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Basic Skull Position
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Question | Answer |
---|---|
What is the average kV range for analog skull radiography? kV range for digital imaging? | Analog: 65-75 kV Digital: 75-90 kV |
List the 5 most common errors made during skull radiography? | Rotation, Tilt, Flexsion, Extension, Incorrect Angle |
Which cranial bone is best demonstrated with an AP Axial (Towne method) projection of the skull? | occipital |
When using a 30* caudad towne method of the skull, which positioning line should be perpendicular to the IR? | OML |
A properly positioned Towne method should place the dorsum sellae into the middle aspect of the: | Foramen magnum |
A lack of symmetry of the petrous ridges indicates which positioning error with an AP axial projection? | Rotation |
What CR angle should be used for the PA Axial (Haas method) | 25* cephalad |
Where is the CR centered for a lateral skull? | 2" above the EAM |
Where will the petrous ridges be projected with a 15* PA Axial (Caldwell) of the skull? | the lower 1/3 of the orbits |
Which specific positioning error is present if the petrous ridges are projected higher in the orbits than expected for a 15* PA Axial/Caldwell? | Excessive flexion or insufficient CR angle |
Which projection of the skull produces an image of the frontal bone with little to no distortion? | PA Skull |
What positioning error has been committed if the EAMs are not superimposed with one more superior than the other on the lateral skull? | Tilt |
What line is parallel to the IR for the SMV? | IOML |
What position best demonstrates the sella turcia in profile? | Lateral |
what position best demonstrates the clivus in profile? | Lateral |
where does the CR exit for a Haas method of the skull? | 1.5" (4 cm) superior to the nasion |
Critical Thinking: A 15* PA Axial (Caldwell) of the skull reveals that the petrous ridges are projected at the inferior orbital margin. What is the positioning error? | Excessive Extension or excessive caudad angle project the petrous ridges lower than expected. (they should be in the lower 1/3 of orbits) |
Critical Thinking: An xray of the SMV position of the skull reveals the mandibular condyles are with the petrous bone. What error led to this? | Insufficient Extension of the skull or the CR was not perpendicular to the IOML |
For a PA waters the petrous ridges should be projected directly below the: | Maxillary sinuses |
For a Modified waters the petrous ridges should be projected below the: | orbital rims |
which sinuses are best demonstrated with a PA Caldwell projection? | Frontal and anterior ethmoid sinuses |
Which group of sinuses is best deomstrated with a waters position? | Maxillary sinuses |
which sinuses are projected through the oral cavity with the PA axial transoral projection? | Sphenoid |