Chest : PA View

Thursday, March 20, 2014


PA Chest Positioning

PA chest projection is the most common projection of all in chest x-ray examination. it can be taken on both ambulatory and trauma patient. Right and left oblique and lateral view are also requested by their physician as required for supplemental studies for the PA projection. Upright position is necessary as possible is patient can tolerate, because in this position it prevents the maximum expansion of the lungs.  On erect position, it best demonstrates pleural effusions, pneumothorax and atelectasis and other sign of infections are also evident if present.
Technical Factors of Chest Radiography
Radiation Protection of Chest

Technician's Preparation on Chest PA - Summary

Ambulatory Patient Chest PA
normal chest xray
PA Upright

IR size :
  • 14 x 14 in. (35 x 35 cm)
  • 14 x 17 in. (35 x 43cm)
  • Lengthwise
  • Hyperstenic patients place IR Crosswise
Grid : Yes
Non-grid : Decrease in kVp
kVp : 110 to 135
mA : 300s
SID : 72 inches (180 cm)
cm : 22
mAs :  2 to 3
Respiration : Second full inspiration

Central Ray

chest xray
Chest PA with Abdominal Shield
  • Perpendicular
  • Level of T7
  • 7-8 inches below the vertebral prominence
  • Level of inferior angle of scapulae
  • Top of IR is 2 inches above shoulder (Normal / Average Patient)
  • Collimate on four sides of lung fields.
  • Light collimation on top border of IR and in lateral border of outer skin margins

Patient Position Ambulatory Patient

  • Patient is erect
  • Slightly spread feet and ensure weight is equally distributed on both feet
  • Rest chin on IR by raising chin.
  • Palm surface of the hands out, and flex elbow
  • Rotate shoulder forward to wing out scapula laterally
  • Depress shoulder downward to move clavicle below the apices
  • Put mobile shield behind patient or use lead shield and put around the waist.

Part Position Ambulatory Patient

  • Mid-sagital plane, Central ray and Image receptor is aligned with equal margins of lateral thorax with sides of IR.
  • Midcoronal Plane is parallel to IR to ensure no rotation of thorax.
  • Top of IR is approximately 1.5 to 2 inches above shoulder on average patients.
  • Adjust CR and IR as needed to place CR perpendicular and directed to level of T7 on average patients or CR is at 7 to 8 inches below vertibral prominence or to the inferior angle of scapula

Chest PA Sitting or on Stretcher if Patient Cannot Stand

A portable machine may be used on this x-ray examination, if the patient cannot be easily transported to the x-ray department. If portable cassette is used because patient cannot place up against the chest board, acquiring a PA projection of the chest patient should hug the image receptor, place pillow or padding on lap to raise and support cassette but keep portable cassette against chest for a minimum Object-image-Receptor-Distance (OID). In some patients this position may be difficult to tolerate an AP sitting projection is the alternative projection.
Note: To stabilize or immobilize patient a compression band or other means may be use to ensure minimized patient motion and prevent waver during exposure.
Film Size :
  • 14 x 14 in. (35 x 35 cm)
  • 14 x 17 in. (35 x 43cm)
  • Lengthwise
  • Hyperstenic patients place IR Crosswise
Grid : Yes
Non-grid : Decrease in kVp
kVp : 60 to 75
mA : 300s
SID : 48 to 72 inches
mAs : 1.5 to 2
Respiration : Second full inspiration

Central Ray and Shielding

  • Perpendicular to IR.
  • Centered to midsagittal plane at the level of T7.
  • Cassette centered to the level of portable cassette.
  • Place lead shield around the waist to shield gonads.
  • Patient Position Sitting Chest PA
  • Patient is seated on cart and put legs over the edge of IR.
  • Arm around cassette or let patient Hug the portable Image ReceptorShoulder rotated forward

Pedriatric Chest PA - Using Pigg-O-stat

Film Size :
chest PA
Pediatric Chest PA
  • 8x10 inches (18x24 cm)
  • 10x12 inches (24x30 cm)
Grid : If grid cannot be removed
Non Grid : Yes
kVp : 75 to 80 kV
SID : 72 inches (minimum)
Central Ray : Mammillary Nipple line, or at Mid-thorax area 
Collimation : Collimate on four sides of IR ensuring no cut-off.
Respiration : Full Inspiration, On crying child make exposure at  full inhalation

Patient Position Pediatric using Pigg-O-Stat

  • Patient is seated
  • Place shoulder 1 inch below the upper end of IR
  • Raise arm and gently place clamp of Pigg-O-stat to hold head and raised hands
  • Right and Left marker is placed above illiac crest 1-2 inches high.
  • Patient Identification marker above shoulder, 1-2 inches high.

    Radiographic Criteria : Chest Radiograph

    Chest PA Criteria

    • Proper patient breathing instructions will have a minimum of 10 posterior ribs above diaphragm and 11 posterior ribs on some patients.
    • Proper patient positioning with no rotation is evident with both sternoclavicular joints is equal in distance from center line of  the spine and lateral rib margins to vertebral column is equidistant on each side from upper to lower ribcage.
    Note: Scoliosis and kyphosis also may cause asymmetry of sternoclavicular joints and rib cage margins, as evidenced by R to L spinal curvature.
      pa chest
    • Proper patient positioning with no motion is evident by sharp outlines of the ribs margins, diaphragm, and heart borders, as well as lung markings in hilar region and throughout of lungs is sharp.
    • Both lungs from apex to costrophrenic angles, air filled trachea from T1 down are included on the chest PA radiograph.
    • Chin is sufficiently elevated, prevented from superimposition to apices
    • Sufficient pulling shoulder forward, prevented the superimposition of scapula over the lung fields.
    • Large breast shadows (if present) is primarily in the lateral lung fields.

    Radiograph Criteria on Exposure

    Sufficient long-scale contrast for visualization of fine vascular markings within lungs
    Faint outlines of at least midthoracic and upper thoracic vertebrae and posterior ribs visible though heart and mediastinal area.

    Chest PA Possible Structure Shown on Radiograph

    • Air filled trachea in the thoracic vescera
    • Diaphragmatic domes
    • Heart and Aortic knob
    • Hilar Region Markings
    • Great Vessels
    • Bony Thorax
    • 10 - 11 Posterior Ribs
    pa chest pneumothorax
    A. PA Chest - Pneumothorax

    PA Chest View Possible Pathology Demonstrated

    Pneumothorax - The patient has a blunt injury, on the entire right lung pneumothorax is seen and resulted a completely collapsed lung is evident near the hilum (arrow) image A..
    Pleural Effusion 

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