Anatomy - Skull, Mandible & Facial Bones Flashcards
Describe the steps in preparing the room for Skull-related radiography.
Get IR ready and place it in portrait/longitudinal orientation in the errect bucky
Prepare the correct anatomical markers
Place chair facing errect bucky/ IR
Ensure that the X-Ray tube is moved to a safe position
Clean surface of errect body with disinfectant wipes
Pre-set Exposure Factors
Patient Positioning for PA Skull/Mandible
Patient is asked to sit facing the erect bucky
The palm of each hand can be placed on the bucky surface, out of the primary beam or on his/her lap.
Head Positioning for PA Skull/Mandible
Ensure MSP is aligned to midline of bucky
Ensure that the head is not rotated.
EAM is equidistant to erect bucky, MSP perpendicular to IR.
Head Positioning for PA Mandibular Rami
Patient is asked to flex his/her neck so that OML is perpendicular to IR (Similar to OF 0)
Tip - nose & forehead in contact with bucky
Position of Central Ray for PA Mandibular Rami
Direct CR perpendicularly to IR along the MSP and exit the acanthion
Head Positioning for PA Mandibular Body
Patient raise the head so that the acanthiomeatal line (AML) is perpendicular to IR.
Tip - nose & chin in contact with the bucky.
Position of Central Ray for PA Mandibular Body
Direct CR perpendicular to IR along the MSP and centred to level of the lips
Patient Positioning of Mandible - Axiolateral/Axiolateral Oblique
From the PA position, the patient is turned and shoulders rotated slightly
Head is then rotated to the left and right side in turn
Ensure that head is in true lateral position
Midsagittal plane (MSP) should be parallel to IR.
Interpupillary line perpendicular to IR
Mouth should be closed with the teeth together
Extend patient’s neck until long axis of the mandibular body is parallel with transverse axis of the image receptor to prevent superimposition of the cervical spine
Centre x-ray tube to erect bucky & direct Central Ray 25 degrees cephalad to pass through the mandibular region of interest.
Both sides should be examined to demonstrate a possible contrecoup fracture.
Where is the region of interest for Mandible - Axiolateral?
Mandibular ramus.
Where is the region of interest for Mandible - Axiolateral Oblique
Mandibular body and symphysis
What is the direction of turning and degree of angulation for Mandibular Body?
Turn patient’s head 30 degrees towards IR
What is the direction of turning and degree of angulation for Mandibular Symphysis?
Turn patient’s head 45 degrees towards IR
Collimation area for PA Mandibular Rami/Body
Superiorly: 2.5cm above EAM
Inferiorly: Symphysis Menti
Laterally: Lateral skin margins
Collimation area for Mandible - Axiolateral Oblique
Superiorly: EAM of side remote from IR
Inferiorly: Prominence of thyroid cartilage
Anteriorly: Lips/symphysis menti
Posteriorly: 2 cm posterior to EAM of the side remote to IR (away from IR)
Head Position for TMJ - Modified Townes - Fronto-occipital 35 degrees projection
Facing the x-ray tube, patient is asked to flex the neck to bring the OML perpendicular to the bucky
Closed-mouth position:
Posterior teeth, not incisors, must be in contact
Open-mouth position:
If not contra-indicated, the patient opens his/her mouth wide just before exposure
Central Ray position for TMJ - Modified Townes - Fronto-occipital 35 degrees projection
CR is directed 35 degrees caudad and centred along the MSP 7.6cm above the nasion or 2 cm superior to glabella exiting at the base of skull.
42 degrees caudal if IOML is perpendicular to bucky. IOML = Infraorbital meatal line
Head Position for Temporo-mandibular Joints - Axiolateral 30 degrees, open & closed mouth
True lateral position:
MSP parallel to IR
Interpupillary line perpendicular to IR
Central Ray position for Temporo-mandibular Joints - Axiolateral 30 degrees, open & closed mouth
Directed 30 degrees caudad and centred to a point 1.3cm anterior and 5 cm superior to upside EAM
Closed-mouth/open mouth position:
TMJ localized to a point 1.3cm anterior and 2.5cm inferior to the EAM
To perform both projections for comparison
Head Position for TMJ - Axiolateral Oblique 15 degrees projection - Modified Law
After ensuring that head is in the true lateral position, rotate head 15 degrees towards the bucky
Central Ray Position for TMJ - Axiolateral Oblique 15 degrees projection - Modified Law
Directed 15 degrees caudad, centred 4cm superior to upside EAM
Collimation Area for TMJ - Modified Townes
Superiorly: 5 cm above the glabella
Inferiorly: Level of mandibular angles
Laterally: Lateral skin margins
Collimation Area for Temporo-mandibular Joints - Axiolateral 30 degrees
Superiorly: 5cm above centring point
Inferiorly: 5cm below centring point
Anteriorly: 5cm anterior to centring point
Posteriorly: 5cm posterior to centring point
