Sternum and SC Joints
Anterior Oblique RAO & LAO - SC Joints: Technical Factors & Positioning
*Best visualizes the SC joint on downside, which also is demonstrated closest to the spine on the radiograph Technical Factors - 40" SID, 8x10 - Grid - kVp range: 75 to 85 Position - Prone or erect with slight rotation (10° to 15°) of thorax with upside elbow flexed and hand placed adjacent to head - With patient rotated 10° to 15°, align and center spinous process 1 to 2" lateral (toward upside) to CR and midline of grid/table/bucky - Center IR to CR *CR perpendicular to level of T2 to T3, or 3" distal to vertebra prominens, and 1 to 2" lateral (toward upside) to midsagittal plane - *Collimate to region of SC joints - *Suspend on expiration for a more uniform density RAO: best demonstrates the right SC joint in the left lung field LAO: best demonstrates the left SC joint in the right lung field
Lateral Sternum: Technical Factors & Positioning
*Perform first to reduce the amount of work Technical Factors - 60-72" SID, minimum of 40" SID - 10x12 or 14x14 - Grid - *75-85 kVp - Erect or lateral recumbent Erect: - Position patient standing or seated with shoulders and *arms drawn back Lateral Recumbent: - Position patient lying on side with *arms up above head and keeping shoulders back Supine: - Cross table trauma - *Place top of IR 1 ½" above the jugular notch - Align long axis of sternum to CR and midline of grid/table/bucky - Ensure a true lateral with no rotation - CR is perpendicular to IR - *CR is directed to center of sternum (midway between the jugular notch and xiphoid process - you basically want it in front of the level of the armpit) - Center IR to CR - *Suspend respiration on full inspiration Note: breasts of female patients may be drawn to the sides and held in position with a wide bandage if necessary
PA vs AP SC Joints
- *PA projections provide the least amount of magnification distortion and reduce the amount of radiation reaching the patient's thyroid. - Sternoclavicular joint projections are typically performed PA, rather than AP, which can be challenging for the technologist. - In the AP projection, the SC joints are more easily located.
Ribs
- 12 pairs, 24 total - Each rib is numbered according to the thoracic vertebra to which it attaches; therefore, the ribs are numbered from the top down
PA SC joints: Radiograph
- Bilateral right and left SC joints - Lateral aspect of manubrium and medial portion of the clavicles visualized lateral to vertebral column through superimposing ribs and lungs - No rotation of patient, demonstrated by equal distance of SC joints from vertebral column on both sides
Sternoclavicular Joint
- Each clavicle articulates medially with the manubrium of the sternum at the clavicular notch; this is called the sternoclavicular joint - It is the only bony connection between each shoulder girdle and the body thorax
Lateral Sternum: Radiograph
- Entire sternum with minimal overlap of soft tissue - Shoulders and arms drawn back - Correct patient position with no rotation demonstrates 1. Entire sternum with no superimposition of ribs 2. Lower aspect of sternum not obscured by breasts for female patient
Bony Thorax
- Main function: to serve as an expandable, bellows-like chamber, wherein the interior capacity expands during inspiration and contracts during expiration; and protect important organs of the respiratory system and vital structures within the mediastinum (heart & great vessels) - These acts of respiration are created by the synchronous work of muscles attached to the rib cage and atmospheric pressure, resulting in air moving into and out of the lungs during respiration - *Consists of the sternum anteriorly, the thoracic vertebrae posteriorly, and the 12 pair of ribs that connect the sternum to the vertebral column - The thin sternum is superimposed by the structures within the mediastinum and the dense thoracic spine in a direct frontal position. Therefore, any AP or PA projection radiograph would demonstrate the thoracic spine but would show the sternum minimally, if at all.
