Where should the petrous ridges be seen in the image of the Parietoacanthial projection waters method of the paranasal sinuses?

Which structures should always be radiographed with the patient in an upright position?

Which of the following is the only projection for paranasal sinuses that adequetely demonstrates all four sinus groups?

With reference to the outer canthus, where should the central ray be directed for the lateral projection of the sinus?

Which sinus group is of primary importance in the lateral projection of the sinuses?

Which sinus groups are best demonstrated wiht the PA axial projection, Caldwell method?

Frontal and anterior ethmoidal [sinuses]

For the PA axial projection, Caldwell method,of the sinuses, which positioning line, in addition to the midsagittal plane, should be perpendicular to the IR?

Where should petrous ridges be seen in the image of the PA axial projection, Caldwell method, of the sinuses?

Lower third of the orbits

Which positiioning line should form an angle of 37 degrees with the IR for the parietoacanthial projection, Waters method?

With reference to the IR, how should the central ray be directed for the parietoacanthial projection, Waters method?

Which paranasal sinus group is best demonstrated with the parietoacanthial projection, Waters method?

Where should the petrous ridges be seen in the image of the parietoacanthial projection, Waters method, of the paranasal sinuses?

Below the maxillary sinuses

Where should the central ray exit the head for the parietoacanthial projection, Waters method?

Which sinus group is not well demonstrated in the image produced by the parietoacanthial projection Waters method?

Which two paranasal sinus groups are better demonstated with the SMV projection than are the other sinuses?

Which projection of the sinuses demonstrates a symmetric image of the anterior portion of the base of the skull?

In which projection of the sinuses is the IR centered to the nasion?

PA axial, Caldwell method

In which projection of the sinuses is the mentomeatal line approximately perpendicular to the plane of the IR?

Parietoacanthial, Waters method

In which projection of the sinuses must the OML form an angle of 15 degrees with plane of the IR?

PA axial, Coldwell method

Which evaluation criterion pertains to the lateral projection of the paranasal sinuses?

All four sinus groups should be included

Which evaluation criterion pertains to the lateral projection of the paranasal sinuses?

The orbital roofs should be superimposed.

Which evaluation criterion pertains to the PA axial projection, Coldwell method, of the sinuses?

The frontal and ethmoidal sinuses should be seen

Which evaluation criterion pertains to the PA axial projection, Coldwell method, for sinuses?

Petrous ridges should lie in the lower third of the orbits.

Which evaluation criterion pertains to the parietoacanthial projection, Waters method, for paranasal sinuses?

Petrous ridges should lie immediately below the floor of the maxillary sinuses

Which evaluation criterion pertains to the SMV projection for paranasal sinuses?

Mental protuberance should superimpose anterior frontal bone

Which evaluation criterion pertains to the SMV projection for sinuses?

Mandibular condyles should be anterior to the petrous ridges

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Chapter 8

Skull, Facial Bones, and Paranasal Sinuses

• Cranial positioning lines

Cranium (Skull Series)

 AP axial (Towne method) and PA axial (Haas method) (R)

 AP axial critique

 Lateral (R)

 Lateral critique

 PA (0°) and PA (15° or 23°) Caldwell (R)

 PA Caldwell critique

 Submentovertex (SMV) (S)

 SMV critique

Trauma (Skull Series)

 Lateral trauma (S)

 AP 0°, AP 15°, and AP axial trauma (S)

 Lateral trauma critique

 AP (0° and 15°) trauma critique

Facial Bones

 Lateral (R)

 Lateral critique

 Parietoacanthial (Waters and modified Waters) (R)

 Parietoacanthial critique

 PA 15° Caldwell (R)

 PA axial 15° Caldwell critique

Trauma (Facial Bone Series)

 Lateral, acanthioparietal (reverse Waters and modified Waters) (S)

Optic Foramina

 Parieto-orbital oblique (Rhese method) (S)

Zygomatic Arches

 Submentovertex (SMV) (R)

 Tangential (R)

 SMV and tangential critique

 AP axial (modified Towne) (S)

Nasal Bones

 Lateral (R)

 Lateral critique

 Superoinferior (axial) (S)

Mandible

 PA and PA axial (R)

 Axiolateral oblique (R)

 Trauma axiolateral oblique (S)

 PA and axiolateral oblique critique

 AP axial (mandible or TMJ) (R)

Temporomandibular Joints

 Axiolateral oblique (Law) (S)

 Axiolateral (Schuller) (S)

 Axiolateral (Law and Schuller) critique

Paranasal Sinuses

 Lateral (R)

 PA (Caldwell) (R)

 Lateral and PA (Caldwell) critique

 Parietoacanthial (Waters) (R)

 Submentovertex (SMV) (S)

 Waters and SMV critique

    (R) Routine, (S) Special

Cranial landmarks and positioning lines used in skull and facial bones positioning.

