X-RAY POSITIONING OF FACIAL BONES (2020 UPDATED)
Summary
TLDRThis educational video script focuses on the radiographic positioning of the facial bones, emphasizing the intricacies involved in capturing clear images of these delicate structures. It covers the importance of understanding the anatomy, the advantages of CT scans for detecting fractures, and the use of plane radiography for identifying fluid levels in sinuses. The script details various projections, including the Waters and submental vertical (SMV) projections, and discusses the challenges and techniques for achieving accurate positioning to visualize structures like the eyes, orbits, and nasal bones.
Takeaways
- 📚 The video is the third in a series of four, focusing on the positioning of the cranial vault and facial bones, with prerequisites to watch videos on the cranial vault and paranasal sinuses.
- 🦴 The facial bones are delicate and thin, making them difficult to visualize, especially when fractured, which is why CT scans are excellent for investigating facial bone injuries.
- 🔬 Despite CT's advantages, plain radiography can still be valuable for detecting fractures, particularly fluid levels within the maxillary sinuses.
- 📐 For imaging the facial bones, a 24x30-inch receptor is used with the central row in the middle and a portrait orientation for all cases.
- 🔄 The standard views of the facial bones are variable and may change based on the radiologist's and maxillofacial surgeon's needs.
- 👁️ The Waters projection is essential for examining the paranasal sinuses and can be adapted for different angles, with the patient's position remaining consistent across multiple images.
- 📏 The positioning for a Waters projection involves a specific angle of the orbit (37 degrees from the vertical axis or 53 degrees from the horizontal) and requires patient cooperation to maintain an uncomfortable position.
- 👁️🗨️ The Waters projection is also useful for eye examinations, especially when looking for foreign bodies, and requires the patient to maintain different gazes for multiple projections.
- 🌡️ The lateral facial bones projection involves a true lateral position of the patient's head, with the central ray 2.5 cm posterior to the outer canthus of the eye.
- 🤔 The Submental Vertical (SMV) projection is challenging and requires significant patient compliance, with the central ray passing through the orbital meatus at a 90-degree angle.
- 🛑 The Towne's projection can serve as an alternative to the SMV for examining the zygomatic arch, especially when the SMV is not feasible for the patient.
Q & A
What is the main focus of the third video in the series?
-The third video focuses on the positioning of the facial bones, particularly the techniques and considerations for radiographic imaging of these structures.
Why are the facial bones considered fine structures in the context of radiography?
-The facial bones are considered fine structures because they are very thin and can be difficult to visualize, especially when they fracture, as the fracture lines are also very fine.
What imaging modality is recommended for investigating facial bone injuries due to their fine structure and superimposition?
-CT (Computed Tomography) is recommended due to its ability to clearly show the fine structures and details of facial bones, despite their superimposition.
Why is plane radiography still advantageous for detecting fractures in facial bones despite the benefits of CT scans?
-Plane radiography can show signs of fractures, such as fluid levels within and around the maxillary sinuses, and it can have a significantly lower dose than a CT scan.
What is the standard size of the image receptor used for imaging the facial bones in the video?
-A 24 by 30 inch receptor is used for imaging the facial bones, ensuring the entirety of the facial bones is covered.
What orientation is used for all cases of facial bone imaging in the video?
-A portrait orientation is used in all cases for imaging the facial bones.
What is the significance of the Waters projection in facial bone radiography?
-The Waters projection is significant because it allows for the visualization of the maxillary sinuses and the detection of fluid levels, which can indicate fractures or other issues.
How does the positioning for a Waters projection differ from a standard chin and nose touch to the image receptor position?
-For a Waters projection, the patient's neck is extended further than in the standard position to achieve the required 53-degree angle for the Waters projection.
What is the purpose of taking multiple Waters projections with the patient in the same position?
-Taking multiple Waters projections in the same position allows for consistent imaging to detect changes or issues that may not be apparent in a single image.
What are the key criteria for a well-positioned Waters projection with zero angulation?