Xiphoid Process (T9-T10)
- Most inferior portion of the sternum - Composed of cartilage during infancy and youth. It does not become totally ossified until about the age of 40 yrs. - Generally is rather small, but can vary in size, shape, and degree of ossification
RAO Sternum: Radiograph
- Sternum is visualized, superimposed on heart shadow (but it's a good thing cause it makes it look like a pillow) - Correct patient rotation is demonstrated by visualizing sternum alongside vertebral column with no superimposition by vertebrae - No distortion of sternum due to excessive rotation of the thorax - Bony margins sharp - Breathing technique makes lung markings appear blurred
Sternum
- The adult sternum is a thin, narrow, flat bone with three divisions 1. Manubrium 2. Body 3. Xiphoid process: at the level of T9-T10 - The total length of the adult sternum is approximately 7" (18 cm) - It is composed of highly vascular cancellous tissue covered by a thin layer of compact bone; allows for the sternum to be a common site for marrow biopsy, in which, under local anesthesia, a needle is inserted into the medullary cavity of the sternum to withdraw a sample of red bone marrow
Rib Articulations
- The first seven pairs of ribs connect anteriorly to the sternum through individual sections of costocartilage. - The sternum has seven pairs of facets, or depressions, located laterally along the manubrium and body to accept the costocartilage. - The 1st pair of facets is located just below the clavicular notch - The 2nd costal cartilage connects to the sternum at the level of the sternal angle. - The 3rd-7th costal cartilage connect directly to the body of the sternum
False Ribs (8-12)
- The last five pairs of ribs - All false ribs, except rib pairs 11 and 12, have costal cartilage that join together at the costocartilage of rib 7
Lateral Supine Sternum Adaptation:
- The lateral image can be obtained with the use of a horizontal x-ray beam with patient in the supine position if patient's condition warrants this modification - For people with a bigger thoracic cavity, you might not have to get the arms out of the way, you will need to get them up and away for skinnier patients
Body of the sternum
- The longest part of the sternum - About 4" (10 cm) long - At birth, the body of the sternum is in four separate segments. The union of these four segments begins during puberty and may not be complete until about the age of 25 years.
Sternal Angle (T4-T5)
- The lower end of the manubrium joins the body of the sternum to form a palpable prominence, the sternal angle (manubriosternal joint) - Located at the level of the intervertebral disk space between T4 and T5
Anterior Oblique RAO & LAO - SC Joints: Radiograph
- The manubrium, medial portion of clavicles, and SC joints are best demonstrated on the downside - SC joint on the upside will be foreshortened - Correct patient rotation demonstrates the downside SC joint visualized with no superimposition of the vertebral column or manubrium
Jugular Notch (T2-T3)
- The upper most border of the manubrium has a slightly notched area between the two clavicles, and is easy to visualize and palpate. This area is termed the jugular notch - The terms suprasternal notch and manubrial notch are also used. - The jugular notch is at the level of T2 to T3
Manubrium
- Upper portion of the sternum - Adult manubrium averages 2" in length
Exposure Factors for Sternum (kVp?)
- Very difficult to obtain optimal density and contrast on sternum images - This is because the sternum is made of primarily spongy bone with a thin layer of hard compact cone surrounding it. This, combined with the close proximity of the easy-to-penetrate lungs and the harder-to-penetrate mediastinum/heart, make exposure factors a challenge - A kVp range of 70-85 is recommended for adult sthenic patients.
Prof. Casey-Gifford Notes for Sternum + SC joints:
- You know it's overexposed when the image is pretty much black & white - Suggests setting your own technique instead of using AEC (kVP: 75, mAS: 20-25) - It's been published that a sternum x-ray can be taken at 32" for better visualization, not that we're doing it in lab - Should be no blurring at xiphoid process - Trauma Tabletop Sternum: needs a grid otherwise you'll just see all white - You approximately get a 15° to 20° rotation by simply telling the patient to put their left arm up - Tell patients to take in a deep breath - You can kinda tell where the sternum is in an RAO by looking for the clavicles and going down that line - For SC joints: collimate to the SC joints + 1/3 clavicle - For a lateral sternum have patient roll their shoulders backward and clamp their hands behind them
Sternum SID
- a minimum SID for an RAO of the sternum is 40" - 60-72" SID, minimum of 40" SID for a lateral sternum - In the past, a common practice was to lower the SID to create magnification of overlying posterior ribs with resultant sharpness (blurring) - This practice is NOT recommended because it increases patient dose.
Adaptation for Anterior Oblique - RAO & LAO: SC Joints
1. If the patient's condition requires this, oblique images may be obtained by using posterior oblique with 10° to 15° rotation with the CR 1 to 2" lateral to midsagittal (toward downside). The upside SC joint would be best visualized in this projection 2. Oblique images may also be obtained by angling the CR 15° across the patient to project the SC joint lateral to the vertebrae. A portable grid would be required and should be placed crosswise on the stretched or tabletop to prevent grid cutoff.
Because the thoracic spine is more dense than the sternum, it is almost impossible to see the sternum in a true AP or PA projection. Therefore, the patient is rotated in a?
15°-20° RAO position to shift the sternum just to the left of the thoracic vertebrae and over the homogeneously dense heart. By rotating the patient and superimposing the sternum over the heart, the outline of the sternum is more easily recognized.
