Facial Bones, Orbits, Sinuses and Nasal Bones Flashcards
Lateral Facial Bones
- erect or recumbent
- MSP parallel to IR
- IPL perpendicular to IR
- IOML perpendicular to front of IR
- CR: perpendicular
- CP - zygoma - 1/2 way between tip of nose and EAM
when would you do erect lateral facial bones
- air-fluid levels shown
- easier for hypersthenic patients
Lateral facial bones criteria
- zygomatic bones in centre of radiograph
- no rotation of sella turcica
- superimposed orbital roofs/plates
- superimposed mandibular rami
- superimposed zygomatic process of the maxilla
- no rotation or tilt
- optimal exposure factors
Parietoacanthial projection - waters method - facial bones
- Prone or Erect (Chin on Bucky)
- MSP & MML ⊥ to IR
- OML 37° from IR
- CR ⊥ (// to MML)
- CP – exits at acanthion
- Collimate to include zygomatic arches
Parietoacanthial projection - waters method - facial bones Criteria
- petrous ridges below maxillary sinuses
- no rotation
- optimal exposure factors
- include orbits and mandible
Acanthioparietal Projection - Reverse waters method - facial bones
- AP projection
- OML 37 from IR
- MML perp to IR
- CR enters at the acanthion
PA Axial Projection - Caldwell Method - Facial Bones
- forehead and nose on table or IR
- MSP and OML perpendicular to IR
- CR - 15 caudad
- CP - exits at naison
- collimate to include entire orbital margin and mandible
PA Axial Projection - Caldwell Method - Facial Bones - criteria
- petrous ridges projected into lower 1/3 of orbits
- no rotation
- optimal exposure factors
Why would you x-ray orbits?
- foreign body - pre MRI
- pathology
- fracture
lateral - orbits
- Bucky/grid
- not table top
- affected side against IR
- IPL perpendicular to IR
- CR - perpendicular
- CP - Outer canthus of remote eye
- Instruct the patient to not move their eyes in foreign body
lateral - orbits - criteria
- affected side against IR
- orbits in centre of radiograph
- no rotation or tilt
- optimal exposure factors
why do we x-ray orbits before MRI?
incase there is metal in the eye
PA Axial projection - modified caldwell - orbits
- Prone
- MSP and OML ⊥ to IR
- CR - 30° caudad
- CP – exits nasion
PA Axial projection - modified caldwell - orbits - criteria
- petrous ridges are seen below the inferior margin of the orbits
- slit or strip collimation to include orbital magins
- optimal exposure factors
- F.B. focus on a spot, do not move eyes
why do you clean IR and Bucky for F.B. x-rays?
to make sure any debris is cleared and not mistaken for a foreign body
Parietoacaanthial projection - modified waters or shallow waters method - orbits
- rest chin and nose on table
- MSP and LML (Lips meatal line) perpendicular to IR
- OML 55 degrees from Bucky
- CR - perpendicular
- CP - outer canthus for orbits - slit collimate
Parietoacaanthial projection - modified waters or shallow waters method - orbits - criteria
- Petrous ridges projected in lower ⅓ of maxillary sinuses
- Orbital floors not distorted
- No rotation
- Optimal exposure factors
- Good for blowout fractures
- Slit collimate to include orbital margins
Lateral - sinuses
- ERECT - affected side closest to IR
- IPL perpendicular to IR
- IOML perpendicular to IR
- CR - perpendicular
- CP - enters 1/2 to 1” posterior to outer canthus
what does the lateral sinus demonstrate?
all 4 sinuses superimposed
what is the collimation of lateral sinuses?
