Lateral Upper Airway Radiographic Positioning and Evaluation

Vocabulary flashcards covering technical factors, positioning requirements, anatomy, and evaluation criteria for the lateral position of the upper airway.

Clinical Indications for Lateral Upper Airway

Investigation of pathology of the air-filled larynx and trachea, including the thyroid and thymus glands and upper esophagus for opaque foreign objects or contrast medium, and ruling out life-threatening epiglottitis in young children.

Epiglottitis

A condition that may be life-threatening for a young child, for which a lateral upper airway radiograph is routinely indicated to rule out.

Minimum SID for Lateral Upper Airway

$72\text{ inches}$ ($180\,\text{cm}$), utilized to minimize magnification.

Recommended Field Size for Lateral Upper Airway

$10 \times 12\text{ inches}$ ($24 \times 30\,\text{cm}$), oriented portrait.

kVp Range for Lateral Upper Airway

$75$ to $85\text{ kVp}$, utilizing a grid.

Shoulder and Arm Positioning for Lateral Upper Airway

Shoulders are rotated posteriorly with arms hanging down and hands clasped behind the back to prevent shoulder shadows from superimposing the trachea.

External Auditory Meatus (EAM)

The opening of the external ear canal; the top of the image receptor (IR) is adjusted to its level during upper airway positioning.

Central Ray (CR) for Routine Lateral Upper Airway

Directed perpendicular to the center of the IR at the level of $C6$ or $C7$, midway between the laryngeal prominence of the thyroid cartilage and the jugular notch.

Respiration for Lateral Upper Airway

Exposure is made during a slow, deep inspiration to ensure the trachea and upper airway are filled with air.

Centering for the Neck Region (Larynx and Upper Trachea)

Centering directed to the laryngeal prominence ($C5$) with exposure factors designated for a soft tissue lateral neck.

Centering for Distal Larynx and Trachea Region

The IR and CR are lowered to position the central ray at the upper jugular notch ($T1$-$T2$), using exposure factors approximately those for a lateral chest.

Collimation for Lateral Upper Airway

Collimate to the region of soft tissue of the neck, ideally with minimal ($\frac{1}{4}\text{ inch}$) borders at the top and bottom.

Positioning Evaluation for Proximal Neck Region

The image must demonstrate the external auditory meatus (EAM) at the upper border and $T2$ or $T3$ on the lower border, with shoulder shadows located posterior to the trachea.

Positioning Evaluation for Distal Larynx and Trachea

The image must include the region from $C3$ to $T4$ or $T5$, with the trachea filled with air and not superimposed by the shoulders.

Exposure Evaluation Criteria for Lateral Upper Airway

Optimal soft tissue technique where the air-filled larynx and upper trachea are well visualized and not overexposed, while the cervical vertebrae appear underexposed.