Pelvis 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 at midline, midway between the asis and the pubic symphysis (~2 inches inferior to the asis).. The central ray is perpendicular to ir at midline, midway between the asis and pubic symphysis.. Image-quality criteria include entire pelvis visible from iliac crests to ischial tuberosities., femoral heads and proximal femora included.. Standard exposure ranges from 75 to 85 kVp, 15 to 25 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Iliac crests and wings.
- Acetabula and hip joints.
- Proximal femoral heads and necks.
- Pubic bones and pubic symphysis.
- Ischial tuberosities.
- Sacroiliac joints.
Patient preparation
- Verify patient identity using two identifiers.
- Remove all radiopaque objects from pelvis and hip region.
- Place patient supine on table.
- Extend legs and internally rotate 15-20 degrees.
- Ensure pelvis is level, shoulders and pelvis symmetric.
Position & centering point
At midline, midway between the ASIS and the pubic symphysis (~2 inches inferior to the ASIS).
Central ray
Perpendicular to IR at midline, midway between the ASIS and pubic symphysis.
Exposure / technique
- kVp
- 75–85
- mAs
- 15–25
- SID
- 40" (102 cm)
- Notes
- Grid required. Shows entire pelvis and proximal femora.
Image-quality criteria
- Entire pelvis visible from iliac crests to ischial tuberosities.
- Femoral heads and proximal femora included.
- Acetabula symmetric and open.
- Pubic bones symmetric without rotation.
- Sacroiliac joints symmetric, no pelvic tilt.
- Collimation: includes entire pelvis within margins.
Common errors / ARRT traps
- 1 Insufficient internal rotation superimposes lesser trochanters over femoral necks.
- 2 Pelvic rotation makes acetabula and ischium asymmetric.
- 3 Flexed legs shorten femoral shafts and distort hip joints.
- 4 Off-centered CR excludes pelvis or femora.
Clinical indications
- Pelvic fracture evaluation.
- Hip dislocation assessment.
- Pelvic instability evaluation.
- Pre-operative pelvic positioning study.
Aligned to the 2025 ARRT Content Specifications.