-The key criteria include the infraorbital margin being horizontal and thin, visualization of the entire facial structure from the top of the orbits to the bottom of the ethmoid and sphenoid sinuses, and no excessive tilt or rotation of the head.
What is the purpose of the submental vertical (SMV) projection in skull radiography?
-The SMV projection is used to create an image at 90 degrees to the PA and lateral projections, passing from the inferior part of the patient's cranium to the top, providing a different perspective for identifying fractures or other issues.
What challenges does the submental vertical projection present for both the patient and the radiographer?
-The SMV projection requires a high degree of patient compliance due to the need for significant hyperextension of the neck, which can be uncomfortable. For the radiographer, it requires precise positioning and tube angulation to achieve the correct projection.
How can the lateral facial bones projection be improved for better visualization?
-The lateral facial bones projection can be improved by ensuring the patient is in a true lateral position with no tilt, and by adjusting the central ray to be 2.5 cm or 1 inch posterior to the outer canthus of the eye.
What is the importance of patient instructions and compliance in Waters projection for eyes or orbits?
-Patient instructions and compliance are critical in Waters projection for eyes or orbits because the patient is required to maintain a fixed gaze in different directions for multiple projections, which helps in identifying the position of a foreign body or other issues within the eye.
Why is the lateral projection the most useful for visualizing the nasal bones?
-The lateral projection is the most useful for visualizing the nasal bones because it provides a true lateral view of the skull, allowing for clear detail of the fine structures of the nasal bone without superimposition from other structures.
Outlines
📚 Introduction to Facial Bone Radiography
This paragraph introduces the third of four videos focusing on the positioning of the cranial vault, specifically the facial bones. It emphasizes the importance of understanding the delicacy of facial bone structures and the challenges in visualizing them due to their thinness and potential for superimposition. CT scans are highlighted as an effective modality for investigating facial bone injuries due to their ability to provide clear images. Additionally, the paragraph mentions the advantages of plane radiography, particularly in identifying fluid levels within the maxillary sinuses, a sign of fracture. The standard views of facial bones are listed, with a note on the variability of these views depending on clinical needs and professional preferences.
🔍 Techniques and Considerations in Facial Bone Imaging
The paragraph delves into the technical aspects of imaging facial bones, discussing the use of a 24 by 30 inch receptor and portrait orientation for all cases. It explains the standard positioning for Waters' projection and the importance of maintaining patient position during multiple exposures to ensure consistency. The explanation includes the correct angle for Waters' projection and the need for patient communication to manage the discomfort of the position. It also covers the zero angulation or Waters' zero, detailing the criteria for proper positioning and the importance of visualizing the entirety of the facial structures.
🌡 Advanced Projection Techniques for Facial Bone Injuries
This section discusses advanced projection techniques, such as the Waters twenty or extended Waters projection, which involves a 20-degree chordal angulation of the tube and a corresponding adjustment of the image receptor position. It notes the variability in angulation preferences depending on the imaging center and the importance of positioning and collimation in these projections. The paragraph also explains how increasing angulation affects the visibility of the maxillary antrum and the inferior orbital margin, and the significance of these structures in diagnosing facial bone injuries.
👁️🗨️ Lateral and Supplementary Projections for Facial Bone Radiography
The paragraph covers the lateral facial bones projection, which is used to obtain multiple views at 90 degrees to existing images, despite the challenge of superimposition due to bilateral structures. It provides instructions for positioning the patient and setting up the central ray and collimation. The importance of patient gaze in Waters' projection for the eyes is discussed, including the need for patient compliance and clear labeling of images to indicate the direction of gaze. The paragraph also touches on the use of these projections in cases of suspected foreign bodies in the eyes.
🛑 Submental Vertical Projection: A Challenging Skull Imaging Technique
This paragraph introduces the submental vertical (SMV) projection, a challenging technique used to create an image at 90 degrees to the PA and lateral projections. It details the patient positioning, either supine or erect, and the extreme hyperextension of the neck required. The paragraph emphasizes the importance of patient compliance, coaching, and clear communication to maintain the position during the procedure. It also describes the ideal appearance of the image, including the visibility of the mandibular symphysis and zygomatic arches.