Top - frontal
Bottom - maxillary
Left - frontal
Right - sphenoid (EAM)
Lateral - sinuses - criteria
- all 4 sets of sinuses - best for sphenoid
- AP and superoinferior dimensions of paranasal sinuses
- thickness of frontal bone
- detail of side closest to IR
Technical considerations of sinus imaging
- upright position - necessary to demonstrate fluid
- clean IR before imaging
- may lower kVp from skull imaging
- CR should remain perpendicular
- proper collimation critical in reducing scatter radiation and patient dose
assessing lateral sinuses
- Evidence of proper collimation
- All four sinus groups - Sphenoid of primary importance
- No rotation of sella turcica
- Superimposed orbital roofs/plates
- Superimposed mandibular rami
- Superimposed zygmatic process of the maxilla
- Clearly visible sinuses
- Close beam restriction
- Clearly visible air-fluid levels, if present
PA Projection - caldwell method - sinuses
- Upright - facing Bucky
- MSP perpendicular to IR
- OML 15º to IR - a line from the TEA to bottom 1/3 of orbit should be perpendicular to the bucky
- Horizontal CR
- Center nasion to IR
- CP exit nasion
- Radiolucent support may be needed at forehead
PA Projection - caldwell method - sinuses - criteria
- frontal sinuses above front-nasal suture
- anterior ethmoid air cells
- sphenoid sinuses seen through nasal fossa below or between ethmoids
- petrous pyramids in lower third of orbits
assessing pa projection - caldwell method - sinuses
- evidence of proper collimation
- no rotation
- petrous ridge lying in lower third of orbit
- frontal sinuses above frontonasal suture and anterior ethmoidal air cells above petrous ridges
how to assess for rotation on caldwell sinuses?
- equal distance between lateral border of skull and lateral border of orbits
- petrous ridges symmetric
Parietoacanthial projection - open mouth waters - sinuses
- erect facing bucky
- OML at 37 degrees from IR
- MML perpendicular to IR
- open mouth wide while holding position
- CR - perpendicular
- CP - exits acanthion
- collimate to maxillary sinus and include frontal sinus
Assessing Parietoacanthial projection - open mouth waters - sinuses
- sphenoid sinuses through open mouth
- maxillary sinuses
- petrous pyramids lying inferior to maxillary floor
Parietoacanthial projection - open mouth waters - sinuses - criteria
- Petrous pyramids immediately inferior to floor of maxillary sinuses
- No rotation
- Clearly visible air-fluid levels, if present
- Sphenoid sinuses projected through open mouth
- ensure mouth is open wide enough
how to asses if there is rotation in parietoacanthial sinuses?
- Equal distance between lateral border of skull and lateral border of orbit
- Orbits and maxillary sinuses symmetric
SMV - sinuses
- upright
- hyperextend neck and rest vertex of head on bucky
- IOML parallel to IR
- CR - perpendicular
- CP - midway between tip of nose and EAM
Assessing SMV sinuses?
- sphenoid and ethmoid sinuses
- mandible superimposing frontal bone
- bony nasal septum
SMV - sinuses - criteria
- Evidence of proper collimation
- No tilt
- Anterior frontal bone superimposed by mental protuberance
- Mandibular condyles anterior to petrous pyramids
- Clearly visible air-fluid levels, if present
how to assess tilt in SMV sinuses?
Equal distance from lateral border of skull to mandibular condyles on both sides
what does the anterior frontal bone being superimposed by mental protuberance indicate?
Indicates IOML is parallel (full extension)
Lateral nasal bones
- NO GRID
- Recovery position
- IPL perpendicular to IR
- IOML perpendicular to front of IR
- CR - perpendicular
- CP - ½ inch (1.25 cm) inferior to nasion
- bilateral
lateral - nasal bones - criteria
- bilateral nasal bones centered
- no rotation or tilt
- optimal exposure factors
- tight collimation
Parietoacanthial Projection - Waters Method - nasal bones
- prone or erect
- MML perpendicular to IR
- OML 37 from table
- CR - perpendicular
- CP - exits at acanthion
- collimate to include length and width of nasal septum and maxillary sinuses
Parietoacanthial Projection - Waters Method - nasal bones - criteria
- Petrous ridges projected below maxillary sinuses
- No rotation
- Optimal exposure factors
- Collimate to include length and width of nasal septum and maxillary sinuses
- Good to assess lateral deviation of nasal septum
