Chest Radiography for the ARRT Exam

Overview

Chest radiography is the most common radiographic procedure and the one with the highest repeat rate in many departments, which is exactly why the ARRT exam leans on its details. The chapter covers the bony thorax, lungs and mediastinum, then all seven chest projections plus the upper airway, image critique and pathology.

The constants apply to every chest projection: 72 inch SID, 110 to 125 kV with a grid, a 35 by 43 cm receptor, and exposure at the end of the second full inspiration. Centering is T7, found 7 to 8 inches below the vertebra prominens or 3 to 4 inches below the jugular notch, and adequate inspiration shows 10 posterior ribs above the diaphragm.

The exceptions are the tested part. The AP chest adds a 5 degree caudad angle to keep the clavicles off the apices, the AP lordotic centers at midsternum instead of T7, and the lateral decubitus keeps a horizontal beam because that is the only way to show an air-fluid level: suspected fluid goes side down, suspected air goes side up. On obliques, an RAO best shows the left lung, the side farthest from the receptor, while posterior obliques show the side closest to it.

Anatomy and pathology round it out. The right lung has three lobes and a horizontal fissure, the left has two, and the right primary bronchus is wider and more vertical, which is where aspirated objects go. Emphysema is destructive, giving radiolucent lungs that need decreased exposure; atelectasis is additive, giving radiodense regions that need an increase. Rotation is checked on the sternoclavicular joints, and a hypersthenic patient takes a landscape receptor to save the costophrenic angles.