The schematic diagram details the use of the average intrapleural distance (in centimeters) to estimate the size of a pneumothorax from a frontal chest radiograph. The average of A + B + C (in centimeters) is applied to the scale to determine pneumothorax size as a percentage (% Ptx).
Panel A: Courtesy of Helga E Stark, MD, PhD.
Panel B: Reproduced with permission from: Rhea JT, DeLuca SA, Greene RE. Determining the size of pneumothorax in the upright patient. Radiology 1982; 144:733. Copyright © 1982 Radiological Society of North America.