10: Bony Thorax

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Summary of Projections

PROJECTIONS, POSITIONS, AND METHODS
Page Essential Anatomy Projection Position Method
520 icon Sternum PA oblique RAO
522 Sternum PA oblique Modified prone MOORE
524 icon Sternum Lateral R or L
526 Sternoclavicular articulations PA
527 Sternoclavicular articulations PA oblique RAO or LAO BODY ROTATION
528 Sternoclavicular articulations PA oblique RAO or LAO CENTRAL RAY ANGULATION
531 icon Upper anterior ribs PA
533 icon Posterior ribs AP
535 icon Axillary ribs AP oblique RPO or LPO
537 icon Axillary ribs PA oblique RAO or LAO

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The icons in the Essential column indicate projections that are frequently performed in the United States and Canada. Students should be competent in these projections.

AP, Anteroposterior; L, left; LAO, left anterior oblique; LPO, left posterior oblique; PA, posteroanterior; R, right; RAO, right anterior oblique; RPO, right posterior oblique.

Anatomy

Bony Thorax

The bony thorax supports the walls of the pleural cavity and diaphragm used in respiration. The thorax is constructed so that the volume of the thoracic cavity can be varied during respiration. The thorax also protects the heart and lungs.
The bony thorax is formed by the sternum, 12 pairs of ribs, and 12 thoracic vertebrae. The bony thorax protects the heart and lungs. Conical in shape, the bony thorax is narrower above than below, more wide than deep, and longer posteriorly than anteriorly.

Sternum

The sternum, or breastbone, is directed anteriorly and inferiorly and is centered over the midline of the anterior thorax (Figs. 10.1 through 10.3). A narrow, flat bone approximately 6 inches (15 cm) in length, the sternum consists of three parts: manubrium, body, and xiphoid process. The sternum supports the clavicles at the superior manubrial angles and provides attachment to the costal cartilages of the first seven pairs of ribs at the lateral borders.
The manubrium, the superior portion of the sternum, is quadrilateral in shape and is the widest portion of the sternum. At its center, the superior border of the manubrium has an easily palpable concavity termed the jugular notch. In the upright position, the jugular notch of the average person lies anterior to the interspace between the second and third thoracic vertebrae. The manubrium slants laterally and posteriorly on each side of the jugular notch, and an oval articular facet called the clavicular notch articulates with the sternal extremity of the clavicle. On the lateral borders of the manubrium, immediately below the articular notches for the clavicles, are shallow depressions for attachment of the cartilages of the first pair of ribs.
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Fig. 10.1  Anterior aspect of bony thorax.

Diagram shows the anterior aspect of the bony thorax. The sternum is directed anteriorly and inferiorly and is centered over the midline of the anterior thorax. The sternum is narrow and flat. The parts labeled in the diagram are as follows. the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth ribs, jugular notch, clavicular notch, manubrium, sternal angle, body, xiphoid process, and costal cartilage.

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Fig. 10.2  Color-coded anterolateral oblique aspect of bony thorax. blue, True ribs; green, false ribs; yellow, floating ribs.

Diagram shows the color-coded anterolateral oblique aspect of the bony thorax. Blue is the true ribs, green is the false ribs, yellow outline with green shading are the floating ribs. The parts labeled are as follows: jugular notch, clavicular notch, manubrium, body, xiphoid process.

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Fig. 10.3  (A) Color-coded anterior aspect of sternum and sternoclavicular joints. Blue, body; green (outline), sternal angle; orange (outline), sternoclavicular joints; pink, manubrium; purple, xiphoid process; yellow (outline), jugular notch. (B) Lateral sternum.

Diagram (A) shows the color-coded anterior aspect of the sternum and sternoclavicular joints. The sternum is narrow and flat. Blue is the body, green (outline) is the sternal angle, orange (outline) is the sternoclavicular joints, pink is the manubrium, purple is the xiphoid process, yellow (outline) is the jugular notch. Diagram (B) shows the lateral sternum. It is long and narrow. The parts labeled in the diagram are marked as follows: first, second, third, fourth, fifth, sixth, seventh costal facets, clavicular notch, manubrium, sternal angle, and manubriosternal joint, body, xiphisternal joint, and xiphoid process.

The body is the longest part of the sternum (4 inches [10.2 cm]) and is joined to the manubrium at the sternal angle, an obtuse angle that lies at the level of the junction of the second costal cartilage. The manubrium and the body contribute to the attachment of the second costal cartilage. The succeeding five pairs of costal cartilages are attached to the lateral borders of the body. The sternal angle is palpable; in the normally formed thorax, it lies anterior to the interspace between the fourth and fifth thoracic vertebrae when the body is upright.
The xiphoid process, the distal and smallest part of the sternum, is cartilaginous in early life and partially or completely ossifies, particularly the superior portion, in later life. The xiphoid process is variable in shape and often deviates from the midline of the body. In the normal thorax, the xiphoid process lies over the tenth thoracic vertebra and serves as a useful bony landmark for locating the superior portion of the liver and the inferior border of the heart.

