How to Examine COVID-19 with Chest X-Rays and CT Scans

Now that COVID-19 has spread across the entire world, hospitals and healthcare systems are struggling to avoid being overwhelmed. Testing kits are limited in supply and offer slow turnaround for results, and with a majority of COVID-19 deaths occurring due to pneumonia, many doctors are turning to chest X-rays and CT scans as frontline diagnostic tests. Both are imaging procedures that help determine the source of an individual’s symptoms, as well as the best course of treatment.


Chest X-rays use a small amount of radiation that quickly goes through a person’s body to capture an internal image of the chest. This helps recognize abnormal formations and diseases such as pneumonia. Chest CT Scans are a more detailed type of chest X-ray that takes a number of detailed pictures, which are then merged into one projection to deliver a 3D view of the position, shape and size of the organs in a person’s chest.


X-rays are the most commonly ordered imaging study for patients with respiratory issues, and are used to examine dense tissues. Chest X-rays can help detect COVID-19 by finding pneumonia or infiltrates, which are fluid and pus that sit in the lungs and show up as white spots on the image.


CT scans capture images of bones, soft tissues and blood vessels, and can be helpful in suggesting a patient’s diagnosis and monitoring patient responses. They can detect abnormalities that tend to occur around the edges and base of the lungs, as well as ground-glass opacities, which are the hazy appearance of lungs on the images (as if sections are obscured by ground glass) caused by the filling of pulmonary airspaces with fluid or the collapse of airspaces.


The journal Radiology published a series of papers in February offering evidence that chest scans can be useful in the fight against COVID-19. Teams in China and the United States noted certain visual hallmarks in the lungs of patients with COVID-19 symptoms that included ground-glass opacities (hazy darkened spots in the lung that don’t block vessels or lung structures) and consolidation (areas of increased lung density). The longer a person was infected, those characteristics appeared more frequent and more likely to spread across both lungs.


In the United Kingdom, radiologists are being asked to prioritize chest X-rays over other imaging studies, and any patient suspected of COVID-19 will receive a chest X-ray along with a blood test. Health care providers then examine the X-rays to determine which cases are highly likely to be COVID-19 in a more timely manner. Radiologists are also reading CT images while patients are in the scanner to assess whether the scanning equipment will need a shorter wipe-down or a prolonged deep clean after the patient’s imaging procedure if the person is suspected of being infected with COVID-19.


Multiple medical and tech companies around the world have announced artificial intelligence-based systems to detect COVID-19 on chest X-rays or CT scans. Among these companies are RADLogics in the United States, Alibaba Group and Yitu Healthcare in China, Ping An Insurance in Hong Kong, and Lunit in South Korea. Currently, these tools are being used in hospitals to screen mild cases, triage new infections and monitor progress.


AI-powered analysis of chest scans could potentially alleviate the increasing burden on radiologists, who review and prioritize a growing number of chest scans daily. There is also the possibility that the technology may help predict which patients need a ventilator and which can be sent home.


Chinese tech company Alibaba Group announced an AI algorithm from DAMO Academy, its research unit, that is said to diagnose suspected cases within 20 seconds with 96 percent accuracy. The algorithm is being used in 26 hospitals in china and has already helped diagnose more than 30,000 cases of COVID-19. It also tracks treatment responses such as detecting signs of improvement, and DAMO is working to bring the system into the cloud so that medical staff can directly upload CT scans to get instant results via their smartphones or laptops.


Within Health offers an app that connects people with radiologists and partner imaging centers who will determine if they need X-rays and their next steps in medical care. For more information, visit

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