Fig. 8-1Positioning lines.

A Glabellomeatal line (GML)

B Orbitomeatal line (OML)

C Infraorbitomeatal line (IOML) (Reid’s base line, or “base line,” base of cranium)

D Acanthiomeatal line (AML)

E Lips-meatal line (LML) (used for modified Waters)

F Mentomeatal line (MML) (used for Waters)

Fig. 8-2Cranial landmarks.

AP (PA) Axial Skull*

AP Towne (or PA Haas Method)

• 24 × 30 cm L.W. (10 × 12″)

• Grid

Position

Fig. 8-3AP axial (Towne)—CR 30° caudad to OML.

• Seated erect, or supine, midsagittal plane aligned to CR and centerline, perpendicular to IR; no rotation or tilt

• Depress chin to bring OML or IOML perpendicular to IR.

• Center IR to projecting CR.

Fig. 8-4PA axial (Haas method), OML ⊥ CR 25° cephalad, through level of EAMs.

Central Ray:

• CR 30° caudal to OML; or 37° caudal to IOML

• CR to ≈2.5″ or 6 cm above glabella (through 2 cm or 0.75″ superior to level of EAMs)

SID:

40-44″ (102-113 cm)

Collimation:

On four sides to skull margins

Respiration:

Suspend during exposure.

Note:

PA Haas (p. 436 in text) is an alternate to AP Towne. Adjust head to bring OML ⊥ to IR.

AP Axial

(Modified Towne Method)

Evaluation Criteria

Anatomy Demonstrated:

• Occipital bone, petrous pyramids, and foramen magnum

Position:

• Dorsum sellae within foramen magnum

• No rotation evident by symmetry of petrous pyramids

Exposure:

• Optimal density (brightness) and contrast to visualize occipital bone

• Sharp bony margins; no motion

Fig. 8-5AP axial skull.

Lateral Skull*

• 24 × 30 cm C.W. (10 × 12″)

• Grid

Fig. 8-6Lateral skull.

Position

• Seated erect or semiprone on table

• No rotation or tilt, midsagittal plane parallel to IR, and IPL perpendicular to IR

• Adjust chin to place IOML parallel to upper and lower IR edges

• Center IR to CR.

Central Ray:

CR ⊥ to IR, ≈2″ (5 cm) superior to EAM

SID:

40-44″ (102-113 cm)

Collimation:

On four sides to skull margins

Respiration:

Suspend during exposure.

Lateral Skull

Evaluation Criteria

Anatomy Demonstrated:

• Superimposed cranial halves

• Entire sella turcica and dorsum sellae

Fig. 8-7Lateral skull.

Position:

• No tilt, evident by superimposition of orbital plates (roofs)

• No rotation, evident by superimposition of greater wings of sphenoid and mandibular rami

Exposure:

• Optimal density (brightness) and contrast to visualize sellar structures

• Sharp bony margins; no motion

PA (0° and 15°) Caldwell Skull*

Note: Some departmental routines include a 0° PA to better demonstrate the frontal bone in addition to the 15° PA axial Caldwell.

• 24 × 30 cm L.W. (10 × 12″)

• Grid

Position

• Seated erect, or prone on table, head aligned to CR and centerline of IR

• With forehead and nose resting on tabletop, adjust head to place OML perpendicular to IR.

• No rotation or tilt, midsagittal plane perpendicular to IR

• Center IR to projected CR.

Fig. 8-8PA—0°.

Fig. 8-9PA axial—15° Caldwell.

Central Ray:

• PA 0°: CR ⊥ to IR, centered to exit at glabella

• PA axial (Caldwell): CR 15° caudad to OML, centered to exit at nasion (25°–30° best demonstrates orbital margins)

SID:

40-44″ (102-113 cm)

Collimation:

On four sides to skull margins

Respiration:

Suspend during exposure.

PA (0°) and PA Axial Caldwell (15° Caudad)

Evaluation Criteria

Anatomy Demonstrated:

• PA 0°: Frontal bone and crista galli demonstrated without distortion

• PA axial 15°: Greater/lesser wings of sphenoid, frontal bone, and superior orbital fissures

Fig. 8-10PA—0°.