Ribs

The 12 pairs of ribs are numbered consecutively from superiorly to inferiorly (Fig. 10.4; also see Figs. 10.1 and 10.2). The rib number corresponds to the thoracic vertebra to which it attaches. Each rib is a long, narrow, curved bone with an anteriorly attached piece of hyaline cartilage, the costal cartilage. The costal cartilages of the first through seventh ribs attach directly to the sternum. The costal cartilages of the eighth through tenth ribs attach to the costal cartilage of the seventh rib. The ribs are situated in an oblique plane slanting anteriorly and inferiorly so that their anterior ends lie 3 to 5 inches (7.6 to 12.5 cm) below the level of their vertebral ends. The degree of obliquity gradually increases from the first to the ninth rib and then decreases to the twelfth rib. The first seven ribs are called true ribs because they attach directly to the sternum. Ribs 8 to 12 are called false ribs because they do not attach directly to the sternum. The last two ribs (eleventh and twelfth ribs) are often called floating ribs because they are attached only to the vertebrae. The spaces between the ribs are referred to as the intercostal spaces.
The number of ribs may be increased by the presence of cervical or lumbar ribs, or both. Cervical ribs articulate with the C7 vertebra but rarely attach to the sternum. Cervical ribs may be free or may articulate or fuse with the first rib. Lumbar ribs are less common than cervical ribs. Lumbar ribs can lend confusion to images. They can confirm the identification of the vertebral level, or they can be erroneously interpreted as a fractured transverse process of the L1 vertebra.
Ribs vary in breadth and length. The first rib is the shortest and broadest; the breadth gradually decreases to the twelfth rib, the narrowest rib. The length increases from the first to the seventh rib and then gradually decreases to the twelfth rib.
A typical rib consists of a head, a flattened neck, a tubercle, and a body (Figs. 10.5 and 10.6). The ribs have facets on their heads for articulation with the vertebrae. The facet is divided on some ribs into superior and inferior portions for articulation with demifacets on the vertebral bodies. The tubercle also contains a facet for articulation with the transverse process of the vertebra. The eleventh and twelfth ribs do not have a neck or tubercular facets. The two ends of a rib are termed the vertebral end and the sternal end.
From the point of articulation with the vertebral body, the rib projects posteriorly at an oblique angle to the point of articulation with the transverse process. The rib turns laterally to the angle of the body, where the bone arches anteriorly, medially, and inferiorly in an oblique plane. Located along the inferior and internal border of each rib is the costal groove, which contains costal arteries, veins, and nerves. Trauma to the ribs can damage these neurovascular structures, causing pain and hemorrhage.
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Fig. 10.4  Lateral aspect of bony thorax.

Diagram shows 12 pairs of ribs that are numbered consecutively from superiorly to inferiorly. The parts labeled in the diagram are marked as follows: the thoracic vertebrae, lumbar vertebrae, intercostal space, true ribs: 1 to 7, false ribs: 8 to 12, floating ribs, and the costal cartilage. The ribs vary in breadth and length.

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Fig. 10.5  Typical rib viewed from posterior.

Diagram shows the typical rib viewed from the posterior. The parts labeled in the diagram are marked as follows. angle neck head, facet, tubercle, body, costal, groove, and facet. The facets are shaded in blue.

Bony Thorax Articulations
The sternoclavicular joints are the only points of articulation between the upper limbs and the trunk (see Fig. 10.3). Formed by the articulation between the sternal extremity of the clavicles and the clavicular notches of the manubrium, these synovial gliding joints permit free movement (the gliding of one surface on the other). A circular disk of fibrocartilage is interposed between the articular ends of the bones in each joint, and the joints are enclosed in articular capsules.

TABLE 10.1

Joints of the bony thorax
Structural classification
Joint Tissue Type Movement
Sternoclavicular Synovial Gliding Freely movable
Costovertebral
1st–12th ribs Synovial Gliding Freely movable
Costotransverse
1st–10th ribs Synovial Gliding Freely movable
Costochondral
1st–10th ribs Cartilaginous Synchondroses Immovable
Sternocostal
1st rib Cartilaginous Synchondroses Immovable
2nd–7th ribs Synovial Gliding Freely movable
Interchondral
6th–9th ribs Synovial Gliding Freely movable
9th–10th ribs Fibrous Syndesmoses Slightly movable
Manubriosternal Cartilaginous Symphysis Slightly movable
Xiphisternal Cartilaginous Synchondroses Immovable

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Fig. 10.6  (A) Superior aspect of rib articulating with thoracic vertebra and sternum. (B) Enlarged image of costovertebral and costotransverse articulations.

Diagram (A) shows the superior aspect of the rib articulating with the thoracic vertebra and the sternum. The parts labeled in the diagram are marked as follows. body, angle, transverse process, tubercle, head, vertebral body, vertebral end, costal cartilage, sternum, and sternum end. Diagram (B) shows the enlarged image of costovertebral and costotransverse articulations. The parts labeled in the diagram are marked as follows: body, costovertebral joint, costotransverse joint, and spinous process. The body has a triangular part in the middle and it appears grainy. There is a small hollow hole below it.