👃 Alternate Projections for Zygomatic and Nasal Bone Imaging
The final paragraph discusses alternative projections for imaging the zygomatic and nasal bones when the SMV projection is not feasible. It mentions the use of the Towne's projection for zygomatic bone imaging and the Waters' projection for nasal bone detail. The paragraph concludes with the most useful projection for nasal bones, the lateral projection, which provides clear detail of the nasal bone structures. It advises on the exposure settings for this projection and the importance of a true lateral cranial vault position.
Mindmap
Keywords
💡Cranial Vault
💡Facial Bones
💡CT Scan
💡Plane Radiography
💡Maxillary Sinuses
💡Waters Projection
💡Image Receptor
💡Tube Angulation
💡Lateral Projection
💡Submental Vertical (SMV) Projection
💡Nasal Bones
Highlights
The video covers the positioning of the facial bones, emphasizing the importance of understanding the fine structures of these bones for radiography.
CT is highlighted as an excellent modality for investigating facial bone injuries due to the thinness and superimposition of structures.
Plane radiography is noted for its lower dose compared to CT and its ability to show fracture signs, such as fluid levels in the maxillary sinuses.
A 24 by 30 inch receptor is used for imaging the facial bones, with the central row in the middle of the image receptor for consistent positioning.
The standard views of the facial bones are described as highly variable, depending on the radiologist's and maxillofacial surgeon's needs.
The Waters projection is detailed, explaining its importance in radiography of the paranasal sinuses and the specific positioning required.
A clear explanation of the 37-degree angle for Waters projection is provided, clarifying its orientation from the vertical axis.
The discomfort of the Waters projection position for patients is acknowledged, and the need for patient communication is emphasized.
The Waters 20 projection is introduced, with a 20-degree tube angulation and the necessity to adjust the image receptor position.
Different angulations of the Waters projection are discussed, showing how they affect the visibility of the maxillary antrum and the inferior orbital margin.
The Lateral facial bones projection is described, noting its similarity to the lateral sinus projection and the importance of patient positioning.
The Submental Vertical (SMV) projection is identified as challenging, requiring significant patient compliance and neck hyperextension.
Instructions for performing the SMV projection in both supine and erect positions are provided, with attention to patient comfort and positioning.
The Towne's projection is suggested as an alternative for examining the zygomatic bone when the SMV projection is not feasible.
The Waters projection is recommended for examining the eyes and orbits, especially in cases of suspected foreign bodies.
The importance of patient gaze direction during the Waters projection for eye examinations is detailed, with instructions for three different gaze positions.
The Lateral projection is highlighted as the most useful for examining the nasal bones, providing clear detail of their structures.
Transcripts
this is the third of four videos
covering positioning of the cranial
vault in this video we'll be looking at
the facial bones prior to watching this
video please ensure that you have had a
look at the videos covering the cranial
vault and also the paranasal sinuses
when first learning positioning of the
facial bones it's important to
understand a couple of background
concepts the first of which being that
the facial bones are very fine
structures there are particular
structures of the facial bones which are
very very thin quite difficult to see
and when they do fracture some of the
fracture structures are quite fine as a
result of this and the fact that the
facial bones often have superimposition
of adjacent structures CT is an
excellent modality for being able to
investigate facial bones injuries one of
the advantages of plane rays however
apart from the fact that it can have a
very very much lower dose than a CT scan
is the fact that plane radiography can
show signs of a fracture and the most
notable of these is fluid levels within
and around the maxillary sinuses for
each of the images of the facial bones
we're going to be using a 24 by 30 in a
receptor the central row will be in the
middle of that image receptor in each
time and the image receptor is going to
cover the entirety of the facial bones
we'll be using a portrait orientation in
all cases in front of you there you can
see that I've listed the standard views
of the facial bones indicating a couple
of water's projections and a lateral I
would like for you to understand that
this is an incredibly variable quantity
and that depending upon the needs of our
desires of the radiologist maxillofacial
surgeon the NT surgeon and so forth
these things may change and in fact are
very very likely to change so please do
recognize that this is quite a variable
body region it is going to change
upon where you find yourself on
placement or working in the professional
environment positioning for the waters