How much rotation and which oblique position are required to best demonstrate the left sternoclavicular joints? A. 10° to 15° LAO B. 35° to 45° LAO C. 10° to 15° RAO D. 5° to 10° RAO
A. 10° to 15° LAO
What is the recommended degree of obliquity for an RAO projection of the sternum for an asthenic type of patient? A. 20° B. 15° C. 30° D. 10°
A. 20°
Which of the following structures connects the anterior aspect of the ribs to the sternum? A. Costocartilage B. Sternal tendons C. Costovertebral joints D. Costotransverse joints
A. Costocartilage
Cont'd Rib Articulations
A. Costochondral Junction -synarthrodial B. Sternoclavicular joint -diarthroidal C.Sternocostal joint (1st rib) -synarthrodial D. Sternocostal joint (2nd-7th) -diarthrodial E. Interchondral joints (6th-10th rib) -Diarthrodial
A PA radiograph of the sternoclavicular (SC) joints demonstrates unequal distance from the SC joints to the midline of the spine. The left SC joint is farther from the sternum than the right. What specific positioning error is present on this radiograph? A. Slight right rotation (right side toward the image receptor) B. Slight left rotation (left side toward the image receptor) C. Tilt of the upper thorax D. Excessive angulation of the CR
A. Slight right rotation (right side toward the image receptor)
The suprasternal, manubrial, or jugular notch all correspond to the level of: A. T2-3. B. T1. C. T4-5. D. C7.
A. T2-3.
The sternal angle is a palpable landmark at the level of: A. T4-5 .B. T2-3. C. T7. D. T9-10.
A. T4-5.
The degree of rotation for the right anterior oblique (RAO) projection of the sternum is dependent on the size of the thoracic cavity. A. True B. False
A. True
In the erect adult bony thorax, the posterior portion of a typical rib is ____ higher or more superior to the anterior portion. A. 1 to 2 inches (2.5 to 5 cm) B. 3 to 5 inches (7.5 to 13 cm) C. 6 to 8 inches (15 to 20 cm) D. 10 to 12 inches (25 to 30 cm)
B. 3 to 5 inches (7.5 to 13 cm)
A lateral projection of the sternum requires that respiration be suspended on expiration. A. True B. False
B. False
The left anterior oblique (LAO) position of the sternum provides the best frontal image of the sternum with a minimal amount of distortion. A. True B. False
B. False - RAO utilizes heart shadow
The only bony connection between the shoulder girdle and the bony thorax is the acromioclavicular joint. A. True B. False
B. False - SC joint
Which ribs are considered to be true ribs? A. First and second ribs B. First through seventh ribs C. First through ninth ribs D. 11th and 12th ribs
B. First through seventh ribs
A radiograph of an RAO projection of the sternum demonstrates excessive lung markings obscuring the sternum. A 1-second exposure time and an orthostatic (breathing) technique were used. Which of the following will produce a more diagnostic image of the sternum? A. Ensure that the patient is not breathing during the exposure. B. Increase the exposure time; decrease the mA. C. Decrease the kV; increase the mA or time. D. Initiate exposure on deeper inspiration.
B. Increase the exposure time; decrease the mA.
Which pair of ribs attaches to the sternum at the level of the sternal angle? A. First B. Second C. Third D. Fourth and fifth
B. Second
What is the joint classification and type of movement for the sternoclavicular joints? A. Cartilaginous with diarthrodial (ginglymus) movement B. Synovial with diarthrodial (gliding) movement C. Synovial with amphiarthrodial, limited movement D. Cartilaginous with synarthrodial or no movement
B. Synovial with diarthrodial (gliding) movement
What is the joint classification and type of movement for the costotransverse joint? A. Cartilaginous with diarthrodial (ginglymus) movement B. Synovial with diarthrodial (plane) movement C. Synovial with amphiarthrodial, limited movement D. Cartilaginous with synarthrodial or no movement
B. Synovial with diarthrodial (plane) movement
The xiphoid process corresponds to the vertebral level of: A. T7. B. T9-10. C. T4-5. D. L1-2.
B. T9-10.
Why is the RAO sternum preferred to the LAO position? A. The RAO produces less magnification of the sternum. B. The RAO projects the sternum over the shadow of the heart. C. The RAO reduces dose to the thyroid gland. D. The RAO projects the sternum away from the hilum and heart
B. The RAO projects the sternum over the shadow of the heart.
At approximately what age does the xiphoid process become totally ossified? A. 12 years old B. 21 years old C. 40 years old D. The xiphoid process never becomes ossified.
