What determines whether a structure appears as a real image or a ghost image?

• A. Whether it is inside the focal trough (real) or outside it (ghost)
• B. Its distance from the center of rotation
• C. Its density
• D. Its color

Answer: (A)

In panoramic radiography, what matters is where the structure sits relative to the focal trough—the curved imaging zone the machine uses as it rotates around the patient. If a structure lies inside that trough, its projection aligns with the imaging plane, producing a true, sharp image on the receptor (a real image). If the structure lies outside the trough, its projection does not sit on the focal plane, so the geometry creates a secondary, distorted image on the opposite side—the ghost image. Ghosts tend to be blurred, magnified, and appear on the opposite side from the actual structure. Density or color affects how bright or dark a structure appears but doesn’t determine whether it becomes a real or ghost image, and distance from the rotation center isn’t the deciding factor in this context.