projection is covered in the previous
video where we had a look at the
radiography of the paranasal sinuses
please note that when you do have a look
at your textbooks with regard to the
waters projection it will indicate that
the positioning is a 37 degree
angulation of the orbit only 8 aligned
i'd like for you to be aware that that
37 degree angle is actually from the
vertical axis as opposed to the
horizontal axis as you can see here for
a well positioned water's projection the
orbit owe me eight aligned is 37 degrees
from vertical or 53 degrees from
horizontal please make sure you were
clear on that in the previous video we
talked about how you can adapt from a
standard chin and nose in touch with the
image receptor and then to extend the
neck further depending upon the facial
maxillary structure and profile of the
patient to be able to get that 53
degrees this photograph shows a patient
in a Watters projection and you can see
that this is a young patient who's very
likely to be able to move quite freely
and yet it's still quite an
uncomfortable position you can see that
the neck has been extended quite a long
way now one of the things about the
waters projection is that when you are
performing this series you need to take
multiple water's projections with the
patient in the same position one of the
things which I would advocate therefore
is to communicate with your patient let
them know that you're going to put them
into a particular position and that you
would like for them to stay in that
position whilst you perform one to three
images in a row the tube angulation is
going to be the only factor that changes
and correspondingly the image receptor
but otherwise the patient position stays
the same so you are essentially going to
be convincing the patient to stay in an
uncomfortable position for a couple of
minutes the positioning of a patient for
a waters projection with a zero
angulation or the water's zero as it is
commonly known is exactly the same as
described in the sinus video previously
available to you the criteria once again
matched that the infraorbital margin
should be a horizontal and thin
structure the entirety of the facial
structures should be visualized so you
should see everything from the top of
the orbits down to essentially the
bottom of the ethmoid and sphenoid or
sinuses should be shown if you don't
show the entirety of the mandible that
is acceptable because the mandible is a
structure which needs to be visualized
as a separate entity there should be no
excessive tilt of the head as shown by
that inferior orbital margin being shown
in as a flat profile structure and there
should be no rotation as evidenced by
symmetry of bilateral structures the
maxillary sinus those approximately
triangular structures that you can see
underneath the patient's orbits should
be shown fairly maximally it's quite
common however for the bony structures
behind it to be visualized over at the
bottom third of the maxillary sinus we
will move on now to the waters twenty or
also known as the extended waters
projection the water's projection has
the patient positioned identically to
the water's zero or zero angulation
projection there are two differences the
first difference is that there is a 20
degree chord ad angulation of the tube
correspondingly because structures will
be projected further inferiorly we need
to move the image receptor inferiorly to
correspond to that otherwise the
projection in all ways is similar to the
waters 0 projection it's important to
note that this projection has a 20
degree chord
angulation but depending upon where you
find yourself working it might be
advocated that a 15-degree waters
projection is utilized indeed there will
be some imaging centers where it may be
the routine projections to perform a
waters 0:15 down and 30 down or 20 down
and 40 down this is something which is
very subjective and is normally
considered and negotiated between the
maxilla facial team and the radiology
team otherwise positioning projection
and collimation
is exactly as before you can see in this
projection this photograph that the
patient is once again in an identical
position and in this situation we would
once again be saying to the patient -
we're going to be taking two or maybe
three projections try to stay in that
position while we continue to perform
these projections and I'll get you to
relax at the end of the series when this
projection has been performed well it
should have slightly different criteria
to the previous the inferior orbital
margin won't be completely flat now it
will be a relatively thin structure the
previous criteria with regard to
rotation or tilt are entirely the same
however the maxillary antrum that is to
say that the entirety of the maxillary
sinus including the inferior most point
should be shown maximally in this image
if you have a look at the inferior part
of the patients maxillary sinus you
should be able to see virtually no
superimposition of other posterior bony
structures the advantage of this
projection is that if there is a fluid
level within the maxillary sinus that it
should be visible certainly because
we're using a tube angulation we will
not be able to see that fluid level as a
