Final answer:
The RAO (Right Anterior Oblique) position is recommended for a contrast study of the esophagus to optimally visualize it between the thoracic vertebrae and cardiac anatomy.
Step-by-step explanation:
To best visualize the esophagus projected between the thoracic vertebrae and cardiac anatomy in a contrast study, the recommended patient position is RAO (Right Anterior Oblique). In this position, the esophagus, which is a muscular tube of length that is located posterior to the trachea, is optimally viewed as it runs through the mediastinum of the thorax into the abdomen through the esophageal hiatus. The RAO position helps to spread out the thoracic structures so that the esophagus can be visualized without superimposition of the spine and heart. Moreover, being aware of the anatomy, such as the thoracic cavity being a division of the anterior (ventral) cavity that houses key structures including the heart, lungs, esophagus, and trachea, aids in understanding why certain positions yield clearer imaging results.