INSPIRATION AND EXPIRATION Occasional exceptions have been noted to taking chest radiographs on full inspiration only. For certain conditions, comparison radiographs are taken on both full inspiration and full expiration. Indicators for this include a possible small pneumothorax (air or gas in the pleural cavity), fixation or lack of normal movement of the diaphragm, the presence of a foreign body, and the need to distinguish between an opacity in the rib and one in the lung. When such comparison radiographs are taken, they should be labeled “inspiration” and “expiration.”
AP LORDOTIC PROJECTION: CHEST Pathology Demonstrated Projection is performed primarily to rule out calcifications and masses beneath the clavicles. 110 to 125kV range Technical Factors:
Shielding Secure lead shield around waist to shield gonads. Patient Position Patient standing about 1 foot (30 cm) away from IR and leaning back with shoulders, neck, and back of head against IR Both patient's hands on hips, palms out; shoulders rolled forward Part Position Center midsagittal plane to CR and to centerline of IR. Center cassette to CR. (Top of IR should be about 3 inches [7 to 8 cm] above shoulders on average patient.) Central Ray CR perpendicular to IR, centered to midsternum (3 to 4 inches [9 cm] below jugular notch) SID of 72 inches (180 cm)
Exception: semiaxial supine AP. If patient is weak and unstable and/or is not able to assume the erect lordotic position, an AP semiaxial projection may be taken with the patient in a supine position. Shoulders are rolled forward and arms positioned as for lordotic position. The CR is directed 15°to 20° cephalad, to the midsternum.
AP PROJECTION: CHEST Supine or Semierect (in Department or as Bedside Portable) Pathology Demonstrated This projection demonstrates pathology involving the lungs, diaphragm, and mediastinum. Determining air-fluid levels (pleural effusion) requires a completely erect position with a horizontal CR, as in a PA or decubitus chest projection.
Shielding Place lead shield to shield gonads. Patient Position Patient is supine on cart; if possible, the head end of the cart or bed should be raised into a semierect position (see Notes). Roll patient's shoulders forward by rotating arms medially or internally. Part Position Place IR under or behind patient; align center of IR to CR (top of IR about 1½ inches [4 to 5 cm] above shoulders). Center patient to CR and to IR; check by viewing patient from the top, near the tube position. Central Ray CR angled caudad to be perpendicular to long axis of sternum (generally requires ± 5° caudad angle, to prevent clavicles from obscuring the apices) CR to level of T7, 3 to 4 inches (8 to 10 cm) below jugular notch Minimum SID of 40 inches (100 cm) for supine.
For semierect position, use 72-inch (180-cm) SID if this is possible. Always place markers on the IR or label the image to indicate the SID used; also indicate those projections obtained, such as AP supine or AP semierect. Semi-erect 72”
LATERAL DECUBITUS POSITION (AP PROJECTION): CHEST Pathology Demonstrated Small pleural effusions are demonstrated by air-fluid levels in pleural space, or small amounts of air in pleural cavity may demonstrate a possible pneumothorax Use decub marker (or arrow)
Patient Position Cardiac board on the cart or radiolucent pad under patient Patient lying on right side for right lateral decubitus and on left side for left lateral decubitus (see Notes below) Patient's chin extended and both arms raised above head to clear lung field; back of patient firmly against IR; cart secured to prevent patient from moving forward and possibly falling; pillow under patient's head Knees flexed slightly and coronal plane parallel to IR with no body rotation Central Ray CR horizontal, directed to center of IR, to level of T7, 3 to 4 inches (8 to 10 cm) inferior to level of jugular notch. A horizontal beam must be used to show air-fluid level or pneumothorax. SID of 72 inches (180 cm)
Part Position Adjust height of IR to center thorax to IR Adjust patient and cart to center midsagittal plane and T7 to CR (top of IR is about 1 inch [2.5 cm] above vertebra prominens).