horizontal structure but rather we
should be able to see it in some extent
whereas in the previous projection it
would have been superimposed over those
posterior fine
base of skull structures with the bottom
third being filled up by those ridges so
the water's projection can be performed
with a series of different angulations
and depending upon your placement center
and professional environment in which
you find yourself working these core dad
angulations may vary you'll notice that
as we increase that core dad angulation
that the inferior orbital margin will no
longer be a horizontal structure but
that we will see more and more of the
maxillary antrum it's important to
recognize that as we Center for with
greater and greater degrees of chord an
angulated it may be necessary for us to
Center rather than the nays Ian on more
inferior structures so as to be able to
include the entirety of the cranial
vault so instead of always centering
through the nazy on it may be necessary
to Center further down as you can see
when we are using it the more extreme
amounts of tube angulation around the
nature of 40 degrees or even more that
at the centering point is almost through
the mental synthesis and obviously the
image receptor has been displaced to
compensate for that so these three
projections show the water's projection
with different angles at the beginning
it's a relatively PA position in the
middle of borders projection with around
about a 20 degree angle yishun and the
image on the far right hand side of
screen shows shows a much higher perhaps
a 30 or 40 degree angulation so as you
increase your angulation the maxillary
Antron becomes clearer but the inferior
orbital margin becomes a thicker
structure and less able to be seen when
a patient receives an injury to the
facial bones it is very common for the
inferior orbital mode
to be fractured and that can then
subsequently cause a filling of the
maxillary sinus with blood and a
demitasse fluid so being able to see the
inferior orbital margin and the
maxillary sinus is an important part of
your facial bones radiography the
water's projection is also quite good
for showing the eyes and the orbits when
we perform a water's projection for the
eyes or the orbits we the nature of the
tube angulation and beam means that we
can see the eyes quite quite well
particularly as I say that inferior
orbital margin you can see in front of
you there some of the anatomy of the
facial bones just to be able to maintain
your knowledge base of facial bones
radiography let's now move on to the
lateral facial bones projection this is
normally undertaken as a projection so
as to be able to have multiple views at
90 degrees it's not a particularly
useful projection in many ways because
it will have superimposition of the
bilateral structures of the facial bones
the lateral facial bones projection is
very very similar to the lateral sinus
projection which we talked about in the
previous video and all of those same
principles apply move the patient into
about a 45 degree of liquidy and towards
the board and then get them to rotate
their head so that they're in a true
lateral position you should be squatting
down in front of the patient with the
intention being to ensure that their
interview pillory line is a horizontal
structure that is that they are in a
true lateral position and their head is
not tilted nor should it be too far
tilted down or up the central rate for a
lateral facial bones projection is two
and a half centimeters or one inch
posterior to the outer canthus of the
eye and the collimation should be
approximately to the border of a 24 by
30 and then bring that collimation in
until it just touches the soft tissues
of the nose anteriorly and about the
middle of the ear posteriorly because
there are no facial bone structures
anterior or posterior to that this is a
lateral facial bones projection you can
see that on this patient and this young
lady is has a fairly slim build but you
can see that she is on a nearly 45
degree rotation of her thorax and only
her the superior part of her neck and
head is in the true lateral position
notice on this particular projection
that the patient's gaze is upward
that will be something which we'll
consider in a short period of time so a
lateral facial bones projection should
have radiographic superimposition of
bilateral structures the closer these
bilateral structures are to the middle
of the image the more likely they are to
be superimposed and those on the
periphery of the image less so we should
see the entirety of the facial bones
that ideally you'll see the soft tissue
contour of the patient's nose anteriorly
you can probably just see the outline of
the lips there and about mid ear is as
far as you want to see posteriorly if
the patient has any fluid levels within
their maxillary sinuses they should be
shown as a horizontal structure that is
you're shooting across that fluid level
and now some supplementary and extra
projections of the facial bones the
water's projection is a very good
projection for the eyes when we have a
look at the eyes much of the time when a
patient presents for and orbits or I
x-ray the clinical history is a queried