Posteriorly, the head of a rib is closely bound to the demifacets of two adjacent vertebral bodies to form a synovial gliding articulation called the costovertebral joint (Figs. 10.6 and 10.7A). The first, tenth, eleventh, and twelfth ribs all articulate with only one vertebral body.
The tubercle of a rib articulates with the anterior surface of the transverse process of the lower vertebra at the costotransverse joint, and the head of the rib articulates at the costovertebral joint. The head of the rib also articulates with the body of the same vertebra and articulates with the vertebra directly above. The costotransverse articulation is also a synovial gliding articulation. The articulations between the tubercles of the ribs and the transverse processes of the vertebrae permit only superior and inferior movements of the first six pairs. Greater freedom of movement is permitted in the succeeding four pairs.
Costochondral articulations are found between the anterior extremities of the ribs and the costal cartilages (see Fig. 10.7B). These articulations are cartilaginous synchondroses and allow no movement. The articulations between the costal cartilages of the true ribs and the sternum are called sternocostal joints. The first pair of ribs, rigidly attached to the sternum, forms the first sternocostal joint. This is a cartilaginous synchondrosis type of joint, which allows no movement. The second through seventh sternocostal joints are considered synovial gliding joints and are freely movable. Interchondral joints are found between the costal cartilages of the sixth and seventh, seventh and eighth, and eighth and ninth ribs (see Fig. 10.7C). These interchondral joints are synovial gliding articulations. The interchondral articulation between the ninth and tenth ribs is a fibrous syndesmosis and is only slightly movable.
The manubriosternal joint is a cartilaginous symphysis joint, and the xiphisternal joints are cartilaginous synchondrosis joints that allow little or no movement (see Figs. 10.3B and 10.7B and C).
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Fig. 10.7  Rib articulations. (A) Anterior aspect of thoracic spine, showing costovertebral articulations. (B) Anterior aspect of manubrium, sternum, and first two ribs, showing articulations. (C) Lower sternum and ribs, showing intercostal, costochondral, and sternocostal joints. (D) Computed tomography (CT) cross-section image of upper thorax showing manubrium and angulation of sternoclavicular joints (arrows).

Diagram (A) shows the anterior aspect of the thoracic spine, with costovertebral articulations. The parts labeled in the diagram are marked as follows: costotransverse articulation, costovertebral articulation, and rib tubercle. Diagram. (B) shows the anterior aspect of the manubrium, sternum, and first two ribs, showing articulations. The parts labeled in the diagram are marked as follows: costochondral articulations, costal cartilage, clavicle, first sternocostal joint, second sternocostal joint, s c joint, manubriosternal joint, manubrium, and body of the sternum. The manubrium is shaped like a hexagon and the body of the sternum attaches itself to the manubrium. Diagram (C) shows the lower sternum and ribs, showing intercostal, costochondral, and sternocostal joints. The parts labeled in the diagram are marked as follows. body of sternum, interchondral joints, sixth and seventh sternocostal joints, seventh costochondral joint, eighth rib, twelfth thoracic, and tenth rib. The costal cartilages are shaded in blue. (D) shows a C T image of the upper thorax showing manubrium and angulation of sternoclavicular joints which is marked by two white arrows. The sternoclavicular joints appear white. The open sternoclavicular joint space appears dark.

Respiratory Movement
The normal oblique orientation of the ribs changes little during quiet respiratory movements; however, the degree of obliquity decreases with deep inspiration and increases with deep expiration. The first pair of ribs, which are rigidly attached to the manubrium, rotates at its vertebral end and moves with the sternum as one structure during respiratory movements.
On deep inspiration, the anterior ends of the ribs are carried anteriorly, superiorly, and laterally while the necks are rotated inferiorly (Fig. 10.8A). On deep expiration, the anterior ends are carried inferiorly, posteriorly, and medially, while the necks are rotated superiorly (see Fig. 10.8B). The last two pairs of ribs are depressed and are held in position by the action of the diaphragm when the anterior ends of the upper ribs are elevated during respiration.
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Fig. 10.8  Respiratory lung movement. (A) Full inspiration with posterior ribs numbered. (B) Full expiration with ribs numbered. Anterior ribs are labeled with A.

(A) An x-ray shows the lungs in full inspiration. The posterior ribs are numbered as 1, 3, 6, 7, 10, and 11. The lungs filled with air appear radiolucent. The heart and the region below the diaphragm appear radiopaque. (B) An x-ray shows the lungs in full expiration. The anterior ribs are labeled as 2 A, 4 A, 5 A, 6 A, 7 A, and 8 A. The lungs appear darker than in (A). The diaphragm is depressed.

Diaphragm
The ribs located above the diaphragm are best examined radiographically through the air-filled lungs, whereas the ribs situated below the diaphragm must be examined through the upper abdomen. Because of the difference in penetration required for the two regions, the position and respiratory excursion of the diaphragm play a large role in radiography of the ribs.
The position of the diaphragm varies with body habitus: it is at a higher level in hypersthenic patients and at a lower level in asthenic patients (Fig. 10.9). In sthenic patients of average size and shape, the right side of the diaphragm arches posteriorly from the level of about the sixth or seventh costal cartilage to the level of the ninth or tenth thoracic vertebra when the body is in the upright position. The left side of the diaphragm lies at a slightly lower level. Because of the oblique location of the ribs and the diaphragm, several pairs of ribs appear on radiographs to lie partly above and partly below the diaphragm.
The position of the diaphragm changes considerably with the body position, reaching its lowest level when the body is upright and its highest level when the body is supine. For this reason, it is desirable to place the patient in an upright position for examination of the ribs above the diaphragm and in a recumbent position for examination of the ribs below the diaphragm.
The respiratory movement of the diaphragm averages approximately 1½ inches (3.8 cm) between deep inspiration and deep expiration. The movement is less in hypersthenic patients and more in hyposthenic patients. Deeper inspiration or expiration and greater depression or elevation of the diaphragm are achieved on the second respiratory movement than on the first. This greater movement should be taken into consideration when the ribs that lie at the diaphragmatic level are examined.
When the body is placed in the supine position, the anterior ends of the ribs are displaced superiorly, laterally, and posteriorly. For this reason, the anterior ends of the ribs are less sharply visualized when the patient is radiographed in the supine position.
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Fig. 10.9  Diaphragm position and body habitus. (A) A hypersthenic patient has a diaphragm positioned higher. (B) An asthenic patient has a diaphragm positioned lower. (C) Chest radiograph of a hypersthenic patient. (D) Chest radiograph of an asthenic patient. Note position of diaphragm on these extremely different body types.

