Critique of the cranium
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Critique of the Cranium. Chapter 9. PA and AP projection. Facility Identification Correct Marker Placement No Preventable Artifacts Correct Film Size. PA and AP projection. Contrast and density are adequate to demonstrates air-filled cavities and bony structures

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Critique of the Cranium

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Critique of the Cranium

Chapter 9


PA and AP projection

  • Facility Identification

  • Correct Marker Placement

  • No Preventable Artifacts

  • Correct Film Size


PA and AP projection

  • Contrast and density are adequate to demonstrates air-filled cavities and bony structures

  • Penetration is sufficient to demonstrate bony trabecular patterns and cortical outlines


PA and AP projection

  • True PA

    • The distances from the oblique orbital lines to the lateral cranial cortices are equal

    • The distance from the Crista galli to the lateral cranial cortices are equal


PA and AP projection

  • Detecting rotation

    • The patient’s face is rotated away from the side that exhibits the greatest distance between the Orbital rim and the lateral cortical border of the cranium


PA and AP projection

  • OML perpendicular to film

    • The petrous ridges should superimpose the supra orbital rims


PA projection

  • Evaluating OML position

    • If petrous ridges are below supra-orbital rim, the chin is too high (will look like a Caldwell view)

    • If petrous ridges are superior to the supra-orbital rim, the chin is too low.( will look like a Towne’s view)


AP trauma projection

  • Instead of moving head, angle central ray so that if forms a perpendicular angle with the OML

  • Evaluating OML position

    • If the petrous ridges are below the supra-orbital rim, angle tube more caudal

    • The central ray should be angled the way that you want the orbits to move.


PA and AP projection

  • The nasal septum and Crista galli should be aligned with the film and in the approximate center of the film


Caldwell Method (AP or PA)

  • Facility Identification

  • Correct Marker Placement

  • No Preventable Artifacts

  • Correct Film Size


Caldwell Method (AP or PA)

  • Contrast and density are adequate to demonstrates air-filled cavities and bony structures

  • Penetration is sufficient to demonstrate bony trabecular patterns and cortical outlines


Caldwell Method (AP or PA)

  • True PA

    • The distances from the oblique orbital lines to the lateral cranial cortices are equal

    • The distance from the Crista galli to the lateral cranial cortices are equal


Caldwell Method (AP or PA)

  • Detecting rotation

    • The patient’s face is rotated away from the side that exhibits the greatest distance between the Orbital rim and the lateral cortical border of the cranium


Caldwell Method (AP or PA)

  • If the angle between the OML and the film is perpendicular and the OML and the Central ray form a 15 degree angle, then

  • The petrous ridges should be projected through the lower 1/3 of the orbits.


Caldwell Method PA

  • If the petrous ridges are in the upper portion of the orbit,(1) the OML was not perpendicular to film or

  • (2)The OML and central ray did not form a 15 degree angle

  • (1) raise the chin

  • (2)increase angle


Caldwell Method PA

  • If the petrous ridges are inferior to the orbital rims,(1) the OML was not perpendicular to film or

  • (2)The OML and central ray did not form a 15 degree angle

  • (1) lower chin

  • (2) decrease angle


Caldwell PA

  • The petrous ridges move with the back of the head in the PA position

    • Raising chin moves petrous ridges down

    • Lowering chin moves petrous ridges up

  • Central ray moves the orbits,

    • Increasing angle moves orbits down

    • Decreasing angle moves orbits up


AP axial – Towne’s Position

  • Facility Identification

  • Correct Marker Placement

  • No Preventable Artifacts

  • Correct Film Size


AP axial – Towne’s Position

  • Contrast and density are adequate to demonstrates air-filled cavities and bony structures

  • Penetration is sufficient to demonstrate bony trabecular patterns and cortical outlines


AP axial – Towne’s Position

  • No rotation

    • The distances from the posterior clinoid process to the lateral borders of the foramen magnum on either side are equal

    • The petrous ridges are symmetrical

    • The dorsum sellae is centered within the foramen magnum


AP axial – Towne’s Position

  • The face is rotated toward the side of the patient which demonstrates the least amount of distance between the posterior clinoid processes and the lateral foramen magnum


AP axial – Towne’s Position

  • If the OML is perpendicular with the film and the CR is 30 degrees with the OML

    • The dorsum sellae and posterior clinoid are demonstrated within the foramen magnum without foreshortening or superimposing of the atlas’s posterior arch


AP axial – Towne’s Position

  • If dorsum sellae is projected inferior to the foramen magnum

    • The OML is not perpendicular with the film and the patient's chin is raised

    • Central ray needs to be increased


AP axial – Towne’s Position

  • If dorsum sellae is projected superior to the foramen magnum and superimposes the atlas's arch

    • The OML is not perpendicular with the film and the patient's chin is too low

    • Central ray needs to be decreased


AP axial – Towne’s Position

  • The sagittal suture and nasal septum are aligned with the long axis of the film