or known foreign body within the eyes
this might be as part of a pre MRI
screening check where a patient may have
a previous history where they have been
working with metal and may have some
ferrous metal within their Globes
we have many industry workers who will
have MRI scans and so I'll be
that's a preventative test that we can
do or we might have a patient presenting
in the acute environment who has a
queried foreign body of the eyes in
either circumstance it's very common to
perform a waters projection for the eyes
or indeed to perform three water's
projections of the eyes the positioning
is very very similar to our previous
waters projections except for the fact
that the central ray passes through the
level of the eyes and that the
collimation is going to include the
entirety of those orbits the patient
instruction is the critical part of this
projection you're going to perform the
projection three times and the inpatient
will be instructed to change the way
that their eyes are looking this is
referred to as the patient's gaze you
are going to tell the patient to look
upwards and to fix their gaze on a
particular point and to keep their eyes
very still and you'll perform one
projection like that the second
projection with their eyes looking
straight ahead
the third projection with the eyes down
cast a downward gaze once again fixed on
a point in space these projections need
to be very very clearly labeled so that
the radiologist or referring physician
is aware of which projection being which
you need to ensure patient compliance to
make sure that the eyes do stay in a
fixed position and one of the things
which I would advocate doing is to have
your marker placement correlate to the
gaze that is to say that when you have
the upward gaze put your marker at the
top of the image at the neutral or
straight-ahead gaze at the middle of the
image and on a downward gaze place your
marker at the bottom of the image that
way there can be no doubt or ambiguity
about which projection has been done the
position of a known or queried foreign
body within the globe will vary
depending upon
depth of that foreign body and the
extent to which the patient has been
able to change their gaze so it does
require a fair amount of patient
compliance and as such I encourage you
to coach and communicate with the
patient well so a Watters projection
with orbital foreign bodies the actual
bony structures themselves will appear
quite quite similar however your marker
placement will be useful in being able
to identify which projection is which
the submental vertical or SM the
projection is probably one of if not the
most challenging projections of the
skull the purpose of the submental
vertical projection is to be able to
create another image at 90 degrees to
your PA and lateral projections by
having the projection pass from the
inferior part of the patient's cranium
to the top this requires a very great
degree of patient compliance the sub
mental vertical projection can be
performed with the patient starting in a
seated to supine position or it can be
in an erect posture I'll start with the
supine position and then work on to the
erect posture when a patient presents
for an SMD projection essentially you're
going to have the central ray passing
through the patient's orbital only 8 on
line at 90 degrees the patient's orbit
home you ate a line ideally would be a
horizontal structure and that would be
achieved by having the vertex or the top
of the patient's head in contact with
the image receptor now on a supine
patient as you can imagine that requires
a very great hyperextension of the
patient's neck and it requires for the
patient to have their head essentially
upside down the extent to which the
patient is able to hyperextend then
will define the tube angulation so one
of the important parts of this
projection is for you to have a look
from the side of the patient find the
orbit owe me eight online that the
patient can maintain and then to change
your tube angulation to cut through that
orbit owe me eight aligned
perpendicularly we start off with the
patient in a seated position they are
shaped like a capital L if you like
you're then going to place three of the
fluffiest pillows you can find in the
department against the patient's lower
back you're going to then encourage the
patient to hyperextend and bend over
those pillows and then to tilt their
chin further back so that their head is
essentially completely upside down the
vertex of the head will be in contact
with the image receptor or the supine
Bucky then you will place your image
receptor such that the primary beam will
be cutting right into the middle of that
image receptor and make sure your
angulation corresponds to that
perpendicularity to the orbital metal
line you'll collimate it to the borders
of the image receptor on a twenty four
by thirty portrait image receptor now
the instructions here stay say stay
still but realistically this is one of
those projections where you absolutely
must coach your patient encourage them
to be compliant and to keep up
communication to let them know that you
will be getting them to be seated back
again to get a normal blood pressure
