Radiographic Procedures · ARRT 2025
Spine and Bony Thorax Positioning
Cervical, thoracic, lumbar spine projections, the Scotty Dog (oblique L-spine), trauma C-spine, sternum, and ribs for the ARRT Radiography Boards.
Overview
Axial Skeleton: Spine and Bony Thorax is dense, high-yield ARRT material. Roughly 8–10% of the registry tests spine and thorax projections, and the chapter rewards memorization of central-ray angulation. The cervical spine has special trauma protocols. The lumbar spine has the famous Scotty Dog. The sternum and ribs require a careful match of projection to clinical question.
Cervical spine routines: AP open-mouth (odontoid view, beam perpendicular, mouth open to demonstrate C1 and the dens), AP axial (15–20° cephalic to demonstrate C3–C7), lateral (horizontal beam, weights pulling shoulders down to clear C7), and oblique (45° rotation, central ray 15–20° cephalic for posterior obliques to demonstrate the intervertebral foramina away from the IR; or caudal for anterior obliques to demonstrate foramina close to the IR). Trauma C-spine: cross-table lateral first, every time, before any other view.
Thoracic spine: AP (perpendicular CR) and lateral (with breathing technique to blur the ribs). Lumbar spine: AP, lateral, oblique (45° rotation, the posterior oblique demonstrates the side closest to the IR; the famous Scotty Dog pattern is on this oblique view). The L5-S1 spot uses a 30° caudal CR for women, 35° caudal for men, centered 1.5 inches inferior to the iliac crest. Sternum: RAO 15–20° and lateral. Ribs above the diaphragm imaged on inspiration, below the diaphragm on expiration.
What you’ll learn in this chapter
The 14 lessons in this chapter break down as follows. The full lesson content is unlocked when you start a free account.
Cervical Spine
- Cervical Anatomy & Foundational Projections
- Cervical Trauma: The Horizontal Beam Lateral
Thoracic Spine
- Thoracic Spine: Anatomy & Core Techniques
- Osteoporosis & Compression Fractures
Lumbar Spine
- Lumbar Spine: AP & Lateral
- The Scotty Dog — Lumbar Oblique
L5-S1, Sacrum & Coccyx
- L5-S1 & Sacrum: Specialized Views
- Coccyx & Scoliosis Series
Bony Thorax
- Visualizing the Sternum
- Rib Radiography: A Systematic Approach
Knowledge Check
- Question 1 of 4 Quiz
- Question 2 of 4 Quiz
- Question 3 of 4 Quiz
- Question 4 of 4 Quiz
Key terms in this chapter
These are the 7 terms most likely to appear on the ARRT registry from this chapter. Use them as a flashcard pre-quiz.
- Open-Mouth Odontoid
- AP cervical projection with the mouth open. Demonstrates C1, C2, and the dens between the upper teeth and skull base.
- Scotty Dog
- Anatomic pattern on a 45° lumbar oblique where the pars interarticularis is the dog's neck. A 'collar' indicates spondylolysis.
- Spondylolysis
- Defect in the pars interarticularis. Visible as a 'collar' on the Scotty Dog (lumbar oblique).
- AP Axial Cervical
- AP projection with 15–20° cephalic central-ray angulation. Demonstrates C3 through C7 with the intervertebral disk spaces open.
- Cross-Table Lateral C-Spine
- Horizontal-beam lateral with the patient supine. The first projection in any C-spine trauma series.
- RAO Sternum
- Right anterior oblique 15–20° rotation. Throws the sternum off the spine and against the heart shadow.
- Breathing Technique
- Slow, shallow breathing during exposure to blur overlying lung markings on T-spine and sternum laterals.
Sample practice question: Head, Spine, and Pelvis
One free sample from the 68-question Head, Spine, and Pelvis bank. See the format, the rationale style, and the difficulty before you sign up.
A 45° posterior oblique projection of the lumbar spine demonstrates the Scotty Dog pattern. A defect appearing as a 'collar' on the dog's neck represents which of the following pathologies?
Show answer and rationale
A, Incorrect: Spondylolisthesis is forward slippage of one vertebra on another, best assessed on lateral imaging.