(A) A diagram shows the anterior view of the human body with lungs highlighted. The diaphragm is positioned higher and arches posteriorly. An x-ray view below shows the anterior view of the human body and the lungs appear radiolucent. The diaphragm arches posteriorly from the level of about the sixth or seventh costal cartilage to the level of the ninth or tenth thoracic vertebra. The left side of the diaphragm lies at a slightly lower level (B) A diagram shows the anterior view of the human body with lungs highlighted. The diaphragm is positioned lower. An x-ray view below shows the anterior view of the human body and the lungs appear radiolucent. The diaphragm is positioned lower. The anterior ends of the ribs are less sharply visualized.

Body Position
Although in rib examinations it is desirable to take advantage of the effect that body position has on the position of the diaphragm, the effect is not of sufficient importance to justify subjecting a patient to a painful change from the upright position to the recumbent position or vice versa. Even minor rib injuries are painful, and slight movement frequently causes the patient considerable distress. Unless the change in position can be affected by a tilting radiographic table, patients with recent rib injury should be examined in the position in which they arrive in the radiology department. An ambulatory patient can be positioned for recumbent images with minimal discomfort by bringing the tilt table to the vertical position for each positioning change. The patient stands on the footboard, is comfortably adjusted, and is then lowered to the horizontal position.
Trauma Patients
The first and usually the only requirement in the initial radiographic examination of a patient who has sustained severe trauma to the rib cage is the need to take anteroposterior (AP) and lateral projections of the chest. These projections are obtained not only to show the site and extent of rib injury but also to investigate the possibility of injury to underlying structures by depressed rib fractures. Patients are examined in the position in which they arrive, usually recumbent on a stretcher. If it is deemed necessary to show the presence of air or fluid levels in the chest, the dorsal decubitus position is preferred.

Summary of Pathology
Condition Definition
Fracture Disruption of the continuity of bone
Metastasis Transfer of a cancerous lesion from one area to another
Osteomyelitis Inflammation of bone due to a pyogenic infection
Osteopetrosis Increased density of atypically soft bone
Osteoporosis Loss of bone density
Paget disease Thick, soft bone marked by bowing and fractures
Tumor New tissue growth where cell proliferation is uncontrolled
Chondrosarcoma Malignant tumor arising from cartilage cells
Multiple myeloma Malignant neoplasm of plasma cells involving the bone marrow and causing destruction of bone

Eponymous (named) pathologies are listed in nonpossessive form to conform to the AMA manual of style: a guide for authors and editors, ed 10, Oxford, 2009, Oxford University Press.

Sample Exposure Technique Chart Essential Projections
These techniques were accurate for the equipment used to produce each exposure. However, use caution when applying them in your department because “there is considerable variability in image receptor response owing to varying scatter sensitivity, the use of grids with different grid ratios, collimation, beam filtration, the choice of kilovoltage, source-to-image distance, and IR size.” a
This chart was created in collaboration with Dennis Bowman, AS, RT(R), Clinical Instructor, Community Hospital of the Monterey Peninsula, Monterey, CA. http://digitalradiographysolutions.com/.
Bony Thorax
Part cm kVp b SID c Collimation CR d DR e
mAs Dose (mGy) f mAs Dose (mGy) f
Sternum—PA oblique g 20 81 30″ 6″ × 11″ (15 × 28 cm) 6.3 h 0.76.5 3.2 h 0.383
Sternum—lateral g 29 81 40″ 5″ × 11″ (13 × 28 cm) 20h 2.790 10h 1.395
Sternoclavicular articulations—PA g 17 81 40″ 6″ × 4″ (15 × 10 cm) 7.1 h 0.670 3.6 h 0.337
Sternoclavicular articulations—PA oblique g 18 81 40″ 6″ × 4″ (15 × 10 cm) 10 h 0.963 5 h 0.479
Upper anterior ribs—PA g 21 81 72″ 9″ × 17″ (23 × 43 cm) 20 h 0.625 10 h 0.312
Posterior ribs—AP upper g 21 81 72″ 9″ × 17″ (23 × 43 cm) 20 h 0.625 10 h 0.312
Posterior ribs—AP lower g 21 85 40″ 9″ × 12″ (23 × 30 cm) 25 h 3.540 12.5 h 1.779
Ribs: axillary—AP oblique g 23 81 72″ 11″ × 17″ (28 × 43 cm) 36 h 1.180 16 h 0.522
Ribs: axillary—PA oblique g 23 81 72″ 11″ × 17″ (28 × 43 cm) 36 h 1.181 16 h 0.523