flow as soon as you possibly can
now this projection can also be
performed with the patient seated and
some patients find this more comfortable
some less so I tend to do mine supine
just because I find that patients move
around a little bit less however if you
wanted to do it in an erect position
start off with the patient in a chair
but not a chair with a very high back on
it because you need to have a certain
amount of extension of the patient's
lumbar spine then
that chair approximately 30 centimeters
away from the erect Bucky then have the
patient seated in an AP position and
then with you holding on to the
patient's shoulders ask them to
hyperextend their neck tilting it all
the way back until the vertex of their
head is in touch with that image
receptor against that erect Bucky
encourage the patient to keep that
extension that hyperextension of their
neck and from there utilize your tube
angulation once again perpendicular to
the orbit immutable line talk to your
patient and find out what position is
going to be most possible for them you
can see on the right hand side a patient
who has who's having an SMD projection
in an erect posture and you can see the
extent of hyperextension
notice how the patient's chair is being
moved away from the erect Bucky the
patient on the left hand side of screen
is about the only smv projection that
can be found but I don't actually
advocate using this position basically
because it's a lot of mucking around
with that image receptor there when we
probably should could get the patient
through a greater degree of
hyperextension by putting some pillows
underneath their back so that photograph
on the left not so useful when you
perform an SM the projection well you
should get something which looks like
this the mandibular symphysis should be
just shutting off the main part of the
skull a little bit you should have the
mandibular condyle in front of the the
petrous pyramids but you know you've
performed this projection well in terms
of rotation or tilt when you can see the
patient's zygomatic arches standing a
proud of or not immediately superimposed
over the rest of the cranial vault
notice how this patient zygomatic arches
are projected really quite a fair way
off the skull as you can imagine if the
patient had a fracture of the zygomatic
bone that this would be a very useful
project
for being able to show the displacement
of that zygomatic arch depending upon
the amount of troub angulation you might
also get a sub mental vertical shot of
the patient's nasal bone
now I mentioned in the previous
projection that the smv projection is
quite good for the zygoma however there
are times when that patient's not able
to undertake that projection in which
case if you wanted to investigate this
eye gamma one alternate is to use the
town's
projection which we covered all the way
back in the first cranial vault video if
you were to use the town's projection
which has that 25 degree cord at
angulation and to Center through the
middle of the zygoma you should end up
with a projection much like you can see
diagrammatically here which cuts through
the zygoma at close to 90 degrees it's
not as good as an SM V but it's quite
close this projection when performed
like this should come up with something
which looks like this you can see how
the patient's zygomatic arch have been
projected out from the rest of the face
it's not as good as an SM V but it does
show any degree of displacement of the
zygomatic arch because this towns
projection has a very tight collimation
down to a slit like exposure area you'll
occasionally hear this referred to as a
slit towns projection the waters
projection also has some utility and
having a look at the patient's nasal
bones if you perform a Watters
projection and for a patient who has a
nasal bones fracture you might want to
take an extra Watters view for every
tightly collimated over the patients
nation to get good detail of that nasal
bone it's quite good for a patient who
has a queried deviation of the nasal
septum however the most useful
projection of the nasal bones is the
lateral projection when a nasal bones
projection is performed with the patient
and a true lateral cranial vault
position and you are sent it over the
middle of the nose
then you can actually get some very very
good detail of the fine structures of
that nasal bone you'll notice that
unlike all of the previous projections
we've mentioned that there is no grid
for this particular one you only need to
use a finger exposure so we're talking
in the range of 50 kVp somewhere around
about 2 or 3 mas is an ideal exposure to
get a true lateral projection of the
patient's nasal bones nasal bone
projection you can see on the right-hand
side of screen that lateral projection
if the patient did have a fracture of
those nasal bones we'd see it displaced
there quite quite nicely on the left
hand side of screen we have a Watters
projection and that blue box indicates
the approximate area that you should be
utilizing for a nasal bones water's
projection and that covers our
positioning of the facial bones if you
have any questions please jump onto
discussion board
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