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2260 Positioning Study > Final Practical study > Flashcards

Final Practical study Flashcards

Cranium, Facial bones, orbits, sinuses

1
Q

What is the central ray for a PA Axial Caldwell projection of the cranial bones?

A

15 degrees caudad, exiting the nasion

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2
Q

What is the central ray for a PA Axial Caldwell projection of the facial bones?

A

15 degrees caudad, exiting the nasion

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3
Q

What is the central ray for a PA Axial Caldwell projection of the sinuses?

A

Perpendicular, exiting the nasion. OML tilted 15 degrees (chin lift)

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4
Q

What is the central ray for a PA Axial Caldwell projection of the orbits?

A

30 degrees caudad, exiting the nasion

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5
Q

With the exception of the sinuses projection, what planes/lines should be perpendicular to the IR for PA Axial Caldwell projections?

A

The OML and the MSP.

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6
Q

How do we ensure there is no rotation for PA Axial Caldwell projections?

A

MSP perpendicular to IR.

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7
Q

What is the central ray for an AP Axial Towne projection if the patient’s OML is perpendicular to the IR?

A

30 degrees caudad, centered 2.5 inches above the glabella

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8
Q

Why is the caudad angle for the PA Axial Caldwell projection increased from 15 to 30 when imaging the orbits?

A

To place the petrous ridges below the inferior margin of the orbits.

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8
Q

What is the central ray for an AP Axial Towne projection if the patient’s IOML is perpendicular to the IR?

A

37 degrees caudad, centered 2.5 inches above the glabella

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9
Q

What anatomy should be seen within the foramen magnum if the AP Axial Townes projection was appropriately angled?

A

Dorsum sella within foramen magnum

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10
Q

What is the central ray for the Parietoacanthial waters projection?

A

Perpendicular and exiting the acanthion.

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11
Q

For the parietoacanthial waters projection, the OML forms a 37 degree angle to the IR. What line is perpendicular to the IR?

A

The MML

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12
Q

How do we achieve a perpendicular MML for the parietoacanthial waters projection?

A

Lift patient chin.

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13
Q

The petrous ridges should be below what anatomy for parietoacanthial waters projections?

A

They should be inferior to the maxillary sinuses

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14
Q

What is the CR for a lateral projection of the cranium?

A

Perpendicular, entering 2 inches superior to EAM

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15
Q

What is the CR for a lateral projection of the facial bones?

A

Perpendicular, centered halfway between outer canthus and EAM on the zygomatic bone.

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16
Q

What is the CR for a lateral projection of the sinuses?

A

Perpendicular, entering ½ to 1 inch posterior to outer canthus

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16
Q

What is the CR for a lateral projection of the nasal bones?

A

Perpendicular, entering ½ inch inferior to the nasion.

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16
Q

What breathing instructions are used for all projections of the skull?

A

Suspend

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17
Q

What is the CR for a lateral projection of the orbits?

A

Perpendicular, entering the outer canthus

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18
Q

Which three routine projections are often done to image the cranial bones?

A

PA Axial Caldwell
AP Axial Townes
Lateral

19
Q

What anatomy can be used to assess rotation on a PA Axial Caldwell projection of the cranium?

A

Distance between lateral border of skull and lateral orbital margins should be equal bilaterally.

19
Q

What is the IR size and orientation for most images of the skull, except the orbits and lateral cranium?

A

Medium, lengthwise.

20
Q

What should collimation of the cranium include for a PA Axial Caldwell projection?

A

Vertex to base of skull. 1 inch beyond skin line.

21
Q

What anatomy can be used to assess tilt on a PA Axial Caldwell projection of the cranium?

A

Petrous pyramids are symmetrical.

22
Q

What should be situated within the lower 1/3 of the orbits if the central ray was appropriately centered and angled for a PA Axial Caldwell projection of the cranium?

A

Petrous ridges

23
Q

How can a patient place their OML perpendicular to the IR for an AP Axial Townes projection?

A

Tuck chin.

24
Q

If the patient was positioned PA, would the petrous ridges move inferior or superior within the orbits as we increase caudal angulation?

A

Inferior.

25
Q

Collimation of the cranium should include what for an AP Axial townes projection?

A

Vertex to base of skull, 1 inch beyond skin line.

26
Q

How can we assess tilt on an AP axial townes projection of the cranium?

A

Symmetrical petrous pyramids

26
Q

How can we assess rotation on an AP axial townes projection of the cranium?

A

Equal distance between lateral border of the skull, and lateral margin of foramen magnum, bilaterally.

27
Q

What does it mean for our CR angulation if the anterior arch of C1 is visible within the foramen magnum for an AP axial townes projection of the cranium?

A

Excessive caudad angulation.

27
Q

If the central ray was appropriately centered and angled for an AP Axial Townes projection of the cranium, what anatomy should be visible within the foramen magnum?

A

Dorsum sellae and posterior clinoid processes.

28
Q

What does it mean for our CR angulation if the dorsum sella is projected above the foramen magnum in an AP Axial Townes projection of the cranium?

A

Insufficient caudad angulation.

29
Q

What side of the skull is placed against the IR for lateral projections?

A

The affected side.

30
Q

Most images of the cranium use a medium sized IR in a LW orientation. What orientation is used for a lateral image of the cranium?

A

Crosswise.

31
Q

How can we assess rotation in a lateral projection of the cranium/facial bones/orbits/sinuses/nasal bones?

A

Greater wings of the sphenoid are displaced anteriorly/posteriorly.

Orbital roofs are displaced anteriorly/posteriorly.

TMJ’s are not superimposed

Sella turcica is not in profile.

31
Q

How can we assess if there is tilt in a lateral projection of the cranium, facial bones, sinuses, orbits or nasal bones?

A

Orbital roofs are displaced inferiorly/superiorly.
Greater wings of the sphenoid are displaced superiorly/inferiorly.

32
Q

The image critique criteria for the PA Axial Caldwell projection of the facial bones is the same as the image critique for the….

A

PA Axial Caldwell projection of the cranium!

32
Q

What should be included in the collimation of a lateral projection for the cranium?

A

Vertex to base of skull, frontal bone and 1 inch beyond skin line.

32
Q

Approximately how much of the forehead is included in the collimation of a PA Axial Caldwell projection of the facial bones?

A

Half.

33
Q

For lateral projections, what line on the patient should be perpendicular to the front edge of the IR, and why?

A

IOML. To ensure the mandible is not superimposing the cervical spine.

33
Q

Where should the collimation end inferiorly for a PA axial Caldwell projection of the facial bones?

A

Inferior aspect of upper incisors.

34
Q

Why is the parietoacanthial waters projection used to assess the cranium?

A

Trick question, it isn’t.

35
Q

How far superiorly to the orbits should collimation end for a parietoacanthial waters projection of the facial bones?

A

About an inch.

36
Q

Why is a horizontal CR always used for sinuses projections?

A

To visualize air/fluid level

37
Q

What anatomical landmark can be used as a reference to the petrous ridges?

A

Top of ear attachment

38
Q

When performing PA Axial projection of the Orbits, why is the caudad angle 30 degrees and not 15?

A

To project the petrous ridges inferior to the inferior orbital margins.

39
Q

Where should posterior collimation end for a lateral projection of the orbits?

A

Approximately EAM to include posterior clinoid.

40
Q

What projection might require pre-collimation and marker placement prior to patient positioning?

A

Waters projection of the nasal bones.

2260 Positioning Study (5 decks)

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