Mandible PA (Rami) is a radiography positioning projection of the Skull. PA mandible. Body and rami. CR perpendicular to IR. The centering point is located level of lips, through body of mandible. oml perpendicular to ir.. The central ray is cr perpendicular to ir at level of lips.. Image-quality criteria include entire mandible visualized from symphysis through angles., mandibular body and rami equally visible bilaterally.. Standard exposure ranges from 75 to 85 kVp, 20 to 30 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Mandibular body from symphysis to angle.
- Mandibular rami bilaterally.
- Mental eminence and mental protuberance.
- Mandibular angles, TMJs just above rami.
- Condyles and coronoid processes.
- Inferior alveolar canal suggested by dental anatomy.
Patient preparation
- Verify patient identity.
- Remove glasses, earrings, dentures, hairpins.
- Position patient prone or upright.
- Forehead and nose against IR; OML perpendicular to IR.
- No rotation: shoulders and head symmetrical.
- Hands at sides or folded over chest.
- Suspend respiration during exposure.
Position & centering point
Level of lips, through body of mandible. OML perpendicular to IR.
Central ray
CR perpendicular to IR at level of lips.
Exposure / technique
- kVp
- 75–85
- mAs
- 20–30
- SID
- 40" (102 cm)
- Notes
- Small focal spot for detail. Suspended respiration.
Image-quality criteria
- Entire mandible visualized from symphysis through angles.
- Mandibular body and rami equally visible bilaterally.
- Mental eminence in midline without rotation.
- No overlap: angles of mandible clearly outlined.
- TMJs projected just above mandibular rami.
- Mandible centered on IR with margin.
Common errors / ARRT traps
- 1 Rotation: mandibular angles appear unequal distance from midline.
- 2 Tilt: one side of mandible appears longer than other.
- 3 CR not at lip level: mandibular body off-center.
- 4 OML not perpendicular: geometric distortion.
- 5 Patient leaning: asymmetrical visualization of rami.
Clinical indications
- Mandibular body and rami fracture evaluation.
- Trauma to lower jaw and chin assessment.
- TMJ area evaluation for pathology.
- Pre- or post-operative mandibular follow-up.
Aligned to the 2025 ARRT Content Specifications.