Thorax and Abdomen
Ribs
Anatomy
Students should be able to identify the following structures on radiographic images:
Count ribs from 1-12. Identify: Head of the rib, neck of the rib, tubercle, angle of the rib, body or shaft of the rib, sternal end of the rib, true ribs, false ribs, floating ribs, costocartilage, sternum, costal facets, manubrium, sternal angle, xiphoid process.
Routine Projections (ARRT Required)
PA or AP Ribs (Above Diaphragm)
CR Location & Positioning
- SID: 72 inches preferred (minimizes magnification; improves detail)
- Patient position: Upright preferred; PA for anterior pain, AP for posterior pain
- Adjustments: Affected area closest to IR; MSP centered; shoulders rolled forward if PA
- CR: Perpendicular to IR at level of T7 (≈ 3–4″ below jugular notch or 7–8″ below vertebra prominens); top of IR ~1.5″ above shoulders
- Pt. Instructions: Deep inspiration; hold breath
- Exposure: On full inspiration
Evaluation Criteria
- Coverage (what anatomy must be included and how you verify it’s complete): Ribs 1–9 visualized above diaphragm
- Rotation checks (how symmetry or alignment tells you if positioning is correct): Sternoclavicular joints equidistant from spine
- Motion checks (how sharpness confirms patient cooperation/exposure timing): Sharp diaphragm and heart margins
- Technique checks (what contrast, density, soft tissue visibility, and artifacts to look for): Adequate penetration of ribs through lung fields
- Clinical aim (what contrast, density, soft tissue visibility, and artifacts to look for): Demonstrate upper ribs and lung apices for trauma or pain localization
PA or AP Ribs (Below Diaphragm)
CR Location & Positioning
- SID: 40–44 inches preferred
- Patient position: Supine preferred (elevates diaphragm)
- Adjustments: Affected area closest to IR; MSP centered
- CR: Perpendicular midway between xiphoid process and lower rib margin; bottom of IR at iliac crest
- Pt. Instructions: Full expiration; hold breath
- Exposure: On full expiration
Evaluation Criteria
- Coverage: Ribs 10–12 clearly demonstrated
- Rotation checks: Lateral rib margins equidistant from spine
- Motion checks: Sharp diaphragm margins; no blurring
- Technique checks: Ribs visualized through abdominal organs
- Clinical aim: Demonstrate lower ribs and costophrenic angles for trauma or pain below diaphragm
Oblique Ribs (Anterior or Posterior Obliques)
CR Location & Positioning
- SID: 72 inches for upper ribs; 40 inches acceptable for lower
- Patient position: Upright for upper ribs; supine for lower if needed
- Adjustments: Rotate patient 45°
- PA obliques (RAO/LAO): Affected side closest to IR
- AP obliques (RPO/LPO): Affected side away from IR
Raise arm on elevated side above head; opposite arm down and behind torso
- CR:
- Upper ribs: Perpendicular at T7 (≈ 3–4″ below jugular notch)
- Lower ribs: Midway between xiphoid and lower rib margin; bottom of IR at iliac crest
- Pt. Instructions: Full inspiration for upper ribs; full expiration for lower ribs
- Exposure: On correct breathing phase
Evaluation Criteria
- Coverage:
- Upper obliques: Ribs 1–10 demonstrated
- Lower obliques: Ribs 8–12 demonstrated
- Rotation checks: Affected-side ribs appear twice as far from spine as opposite side
- Motion checks: Sharp axillary rib borders; no blur
- Technique checks: Diaphragm included; uniform brightness
- Clinical aim: Demonstrate axillary and lateral rib portions free of superimposition
Supplemental Projections
Cross-Table Lateral (Trauma or Pneumothorax Assessment)
CR Location & Positioning
- SID: 40 inches
- Patient position: Supine (trauma); dorsal decubitus with side of interest closest to IR
- Adjustments: Elevate arms above head if possible; ensure IR positioned to include area of trauma