Position:

• PA 0°: Petrous ridges at level of superior orbital margin. No rotation; equal distance between orbits and lateral skull

• PA axial 15°: Petrous ridges projected in lower ⅓ of orbits. No rotation; equal distance between orbits and lateral skull

Exposure:

• Optimal density (brightness) and contrast to visualize frontal bone and surrounding structures

• Sharp bony margins; no motion

Fig. 8-11PA axial—15° Caldwell.

Submentovertex (SMV) Skull*

• 24 × 30 cm L.W. (10 × 12″)

• Grid

• AEC optional

Fig. 8-12SMV—CR ⊥ to IOML.

Position

• Seated erect or supine with head extended over end of table resting top of head against grid IR (may tilt table up slightly)

• Adjust IR and head to place IOML parallel to IR.

• Ensure no rotation or tilt.

• Center IR to CR.

Central Ray:

CR angled to be ⊥ to IOML, centered to 0.75″ (2 cm) anterior to level of EAMs (midpoint between angles of mandible)

Note:

If patient cannot extend head this far, adjust CR as needed to remain perpendicular to IOML.

SID:

40-44″ (102-113 cm)

Collimation:

On four sides to skull margins

Respiration:

Suspend during exposure.

Submentovertex (SMV) Skull

Evaluation Criteria

Anatomy Demonstrated:

• Base of skull, including mandible and occipital bone

• Foramen ovale and spinosum

Position:

• Mandibular condyles are anterior to the petrous bones

• No tilt; equal distance between mandibular condyles and lateral skull

• No rotation; MSP parallel to edge of radiograph

Fig. 8-13 SMV.

Exposure:

• Optimal density and contrast (brightness) to visualize outline of foramen magnum

• Sharp bony margins; no motion

Lateral Trauma Skull*

Warning: Do NOT elevate or move patient’s head before cervical spine injuries have been ruled out.

• 24 × 30 cm C.W. (10 × 12″)

• Grid

Fig. 8-14Lateral, with possible spinal injury.

Position

• Supine, without removing cervical collar if present

• With possible spinal injury, move patient to back edge of table and place IR about 1″ (2.5 cm) below tabletop and posterior skull (move floating tabletop forward).

• Center IR to horizontal beam CR (to include entire skull).

• Ensure no rotation or tilt.

Central Ray:

CR horizontal, ⊥ to IR, centered to ≈2″ (5 cm) superior to EAM

SID:

40-44″ (102-113 cm)

Collimation:

On four sides to skull margins

Respiration:

Suspend respiration.

AP Trauma Skull Series*

Warning: With possible spine or severe head injuries, take all projections AP without moving head or without removing cervical collar if present.

• 24 × 30 cm L.W. (10 × 12″)

• Grid (Bucky)

Fig. 8-15AP—0° to OML.CR—parallel to OML—centered to glabella

Position

• Patient carefully moved onto x-ray table in supine position

• All projections taken as is without moving head

SID:

40-44″ (102-113 cm)

Collimation:

On four sides to skull margins

Respiration:

Suspend during exposure, or take “as is.”

CR Angle and Centering

• As indicated under each photo

• IR centered to projected CR

Fig. 8-16AP reverse Caldwell. CR—15° cephalad to OML—centered to nasion

Fig. 8-17AP axial (Towne). CR—30° caudad to OML—centered to midpoint between EAMs

Lateral Trauma Skull

Evaluation Criteria

Anatomy Demonstrated:

• Superimposed cranial halves

• Entire sella turcica and dorsum sellae

Position:

• No rotation or tilt (see p. 229 for specific criteria)

Exposure:

• Optimal density (brightness) and contrast to visualize sellar structures

• Sharp bony margins; no motion

Fig. 8-18Lateral trauma skull.

Trauma AP (0°) and AP Axial (15° Cephalad) Projections

Fig. 8-19AP—0° to OML.

Fig. 8-20AP axial (“reverse” Caldwell) (15° cephalad).

Evaluation Criteria

Anatomy Demonstrated:

• AP 0°: Frontal bone and crista galli demonstrated (magnified because of OID)

• AP axial 15°: Greater/lesser wings of sphenoid, frontal bone, and superior orbital fissures (magnified)

Position:

• AP 0°: Petrous ridges at level of superior orbital margin. No rotation; equal distance between orbits and lateral skull

• AP axial 15°: Petrous ridges projected in lower ⅓ of orbits. No rotation; equal distance between orbits and lateral skull

Exposure:

• Optimal density (brightness) and contrast to visualize frontal bone and surrounding structures

• Sharp bony margins; no motion

Facial Bones—Lateral*

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