Radiographic Procedures · ARRT 2025
Chest X-Ray for ARRT
PA and lateral chest, lordotic, decubitus, and the quality criteria (10 ribs, no rotation, sharp diaphragm, scapulae out) for the ARRT Radiography Boards.
Overview
Chest Radiography is the most-ordered radiograph in the world. It is also the most-tested clinical chapter on the ARRT registry. The chapter is short because the routine is short, but the quality criteria are deeply detailed, and the registry asks about them in granular form.
The routine PA chest: 72-inch SID (long SID minimizes magnification of the cardiac silhouette), patient erect, chin extended, arms back so the scapulae are clear of the lung fields, second exposure on full inspiration to demonstrate at least 10 posterior ribs above the diaphragm. The cardiothoracic ratio is meaningful only on PA, never on AP. Quality checks: no rotation (sternal ends of clavicles equidistant from the spinous process), penetration adequate (you can see vertebral bodies through the cardiac shadow on a properly exposed PA), sharp costophrenic angles.
The lateral chest: left lateral by default (places the heart closer to the IR, less magnification), arms raised over the head, true lateral with no rotation. Lordotic AP (CR perpendicular, beam directed cephalic 15–20° if patient cannot lean back) demonstrates the apices and middle lobe free of clavicular superimposition. Lateral decubitus (patient on the affected side for free fluid, opposite side for free air) uses a horizontal beam to demonstrate small pleural effusions or pneumothorax not visible on the upright PA. Pediatric chests use AP because the child is supine, and the heart magnification penalty is acceptable for the workflow gain. Common pathology tested: pneumonia (consolidation), pneumothorax (visceral pleural line, no lung markings beyond), atelectasis, pleural effusion, cardiomegaly.
What you’ll learn in this chapter
The 9 lessons in this chapter break down as follows. The full lesson content is unlocked when you start a free account.
Standard Projections
- PA Chest: The Gold Standard
- Lateral Chest: The Orthogonal View
Quality Control
- Anatomy of a High-Quality Chest Radiograph
Problem-Solving Projections
- Lordotic & Lateral Decubitus
- Pathology Pearls: Emphysema & Pleural Effusion
Knowledge Check
- Question 1 of 4 Quiz
- Question 2 of 4 Quiz
- Question 3 of 4 Quiz
- Question 4 of 4 Quiz
Key terms in this chapter
These are the 7 terms most likely to appear on the ARRT registry from this chapter. Use them as a flashcard pre-quiz.
- PA Chest
- Posteroanterior chest projection. 72-inch SID, patient erect, scapulae cleared, full inspiration. The standard adult chest.
- 10 Posterior Ribs Rule
- On a properly inspired PA chest, at least 10 posterior ribs should be visible above the diaphragm.
- Lordotic Position
- Patient leans back so the central ray is angled relative to the body. Demonstrates apices and middle lobe free of clavicles.
- Left Lateral Decubitus
- Patient lies on the left side, horizontal CR. Demonstrates free fluid on the left or free air on the right.
- Cardiothoracic Ratio
- Ratio of heart width to chest width. Greater than 50% suggests cardiomegaly. Valid only on PA chest.
- Pneumothorax
- Air in the pleural space. Best seen on upright expiratory PA or lateral decubitus with the affected side up.
- Costophrenic Angle
- Sharp angle where diaphragm meets chest wall on PA chest. Blunting indicates pleural effusion.
Sample practice question: Thorax and Abdomen
One free sample from the 75-question Thorax and Abdomen bank. See the format, the rationale style, and the difficulty before you sign up.
On a properly positioned and exposed PA chest radiograph in an adult, how many posterior ribs should be visible above the diaphragm to indicate adequate inspiration?
Show answer and rationale
A, Incorrect: 8 posterior ribs typically indicates underinspiration. Repeat with full inspiration.
B, Correct: Correct. The standard is at least 10 posterior ribs visible above the diaphragm on a properly inspired adult PA chest. Underinspiration (only 8 visible) compresses lung markings and may mimic pulmonary disease.
C, Incorrect: Counting anterior ribs is less reliable because they're more variable and angle differently. Use posterior ribs as the standard.
D, Incorrect: Costophrenic angle visibility is part of quality assessment but does not specifically indicate inspiration adequacy.
Hands-on
Practice the positioning
Open the Positioning Lab to drill body position, central ray, anatomy, and common errors for each projection in this chapter.
- Chest PA Standard upright posteroanterior chest projection. SID 72".
- Chest AP Anteroposterior chest. Used when patient cannot stand for PA.
- Chest Left Lateral Upright left lateral chest. Complement to PA. SID 72".
- Chest AP supine Bedside supine chest. ICU/trauma. SID 40".
- Chest Lordotic AP axial / lordotic. Projects clavicles above lung apices. SID 72".
Read the full chapter, free.
The free tier unlocks one complete chapter (9 lessons), 50 practice questions, and 1 sample timed exam. No credit card required.
Frequently asked questions
What does the ARRT Radiography Radiographic Procedures category cover?
Chest Radiography is the most-ordered radiograph in the world. It is also the most-tested clinical chapter on the ARRT registry. The chapter is short because the routine is short, but the quality criteria are deeply detailed, and the registry asks about them in granular form.
How many lessons are in the Chest X-Ray for ARRT chapter?
This chapter contains 9 lessons across 4 sections, plus a knowledge-check quiz at the end. The full lesson content is unlocked with a Premium subscription. The free tier includes the first chapter complete.
Is this chapter aligned with the ARRT 2025 Content Specifications?
Yes. Every chapter on this site maps directly to the ARRT Radiography Content Specifications effective 2025. This chapter falls under the Radiographic Procedures domain of the official ARRT exam blueprint.