Sinus Radiographic Projections

Practice flashcards covering technical considerations, positioning, central ray placement, and structures demonstrated for lateral, Caldwell, Waters, and SMV sinus projections.

Upright position (Sinuses)

The required patient position to demonstrate fluid levels during sinus radiography.

Lateral Sinus Central Ray (CR)

The CR is horizontal and perpendicular to the IR, entering $1.3$ to $2.5\,cm$ ($0.5$ to $1\,inch$) posterior to the outer canthus.

Lateral Sinus Collimation

The radiation field extends $2.5\,cm$ ($1\,inch$) beyond the tip of the nose, $8\,cm$ ($3\,inches$) above the nasion, inferiorly to the occlusal plane, and posteriorly to the auricle.

Preoperative Sinus SID

A $183\,cm$ ($72\,inches$) Source-to-Image Receptor Distance used to minimize magnification and distortion.

Lateral Projection (Structures Shown)

Provides a view of all four sinuses, specifically best demonstrating the sphenoidal sinus and the sella turcica in profile.

PA Axial (Caldwell Method) Part Position

For the angled grid technique, the vertical grid is tilted down $15^{\circ}$ with the forehead and nose resting on the device; the MSP and OML are perpendicular to the IR.

PA Axial (Caldwell Method) Structures Shown

Primarily demonstrates the frontal sinuses superior to the frontonasal suture and the anterior ethmoid air cells.

Petrous Pyramids (Caldwell Method)

Criteria for a successful projection shows these structures in the lower third of the orbits.

Parietoacanthial Projection (Waters Method)

Patient position where the neck is hyperextended to place the OML at a $37^{\circ}$ angle from the IR plane while the MSP and MML are perpendicular to the IR.

Maxillary Sinuses

The primary structures demonstrated in the Parietoacanthial (Waters Method) projection.

Insufficient neck extension (Waters Method)

A technical error that causes the petrous ridges to be projected over the inferior portions of the maxillary sinuses.

Submentovertical (SMV) Projection Part Position

The neck is hyperextended to place the IOML parallel to the IR plane and the MSP perpendicular to the IR plane.

SMV Projection Central Ray (CR)

Horizontal and perpendicular to the IOML, entering the MSP $2\,cm$ ($0.75\,inch$) anterior to the level of the external acoustic meatus (EAM).

SMV Projection (Structures Shown)

Demonstrates the sphenoid sinus, ethmoid air cells, and maxillary sinus; specifically, the sphenoid and ethmoid sinuses are criteria for evaluation.