Thorax and Abdomen
3 Ribs
Anatomy
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.
Projections
Ribs, Bilateral PA or AP, above the diaphragm
CR Location
Patient in upright position at 72 inch SID is preferred (40 inch SID minimum). For PA or AP, place the area of interest closer to the IR. CR perpendicular to IR, centered to the midsagittal plane at a level of T7 (3 or 4 inches below jugular notch; or Top of IR 1.5 inches above shoulders). Expose on deep inspiration.
For unilateral images, center midway between the midsagittal plane and the lateral margin of the ribs on the affected side.
Evaluation Criteria
No motion, no rotation (sternoclavicular joints equidistant from spine), optimum exposure to visualize ribs through the heart shadow or abdominal organs without burning out the mid lung area when concerned with the upper ribs. A minimum of 9 posterior ribs should be visualized above the dome of the diaphragm (indicating exposure on full inspiration).
Ribs, Bilateral PA or AP, below the diaphragm
CR Location
Patient in supine position at 40 or 44 inch SID is preferred. For PA or AP, place the area of interest closer to the IR. CR perpendicular to IR, centered to the midsagittal plane at a level midway between xiphoid process and the lower rib margin. Expose upon full expiration.
For unilateral images, center midway between the midsagittal plane and the lateral margin of the ribs on the affected side.
Evaluation Criteria
No motion, no rotation (lateral border of the ribs equidistant from spine), optimum exposure to visualize ribs 10-12 through the heart shadow or abdominal organs.
Ribs, Anterior or posterior obliques
CR Location
Position patient and IR as for the AP or PA projection above. Oblique the patient 45 degrees, moving the patient so that the spine is projected away from the area of interest (affected side toward the IR on PA obliques, affected side away from the IR for AP obliques). Raise elevated side arm above head. Extend opposite arm down and behind patient, away from the thorax. Direct CR perpendicular to the IR at the level of T7 (3-4 inches below jugular notch, or 7-8 inches below vertebra prominens) for upper ribs, at the level midway between the xiphoid process and the lower rib margin (bottom of IR at iliac crest) for lower ribs. Expose on full inspiration for upper ribs and full expiration for lower ribs.
Evaluation Criteria
The diaphragm and heart borders should be sharp and free from motion blur. Appropriate obliquity (the distance from the vertebral column to the lateral border of the ribs on the affected side is approximately twice that of the unaffected side). The axillary (lateral) portion of the ribs should be demonstrated in profile and free from superimposition of the spine. The entire rib cage, from the 1st to the 12th ribs, should be visualized. For upper rib projections, the first 10 ribs are assessed, while lower rib projections focus on ribs 8-12. The ribs should be visible through the lungs or abdomen depending on the region being examined.
Hows & Whys of Rib Radiography
- What projection may be added to a rib series if the patient has been coughing up blood?
- PA chest.
- Why might you see fewer than ten pairs of ribs above the diaphragm when the patient takes in a deep breath?
- Rib injuries are painful and the patient may not be able to take in as full an inspiration.
- How do you decide whether to perform AP or PA ribs?
- The injured area should be closest to the image, so if the patient’s front ribs hurt, the PA projection is done; if their back ribs hurt, the AP projection is done.
- Why is it better to do upper ribs erect?
- It allows better inspiration, so the diaphragm drops lower and is usually more comfortable for the patient.
- Why is it better to do lower ribs with the patient lying down?
- This allows the diaphragm to rise to the highest position and flattens out the abdomen giving you a more uniform thickness to penetrate.
- How do you choose which oblique images to do?
- Select the projection that places the area of interest closest to the image and rotates the spine out of the way.
- Why is an SID of 72 inches preferred?
- The longer SID minimizes magnification of the thorax and reduces skin dose.
- What is often done to help the radiologist locate small rib fractures?
- A “BB” or other small marker is often taped to the site of injury.
- Why is the image receptor placed crosswise when an SID of 40 inches is used?
- The shorter SID (40 inches rather than 72 inches) gives greater magnification and can project the ribs off of lengthwise placed images.