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301 MEDIMAGE > 2a. Skull Bones Views and Positioning > Flashcards

2a. Skull Bones Views and Positioning Flashcards

1
Q

How many views are there for the skull

name them

A

3 views

AP or PA/FO or OF 20-25
Townes/FO30/30Half axial/AP axial
Lateral (HR)

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2
Q

what is the patients position for the FO/AP projection

in terms of patient sitting/lying down, chin position, MSP

A

patient seated erect/supine
chin raised to bring RBL to 20-25*
MSP perpindicular to IR

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3
Q

what is the central ray and centering point for the FO/AP view

A

CR perpindicular to IR and centered in the midline to the nasion

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4
Q

what are the exposure factors for the FO/AP view

mAs and kVp

A

70kVp and 16mAs

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5
Q

what is the SID for the FO/AP view

A

110cm

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6
Q

what do you want the petrous ridges position for the FO/AP view

A

petrous ridge in lower 1/3 of orbit

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7
Q

how will you position patient when their OMBL is at 90, how will you get the baseline to be 20-25

A

raise head up so baseline is at 20-25*

this pulls the petrous ridge down

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8
Q

what does it mean if the petrous ridge is too low/below the orbit

A

youve tilted head too far back/raised head too much

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9
Q

what is the image criteria for the FO/AP view in terms of rotation

A

Want to measure lateral border of orbit to the lateral border of skull/equidistant = no rotation

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10
Q

what is the image criteria for the FO/AP view in terms of structure superimposition

A

petrous ridge superimpose infraorbital margin and should not be sitting higher than lower 1/3 of orbit

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11
Q

what is the image criteria for the FO/AP view in terms of area of interest

A

entire cranial vault visualised

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12
Q

what is the image criteria for the FO/AP view in terms of exposure

A

sufficient exposure to visualise frontal bone without overexposing the perimeter regions of the skull

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13
Q

for the FO/AP view how do you adjust/detect the OMBL/RBL alignment

A

for superimposition of the petrous ridge and lower orbital margin:
increase OMBL by 5*
approx 5 degrees for every 1cm

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14
Q

for the FO/AP view how do you adjust/detect the OMBL/RBL alignment in terms of correcting the tilt

A

for superimposition of the petrous ridge and lower orbital margin:
increase OMBL by 10*
approx 5* for every 1cm

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15
Q

what is the townes projection also named as

2 names

A

30* Half-axial or AP axial

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16
Q

what 3 bones and landmarks are of import in the FO projection

A

frontal sinus
supraorbital rim
petrous ridge

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17
Q

what 4 bones and landmarks are of import in the townes projection

A

occipital bone
foramen magnum
petrous ridge
mastoid air cells on lateral borders

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18
Q

what info about the skull does the townes view give

A

info about the back of the skull

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19
Q

what is the patients position for the townes projection

in terms of patient sitting/lying down, chin position, MSP, distance between IR and ___

A

patient erect/supine

chin tucked down so OMBL/RBL is perp to IR

MSP perpind to IR

Equal distance between EAM and IR

20
Q

what is the central ray for the townes view

A

CR angled 30* caudally

21
Q

what are the exposure factors for the townes view

mAs and kVp

A

77kV, 25mAs

22
Q

what is the SID for the townes view

A

110cm

23
Q

what is the image criteria for the townes view in terms of rotation

A

cranium demonstrated without rotation

check rotation by distance from foramen magnum to either outer side of skull, make sure its equidistant

24
Q

what is the image criteria for the townes view in terms of structural superimposition

A

dorsum sellae centered within the foramen magnum

25
Q

what is the image criteria for the townes view in terms of structural distortion

A

foramen magnum is not foreshortened or elongated

26
Q

what is the centering point for the townes view

A

midline 5cms above nasion

27
Q

what is the patients position for the lateral skull projection

in terms of patient sitting/lying down, what is perp to IR, sponge use

A

patient supine

interpupillary line perp to IR

place head on sponge pad to ensure back of skull is not cut off

28
Q

what is the central ray for the lateral skull view

A

horizontal ray

29
Q

what is the centering point for the lateral skull view

A

5cm above EAM

30
Q

what are the exposure factors for the lateral skull view

mAs and kVp

A

70kVp

12mAs

31
Q

what is the SID for the lateral skull view

A

110cm

32
Q

what is the image criteria for the lateral skull view in terms of area of interest

A

entire skull visualized

33
Q

what is the image criteria for the lateral skull view in terms of rotation

A

head in neutral position, without rotation or tilt (chin in neutral)

Check for rotation by using anterior skull line to check superimposition and use Pituitary fossa to make sure clinoid processes are symmetrical

34
Q

why is the lateral skull view done supine

A

to see air fluid levels

also easier to check whether patient is straight or not

35
Q

If patient cant do supine lateral skull view what else can you do

A

patient standing erect and side on to IR

36
Q

what is the OMBL baseline, where is it and what is it used for

A

orbito-meatal baseline

From EAM to lateral canthus of eye

baseline position OMBL is perpendicular to the IR and for other views we will move patients head from this baseline position

37
Q

what is the IOML

A

infraorbital meatal line

line that runs between infraorbital margin and EAM

38
Q

what is the interpupillary line

where is it and what is it used for

A

horizontal line between centre of pupils of eyes

used to make sure patient isnt rotated

39
Q

is the lateral skull xray view a angled view

what is structure is shown in profile
what should be superimposed

A

non angled view

sella turcica in profile
TMJ superimposed

40
Q

what structures are the caldwell skull view used to visualise (2things)

A

frontal and paranasal sinuses

41
Q

what is the townes skull view used to evaluate (2things)

what structures is it good for visualising (3 structures)

A

evaluate skull fractures and neoplasia

petrous temporal bone, dorsum sella, laboid suture

42
Q

is the AP skull xray view a angled view

when is this view useful

A

non angled

when you cant get the pateint in a PA position

43
Q

is the PA skull xray view a angled view

what is structures should overlap

A

non angled view

petrous ridge will overlap lower 1/3 of orbits

44
Q

what is PA view better than AP skull view 2 reasons

A

lower dosage to eyes

crisper facial stuctures as closer to detectors so less magnification

45
Q

AP skull view ends up with which part being more blurry

A

orbit more blurry as further away from detector

301 MEDIMAGE (18 decks)

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