X-RAY POSITIONING OF FACIAL BONES (2020 UPDATED)

Summary

This 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

00:00

📚 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.

05:01

🔍 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.

10:07

🌡 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.

15:10

👁️‍🗨️ 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.

20:10

🛑 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.

25:11

👃 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.

Keywords

💡Cranial Vault

The cranial vault refers to the upper part of the skull that encloses and protects the brain. In the context of the video, the cranial vault is mentioned as a prerequisite topic for understanding the positioning of the facial bones, emphasizing the interconnected nature of different anatomical regions in radiography.

💡Facial Bones

Facial bones are the structures that form the face, including the maxilla, mandible, zygomatic bones, and others. The video focuses on the positioning and radiographic imaging of these bones, highlighting their delicacy and the challenges in visualizing them due to their thinness and potential for superimposition.

💡CT Scan

CT stands for Computed Tomography, a medical imaging technique that produces cross-sectional images of the body, providing detailed views of bones and soft tissues. The video mentions CT as an excellent modality for investigating facial bone injuries due to its ability to provide clear images of fine structures.

💡Plane Radiography

Plane radiography, also known as X-ray, is a technique that uses electromagnetic radiation to generate images of the internal structures of the body. The script notes its advantages, such as lower dose compared to CT and its ability to show signs of fractures, like fluid levels in the maxillary sinuses.

💡Maxillary Sinuses

The maxillary sinuses are air-filled cavities located within the maxillary bones. The video discusses how fluid levels within these sinuses can indicate fractures and are visible in certain radiographic projections, such as the Waters projection.

💡Waters Projection

Waters projection is a specific radiographic technique used to image the facial bones, particularly focusing on the maxillary sinuses. The video describes different variations of the Waters projection, such as the Waters 0 and Waters 20, and their importance in visualizing fractures and fluid levels.

💡Image Receptor

An image receptor in radiography is the part of the equipment that captures the X-ray image. The script mentions the use of a 24 by 30-inch receptor and its positioning relative to the patient's facial bones to ensure comprehensive imaging of the area.

💡Tube Angulation

Tube angulation refers to the adjustment of the angle of the X-ray tube in relation to the patient. The video explains how different angulations can affect the visualization of structures like the maxillary sinus and the inferior orbital margin in various Waters projections.

💡Lateral Projection

Lateral projection is a radiographic view taken from the side of the patient. The video describes the positioning for a lateral facial bones projection, emphasizing the importance of ensuring the patient's head is in a true lateral position to avoid superimposition of structures.

💡Submental Vertical (SMV) Projection

The submental vertical projection is a challenging radiographic technique that requires the patient to hyperextend their neck to create an image at 90 degrees to the standard anterior-posterior view. The video details the positioning and patient compliance necessary for this projection, which is useful for visualizing the zygomatic arch and nasal bones.

💡Nasal Bones

Nasal bones are the small bones that form the bridge of the nose. The video discusses the importance of imaging these bones in cases of suspected fractures and how specific projections, like the lateral projection, can provide detailed views of the nasal bone structure.

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