Chest

Published on 03/05/2015 by admin

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Last modified 22/04/2025

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Chest

Chest—Positioning Considerations and Radiation Protection ^*

Restricting the primary beam coverage is a very effective way to reduce patient exposure in chest radiography. This requires accurate and correct location of the central ray (CR).

Correct CR Location

Correct CR location to the midchest (T7) allows for accurate collimation and protection of the upper radiosensitive region of the neck area. It also prevents exposure to the dense abdominal area below the diaphragm, which produces scatter and secondary radiation to the radiosensitive reproductive organs.

Fig. 1-1 Correct CR location.

T7 for the PA chest can be located posteriorly in reference to C7, the vertebra prominens. Level of T7 is 7-8 inches (18-20 cm) below the vertebra prominens.

The CR for the AP chest is 3-4 inches (8-11cm) below the jugular notch and angled 3°–5° caudad.

Shielding

Shielding of radiosensitive organs and tissues should be used for all procedures unless it obscures key anatomy. Shielding is not a substitute for close collimation.

Backscatter Protection

Shields placed between the patient and the wall Bucky and wall can also be used to keep scatter and secondary radiation from these structures from reaching the patient’s gonadal regions.

Digital Imaging Considerations ^*

The following technical factors will reduce dose to the patient and improve image quality:

Collimation:

Close collimation reduces dose to the patient and scatter radiation reaching the image receptor.

Accurate Centering:

Most digital systems recommend that the anatomy be centered to the receptor.

kV Range:

Digital systems allow the use of higher kV as compared to analog (film-based) systems, which will reduce patient dose.

Exposure Indicator:

Check the exposure indicator to verify that the optimal exposure factors were used to produce the least amount of radiation to the patient.

Grids:

Grids generally are not used with analog (film-screen) imaging for body parts measuring 10 cm or less. However, with certain digital systems, the grid may or may not be able to be removed from the receptor. In those cases it is departmental protocol that determines if a grid is left in place or removed.

PA Chest ^*

• 35 × 43 cm L.W. or C.W. (14 × 17″)

Fig. 1-2 PA chest (CR ≈20 cm [8″] below vertebra prominens) (average female, 18 cm [7″]).

Position

• Erect, chin raised, hands on hips with palms out, roll shoulders forward

• Center CR to T7 region. Top of IR will be approximately 2″ (5 cm) above shoulders on average patient.

• Center thorax bilaterally to IR borders with equal margins on both sides; ensure there is no rotation of thorax.

Central Ray:

CR ⊥, to T7, or 7-8″ (18-20 cm) below vertebra prominens (is also near level of inferior angle of scapula)

SID:

72-120″ (183 to 307 cm)

Collimation:

Upper border to vertebra prominens; sides to lateral skin borders

Respiration:

Expose at end of 2nd deep inspiration.

Lateral Chest ^*

• 35 × 43 cm L.W. (14 × 17″)

Fig. 1-3 Left lateral chest.

Position

• Erect, left side against IR (unless right lateral is indicated)

• Arms raised, crossed above head, chin up

• True lateral, no rotation or tilt. Midsagittal plane parallel to IR (Don’t push hips in against the IR holder.)

• Thorax centered to CR, and to IR anteriorly and posteriorly

Central Ray:

CR ⊥, to midthorax at level of T7. Generally IR and CR should be lowered ≈1″ (2.5 cm) from PA on average patient.

SID:

72-120″ (183-307 cm)

Collimation:

Upper border to level of vertebra prominens, sides to anterior and posterior skin margins

Respiration:

Expose at end of 2nd full inspiration.

Lateral, Wheelchair or Stretcher ^*

• 35 × 43 cm L.W. (14 × 17″)

Fig. 1-4 Left lateral on stretcher.

