Exam 1.13: Extraoral Plain Skull Radiographs Flashcards Preview

D2: 621 Radiology > Exam 1.13: Extraoral Plain Skull Radiographs > Flashcards

Flashcards in Exam 1.13: Extraoral Plain Skull Radiographs Deck (39)
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1

What is the extraoral film cassette

Rigid container for screen/film combination

2

What should the tube side of the cassette be made from

Bakelite, plastic
Something with a small atomic number

3

What are intensifying screens made from

layer of flat crystals of lanthanum or gadolinium

4

What size screens are there

8x10
10x12

5

What is the purpose of the intensifying screen?

Radiation hits the crystals and emits a flash of visible green light that helps expose the film

6

Can you mix and match film types with screen types?

No, they are specifically paired

7

Can you view the radiograph after the film is exposed?

No, you still have to develop it

8

What is the purpose of a plain skull radiograph

When pathoses are discovered on the pan, you need at least one more film perpendicular to the original to assist in the spatial localization of the pathosis

9

What anatomical land mark is important for extraoral plain skull projections?

Canthomeatal line which runs from the external auditory meatus to the outer cantus of the eye

10

Extraoral films should be checked for this bewteen contralateral structures

Symmetry

11

All major structures of the midface border at leasts one of these...

Paranasal sinus

12

Swelling, sings of penetrating injury, intraorbital air and soft tissue calcifications and masses are all...

soft tissue abnormalities

13

This view demonstrates medial and lateral walls of the maxillary sinuses and anterior facial structures including the medial wall of the orbit free of superimposition of the petrous ridges of the temporal bone

Waters view (Occipitomental)

14

What does waters view permit assessment of?

Zygomatic buttresses, orbital rims, nasal bones, anterior lamina, papyracea, ethmoid air cells, frontal sinuses

15

Only this view projects the anterior and posterior ethmoid air cells seperately

Water's view

16

How do you position the patient for water's view

Sagittal plane perpendicular to film
Chin raised high so that the canthomeatal line is 37 degrees above horizontal
Central ray should be perpendicular to the film at the level of the maxillary sinus
Source-film distance is 36-40

17

What abnormality of the maxillary sinus can be projected by a water's view

Pseudocyst

18

This projection best demonstrates midline and posterior facial structures

Posteroanterior projection

19

What is the projection of choice for demonstrating orbits, frontal and ethmoid sinuses and nasal fossa

Posteroanterior projection

20

What is not well visualized due to the superimposition of the petrous ridges in a posteroanterior projection?

Maxillary Sinuses

21

What is well visualized in a posteroanterior projection thanks to seperation of the ethmoid air cells from the orbits

Lamina papyracea

22

What radiograph is good for detecting mediolateral changes in the skull including asymmetry

Posteroanterior projection

23

How do you position the patient for a posteroanterior projection

Head centered in front of the cassette
Canthommeatal line parallel to the floor so the occlusal plane is horizontally oriented
Central ray is directed perpendicular to the plane of the film
Source to film distance of 36-40

24

What pathosis are illustrated by the posteroanterior projection

Cysts in ethmoid airspaces
Pagets ds CX
Cherubism
Fibrous dysplasia
Leiomyosarcoma
Surgery results
Glass eyes

25

This projection is the best for evaluating the anterior and posterior walls of the maxillary, frontal, ethmoid, and sphenoid sinuses and the pterygomaxillary buttress

Lateral projection

26

What is the best projection for evaluating an air fluid level in the maxillary sinuses

Lateral projection

27

What is the lateral projection essential for

Evaluating trauma to the sinuses

28

The lateral projection illustrates the relationship of the sphenoid sinus to this

sella turcica

29

Patient placement for lateral projection

Left side of face adjacent to the cassette and midsagittal plane parallel with the film
central ray is oriented toward the external auditory meatus and perpendicular to the midsagittal plane

30

For the lateral projection, what is the difference in source to film distances for a standard skull vs. a Ceph?

Std. = 36-40
Ceph = 60 with wedge filter