The risk of death from COVID-19 far outweighs the risk of death from imaging exams that impart radiation such as chest x-ray or CT, according to a study published October 7 in the Journal of Radiological Protection.
The findings address the concern that patients being diagnosed with and tracked for COVID-19 may be undergoing so many radiological exams that they could be at risk for harm from radiation, wrote a team led by Francesco Ria, Doctor of Medical Physics, of Duke University in Durham, NC.
"The scientific community already understands that the risks induced by most radiological procedures are small, compared with other lifetime risks from various sources, and that the risk-to-benefit ratio is favorable when such techniques are used for symptomatic patients, even in the case of CT, the modality with the highest associated radiation burden," the group wrote.
Although reverse transcription polymerase chain reaction (RT-PCR) testing is considered the gold standard for diagnosing COVID-19, getting results can be slow, and radiological imaging has also been used to diagnose the disease -- even though many professional organizations, including the American College of Radiology, do not recommend that CT in particular be used for this purpose, in part because of concerns about its specificity, but also because it exposes patients to radiation.
"[Radiation] risk is obviously not the primary factor that should be taken into account for justifying the use of imaging in COVID care; nonetheless, it is a factor that is of high public concern needing an explicit management of its own," the group noted. "This is particularly the case considering the different radiation burdens of CT and radiography, regardless of their diagnostic accuracy."
Ria and colleagues sought to compare the radiation risk associated with chest CT and x-ray to the mortality risk of infection with COVID-19. The study used COVID-19 mortality rate data from 299,004 patients from Italy's Instituto Superiore di Sanità and compared them with mortality risk rates in a cohort of 659 Duke patients who underwent chest radiography between March 2018 and January 2019.
The group found a rapid rise in the mortality rate in COVID-19 patients over 30, with a median mortality rate for COVID-19 patients across all age groups of 12%. Mortality rates due to radiation decreased across all age groups in the cohort of 659 patients who underwent radiography; the median mortality rate was 0.0003% for chest CT and 0.007% for chest x-ray.
The study findings underscore that risk of death from radiation exposure is low and that imaging can be safely used as a diagnostic tool in a pandemic situation, according to the authors. But patient age should be taken into consideration.
"As COVID-19 mortality shows significant difference across age groups, the justification and the choice of the appropriate diagnostic strategy should include patient age, considering younger patients that are more sensitive to ionizing radiation," they concluded.