What causes the "V" or shark's fin appearance on a panoramic radiograph?

The "V" or shark's fin appearance on a panoramic radiograph typically results from improper positioning of the lead collar. When the lead collar is not placed correctly around the patient's neck, it can block the x-ray beam to varying degrees, leading to an area of increased radiopacity with a pointed shape that resembles a shark's fin. This obstruction creates an artifact in the image that disrupts the clarity and accuracy of the radiographic view.

This phenomenon highlights the importance of correct patient positioning and equipment setup in obtaining a diagnostic-quality panoramic image. Ensuring that the lead collar is properly adjusted not only prevents such artifacts but also protects sensitive areas from unnecessary radiation exposure, ultimately leading to better patient safety and an accurate diagnosis.