Radiograph may be taken as a right or left lateral decubitus. To produce the most diagnostic images, both lungs should be included on the image. For possible fluid in the pleural cavity (pleural effusion), the suspected side should be down. Do not cut off that side of the chest. The anatomic side marker must correspond with the patient's left or right side of the body. The marker must be placed on the IR prior to exposure. It is not acceptable practice to indicate the side of the body either digitally or with a marking pen following the exposure. For possible small amounts of air in the pleural cavity (pneumothorax), the affected side should be up, and care must be taken not to cut off this side of the chest.
ANTERIOR OBLIQUE POSITIONS—RAO AND LAO: CHEST Pathology Demonstrated Pathology involves the lung fields, trachea, and mediastinal structures, including the size and contours of the heart and great vessels.
Patient Position Patient erect, rotated 45° with left anterior shoulder against IR for the LAO and 45° with right anterior shoulder against IR for the RAO. Patient's arm flexed nearest IR and hand placed on hip, palm out Opposite arm raised to clear lung field and hand rested on head or on chest unit for support, keeping arm raised as high as possible Patient looking straight ahead; chin raised
Central Ray CR perpendicular, directed to level of T7 (7 to 8 inches [8 to 10 cm] below level of vertebra prominens) SID of 72 inches (180 cm)
Notes: For anterior obliques, the side of interest generally is the side farthest from the IR. Thus the RAO will provide best visualization of the left lung. Certain positions for studies of the heart require an LAO with an increase in rotation to 60°. Less rotation (15° to 20°) may be of value for better visualization of the various areas of the lungs for possible pulmonary disease. 45 deg RAO45 deg LAO
POSTERIOR OBLIQUE POSITIONS—RPO AND LPO Pathology Demonstrated Pathology involves the lung fields, trachea, and mediastinal structures, including the size and contours of the heart and great vessels. Patient Position (Erect) Patient erect, rotated 45° with right posterior shoulder against IR for RPO and 45° with left posterior shoulder against IR for LPO Arm closest to the IR raised resting on head; other arm placed on hip with palm out Patient looking straight ahead
Pathology Demonstrated Abnormal masses, air-fluid levels, and accumulations of intraperitoneal air under diaphragm are demonstrated. Perform erect radiograph first if patient comes to department ambulatory or in wheelchair in an erect position.
LATERAL DECUBITUS POSITION (AP PROJECTION): ABDOMEN Pathology Demonstrated Abdominal masses, air-fluid levels, and possible accumulations of intraperitoneal air are demonstrated. (Small amounts of free intraperitoneal air are best demonstrated with chest technique on erect PA chest.) Important: Patient should be on side a minimum of 5 minutes before exposure (to allow air to rise or abnormal fluids to accumulate); 10 to 20 minutes is preferred, if possible, for best visualization of potentially small amounts of intraperitoneal air. Left lateral decubitus best visualizes free intraperitoneal air in the area of the liver in the right upper abdomen away from the gastric bubble.
70 to 80 kV range Patient Position Lateral recumbent on radiolucent pad, firmly against table or vertical grid device (with wheels on cart locked so as not to move away from table) Patient on firm surface, such as a cardiac or back board, positioned under the sheet to prevent sagging and anatomy cutoff Knees partially flexed, one on top of the other, to stabilize patient Arms up near head; clean pillow provided Marker: Place arrow or other appropriate marker to indicate “up” side.
Central Ray CR horizontal, directed to center of IR, at about 2 inches (or 5 cm) above level of iliac crest; use of a horizontal beam to demonstrate air-fluid levels and free intraperitoneal air Minimum SID of 40 inches (100 cm)
Radiographic Criteria Structures Shown: Air-filled stomach and loops of bowel and air-fluid levels where present. Should include bilateral diaphragm. Position: No rotation; iliac wings appear symmetric, and outer rib margins are the same distance from spine. Spine should be straight (unless scoliosis is present), aligned to center of IR.