Dynamic digital radiography (DDR) is a new advanced version of chest radiography that captures dynamic images at a rate of 15 frames per second. It is coupled with an analytical software that allows it to provide more advanced measures of lung motion, ventilation, and perfusion compared to traditional chest radiography. While implementation of DDR fixed machines are beginning elsewhere in the US, this trial involves the first applications of an FDA-approved portable DDR machine, for use at the bedside in the ICU. The goal of this clinical trial is to determine the feasibility and safety of portable DDR technology in the ICU, as well as to evaluate the improved clinical diagnostic value of the portable DDR system over current standards of care. Participants will receive one to three sets of DDR images, which will then be compared to their clinical gold standard exams (such as chest x-rays, CTs, or VQ scans) to assess and improve the precision and accuracy of measurements such as diaphragmatic motion, lung movement, and perfusion.