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Nasal Zygoma ch 13

Water's, Nasal, Zygoma, and Orbital Positioning

QuestionAnswer
Should facial bone studies be performed recumbent whenever possible? No, they may be performed erect.
Does the common basic PA axial projection for facial bones require a 15 degree caudad angle of the CR which projects the dense petrous ridges into the lower 3rd of the orbits? Yes
What is the major disadvantage of performing a straight PA projection for facial bones with no CR angulation, or neck extension as compared with other facial bone projections? The petrous pyramids superimpose the orbits and facial bone structures.
Where is the CR centered for a lateral position of the facial bones? On the Zygoma or in between the outer canthus and EAM.
What is the proper method name for the parietoacanthial projection of the facial bones? Water's method
Which facial bone structures are seen with a parietoacanthial (Water's) projection? Orbits, including infraorbital rims, bony nasal septum, maxillae, zygomatic bones and arches.
Which direction and how many degrees is the skull tilted and rotated for the oblique inferosuperior (tangential) projection for the zygomatic arch? The head is rotated 15 degrees from midline towards the side being radiographed and the chin is tilted 15 degrees towards the zygomatic arch being examined.
Where is the CR centered? The CR is centered to traverse through the zygomatic arch, skimming the mandibular ramus and parietal eminence.
The IR is placed perpendicular to which positioning line for the superoinferior projection of the nasal bones? Where is the CR centered? The IR is perpendicular to the GlabelloAlveolar Line (GAL) for the superoinferior nasal bone projection. The CR is centered to just skim the Glabella and front teeth.
What specific facial bone structures are demonstrated (besides the mandible) with the SMV projection if the soft tissue exposure factors are used? Zygomatic Arches
Where is the CR centered for an AP axial (Towne's) projection for the zygomatic arches? 1" superior to the glabella to pass through zygomatic arches.
What is the proper method name and common descriptive name for the parieto-orbital oblique projection for the optic foramen? Rheese Method & 3 Point Landing
Which 3 aspects of the face should be in contact with the IR for the parieto-orbital oblique (Rheese Method) projection? The cheek (zygoma), nose, and chin
Regarding: Rheese Method, or 3 point landing (parieto-orbital oblique projection) What is the final angle between MSP and IR? WHich positioning line is perpendicular to the IR? Which quadrant of the orbit is the optic foramen placed in with this method? The final angle between MSP & IR should be 53 degrees. The AML (AcanthioMeatal LIne) is perpendicular to the IR. The optic foramen is placed in the lower outer quadrant of the orbit with this method.
Which projection demonstrates the floor of the orbits for a blow-out fracture? Modified Water's method (the LML perpendicular to the IR).
Which projection demonstrates the optic foramen? Parieto-orbital Oblique projection (Rheese Method, or 3 Point Landing).
Which projection demonstrates a single zygomatic arch? Oblique Inferosuperior projection.
Which projection demonstrates a profile image of the nasal bones and nasal septum? Lateral nasal bones
Which projections demonstrate bilateral zygomatic arches? Sub-Mento Vertex (SMV) projection
Which projection demonstrates the inferior orbital rim, maxillae, nasal septum, nasal spine, zygomatic bones and arches? Parietoacanthial projection
A radiograph of a lateral projection of facial bones reveals the mandibular rami are not superimposed. What positioning error led to this? Rotation of the head.
A radiograph of a parietoacanthial (Water's) projection reveals the petrous ridges are projected within the maxillary sinuses. Is this acceptable? If not, what must be done to correct it? It is not, the petrous ridges should be projected just below the maxillary sinuses. The patient's head needs to be extended more.
A radiograph of a 30 degree PA axial projection of the facial bones reveal the petrous ridges are projected at the level of the inferior orbital margins. Is this acceptable? If not, what must be done to correct it? It is acceptable. For a 30 degree PA axial projection the petrous ridges should be at the level of the inferior orbital margins.
If the glabella is superimposed over the nasal bones on a superoinferior projection, what positioning error led to it? What can be done to correct it. There is either excessive flexion of the head and neck, or the incorrect CR angle was used. The CR needs to be parallel to the GAL.
A radiograph of the [arieto-orbital oblique (Rheese) projection reveals the optic foramen is located in the upper outer quadrant of the orbit. Is this acceptable? If not, what must be done to correct this? It is not. The extension of the head & neck should be increased bringing the AML perpendicular to the IR (the head rotation was correct).
A patient with possible fracture of the nasal bones presents for x-ray. The referring physician is concerned for deviated nasal septum along with possible bone fracture. What projections would be best for this? PA Water's, along with R & L lateral's of the nasal bones.
If a zygomatic arch cannot be demonstrated well on on the AP axial (Towne's) or SMV, which projection can be done to better define the Zygomatic arch? The oblique inferosuperior projection
If a patient is unable to flex the neck adequately to bring the IOML parallel to the IR for an SMV projection of the zygomatic arches, what other option does the RT have? To place an angled support under the IR to bring it parallel to the IOML and then angle the CR to be perpendicular to the IOML and IR.
How many degrees do the orbits project superiorly to the apex? How many degrees do the orbits project to the mid sagittal plane? the orbits project 30 degrees superiorly to the apex. The orbits project towards the midsagittal plane at a 37 degree angle.
For positioning with the Rheese method for the optic foramen, how many degrees should the patients chin be extended? How many degrees should the patients head be rotated and which direction? How many degrees should the mid sagittal plane be to the IR? The patients chin should be extended 30 degrees. The patients head should be rotated 37 degrees towards the affected side. This should form a 53 degree angle from the MSP to the IR.
For the Rheese method, if the optic foramen appears elongated (oval from top to bottom), what is the positioning error? If the optic formaen appears oval (side to side) what positioning error is present? If the optic foramen appears elongated the AML was not perpendicular. If the optic foramen appears elongated the ohead was not rotated into 37 degrees.
Going anteriorly to posteriorly, which order are the following foramen on the Sphenoid bone? Foramen Spinosum, Foramen Rotundum, Foramen Ovale. The Foramen Rotundum is anterior, then Foramen Ovale, then Foramen Spinosum is posterior.
When using occlusal film in the patient's mouth for the nasal bones, what technique is used? 60 kVp at 100 mAs.
Which cranial line is placed parallel to the floor to the floor of the Panorex of the Mandible? The IOML
Created by: jamestkelley