PA Chest Projection (Ambulatory Patient)

Comprehensive practice flashcards covering technical factors, patient positioning, central ray placement, and evaluation criteria for the ambulatory PA chest projection.

What clinical indications are demonstrated when a PA chest projection is performed erect?

Pleural effusion, pneumothorax, atelectasis, and signs of infection.

What is the minimum source-to-image receptor distance (SID) required for a PA chest projection?

$72\text{ inches}$ ($180\,\text{cm}$).

What is the recommended kVp range for a PA chest radiograph?

$110\text{--}125\,\text{kVp}$.

What is the recommended field size and image receptor orientation for a PA chest projection on an average patient?

$14 \times 17\text{ inches}$ ($35 \times 43\,\text{cm}$), portrait or landscape.

How should the patient's shoulders and arms be positioned for a PA chest projection to prevent anatomy from obscuring the lungs?

Hands placed on lower hips with palms out and elbows partially flexed; shoulders rotated forward against the IR to move the scapulae laterally clear of the lung fields, and depressed downward to move the clavicles below the apices.

Why is the patient's chin raised and rested against the IR during a PA chest projection?

To prevent superimposition of the chin over the lung apices.

How are the patient's body planes aligned relative to the central ray (CR) and image receptor (IR) to prevent rotation on a PA chest?

The midsagittal plane is aligned with the CR and midline of the IR, and the midcoronal plane is placed parallel to the IR.

Where is the central ray (CR) centered for a PA chest projection?

Perpendicular to the IR and centered to the midsagittal plane at the level of T7 ($7\text{ to }8\text{ inches}$ [$18\text{ to }20\,\text{cm}$] below the vertebra prominens, or to the inferior angle of the scapula).

For an average patient, where should the top of the image receptor be positioned relative to the shoulders?

Approximately $1\frac{1}{2}\text{ to }2\text{ inches}$ ($4\text{ to }5\,\text{cm}$) above the shoulders.

What are the recommended collimation borders for a PA chest projection?

Collimate on four sides to the area of the lung fields, with the top border to the level of the vertebra prominens and the lateral borders to the outer skin margins.

At what point in the patient's breathing cycle should the exposure be made for a PA chest radiograph?

At the end of the second full inspiration.

How should the $14 \times 17\text{-inch}$ ($35 \times 43\text{-cm}$) IR be oriented for hypersthenic and broad-chested patients?

Landscape (or collimated to at least this size when possible with larger digital receptors).

What anatomy must be demonstrated on an acceptable PA chest projection?

Both lungs from apices to costophrenic angles, the air-filled trachea from T1 down, hilum region markings, heart, great vessels, and bony thorax.

What positional criteria confirm the absence of rotation on a PA chest radiograph?

Both sternoclavicular joints are equidistant from the center line of the spine, and the distance from the lateral rib margins to the vertebral column is the same on each side from the upper to lower rib cage.

How many posterior ribs must be visualized above the diaphragm to indicate full inspiration on a PA chest projection?

A minimum of $10$ posterior ribs above the diaphragm ($11$ on many patients).

What visual evidence on a PA chest radiograph demonstrates optimal exposure and contrast penetration through dense structures?

Faint outlines of at least midthoracic and upper thoracic vertebrae and posterior ribs visible through the heart and mediastinal structures.

According to Note 2, what patient conditions can cause asymmetry of the sternoclavicular joints and rib cage margins without true positioning rotation?

Scoliosis and kyphosis, as evidenced by right-to-left spinal curvature.