Chest X-Ray Interpretation Basics for RTs

Overview

The chest radiograph is one of the most frequent images the respiratory therapist will encounter, and the RT is often the first person to act on it — verifying the endotracheal tube after an intubation, or correlating a new white-out with absent breath sounds. The film never replaces the bedside exam; it confirms it. The goal of this guide is a repeatable read: a fixed sequence that checks technical quality, walks the anatomy the same way every time, and flags the handful of patterns that change what you do next.

A systematic approach matters because the eye is drawn to the obvious finding and skips the subtle one. By reading every film in the same order, and by always comparing with the prior film, you stop missing the second pneumothorax, the slowly migrating tube, or the early effusion.

A Systematic Read

Pick a scheme and use it on every film. One common approach checks technical quality first with RIPE, then surveys the anatomy with ABCDE.

• Rotation, Inspiration, Penetration, Exposure — the RIPE check for technical adequacy before you trust anything else on the film.
• Airway / Adequacy — trachea midline, tubes and ETT depth.
• Bones and soft tissue — ribs, clavicles, subcutaneous air.
• Cardiac silhouette and mediastinum — size, contour, and any shift.
• Diaphragm and costophrenic angles — sharp or blunted, level or elevated.
• Everything else — lung fields, pleura, and lines. Then compare with the prior film.

Film Quality First

A technically poor film will fool you, so judge quality before you interpret. On a good AP/PA film you should count roughly 9–10 posterior ribson inspiration. An underinflated, essentially expiratory film crowds the lung markings and mimics congestion — calling that “pulmonary edema” is a classic error. Rotation distorts the mediastinum and can fake a shifted trachea or an enlarged heart.

Remember that the portable AP film — the usual ICU view — magnifies the cardiac silhouette because of the shorter source-to-film distance and the anterior position of the heart. Do not over-read heart size on a portable. Penetration and exposure determine whether you can see lung markings behind the heart and through the spine.

Tube and Line Placement

Confirming hardware is the RT’s first job after an intubation or a line placement.

• Endotracheal tube: the tip should sit roughly 3–5 cm above the carinawith the head neutral — in other words, mid-trachea. Too low means a right mainstem intubation: the right lung overinflates while the left lung collapses or develops atelectasis, and you lose left-sided breath sounds.
• The tip moves with the neck— the hose follows the nose. Neck flexion advances the tip toward the carina; extension withdraws it, each by up to about 2 cm. A tube confirmed in good position can migrate after the head is repositioned, so re-check after any move.
• Central venous catheter:the tip belongs in the lower superior vena cava at the cavoatrial junction — about the level of the carina — not down in the right atrium.
• Nasogastric tube: it should cross the diaphragm in the midline with the tip below the diaphragm in the stomach.
• After any procedure, confirm placement on the film and look for a post-procedure pneumothorax after central-line or chest-tube placement.

Common Patterns

Five patterns account for most of what changes the bedside plan. Learn the signature of each.

The single most useful distinction is atelectasis versus effusion. Both look white, but atelectasis is volume loss and pulls structures toward it, while a large effusion or mass occupies space and pushes them away. When you see a white hemithorax, decide which way the mediastinum and diaphragm have shifted before you name it.

What the RT Does With It

Reading the film is only useful if it drives action. The RT’s priorities are concrete:

1. Verify ETT depth immediately after intubation and after any repositioning of the head or the tube.
2. Correlate a new white-out or absent breath sounds with the film — mainstem intubation, mucus plug, effusion, and pneumothorax all present differently, and the shift direction and tube position tell them apart.
3. Recognize the post-procedure pneumothorax after a central line or chest tube, and escalate promptly.
4. Use the film to confirm, not replace, the bedside exam — the auscultation, the capnography, and the ventilator graphics still lead.

Common Pitfalls

• Trusting a poor film.An expiratory or rotated film mimics congestion and distorts the mediastinum — judge quality before you interpret.
• Calling a right mainstem intubation a “collapse.” A white-out left lung with the tube sitting too low is a malpositioned tube, not primary lung disease — check the ETT first and pull it back.
• Waiting for a film to treat tension. A tension pneumothorax is treated on clinical grounds; do not delay decompression for the radiograph.
• Confusing atelectasis with effusion.Both are white; the shift direction settles it — volume loss pulls toward, a space-occupying effusion pushes away.

Board Exam Pearls

• ETT tip 3–5 cm above the carina with the head neutral.
• Right mainstem intubation = left lung collapse with absent left breath sounds.
• Atelectasis shifts toward, effusion shifts away — the shift direction names the white hemithorax.
• Tension pneumothorax is clinical, not radiographic — decompress before the film.

FAQ

Related Resources

Sources

1. Kacmarek RM, Stoller JK, Heuer AJ. Egan's Fundamentals of Respiratory Care. 12th ed. Elsevier; 2021. Chest imaging and the chest radiograph.
2. National Board for Respiratory Care. Therapist Multiple-Choice Examination Detailed Content Outline. NBRC; 2024. Patient data evaluation: imaging studies.