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Radiography

Sternum

Rotation of the body or angulation of the CR to project the sternum to the right of the thoracic vertebrae clears the sternum of the vertebrae but superimposes it over the posterior ribs and the lung markings (Fig. 10.11). If the sternum is projected to the left of the thoracic vertebrae, it is projected over the heart and other mediastinal structures (Fig. 10.12). The superimposition of the homogeneous density of the heart can be used to advantage (compare Figs. 10.11 and 10.12). For this reason, the PA oblique projection in the right anterior oblique (RAO) position is recommended.
The pulmonary structures, particularly in elderly persons and heavy smokers, can cast confusing markings over the sternum, unless the motion of shallow breathing is used to eliminate them. If motion is desired, the exposure time should be long enough to cover several phases of shallow respiration (Figs. 10.13 and 10.14). The milliampere (mA) must be relatively low to achieve the desired milliampere-second (mAs).
When female patients with large, pendulous breasts are imaged, the inferior portion of the sternum may be obscured. To prevent larger breasts from overlapping the sternum, instruct the patient to separate the breasts laterally, where the breasts can be held in place with a wide bandage. This positioning maneuver will also place the sternum closer to the IR. This positioning strategy for patients with pendulous breasts is also suggested for chest radiography. Pendulous breasts can also obscure the inferior portion of the sternum on the lateral projection and may need to be repositioned.

Radiation Protection

Protection of the patient from unnecessary radiation is a professional responsibility of the radiographer (see Chapter 1 for specific guidelines). In this chapter, the Shield gonads statement indicates that the patient is to be protected from unnecessary radiation by restricting the radiation beam using proper collimation. In addition, placement of lead shielding between the gonads and the radiation source may be used if requested by the patient or caregiver and when the clinical objectives of the examination are not compromised.

TABLE 10.2

Sternum: thickness versus rotation/CR angulation
Depth of thorax (cm) Amount of rotation or CR angulation
15 22
16.5 21
18 20
19.5 19
21 18
22.5 17
24 16
25.5 15
27 14
28.5 13
30 12
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Fig. 10.10  (A) Drawing of 24-cm chest. (B) Drawing of 18-cm chest.

(A) A drawing of a chest shows s the central ray is at a 15-degree angle to the sternum. The line drawn next to it is the axial view of the right anterior oblique position and it passes through the sternum. (B) A drawing of a chest shows s the central ray is at a 20-degree angle to the sternum. The line drawn next to it is the axial view of the right anterior oblique position and it passes through the sternum

An x-ray shows the sternum on the right and the posterior ribs rise from it. The lungs appear radiolucent.
Fig. 10.11  PA oblique sternum, LAO position.
An x-ray shows the sternum on the left. The heart appears radiolucent and the other mediastinal structures appear radiopaque.
Fig. 10.12  PA oblique sternum, RAO position.
An x-ray shows the sternum on the left and ribs rise from it. The lungs appear radiolucent.
Fig. 10.13  Suspended respiration.
An x-ray shows the entire sternum from the jugular notch to the tip of the xiphoid process. It appears hazy.
Fig. 10.14  Shallow breathing during exposure.
icon PA Oblique Projection
RAO position
Image receptor + grid: Positioned by manufacturer or department protocol for proper anatomy display orientation; CR plate: 10 × 12 inches (24 × 30 cm) lengthwise.
NOTE: This position may be difficult to perform on trauma patients. Use an upright position if possible.
SID:

Position of patient

Position of part

  1. • Adjust the elevation of the left shoulder and hip so that the thorax is rotated just enough to prevent superimposition of the vertebrae and sternum.
  2. • Estimate the amount of rotation with sufficient accuracy by placing one hand on the patient’s sternum and the other hand on the thoracic vertebrae to act as guides while adjusting the degree of obliquity. The average rotation is approximately 15 to 20 degrees (Fig. 10.15).
  3. • Align the patient’s body so that the long axis of the sternum is centered to the midline of the grid.
  4. • Place the top of the IR approximately 1½ inches (3.8 cm) above the jugular notch.
  5. • Shield gonads.
  6. • Respiration: When a breathing technique is to be used, instruct the patient to take slow, shallow breaths during the exposure. When a short exposure time is to be used, instruct the patient to suspend breathing at the end of expiration to minimize the visibility of the pulmonary vasculature.
NOTE: For trauma patients who are recumbent and unable to lie prone, obtain this projection with the patient in the left posterior oblique (LPO) position, resulting in an AP oblique projection.
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Fig. 10.15  PA oblique sternum, RAO position. Line drawing is an axial view (from feet upward).

The patient is in a prone position supporting his body with his forearm. A support is placed under the patient's head. The central ray is directed to the elevated side of the posterior thorax perpendicularly. The diagram next to it shows the central ray is at a 15-degree angle to the sternum. The line drawn next to it is the axial view of the right anterior oblique position.

