Final answer:
In a lateral chest x-ray procedure, the Image Receptor (IR) should be sized large enough to cover the entire lung field and inserted in a vertical or horizontal orientation depending on patient positioning. For proper imaging, the patient should stand or lie with the side of interest against the IR.
Step-by-step explanation:
In performing a lateral chest x-ray, the Image Receptor (IR) should typically be a large size, in order to capture the entire lung field. The IR size can range from a 14x17 inch to a 35x43 centimeter cassette or the corresponding digital receptor size. This depends on the protocol of the facility and the build of the patient. The positioning of the IR is crucial; it should be placed in a portrait orientation. When inserting the IR for a lateral chest x-ray, it should be positioned horizontally if the patient is lying down (lateral decubitus position) or vertically if the patient is standing or sitting (upright position).
For the patient's positioning, they should stand with either their left or right side against the IR, with the arms elevated and the shoulders rolled forward to move the scapulae out of the lung field. The x-ray beam will be directed horizontally through the thorax, centering on the lung fields. An important point to note is that the side of interest (commonly the side with pathology) should be closest to the IR to capitalize on the increased resolution that comes with decreased object-to-image receptor distance.