- CR: Horizontal beam, perpendicular to IR, centered midway between midaxillary line and region of interest
- Pt. Instructions: Suspend respiration to minimize motion
- Exposure: On inspiration for upper ribs, expiration for lower ribs
Evaluation Criteria
- Coverage: Entire side of interest from sternum to posterior ribs
- Rotation checks: Posterior ribs superimposed; spine lateral
- Motion checks: Sharp diaphragm margins; lung markings clear
- Technique checks: Sufficient contrast to visualize ribs through thoracic structures
- Clinical aim: Evaluate displaced rib fragments, pleural air (pneumothorax), or fluid (hemothorax) without patient rotation
Oblique Chest (Steep 60° RAO/LAO)
CR Location & Positioning
- SID: 72 inches preferred
- Patient position: Upright preferred; rotate 60° from PA position
- Adjustments: Affected anterior ribs closest to IR; arms raised above head; shoulders rotated anteriorly
- CR: Perpendicular to IR at level of T7 (≈ 3–4″ below jugular notch or 7–8″ below vertebra prominens)
- Pt. Instructions: Full inspiration; hold breath
- Exposure: On full inspiration
Evaluation Criteria
- Coverage: Sternum and anterior ribs demonstrated with minimal overlap of vertebral column
- Rotation checks: Adequate 60° obliquity evident by lateral ribs well separated from spine
- Motion checks: Clear lung markings and sharp diaphragm
- Technique checks: Ribs visualized through lung fields without overexposure
- Clinical aim: Evaluate anterior rib fractures near sternum or costal cartilage region
PA Chest (Adjunct View for Rib Trauma)
CR Location & Positioning
- SID: 72 inches
- Patient position: Upright facing IR; MSP centered
- Adjustments: Chin raised; shoulders rolled forward and down; arms at sides
- CR: Perpendicular to IR at level of T7 (≈ 7–8″ below vertebra prominens or inferior angle of scapula)
- Pt. Instructions: Deep inspiration; hold breath
- Exposure: On full inspiration
Evaluation Criteria
- Coverage: Entire lungs from apices through costophrenic angles
- Rotation checks: SC joints equidistant from spine
- Motion checks: Sharp vascular markings; clear diaphragm
- Technique checks: Heart and mediastinum faintly visible through lung fields
- Clinical aim: Evaluate associated lung pathology such as pneumothorax, hemothorax, or contusion from rib injury
Hows & Whys of Rib Radiography
Projection Choices
-
How do you decide between AP vs. PA ribs?
Place injured side closest to IR (AP for posterior pain, PA for anterior pain). -
What projection may be added if patient has hemoptysis (coughing blood)?
A PA chest, to evaluate lungs along with ribs. -
Why do obliques?
To move the spine away from the affected side and demonstrate axillary rib portions.
Breathing Phases & Positioning
-
Why are upper ribs done erect?
Inspiration drops diaphragm, improves lung expansion, more comfortable for patient. -
Why are lower ribs done supine?
Expiration raises diaphragm, evens abdominal thickness, improves penetration of lower ribs. -
Why use full inspiration for upper ribs and expiration for lower ribs?
To position diaphragm at its lowest point (upper ribs) or highest point (lower ribs) for best visualization.
Image Quality
-
Why is 72″ SID preferred?
Minimizes thoracic magnification, improves detail, reduces skin dose. -
Why place IR crosswise at 40″ SID?
To compensate for magnification and ensure lateral ribs don’t project off the film. -
Why might fewer than 10 ribs be seen above the diaphragm, even with inspiration?
Rib fractures may limit full expansion due to pain. -
How do you confirm proper obliquity?
The distance from vertebral column to lateral rib border on affected side is about 2× that of unaffected side.
Clinical Practice
-
What helps the radiologist localize small fractures?
A “BB” marker taped to site of pain.