Central ray

Collimation

Structures shown

A slightly oblique projection of the sternum (Fig. 10.16). The detail depends largely on the technical procedure used. If a breathing technique is used, the pulmonary markings are obliterated.
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Fig. 10.16  (A) PA oblique sternum, RAO position. (B) CT is often used today to image the sternum. Image shows sternum in axial plane. B, Modified from Kelley LL, Petersen CM. Sectional anatomy for imaging professionals, 2nd ed. St. Louis: Mosby; 2007.

(A) An x-ray shows the entire sternum from the jugular notch to the tip of the xiphoid process. It appears hazy. The parts labeled in the x-ray on the left are marked from top to the bottom as follows: left clavicle, jugular notch, s c joint, first rib, manubrium, sternal angle, body, xiphoid process. (B) The C T shows the sternum in axial plane. The sternum is rectangular and is labeled on the top. The lungs appear dark and the outline of the sternum appears white and prominent.

PA Oblique Projection
Moore Method

Modified prone position

Image receptor + grid: Positioned by manufacturer or department protocol for proper anatomy display orientation; CR plate: 10 × 12 inches (24 × 30 cm) lengthwise.
SID:
A 30-inch (76-cm) SID is recommended. This short distance assists in blurring the posterior ribs.
Radiography of the sternum can be difficult to perform on an ambulatory patient who is having acute pain. The alternative positioning method described by Moore 1 uses a modified prone position, which makes it possible to produce a high-quality sternum image in a more comfortable manner for the patient.

Position of patient

Position of part

Central ray

Collimation

Structures shown

A slightly oblique projection of the sternum (Fig. 10.18). The degree of detail shown depends largely on the technique used. If a breathing technique is used, the pulmonary markings are obliterated.
An x-ray shows the entire sternum from the jugular notch to the tip of the xiphoid process. The xiphoid process has irregular outlines with projections around it.
Fig. 10.18  PA oblique projection: Moore method.
icon Lateral Projection
Right or left position
Image receptor + grid: Positioned by manufacturer or department protocol for proper anatomy display orientation; CR plate: 10 × 12 inches (24 × 30 cm) lengthwise.
SID:
72-inch (183-cm) SID to reduce magnification and distortion of the sternum.

Position of patient

Position of part

Upright

Central ray

Collimation

Structures shown
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Fig. 10.19  Lateral sternum.

The patient is standing in an upright position, lateral to the vertical grid. His hands are held behind his back. The central ray is perpendicular to the vertical grid and directed to the lateral border of the mid sternum.

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Fig. 10.20  (A) Lateral sternum. (B) Dorsal decubitus position for lateral sternum.

(A) The patient is lying in a right lateral recumbent position with his arms extended over his head. The central ray is directed to the lateral border of the midsternum. (A)The patient is lying in a supine position. The patient's arms are extended over his head. The central ray is directed to the lateral border of the midsternum.

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Fig. 10.21  Lateral sternum.

An x-ray shows the lateral sternum. The parts labeled in the x-ray on the left are marked from top to the bottom as follows: the manubrium, sternal angle, body, xiphoid process. The xiphoid process has a white outline and is long and narrow. The sternal angle appears dark.

Sternoclavicular Articulations

PA Projection

NOTE: This position may be difficult to perform on trauma patients. Use the upright position if the patient is able.
Image receptor + grid: Positioned by manufacturer or department protocol for proper anatomy display orientation; CR plate: 10 × 12 inches (24 × 30 cm) lengthwise.

Position of patient

Position of part
Central ray
Collimation
Structures shown
The patient is lying on the radiographic table in the prone position with his arms along the sides of his body. The central ray is directed perpendicular to the third thoracic vertebrae.
Fig. 10.22  Unilateral examination to show left sternoclavicular articulation.
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Fig. 10.23  Bilateral sternoclavicular joints (arrows).

An x-ray shows both sternoclavicular joints and the medial ends of the clavicles. The sternum appears radiopaque. There are oval patches with white outlines on the upper portion of the sternum. Two black arrows indicate the bilateral sternoclavicular joints. The clavicle is labeled.

An x-ray shows both sternoclavicular joints and the medial ends of the clavicles. The Unilateral sternoclavicular joint is marked by a black arrow. The sternum appears radiopaque.
Fig. 10.24  Unilateral sternoclavicular joint (arrow).

PA Oblique Projection

Body Rotation Method
RAO or LAO position
NOTE: This position may be difficult in trauma patients. Use the upright position if the patient is able.
Image receptor + grid:
Positioned by manufacturer or department protocol for proper anatomy display orientation; CR plate: 10 × 12 inches (24 × 30 cm) lengthwise.
Position of patient
Position of part
Central ray
Collimation
Structures shown
image
Fig. 10.25  (A) PA oblique sternoclavicular joint, LAO position: Body rotation method. (B) Axial view (from feet upward) of central ray position in relation to spine and sternoclavicular joint. (C) PA oblique sternoclavicular joint, LAO position. The joint closest to the IR is shown (arrow).

(A) The patient is lying on the radiographic table in the prone position with his arms along the sides of his body. The patient is positioned at an oblique angle of about 10 to 15 degrees. The central ray is directed perpendicular to the sternoclavicular joint. (B) shows the central ray is at a 15-degree angle to the spine. The line is drawn in the axial view of the right anterior oblique position. (c) The x-ray view of the oblique sternoclavicular joint has an arrow pointing at the point.