B, Correct: Correct. The Scotty Dog's neck represents the pars interarticularis. A 'collar' on the neck indicates spondylolysis, a defect or fracture of the pars. This finding is pathognomonic on the 45° lumbar oblique.
C, Incorrect: Disk herniation is not directly visible on plain radiographs and requires MRI for diagnosis.
D, Incorrect: Compression fractures involve loss of vertebral body height and are best demonstrated on lateral views.
Hands-on
Practice the positioning
Open the Positioning Lab to drill body position, central ray, anatomy, and common errors for each projection in this chapter.
- AP Odontoid (Open Mouth) Supine, mouth open wide, CR perpendicular. C1-C2 visualization.
- AP Dens (Fuchs) Supine, head extended, CR perpendicular. Alternate dens visualization.
- AP Axial Cervical Supine, CR 15-20° cephalad, centered C4. Lower cervical survey.
- Lateral Cervical Erect lateral, CR perpendicular to C4, 72" SID. Standard survey.
- Lateral Cervical (Swimmers) Erect lateral, arm raised, CR to C7-T1. Twining method.
- Lateral Cervical (Flexion) Erect lateral, head flexed forward, CR to C4.
- Lateral Cervical (Extension) Erect lateral, head extended backward, CR to C4.
- AP Thoracic Supine, arms at sides, CR perpendicular to T7. Grid required.
- Lateral Thoracic Lateral recumbent, CR perpendicular to T7. Breathing technique.
- AP Lumbar Supine, knees flexed, CR perpendicular to the iliac crest (L4). Grid required.
- Lateral Lumbar Lateral recumbent, knees flexed, CR perpendicular to the iliac crest (L4).
- AP Oblique Lumbar Zygapophyseal Joints 45° oblique, RPO or LPO, CR to L3. Facet joints.
- L5-S1 Lumbosacral Junction Lateral recumbent, CR to L5-S1 junction. Flexed knees.
- Chest PA Upright PA chest. SID 72". Inspiration on second breath.
- Chest AP Anteroposterior upright chest projection. SID 72".
- Chest Lateral Left or right lateral upright chest projection. SID 72".
- Chest Lateral Decubitus Patient on side with horizontal beam. SID 72".
- Chest Dorsal Decubitus Supine chest with horizontal beam. SID 72".
- Lungs AP Axial Lordotic AP lordotic for pulmonary apices. Patient leans back ~30°. SID 72".
- Ribs Posterior AP AP posterior ribs, erect. SID 40". Breathing varies by location.
- Ribs Anterior PA PA anterior ribs, erect. SID 40". Full inspiration.
- Ribs AP Oblique AP oblique ribs, 45-degree. SID 40". Full inspiration.
- Ribs PA Oblique PA oblique ribs, 45-degree. SID 40". Full inspiration.
- Sternum PA Oblique RAO PA oblique sternum (RAO), 15-20 degrees. SID 30". Breathing technique.
- Sternum Lateral Lateral sternum, erect. SID 72". Arms raised.
- Sternoclavicular Joints PA PA sternoclavicular joints. SID 40".
- Sternoclavicular Joints PA Oblique PA oblique SC joints, 15 degrees. SID 40".
Read the full chapter, free.
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Frequently asked questions
What does the ARRT Radiography Radiographic Procedures category cover?
Axial Skeleton: Spine and Bony Thorax is dense, high-yield ARRT material. Roughly 8–10% of the registry tests spine and thorax projections, and the chapter rewards memorization of central-ray angulation. The cervical spine has special trauma protocols. The lumbar spine has the famous Scotty Dog. The sternum and ribs require a careful match of projection to clinical question.
How many lessons are in the Spine and Bony Thorax Positioning chapter?
This chapter contains 14 lessons across 6 sections, plus a knowledge-check quiz at the end. The full lesson content is unlocked with a Premium subscription. The free tier includes the first chapter complete.
Is this chapter aligned with the ARRT 2025 Content Specifications?
Yes. Every chapter on this site maps directly to the ARRT Radiography Content Specifications effective 2025. This chapter falls under the Radiographic Procedures domain of the official ARRT exam blueprint.