ANTERIOR OBLIQUE POSITION - RAO AND LAO: CHEST

Pathology Demonstrated:

• Pathology involving the lungs fields, trachea, and mediastinal structures, including the size and contours of the heart and great vessels.

Technical Factors:

• IR size - 35 x 43cm (14 x 17 inches), lengthwise
• Moving or stationary grid
• 110 to 125 kV range

Shielding:

• Secure lead shield around waist to shield gonads.

Patient Positions:

• Patient erect, rotated 45degrees with left anterior shoulder against IR for the LAO and 45degrees with right anterior shoulder against IR for the RAO (see note below for 60degrees LAO)
• 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

Part Position:

• As viewed from the x-ray tube, center the patient to CR and to IR, with top of IR about 1inch (2.5cm) above vertebral prominens.

Central Ray:

• CR perpendicular, directed to level  of T7 (7 to 8 inches [8 to 10cm] below level of vertebral prominens)
• SID of 72 inches (180cm)

Collimation:

• Collimate to area of lungs.

Respiration:

• Make exposure at end of second full inspiration.

Note:

• 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 60degrees.
• Less rotation (15 to 20degrees) may of value for better visualization of the various areas of the lungs for possible pulmonary disease.

Exception:

• Either erect or recumbent posterior obliques can be taken if the patient cannot assume an erect position for anterior obliques, or if supplementary projections are required.