What primarily causes size distortion in fluoroscopic imaging?

In fluoroscopic imaging, size distortion is primarily influenced by the object-to-image distance (OID). This relationship dictates how objects are projected onto the imaging receptor. When the OID increases, the size of the object’s image can appear larger or more distorted due to geometry and the angle at which the radiation beam interacts with the object and the detector. A greater OID increases the likelihood of distortion because the X-ray beam diverges as it travels, which can result in variations in size and shape of the resultant image compared to the actual object.

Understanding OID is crucial for practitioners, as minimizing OID can help achieve more accurate representations of the anatomical structures being examined, thereby enhancing diagnostic quality. Techniques to keep OID as low as possible can include positioning the patient and the imaging receptor appropriately and using the necessary equipment settings to reduce this distance while obtaining optimal images.