Position

• Erect, on stretcher or in wheelchair

• Arms raised, crossed above head, or hold on to support bar

• Center thorax to CR, and to IR anteriorly and posteriorly

• No rotation or tilt, midsagittal plane parallel to IR, keep chin up

Central Ray:

CR ⊥, to midthorax at level of T7

SID:

72-120″ (183-307 cm)

Collimation:

Upper border to level of vertebra prominens, sides to anterior and posterior skin margins

Respiration:

Expose at end of 2nd full inspiration.

PA (AP) Chest

Evaluation Criteria

Anatomy Demonstrated:

• Both lungs from apices to costophrenic angles

• 9-10 ribs demonstrated above the diaphragm

Position:

• Chin sufficiently elevated

• No rotation, SC joints and lateral rib margins equal distance from spine

Exposure:

• No motion, sharp outlines of diaphragm and lung markings visible

• Exposure sufficient to visualize faint outlines of midthoracic and upper thoracic vertebrae through heart and mediastinal structures

Fig. 1-5 PA chest.

Lateral Chest

Evaluation Criteria

Anatomy Demonstrated:

• From apices to costophrenic angles, from sternum to posterior ribs

Position:

• Chin and arms elevated to prevent superimposing apices

• No rotation, R and L posterior ribs superimposed except side away from IR projected slightly (1-2 cm) posteriorly because of divergent rays

Exposure:

• No motion, sharp outlines of diaphragm and lung markings

• Sufficient exposure and contrast to visualize rib outlines and lung markings through heart shadow

Fig. 1-6 Lateral chest.

Lateral Decubitus ^*

• 35 × 43 cm (14 × 17″) L.W. with respect to patient

Fig. 1-7 Left lateral decubitus chest (AP).

Position

• Patient on side (R or L, see Note) with pad under patient

• Ensure that stretcher does not move (lock wheels)

• Raise both arms above head, chin up

• True AP, no rotation, patient centered to CR at level of T7

Central Ray:

CR horizontal to T7, 3-4″ (8-10 cm) below jugular notch

SID:

72-120″ (183-307 cm) with wall Bucky; 40-44” (102-113 cm) with erect table and Bucky

Collimation:

Collimate on four sides to area of lung fields (top border of light field to level of vertebra prominens).

Respiration:

End of 2nd full inspiration

Note:

For possible fluid (pleural effusion), suspected side down; possible air (pneumothorax), suspected side up.

AP Lordotic ^*

• 35 × 43 cm L.W. (14 × 17″)

Fig. 1-8 AP lordotic (best demonstrates apices of lungs).

Position

• Patient stands ≈1 ft (30 cm) away from IR, leans back against chest board

• Hands on hips, palms out, shoulders rolled forward

• Center midsternum and IR to CR, top of IR should be 3-4″ (8-10 cm) above shoulders

Fig. 1-9 AP supine, CR 15-20″ cephalad.

Central Ray:

CR ⊥ to IR, 10-12 cm below jugular notch

SID:

72-120″ (183-307 cm)

Collimation:

Collimate on four sides to area of lung fields (top border of light field to level of vertebra prominens).

Respiration:

End of 2nd full inspiration

Lateral Decubitus Chest—AP (PA)

Evaluation Criteria

Anatomy Demonstrated:

• Entire lung fields, including apices and costophrenic angles

Position:

• No rotation, equal distance from lateral rib borders to spine

Exposure:

• No motion; diaphragm, ribs, and lung markings appear sharp

• Faint visualization of vertebrae and ribs through heart shadow

Fig. 1-10 Left lateral decubitus.

AP Lordotic Chest

Evaluation Criteria

Anatomy Demonstrated:

• Entire lung fields; include clavicles, which should appear above apices

Position:

• Clavicles appear nearly horizontal, superior to apices

• No rotation as evident by equal distance between medial ends of clavicles and lateral borders of ribs and spinal column

Fig. 1-11 AP lordotic chest.

