Hip AP is a radiography positioning projection of the Pelvis. Supine, legs extended and internally rotated 15-20 degrees. SID 40". The centering point is located 1.5-2.5 inches distal to the midpoint of the asis-pubic symphysis line, at the femoral neck.. The central ray is perpendicular to ir, centered to the femoral neck.. Image-quality criteria include femoral head, neck, and proximal shaft visible., lesser trochanter visible in profile, not superimposed.. Standard exposure ranges from 75 to 85 kVp, 12 to 20 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Femoral head and neck.
- Greater and lesser trochanters.
- Proximal femoral shaft.
- Acetabulum and pelvic inlet.
- Ischium, pubis, and ilium.
- Hip joint space.
Patient preparation
- Verify patient identity using two identifiers.
- Remove all radiopaque objects from the hip region.
- Place patient supine on the table.
- Extend legs and internally rotate 15-20 degrees to align femoral neck.
- Ensure pelvis is level and not rotated.
Position & centering point
1.5-2.5 inches distal to the midpoint of the ASIS-pubic symphysis line, at the femoral neck.
Central ray
Perpendicular to IR, centered to the femoral neck.
Exposure / technique
- kVp
- 75–85
- mAs
- 12–20
- SID
- 40" (102 cm)
- Notes
- Grid required. Tabletop technique with grid cassette.
Image-quality criteria
- Femoral head, neck, and proximal shaft visible.
- Lesser trochanter visible in profile, not superimposed.
- Acetabulum open and symmetric.
- Ischium and pubis visible with minimal distortion.
- No motion blur; bone trabeculae sharp.
- Collimation: 2 inches beyond hip joint margins.
Common errors / ARRT traps
- 1 Insufficient internal rotation superimposes lesser trochanter over femoral neck.
- 2 External rotation foreshortens femoral neck and closes acetabulum.
- 3 Pelvic rotation obscures symmetry and distorts anatomy.
- 4 Off-centered CR clips femoral head or excessive pelvis.
Clinical indications
- Hip fracture evaluation (femoral neck, intertrochanteric, subtrochanteric).
- Suspected hip dislocation.
- Hip osteoarthritis assessment.
- Post-operative follow-up of hip fixation or replacement.
Aligned to the 2025 ARRT Content Specifications.