PA Oblique Projection

CR Angulation Method
Image receptor: Positioned by manufacturer or department protocol for proper anatomy display orientation; CR plate: 10 × 12 inches (24 × 30 cm) lengthwise.
NOTE: For this projection, the joint is closer to the IR, and less distortion is obtained than when the previously described body rotation method is used. A grid IR placed on the tabletop enables the joint to be projected with minimal distortion. This position may be difficult to perform on trauma patients. Use the upright position if the patient is able.
Position of patient
Position of part
Central ray
Collimation
Structures shown
image
Fig. 10.26  PA oblique sternoclavicular joint: CR angulation method. CR enters left side to show right joint.

(A) The patient is lying on the radiographic table in the prone position with his arms along the sides of his body. The central ray is directed at a 15-degree angle at the M S P. (B) shows the line drawing of the axial view of the sternum that illustrates the central ray is at a 15-degree angle to the spine and sternum.

A C T image shows a slightly oblique sternoclavicular joint. It is marked by white arrows. There are two circular dark regions on either side. The central ray is directed through the joints.
Fig. 10.27  CT axial image with patient prone, showing sternoclavicular joints (white arrows) and path of CR. View is from feet looking upward.
An x-ray shows the sternoclavicular joint. It is indicated by a white arrow and it appears hazy. The sternum appears radiopaque.
Fig. 10.28  Central ray angulation method for sternoclavicular joint (arrow). From Kurzbauer R. The lateral projection in the roentgenography of the sternoclavicular articulation, AJR Am J Roentgenol. 1946;56:104.

Ribs

In radiography of the ribs, an IR 14 × 17 inches (35 × 43 cm) should be used to identify the ribs involved and to determine the extent of trauma or the pathologic condition. Projections can be made in recumbent and upright positions.
After the lesion is localized, the next step is to determine (1) the position required to place the affected rib region parallel with the plane of the IR, and (2) whether the radiograph should be made to include the ribs above or below the diaphragm.
The anterior portion of the ribs, usually referred to simply as the anterior ribs, is often examined with the patient facing the IR for a PA projection. The posterior portion of the ribs—the posterior ribs—is more commonly radiographed with the patient facing the x-ray tube in the same manner as for an AP projection.
The axillary portion of the ribs is best shown using an oblique projection. Because the lateral projection results in superimposition of the two sides, it is generally used only when fluid or air levels are evaluated after rib fractures.
When the ribs superimposed over the heart are involved, the body must be rotated to obtain a projection of the ribs free of the heart, or the radiographic exposure must be increased to compensate for the density of the heart. Although the anterior and posterior ends are superimposed, the left ribs are cleared of the heart when the LAO position or the right posterior oblique (RPO) position is used. These two body positions place the right-sided ribs parallel with the plane of the IR and are reversed to obtain comparable projections of the left-sided ribs. Lower kVp, compared with that used for chest radiography, should be used to increase beam attenuation in the ribs. The kVp chosen will vary based on expected rib mineralization of the patient.

Respiration

In radiography of the ribs, the patient is usually examined with respiration suspended in either full inspiration or full expiration. Occasionally, shallow breathing may be used to obliterate lung markings. If this technique is used, breathing must be shallow enough to ensure that the ribs are not elevated or depressed, as described in the anatomy portion of this chapter.
Rib fractures can cause a great deal of pain and hemorrhage because of the closely related neurovascular structures. This situation commonly makes it difficult for the patient to breathe deeply for the required radiograph. Deeper inspiration is attained if the patient fully understands the importance of expanding the lungs, and if the exposure is taken after the patient takes the second deep breath.

SID

Upper Anterior Ribs

icon PA Projection

Image receptor + grid: Positioned by manufacturer or department protocol for proper anatomy display orientation; CR plate: 14 × 17 inches (35 × 43 cm) lengthwise.

Position of patient

Position of part
  1. • Center the MSP of the patient’s body to the midline of the grid for bilateral ribs.
  2. • For unilateral ribs, center the affected side on a longitudinal plane drawn midway between the MSP and the lateral surface of the body to the midline of the grid.
  3. • Adjust the IR position to project approximately 1½ inches (3.8 cm) above the upper border of the shoulders. Less may be required for hypersthenic patients and for those with very muscular shoulders.
  4. • Rest the patient’s hands against the hips with the palms turned outward to rotate the scapulae away from the rib cage.
  5. • Adjust the shoulders to lie in the same transverse plane.
  6. • If the patient is prone, rest the head on the chin and adjust the MSP to be vertical (Fig. 10.30).
  7. • For hypersthenic patients with wide rib cages, it may be necessary to move the patient laterally to include the entire lateral surface of the affected rib area on the radiograph.
  8. • Shield gonads.
  9. • Respiration: Suspend at full inspiration to depress the diaphragm as much as possible.
image
Fig. 10.29  PA ribs, upright position.

The patient is standing in an upright position, facing the vertical grid. The patient's hands are resting on his hips with his palm turned outward. The central ray is perpendicular to the center of the I R at the level of T 7.

image
Fig. 10.30  PA ribs, recumbent position.

The patient is lying on the radiographic table in the prone position with his arms along the sides of his body. The central ray is directed perpendicular to the third thoracic vertebrae. The central ray is directed at the seventh thoracic vertebrae perpendicularly.