Exposure:

• No motion; diaphragm, heart, and rib borders appear sharp

• Optimum contrast and density (brightness and contrast for digital images) to visualize vertebral outlines through mediastinal structures

Anterior Oblique Chest (RAO and LAO)^*

• 35 × 43 cm L.W. (14 × 17″)

Fig. 1-12 45° RAO.

Position

• Erect, rotated 45°, right shoulder against IR holder (RAO) (Certain heart studies require LAO, 60° rotation from PA.)

• Arm away from IR up resting on head or on IR holder

• Arm nearest IR down on hip, keep chin up

• Center thorax laterally to IR margins; vertically to CR at T7

Central Ray:

CR ⊥, to level of T7

SID:

72-120″ (183-307 cm)

Collimation:

Collimate on four sides to area of lung fields (top border of light field to level of vertebra prominens).

Respiration:

End of 2nd full inspiration

Note:

Site of interest should be farthest from IR on anterior oblique, and closest to IR on posterior oblique.

Anterior Oblique Chest—RAO and LAO

Evaluation Criteria

Anatomy Demonstrated:

• Included both lung fields from apices to costophrenic angles

Position:

• With 45° rotation, distance from outer rib borders to vertebral column on side farthest from IR should be approximately 2 times distance of side closest to IR.

Fig. 1-13 45° RAO.

Exposure:

• No motion; diaphragm and rib margins appear sharp

• Vascular markings throughout lungs and rib outlines visualized faintly through heart

Notes:

• Anterior oblique projections best demonstrate the side farthest from IR.

• Less rotation (15–20° may better visualize areas of lungs for possible pulmonary disease)

• Posterior oblique projections best visualize side closest to IR.

Fig. 1-14 45° LAO.

AP and Lateral Upper Airway (Trachea and Larynx)^*

• 24 × 30 cm L.W. (10 × 12″)

Position

• Erect, seated or standing, center upper airway to CR

• Arms down, chin raised slightly

• Lateral: Depress shoulders and pull shoulders back

• Center of IR to level of CR

Fig. 1-16 Lateral.

Central Ray:

CR ⊥, to midpoint between lower margin of thyroid cartilage and jugular notch (C6–C7); or ≈2″ (5 cm) lower if trachea is of primary interest

SID:

72-120″ (183-307 cm)

Collimation:

Collimate to region of soft tissue neck.

Respiration:

Expose during slow, gentle inspiration.

AP and Lateral Upper Airway

Evaluation Criteria

Anatomy Demonstrated:

AP and Lateral:

• Larynx and trachea well visualized, filled with air

Fig. 1-17 AP upper airway.

Position:

• No rotation, symmetric appearance of sternoclavicular joints

• Mandible superimposes base of skull

• To visualize neck region, include EAM at upper border of image.

• If distal larynx and trachea is of primary interest, center lower to include area from C3 to T5 (Fig. 1-18).

Fig. 1-18 Lateral upper airway.

Exposure:

• Optimum exposure visualizes air-filled trachea through C and T vertebrae.

• Optimum exposure includes air-filled larynx, and upper trachea not overexposed

• Cervical and thoracic vertebrae will appear underexposed.

AP Pediatric Chest ^*

• 18 × 24 cm or 24 × 30 cm C.W. (8 × 10″ or 10 × 12″)

• TT (tabletop; nongrid). Grid with systems when it can’t be removed.

Fig. 1-19 Immobilization device.

Position

• Supine, arms and legs extended, tape and sandbags or other immobilization of arms and legs

• No rotation of thorax, gonadal shield over pelvic area

• IR and thorax centered to CR

Central Ray:

CR ⊥, to midlung fields, mammillary (nipple) line

SID:

Minimum 50-60″ (128-153 cm); x-ray tube raised as high as possible

Collimation:

Closely collimate on four sides to outer chest margins.

Respiration:

Full inspiration; if crying, time the exposure at full inhalation

Note:

If parental assistance is necessary, have parent hold arms overhead with head tilted back with one hand, and other hand holding down legs (provide with lead apron and gloves).

