Mandible Submentovertical (SMV) is a radiography positioning projection of the Skull. SMV mandible. Entire mandible. IOML parallel to IR. The centering point is located midline under chin. ioml (infraorbitomeatal line) parallel to ir.. The central ray is perpendicular to ioml. centered at midline under chin.. Image-quality criteria include entire mandible visualized from symphysis through both angles., mandibular body and rami without superimposition.. Standard exposure ranges from 75 to 85 kVp, 25 to 40 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Mandibular body from symphysis to angle.
- Ascending mandibular rami.
- Mandibular angles and gonial angle.
- TMJs lateral to rami without overlap.
- Condyles, coronoid processes.
- Mental eminence, lingual landmarks.
Patient preparation
- Verify patient identity.
- Remove glasses, earrings, dentures, hairpins.
- Position patient supine or upright with head tilted back.
- Vertex of head against IR; chin fully extended upward.
- IOML (infraorbitomeatal line) parallel to IR.
- No rotation: shoulders and head symmetrical.
- Suspend respiration during exposure.
Position & centering point
Midline under chin. IOML (infraorbitomeatal line) parallel to IR.
Central ray
Perpendicular to IOML. Centered at midline under chin.
Exposure / technique
- kVp
- 75–85
- mAs
- 25–40
- SID
- 40" (102 cm)
- Notes
- Chin extension critical. IOML must be parallel to IR.
Image-quality criteria
- Entire mandible visualized from symphysis through both angles.
- Mandibular body and rami without superimposition.
- TMJs projected lateral to mandibular rami.
- No rotation: symphysis in midline, angles equidistant.
- No foreshortening: rami parallel to border of IR.
- Mandible centered on IR with margin.
Common errors / ARRT traps
- 1 Head not extended enough: mandible superimposed on spine.
- 2 IOML not parallel to IR: rami foreshortened.
- 3 Rotation: symphysis off-center, angles asymmetrical.
- 4 Tilt: one ramus appears longer than other.
- 5 Chin pressed toward chest: mandible not fully visualized.
Clinical indications
- Entire mandible fracture assessment.
- Evaluation of mandibular body, rami, and angles.
- TMJ visualization without overlap.
- Mandibular trauma with multiple suspected fractures.
- Pre- or post-operative mandibular evaluation.
Aligned to the 2025 ARRT Content Specifications.