What instruction should be given to the patient during the lateral thoracic x-ray?

During a lateral thoracic x-ray, instructing the patient to take a deep breath in and hold it is essential for obtaining a high-quality image. This instruction helps to expand the lungs fully and provides better visualization of the thoracic cavity structures, such as the heart and lungs, without interference from respiratory motion. Holding the breath also minimizes blurring, which can occur if the patient breathes during the exposure, ensuring that the anatomical details are clearly captured on the radiograph.

The other choices do not contribute effectively to image quality in this context. Taking a deep breath and exhaling slowly may result in a less defined image due to motion during the exposure. Swallowing during the exposure is unnecessary and can also compromise the positioning, as it may disrupt the patient's focus on holding their breath. Lastly, relaxing and breathing normally does not provide the stability needed for the thoracic structures to be accurately imaged, as it may lead to inconsistent positioning of the diaphragm and affect the clarity of the x-ray.