended during lateral thoracic spine imaging to minimize pulmonary vascular markings, making thoracic spine structures clearer on the X-ray.
Step-by-step explanation:
The procedure that recommends quiet, shallow breathing during the exposure to diminish prominent pulmonary vascular markings is lateral thoracic spine imaging. When performing a lateral thoracic spine X-ray, patients are usually asked to breathe quietly and shallowly to prevent the blurring of the thoracic spine structures due to lung movement. This technique helps in producing a clearer image of the thoracic spine by reducing the prominence of the pulmonary vessels, which may otherwise obscure the view of the spine. In contrast, procedures like the RAO sternum and AP scapula do not typically require quiet, shallow breathing as the focus is not primarily on the spine and the pulmonary vessels are less likely to interfere with the area of interest.