C. 40 years old
A radiograph of a lateral projection of the sternum reveals that the patient's ribs are superimposed over the sternum. What needs to be done to correct this problem during the repeat exposure? A. Increase the SID. B. Angle the CR 5° anterior. C. Ensure that the patient is not rotated. D. Increase the kVp
C. Ensure that the patient is not rotated.
A radiograph of an RAO sternum reveals that it is partially superimposed over the spine. What must be done to eliminate this problem during the repeat exposure? A. Perform an LPO projection instead of an RAO B. Angle CR 5˚ to 10˚ laterally to the sternum C. Increase rotation of the body D. Increase kVp
C. Increase rotation of the body
Which position can replace the RAO of the sternum if the patient cannot lie prone? A. LAO B. Left lateral decubitus C. LPO D. RPO
C. LPO
A patient enters the ED with blunt trauma to the sternum. The patient is in great pain and cannot lie prone on the table or stand erect. Which of the following routines would be best for the sternum examination in this situation? A. RPO and lateral recumbent projections B. AP and horizontal beam lateral projections C. LPO and horizontal beam lateral projections D. LPO and lateral recumbent projections
C. LPO and horizontal beam lateral projections
Which of the following ribs is considered to be a false rib? A. Seventh B. First C. Ninth D. None of the above
C. Ninth
Initial PA projections of the SC joints indicate a possible defect involving the left SC joint. The vertebral column is preventing a clear view of it. Which of the following projections will demonstrate the right SC joint without superimposition over the spine? A. Horizontal beam lateral B. LAO C. RAO D. Erect lateral projection
C. RAO
Which of the following statements is true about floating ribs? A. They do not possess a head. B. They do not possess a costovertebral joint. C. They do not possess costocartilage. D. They are ribs 10 through 12.
C. They do not possess costocartilage.
Where is the CR centered for a PA projection of the sternoclavicular joints? A. At the level of the vertebra prominens (T1) B. At the level of the sternal angle (T4-5) C. Three inches (7 cm) distal to vertebra prominens (T2-3) D. At the level of the thyroid cartilage (T9)
C. Three inches (7 cm) distal to vertebra prominens (T2-3)
1st sternocostal joint
Classification: Cartilaginous (Synchondrosis) Mobility Type: Synarthrodial (immovable) Movement Type:N/A - between 1st rib and sternum - the cartilage of the first rib attaches directly to the manubrium with no synovial capsule
6th-9th interchondral joints
Classification: Synovial Mobility Type: Diarthrodial Movement Type: Plane (gliding) - between anterior 6th and 9th costal cartilages - *Interchondral joints between the ninth and tenth cartilages are not synovial and are classified as fibrous syndesmosis
Sternoclavicular joints
Classification: Synovial Mobility Type: Diarthrodial Movement Type: Plane (gliding) - between clavicles and manubrium of sternum
2nd-7th sternocostal joints
Classification: Synovial Mobility Type: Diarthrodial Movement Type: Plane (gliding) - between costal cartilage and sternum
1st-10th costochondral unions
Classification: Unique type of union Mobility Type: Synarthrodial (immovable) Movement Type:N/A - between costocartilage and ribs - cartilage and bone are bound together by periosteum of the bone itself
Inferior Rib Angle (inferior costal margin)
Corresponds to the level of L2-L3
What is the recommended SID for the lateral sternum position? A. 40 inches (102 cm) B. 44 inches (113 cm) C. 46 inches (117 cm) D. 60 to 72 inches (152 to 183 cm)
D. 60 to 72 inches (152 to 183 cm) Reduces OID
What is the primary term for the superior margin of the sternum? A. Sternal notch B. Manubrial notch C. Suprasternal notch D. Jugular notch
D. Jugular notch
Which of the following techniques is most effective in preventing lung markings from obscuring the sternum on an oblique projection? A. Use a high kV. B. Oblique as much as needed to not superimpose the sternum over the hilum region. C. Decrease the source image receptor distance (SID) to magnify the sternum. D. Use an orthostatic (breathing) technique.
D. Use an orthostatic (breathing) technique.
The widest aspect of the thorax generally occurs at the level of: A. the eleventh and twelfth ribs. B. T7. C. the sternoclavicular joints. D. the eighth or ninth ribs.
D. the eighth or ninth ribs.
Why is it recommended to perform the lateral projection of the sternum first and then the RAO?
It reduces the amount of work you need to do (you keep the same height)
An RAO: Sternum of a hypersthenic patient typically requires more/less rotation?
Less rotation
An RAO: Sternum of an asthenic patient typically requires more/less rotation?
