Radiology Flashcards
What is the selection criteria for Cephalometric Radiographs
- Evaluate growth and development of the cranium and face
- Evaluate the relationship betweeen orofacial and dental structures
- Monitor orthodontic/orthognathic treatment progression
- Evaluate other craniofacial abnormalities and trauma
Imaging Technique
- Cephalostat: ear rods & nasion indicator help stabilize the patient
- Distances are maintained constant for comparison of sequential radiographs
- Structures furtheresst from receptor=most magnification
- Structures closest to receptor=least magnification
- Less discrepancy of (bilateral) midline structures (5-6% magnification)
Source to object distance
5 Ft
* Minimizes image magnification
Image Receptor Dimensions
20x25 cm (8x10 inch)
Object to receptor distance
10-15 cm
Lateral vs PA Cephalometric image:
1. Head Placement
2. Receptor Placement
3. Beam Direction
4. Beam centers at
Lateral:
* Beam: also directed perpendicular to midsagittal plane
Patient Positioning for Cephalometric imaging
- Remove Jewelry and oral appliances
- Shielding (lead apron) and barriers
- Ear rods inside ear canals
- Ruler on Nasion
- NHP-look straight ahead into mirror, focus on eyes facilitates NHP
- Frankfort plane parallel to the floor
- Lips relaxed (no smile or grimace)
Lateral Cephalometric: Indications
Most common
* Evaluate the AP relationships b/w maxilla, mandible, and cranial base
* Assess skeletal and soft tissue relationships
* Proceed with orthognathic sx tx planning
* Monitor progress of tx and tx outcomes
Point A
- Deepest anterior concavity on the maxillary alveolus
Point B
- Deepest anterior concavity on mandibular symphysis
Sella (S)
- Midpoint of the sell turcica
- Pituitary Fossa
Nasion(N)
- The most anterior point on the fronto-nasal suture
Orbitale (Or)
- The most anterior, inferior point on the infraorbital rim
Anterior Nasal Spine (ANS)
- Tip of the anterior nasal spine
Posterior Nasal Spine (PNS)
- Tip of the posterior nasal spine
Gonion (Go)
- Most posterior, inferior point on the mandibular angle
Gnathion (Gn)
- Most anterior, inferior point on the mandibular symphysis
Menton (Me)
- Most inferior point on the mandibular symphysis
Pogonion (Pog)
- most anterior point on the mandibular symphysis
Sn Line
Nasion to sella
Frankfort Plane
orbitale and porion
Mandibular Plane (MnPl)
- Gonion to Menton
Maxillary Plane (MxPl)
- Anterior nasal spine to Posterior Nasal Spine
SNA
AP Position of the maxilla to the cranial base
SNB
AP Position of the mandible to the cranial base
ANB
- AP postion of the Maxilla to the Mandible
- Skeletal Class
Maxillary-mandibular plane angle (MMPA)
Angle formed b/w the Maxillary plane and mandibular plane
Maxillary Incisal Inclination
Angle b/w the maxillary plane (MxPl) and maxillary incisors axis (UInc)
Mandibular Incisal Inclination
- Angle b/w the mandibular plane and mandibular incisors axis (LInc)
Posteroanterior Cephalometric: Indications
- Evaluate craniofacial asymmetry
- Assess Jawl Skeletal Relationships
- Proceed with orthognathic sx tx planning
- Monitor Progress of tx and tx outcomes
SAME AS Lateral
What is circled in purple?
Ethmoid air cells
What is circled in green?
Frontal Sinus
What is circled in red?
Maxillary Antrum
Indicationos for CBCT in ortho
- Assess skeletal and dentofacial structures
- 3D Localization of impacted teeth
- Growth Assessment
- Pharyngeal airway analysis
- Cleft palate assessment
- Orthognathic sx planning
- Planning the placment of temporary anchorage devices
- custom ortho appliance fabrication
What is required to spatially localize pathology?
- Take at least 2 radiographs that are right angles to each other
What is the main anatomical landmark used in patient positioning during extraoral radiography?
Canthomeatal Line
Canthomeatal Line
- External auditory canal center to outer canthus of the eye
- 10 degrees from FP
What is the sequence for interpretation of Lateral Cephalometric projections?
- Skull & Calvaria
- Upper & Middle Face
- Mandible
- Cervical Spinne/airway/neck
- ALveolar Bone/Teeth
What is the sequence for interpretation of Anteroposterior Cephalometric projections?
- Calvaria & Sutures
- Upper & Middle Face
- Lower Face
- Cervical Spine
- Alveolar Bone & Teeth
Cephalometric Projections
Allow for reproducible imaging of the craninofacial region
Made w/a cephalostat
* maintains a constant relationship b/w skull, receptor, & x-ray beam
film or digital receptors
Lateral Cephalometric projections: Structures close to midsagittal plane
Structures close to midsagittal plane: Nearly Superimposed
* clinoid process
* inferior turbinates
Identify 1
Sella Turcica
Identify 2
Nasion (N)
Identify 3
Orbitale (Or)
Identify 4
Porion (Po)
Identify 5
Point A
Identify 6
Point B
Identify 7
Pogonion (Pog)
Identify 8
Menton (Me)
Identify 9
Gnathion (Gn)
Identify 10
Gonion (Go)
Identify 11
Mandibular Incisal Edge
Identify 12
Maxillary Incisal Edge
Identify 13
Upper Lip
Identify 14
Lower Lip
Identify 15
Subnasale
Identify 16
Soft Tissue Pogonion
Identify 17
Posterior Nasal Spine (PNS)
Identify 18
Anterior Nasal Spine (ANS)
Identify 19
Articulare
