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Spine and Pelvis Radiography

Jun 26, 2025

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Overview

This lecture covers spine and pelvis anatomy, imaging techniques, standard projections, trauma protocols, and specialty studies such as myelograms and hysterosalpingograms (HSG), with key focus on radiographic positioning and anatomy identification important for exams.

Spine Anatomy & Positioning

  • Know vertebral anatomy (pedicle, lamina, spinous process) and their radiographic appearances.
  • Identify key vertebral landmarks and their topographical levels.
  • Understand central ray (CR) placement and source-image distance (SID) for different spine studies.
  • Review AP, lateral, and oblique positions for cervical, thoracic, and lumbar spine.
  • Cervical spine: 15–20° cephalic angle for AP axial, 72" SID for lateral due to object-image distance.
  • Oblique cervical spine: 45° obliquity; know which side is demonstrated in anterior vs. posterior oblique.
  • Lateral cervical shows vertebral bodies, not foramina; obliques visualize intervertebral foramina.
  • Thoracic spine: CR at T7; lateral shows intervertebral foramina ("O's").
  • Lumbar spine: AP centering usually at crest; lateral just anterior to posterior surface; obliques at 45° centering two inches medial to ASIS.

Specialty Views & Trauma

  • Swimmer’s view used for cervicothoracic junction, check textbook for CR.
  • Flexion/extension views (cervical/lumbar) assess instability or whiplash; only remove cervical collar with physician order.
  • AP Dens (Fuchs) and PA (Judd) methods show odontoid; PA reduces thyroid dose.
  • Know orthostatic breathing technique and anode heel effect (fat under the cathode) for spine images.

Scoliosis Imaging

  • PA projection reduces breast tissue dose, especially important for adolescents.
  • Longer SID used for scoliosis studies, Ferguson (elevated hip) and Cobb methods (angle measurement) may be tested.

Sacrum, Coccyx & SI Joints

  • AP sacrum: 15° cephalic; AP coccyx: 10° caudal ("15 to the nose, 10 to the toes").
  • SI joint AP cephalic angle: 30° male, 35° female. SI joint obliques are less steep; posterior oblique opens side up.

Pelvis & Hip Imaging

  • Know detailed pelvis/hip anatomy and gender differences.
  • AP hip: internally rotate leg 15–20° to place femoral neck in true AP.
  • Frog lateral hip: abduct leg 40°; cross-table lateral (Danelius-Miller), Clements-Nakayama for bilateral hip trauma.
  • Pelvic inlet view: 40° caudal, shows pubic symphysis; outlet view: higher angle in females, shows pelvic rami.

Myelogram & HSG

  • Myelogram: contrast injected into subarachnoid space at L3-L4, below conus medullaris (L1).
  • HSG: evaluates patency of fallopian tubes for infertility; can be both diagnostic and therapeutic.

Key Terms & Definitions

  • Pedicle — part of vertebral arch closest to vertebral body.
  • Lamina — part of vertebral arch connecting spinous process and pedicle.
  • SID (Source-Image Distance) — distance from X-ray source to image receptor.
  • Oblique Position — angled patient/body to visualize certain anatomic structures.
  • Spondylolisthesis — forward displacement of a vertebra.
  • Scotty Dog — lumbar oblique image showing vertebral anatomy.
  • Ferguson Method — scoliosis view with hip block under convex side.
  • Cobb Method — angle measurement for scoliosis.
  • Conus Medullaris — lower end of the spinal cord at L1.
  • HSG (Hysterosalpingogram) — radiographic study of uterus and fallopian tubes.

Action Items / Next Steps

  • Review pelvis, hip, and spine anatomy diagrams.
  • Practice positioning charts and landmark identifications.
  • Study specialty views (Judet, inlet/outlet, Danelius-Miller, Clements-Nakayama).
  • Review myelogram and HSG procedural steps.
  • Prepare for exam questions on positioning, anatomy, and radiation safety.

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