Thorax and Abdomen
Sternum
Anatomy
jugular or suprasternal notch, clavicular notch, costal facets, manubrium, sternal angle, sternal body, xiphoid process.
Routine Projections (ARRT Required)
RAO Sternum
CR Location & Positioning
- SID: 40 inches or less (short distance increases magnification of sternum for contrast)
- Patient position: Upright or prone; 15–20° RAO (right anterior chest closest to IR)
- Adjustments: Rotate shoulders forward to bring sternum closer to IR
- CR: Perpendicular to IR, centered midway between jugular notch and xiphoid process, about 1 inch left of MSP
- Pt. Instructions: Suspend respiration on expiration, or use breathing technique (low mA, 2–3 sec exposure) to blur lung markings
- Exposure: On expiration or during breathing technique
Evaluation Criteria
- Coverage (what anatomy must be included and how you verify it’s complete): Entire sternum from jugular notch through xiphoid process
- Rotation checks (how symmetry or alignment tells you if positioning is correct): Sternum projected over heart shadow, free from spine
- Motion checks (how sharpness confirms patient cooperation/exposure timing): Sharp bony margins (if suspended) or blurred lung fields (if breathing technique used)
- Technique checks (what contrast, density, soft tissue visibility, and artifacts to look for): Sternum visible through heart shadow without overexposure
- Clinical aim (what contrast, density, soft tissue visibility, and artifacts to look for): Demonstrate the sternum free of vertebral superimposition
Lateral Sternum
CR Location & Positioning
- SID: 60–72 inches (longer distance compensates for large OID)
- Patient position: Upright preferred; left side against IR
- Adjustments: Arms drawn back with hands clasped; shoulders rotated posteriorly; MSP parallel to IR
- CR: Perpendicular to IR, centered midway between jugular notch and xiphoid process; top of IR about 1.5″ above jugular notch
- Pt. Instructions: Suspend respiration on full inspiration to move sternum laterally away from spine
- Exposure: On full inspiration
Evaluation Criteria
- Coverage: Entire sternum visualized without superimposition from ribs, humeri, or soft tissue
- Rotation checks: Posterior ribs directly superimposed (true lateral)
- Motion checks: Sharp anterior and posterior borders of sternum
- Technique checks: Adequate density and contrast; margins well defined
- Clinical aim: Demonstrate lateral sternum in profile for evaluation of displacement or deformity
Supplemental Projections
LPO Sternum (Alternative for Trauma or Limited Mobility)
CR Location & Positioning
- SID: 40 inches
- Patient position: Supine or upright in LPO (left posterior oblique)
- Adjustments: Rotate 15–20° (opposite of RAO) so sternum projects over heart shadow
- CR: Perpendicular to IR, centered midway between jugular notch and xiphoid process, about 1 inch right of MSP
- Pt. Instructions: Suspend respiration on expiration, or use slow breathing if tolerated
- Exposure: On expiration or during breathing technique
Evaluation Criteria
- Coverage: Entire sternum from jugular notch through xiphoid process
- Rotation checks: Sternum projected over heart shadow, free from spine
- Motion checks: Lung markings blurred if breathing technique used
- Technique checks: Uniform exposure across sternum and mediastinum
- Clinical aim: Substitute for RAO in trauma or nonambulatory patients
Hows & Whys of Sternum Radiography
Anatomy
- How many parts make up the sternum, and what are they?
Three — the manubrium, body, and xiphoid process. - How do the costal notches function?
They provide articulation points for the costal cartilages of the first seven ribs. - How can vertebral levels help with positioning?
They guide centering: T2–T3 (jugular notch), T4–T5 (sternal angle), T9–T10 (xiphoid process).
Positioning
- Why is the RAO position used for the sternum?
It projects the sternum over the heart shadow, avoiding superimposition with the thoracic spine. - Why might an LPO be used instead of RAO?
For trauma or limited mobility; LPO provides equivalent projection geometry. - Why is 15–20° rotation used?
Rotation varies by body habitus — larger patients require more rotation, thinner patients less — to keep the sternum clear of the spine. - Why is the breathing technique helpful for the RAO?
It blurs lung and rib detail, making the sternum margins more distinct. - Why is the lateral sternum performed on inspiration?
Inspiration expands the chest, moving the sternum away from the thoracic spine. - Why use a long SID for the lateral sternum?
To compensate for large OID and reduce magnification.
Technique & Image Evaluation
- How do you know there’s no rotation on the lateral sternum?
Posterior ribs are directly superimposed, and the sternum appears as a sharp vertical structure. - How do you verify correct density and contrast?
Sternum should be visible through heart shadow with clear cortical margins. - How do you confirm correct positioning on the RAO?
Sternum centered over the cardiac shadow, not over the spine or lateral ribs. - How do you ensure radiation safety during the exam?
Keep the tube at least 12 inches from the patient; use tight collimation and shielding when possible.
Clinical Applications
- Why perform a sternum study after blunt chest trauma?
To identify fractures and evaluate for potential cardiac or pulmonary injury. - Why include both RAO and lateral views?
RAO visualizes the sternum free of the spine, while the lateral shows displacement or depression fractures. - Why might the technologist adjust mAs for a sternum exam?
Moderate increases may be necessary for trauma patients with immobilization devices, swelling, or thick body habitus. - Why is careful rotation selection important?
Incorrect rotation either superimposes the sternum on the spine or shifts it too far laterally over the lung field, obscuring margins.