Central ray
Collimation
Structures shown
The anterior ribs above the diaphragm (Figs. 10.31 and 10.32). Although the posterior ribs are seen, the anterior ribs are shown with greater detail because they are closer to the IR.
An x-ray shows anterior ribs with more details above the diaphragm and posterior ribs with fewer details. A radiopaque area is aligned towards the right side of the radiograph towards the bottom.
Fig. 10.31  PA ribs, normal centering.
image
Fig. 10.32  PA ribs, with 10- to 15-degree caudal angulation.

An x-ray shows the anterior ribs above the diaphragm. The left side is labeled posterior rib numbers and the right side is labeled anterior rib numbers. A radiopaque area is aligned towards the right side of the radiograph towards the bottom.

Posterior Ribs

icon AP Projection

Image receptor + grid: Positioned by manufacturer or department protocol for proper anatomy display orientation; CR plate: 14 × 17 inches (35 × 43 cm) lengthwise.

Position of patient

Position of part

Ribs above diaphragm

Ribs below diaphragm

image
Fig. 10.33  AP ribs above diaphragm.

The patient is lying in a supine position. The patient's arms are extended to the vertical position, supporting his head. The central ray is directed to 3.8 centimeters above the upper border of the shoulders.

image
Fig. 10.34  AP ribs below diaphragm.

The patient is lying in a supine position. The patient's arms are extended to the sides, supporting his head. The central ray is directed to the point between the xiphoid process and the lower rib margin.

Central ray
Collimation
Structures shown
The posterior ribs above or below the diaphragm, according to the region examined (Figs. 10.35 and 10.36). Although the anterior ribs are seen, the posterior ribs are shown in greater detail because they are closer to the IR.
An x-ray shows the posterior ribs above the diaphragm. They are labeled as 3, 5, 7, 9, 11. The lungs appear radiolucent. The heart, sternum, and the region below appear radioopaque.
Fig. 10.35  AP ribs above diaphragm.
An x-ray shows the posterior ribs below the diaphragm. They appear hazy. The parts labeled are anterior ribs and posterior ribs.
Fig. 10.36  AP lower ribs.

Axillary Ribs

icon AP Oblique Projection

RPO or LPO position

Image receptor + grid: Positioned by manufacturer or department protocol for proper anatomy display orientation; CR plate: 14 × 17 inches (35 × 43 cm) lengthwise.
Position of patient
Position of part
  1. • Position the patient’s body for a 45-degree AP oblique projection using the RPO or LPO position. Place the affected side closest to the IR.
  2. • Center the affected side on a longitudinal plane drawn midway between the MSP and the lateral surface of the body.
  3. • Position this plane to the midline of the grid.
  4. • If the patient is in the recumbent position, support the elevated hip.
  5. • Abduct the arm of the affected side, and elevate it to carry the scapula away from the rib cage.
  6. • Rest the patient’s hand on the head if the upright position is used (Fig. 10.37), or place the hand under or above the head if the recumbent position is used (Fig. 10.38).
  7. • Abduct the opposite limb with the hand on the hip.
  8. • Center the IR with the top 1½ inches (3.8 cm) above the upper border of the relaxed shoulder to image ribs above the diaphragm or to a point halfway between the xiphoid process and the lower rib margin to image ribs below the diaphragm.
  9. • Shield gonads.
  10. • Respiration: Suspend at the end of full inspiration for ribs above the diaphragm and at the end of deep expiration for ribs below the diaphragm.
image
Fig. 10.37  Upright AP oblique ribs, LPO position.

The patient is standing in an upright position facing the I R at a 45-degree angle to the vertical grid. The arm of the affected side is abducted and extended above and resting on his head. The central ray is directed to 3.8 centimeters above the upper border of the shoulders.

image
Fig. 10.38  Recumbent AP oblique ribs, RPO position.

The patient is lying in a supine position with his hips elevated to a 45-degree angle. The arm of the affected side is abducted and extended above, supporting his head. The central ray is directed to 3.8 centimeters above the upper border of the shoulders.

Central ray
Collimation
Structures shown
image
Fig. 10.39  (A) AP oblique ribs. LPO position shows left-side ribs. (B) Axial view (from feet upward) of ribs and CR, LPO position.

(A) An x-ray shows the axillary portion of the ribs free of superimposition with the thoracic spine. The ribs labeled are 3, 6, 9, 12. The axillary ribs are labeled. (B) A diagram shows the L P O position with hips elevated. The central ray is directed perpendicular to the center of the I R.

icon PA Oblique Projection

RAO or LAO position
Image receptor + grid: Positioned by manufacturer or department protocol for proper anatomy display orientation; CR plate: 14 × 17 inches (35 × 43 cm) lengthwise.
Position of patient
Position of part
Central ray
Collimation
Structures shown
image
Fig. 10.42  (A) PA oblique ribs. LAO position shows right-side ribs. PA projection radiograph is placed in the anatomic position for display. (B) Axial view (from feet upward) of ribs and CR with the patient in LAO position.

An x-ray shows the axillary portion of the ribs free of superimposition with the thoracic spine. The axillary ribs labeled appear light over the radiolucent area. The eighth through twelfth ribs are visible below the diaphragm for lower ribs. The sternum appears radiopaque.