More rotation
Things to look out for when performing SC Joint procedure
Note 1: A 10° to 15° rotation in an anterior oblique position will rotate the SC joint across the spine to the opposite lung field, thus demonstrating the downside SC joint. - RAO: best demonstrates the right SC joint in the left lung field - LAO: best demonstrates the left SC joint in the right lung field - The one you're not looking at is the one crossing over the spine (looks like if it's in the middle of spine) Note 2: With less obliquity (5° to 10°), the opposite SC joint (the upside joint) would be visualized next to the vertebral column)
RAO Sternum Breathing Technique
RAO: Orthostatic technique preferred (@ lower 70-80 kVp, low mA, long exposure time 3-4 secs) to purposefully blur lung markings overlying the sternum - Orthostatic technique is not recommended for the erect RAO position. The thorax tends to move even during quiet respiration - only recommended for recumbent position
Floating Ribs (11 and 12)
Rib pairs 11 and 12 do not have costocartilage and therefore do not connect to the sternum. They are termed floating
True Ribs (1-7)
Ribs that connect directly to the sternum with a short piece of costocartilage
Routine positions
Sternum -Lateral (Perform first) - RAO Sternoclavicular joints -PA -Oblique
RAO Sternum
Technical Factors - *40" SID, 10 x 12 - Grid - *70-85 kVp - *Orthostatic breathing if possible, if not then suspend respiration on expiration (Orthostatic technique is not recommended for the erect RAO position. The thorax tends to move even during quiet respiration - only recommended for recumbent position) Position - Erect or semiprone position with slight rotation, right arm down by side, and left arm up - *Position patient oblique 15° to 20° toward the right side, RAO - Align long axis of sternum to CR and to midline of table/upright bucky - *Place top of IR 1 ½" superior to the jugular notch - CR perpendicular to IR Central Ray - *CR directed to center of sternum (1" to left of midline and midway between the jugular notch and xiphoid process) ↳This is where doing the Lateral first plays its part because you keep the same height level as you had in the lateral, so basically your only job is to position the patient -*Collimate to about a 5 inch wide field size Note: -A large deep chest thorax requires less rotation than a thin chest thorax
PA SC joints: Technical Factors & Positioning
Technical Factors - 40" SID - 8x10 - Grid - kVp: 75 to 85 Position - *Patient prone, chin resting on radiolucent positioning sponge, arms up and over head or down by side. - Projection may also be taken erect. - Align midsagittal plane to CR and to midline of grid/table/bucky - Allow no rotation of shoulders or thorax - Center IR to CR (3" distal to vertebra prominens at level of T2-T3) *CR perpendicular, centered to midsagittal plane at the level of T2-T3, or 3" distal to vertebra prominens (spinous process of C7) - Collimate to region of SC joints (2" on either side of the thoracic spine with light field 1 1/2" above the jugular notch) - *Suspend on expiration for a more uniform density
RAO Rotation Tip:
The amount of required rotation also can be determined by placing one hand on the sternum and the other on the spinous processes and determining that these two points are not superimposed, as viewed from the position of the x-ray tube (sternum goes left, spine goes right)
D. of the sixth rib.
The structure labeled iii is costocartilage: A. of the 10th rib. B. portion of the first false rib. C. of the last true rib. D. of the sixth rib.
RAO Sternum Adaptation (LPO):
This can be obtained in an LPO position if the patient's condition does not permit an RAO position. If the patient cannot be rotated, an oblique image may be obtained by angling the CR 15° to 20° across the right side of the patient to project the sternum lateral to the vertebral column, onto the heart shadow. A portable grid would be required and should be placed crosswise on the stretcher of tabletop to prevent grid cutoff.
Why does a lateral projection of the sternum have a bigger SID than an RAO of the sternum?
We have a bigger OID and in order to compensate we bring back the tube. Straighter photons and good collimation result in a better image by reducing magnification of the mediastinum (heart and great vessels).
C. Sternoclavicular joint
What is the name of the part labeled i in this figure? A. Facet for the first rib B. Body C. Sternoclavicular joint D. Sternal angle
D. Sternal angle
What is the name of the part labeled ii? A. Xiphoid process B. Body C. Sternoclavicular joint D. Sternal angle
D. Costocartilage for the first rib attachment
What is the name of the part labeled iv? A. Facet for the sternum attachment B. Head of the sternum C. Facet for the second rib attachment D. Costocartilage for the first rib attachment
C. Manubrium
What is the name of the structure labeled v? A. Head B. Body C. Manubrium D. Xiphoid proces
Facet
holes where costocartilage attaches to
Positioning Considerations for Sternum: The degree of obliquity required is dependent on the?
size of the thoracic cavity - A patient with a shallow or thin chest requires more rotation than a patient with a deep chest to cast the sternum away from the thoracic spine
An LAO of the SC joints best demonstrates
the left SC joint in the right lung field
An RAO of the SC joints best demonstrates
the right SC joint in the left lung field