Erect PA Pediatric Chest (with Pigg-O-Stat)^*

• 18 × 24 cm or 24 × 30 cm C.W. (8 × 10″ or 10 × 12″)

• IR (nongrid) or grid with systems when it can’t be removed

Position

• Patient on seat, legs through openings

• Adjust height of seat to place shoulders ≈1″ (2.5 cm) below upper margin of IR.

• Raise arms, and gently but firmly place side body clamps to hold raised arms and head in place.

• Set upper border of lead shield with R and L markers 1-2″ (2.5-5 cm) above level of iliac crest.

Fig. 1-20 PA chest (Pigg-O-Stat, for 5-year-old) (DR).

Central Ray:

CR ⊥, to midlung fields, mammillary (nipple) line

SID:

Minimum of 72″ (183 cm)

Collimation:

Collimate closely on four sides to outer chest margins.

Respiration:

Full inspiration; if crying, expose at full inhalation

Lateral Pediatric Chest ^*

• 18 × 24 cm or 24 × 30 cm L.W. (8 × 10″ or 10 × 12″)

• TT (tabletop, nongrid) or grid with systems when it can’t be removed

Fig. 1-21 Lateral chest (with tape and sandbags).

Position

• Lying on side, arms up with head between arms

• Support arms with tape and sandbags; ensure a true lateral.

• Flex legs; secure with tape and sandbags or with retention band across legs and hips. Lead shield over pelvic region

Central Ray:

CR ⊥, to midlung fields, level of mammillary (nipple) line

SID:

Minimum of 50-60″ (128-153 cm); x-ray tube raised as high as possible

Collimation:

Closely collimate on four sides to outer chest margins.

Respiration:

Full inspiration; if crying, time exposure at full inhalation

Note:

If parental assistance is necessary, have parent hold arms overhead with head tilted back with one hand, and other hand holding down legs (provide with lead apron and gloves).

Erect Lateral Pediatric Chest (with Pigg-O-Stat)^*

• 18 × 24 cm or 24 × 30 cm L.W. (8 × 10″ or 10 × 12″)

• IR (nongrid) or grid with systems when it can’t be removed

Position

• With patient remaining in same position as for PA chest, change IR and rotate entire seat and body clamps 90° into a left lateral position. Lead shield just above iliac crest

• Change lead marker to indicate left lateral.

Fig. 1-22 Lateral chest (Pigg-O-Stat, for 5-year-old).

Central Ray:

CR ⊥, to midlung fields, mammillary (nipple) line

SID:

72-120″ (183-307 cm)

Collimation:

Closely collimate on four sides to outer chest margins.

Respiration:

Full inspiration; if crying, time exposure at full inhalation

PA (AP) Pediatric Chest

Evaluation Criteria

Anatomy Demonstrated:

• Entire lungs from apices to costophrenic angles

Position:

• Chin elevated sufficiently

• No rotation, equal distance from lateral rib margins to spine

• Full inspiration, visualizes 9 or 10 posterior ribs above diaphragm

Fig. 1-23 AP (PA) pediatric chest (breathing motion is evident, blurred diaphragm, needs repeat).

Exposure:

• No motion, sharp outlines of rib margins and diaphragm

• Faint outline of ribs and vertebrae through mediastinal structures

Lateral Pediatric Chest

Evaluation Criteria

Anatomy Demonstrated:

• Entire lungs from apices to costophrenic angles

Position:

• Chin and arms elevated sufficiently

• No rotation, bilateral posterior ribs superimposed

Exposure:

• No motion; sharp outline of diaphragm, rib borders, and lung markings

• Sufficient exposure to faintly visualize ribs and lung markings through heart shadow

Fig. 1-24 Lateral pediatric chest (DR).

Bontragers Handbook of Radiographic Positioning and Techniques