Sternum PA Oblique RAO is a radiography positioning projection of the Thorax. PA oblique sternum (RAO), 15-20 degrees. SID 40". Breathing technique. The centering point is located center of the sternum, about 1 inch left of midline, midway between the jugular notch and xiphoid. Patient in RAO position, 15-20 degrees oblique. The central ray is perpendicular to IR (patient is the rotated element, not the tube). Image-quality criteria include sternum alongside the vertebral column, superimposed on the heart shadow, sternal body, angle, and xiphoid process all visible. A sample technique is 81 kVp with DR 3.2 or CR 6.3 mAs, at the chart's 30 in SID. The working SID is 40 inches (102 cm).
Anatomy demonstrated
- Manubrium.
- Sternal body.
- Xiphoid process.
- Sternal angle and articulations.
Patient preparation
- Verify patient identity using two identifiers.
- Remove all radiopaque objects from the chest.
- Position patient in RAO position, right anterior side closest to IR.
- Rotate 15-20 degrees from true PA position; a deep chest needs less rotation than a thin one.
- Right arm down by the side, left arm up.
- Explain breathing technique: shallow breathing during exposure to blur structures (if not possible, suspend on expiration).
- If the patient cannot be rotated, Bontrager angles the CR 15-20 degrees across the right side of the patient instead.
Position & centering point
Center of the sternum, about 1 inch left of midline, midway between the jugular notch and xiphoid. Patient in RAO position, 15-20 degrees oblique.
Central ray
Perpendicular to IR (patient is the rotated element, not the tube).
Exposure / technique
- kVp
- 81
- mAs
- DR 3.2 / CR 6.3
- Chart row
- kVp and mAs at the chart's 30 in SID
- Working SID
- 40" (102 cm)
- Notes
- Bontrager minimum SID is 40 in; Merrill's uses 30 in to blur the posterior ribs. Breathing technique: low mA and at least a 3-second exposure, with shallow breathing to blur overlying vascular structures. Sample technique: DR 3.2 / CR 6.3 mAs at 81 kVp, 30 in SID, for a 20 cm part (Merrill's sample chart). Adjust for your equipment. Bontrager prints digital 80 +/- 5 kV.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Sternum alongside the vertebral column, superimposed on the heart shadow.
- Sternal body, angle, and xiphoid process all visible.
- Sternal bony margins sharp; lung markings blurred if breathing technique was used.
- Sternum outlined through the overlying ribs, lung and heart.
- Vertebral column visible but not overlapping the sternum.
- Sternum projected left of the vertebral column, over the heart shadow.
Common errors
- 1 Excessive rotation distorts the sternum.
- 2 Breathing technique not performed leaves lung markings sharp over the sternum.
- 3 Insufficient rotation leaves the sternum superimposed on the vertebral column.
- 4 Rotation not matched to habitus: deep chests need less rotation than thin chests.
Clinical indications
- Evaluation of sternal fractures.
- Assessment of sternal osteomyelitis or infection.
- Detection of sternal metastases or pathology.
- Post-operative follow-up after cardiac surgery.