  • The inferior occipital bone is centered on the film

  • The outer cranial cortex, petrous ridges, dorsum sellae and foramen magnum are on the film


Lateral Positioncranium – facial bones - sinus

  • Facility Identification

  • Correct Marker Placement

  • No Preventable Artifacts

  • Correct Film Size


Lateral Positioncranium – facial bones - sinus

  • Contrast and density are adequate to demonstrates air-filled cavities and bony structures

  • Penetration is sufficient to demonstrate bony trabecular patterns and cortical outlines


Lateral Positioncranium – facial bones - sinus

  • True lateral

    • The sella turcica is demonstrated in profile

    • The orbital roofs, mandibular rami, greater wings of sphenoid, external auditory canals, and cranial cortices are superimposed


Lateral Positioncranium – facial bones - sinus

  • Detecting rotation

    • The sella turcica will e distorted

    • The mandibular rami, greater wings of sphenoid, EAC will be demonstrated anterior to one another.


Lateral Positioncranium – facial bones - sinus

  • Detecting tilt

    • The orbital roofs, greater wings of sphenoid, and EAC will appear superior to one another


Lateral Positioncranium

  • An area 2 inches above the EAM is in the center of the film


Lateral Positionfacial bones - sinus

  • The greater wings of sphenoid are in the center of the film


Submentovertex

  • Facility Identification

  • Correct Marker Placement

  • No Preventable Artifacts

  • Correct Film Size


Submentovertex

  • Contrast and density are adequate to demonstrates air-filled cavities and bony structures

  • Penetration is sufficient to demonstrate bony trabecular patterns and cortical outlines


Submentovertex

  • True SMV

    • IOML is parallel with image receptor

    • Mandibular mentum is demonstrated anterior to the ethmoid sinus

    • The distances between the mandibular rami and the cranial cortex on either side is equal


Submentovertex

  • If mandibular mentum lies to far anterior to ethmoid sinus

    • Head was tilted back to far

  • If mandibular mentum overlies ethmoid sinus

    • Head was not tilted enough

    • The most common error


Submentovertex

  • Detecting tilt

    • The distances between the mandibular rami and the outer cortex of the skull are not equal

    • The side that exhibits the greatest distance is the side that the cranial vertex is rotated toward


Submentovertex

  • The vomer and bony nasal septum are aligned with the long axis of the collimated field.


Submentovertex (basilar position)

  • The dens is in the center of the film


Submentovertex

  • The sphenoid sinuses are in the center of the film


SMV for Zygomatic arches

  • If right zygomatic arch is visalized, head is rotated toward the right

  • The head is rotated toward the side of interest


Parietoacanthal ProjectionWaters Position

  • Facility Identification

  • Correct Marker Placement

  • No Preventable Artifacts

  • Correct Film Size


Parietoacanthal ProjectionWaters Position

  • Contrast and density are adequate to demonstrates air-filled cavities and bony structures

  • Penetration is sufficient to demonstrate bony trabecular patterns and cortical outlines


Parietoacanthal ProjectionWaters Position

  • No rotation

    • The distances from the outer rim of the orbit to the outer cranial cortices are equal

    • The distance from the bony nasal septum to the lateral cranial cortex on either side are equal


Parietoacanthal ProjectionWaters Position

  • Detecing rotation

    • If the distance from the orbital rim to the cranial cortices are not equal

    • The side that exhibits the greatest distance is the side that the patient’s face is rotated away from

    • The side with the least amount of distance is the side in which the face was rotated toward


Parietoacanthal ProjectionWaters Position

  • OML forms a 37 degree angle with the image receptor

  • The petrous ridges should appear below the maxillary sinus


Parietoacanthal ProjectionWaters Position

  • If petrous ridges are too low

    • Lower chin

    • Angle tube cephalic

  • If petrous ridges are too high

    • Raise chin

    • Angle tube caudal


Parietoacanthal ProjectionWaters Position

  • The bony nasal septum is alighned with the long axis of the film


Parietoacanthal ProjectionWaters Position

  • All 4 sets of sinus are demonstrated on an open mouth view


Orbits

  • The optic foramen is open and in the lower half of orbit, and adjacent orbital margins

  • Tuck the chin until the AML is perpendicular to IR

  • Rotate the head toward the affected orbit until the midsagittal plane is at a 53 degree angle with the IR


AML Alignment

  • If correct the foramen in the half of orbit.

  • If chin not tucked enough>the foramen will superimpose the inferior orbital margin.

  • If chin tucked to much> the foramen will be in the superior half of the orbit


Degree alignment

  • If head is less than 53 degrees> the foramen will be closer to the center of the orbit

  • If rotated more than 53 degrees> the foramen will superimpose the lateral margin


Anatomy

  • The optic canal and foramen are centered to IR

  • Optic canal, foramen, lesser wing of sphenoid, and the orbital margins

  • 8x10 cassette


  • THE END


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