In the parietoacanthial projection (Waters method) of the sinuses, which statement is true about the central ray exit point?

In the parietoacanthial projection (Waters method) of the sinuses, which statement is true about the central ray exit point?

• A. It exits at the acanthion
• B. It exits at the nasion
• C. It exits at the external acoustic meatus
• D. It exits at the infraorbital margin

Answer: (A)

In the Waters parietoacanthial projection of the sinuses, the central ray is directed to exit through the acanthion. This is achieved by tilting the chin and orienting the head so that the orbitomeatal line (or a related alignment) places the maxillary sinuses in the correct position relative to the film, making the CR perpendicular to the IR and exiting at the acanthion. Exiting at the acanthion provides the best visualization of the maxillary sinuses with reduced superimposition from the facial bones. Exits at the nasion, external acoustic meatus, or infraorbital margin would reflect different projection geometries and would not produce the intended view of the sinuses.

In the Waters parietoacanthial projection of the sinuses, the central ray is directed to exit through the acanthion. This is achieved by tilting the chin and orienting the head so that the orbitomeatal line (or a related alignment) places the maxillary sinuses in the correct position relative to the film, making the CR perpendicular to the IR and exiting at the acanthion. Exiting at the acanthion provides the best visualization of the maxillary sinuses with reduced superimposition from the facial bones. Exits at the nasion, external acoustic meatus, or infraorbital margin would reflect different projection geometries and would not produce the intended view of the sinuses.