Management of Patients Suspected of COVID 19 With Ultra Low Dose Thoracic Scanner (COVID-19 ULD)

The year 2020 was marked by the emergence of a new respiratory disease: COVID19 related to an infection with the coronavirus SARS-CoV-2 (name given by the WHO on February 11, 2020). Initially appearing in China, in the province of Hubei, this epidemic has rapidly spread to be declared a global pandemic on March 12, 2020 by the WHO.Given the current context of the COVID-19 epidemic, strict hygiene measures have been taken in scanning rooms with systematic bio-cleaning. Strategies have been modified as a matter of urgency, with changes in the practices of electro radiology manipulators who work in "isolation" to avoid contamination. The number of scanners has increased exponentially following the curve of the epidemic, making it more and more difficult to systematically check the images before the patient leaves the room. To ensure sufficient image quality for interpretation of all scans, a complementary acquisition in ULD, with very low exposure, was systematically added to the acquisition protocol. The standard acquisition in LD, associated with this acquisition in ULD remain well below the diagnostic reference thresholds dictated by the nuclear safety authority (NRD: 350 mGy.cm. In Nîmes: LD: 100 to 150 mGy.cm and ULD: < 15 mGy.cm). These two acquisitions allow us to avoid breathing and movement artifacts, etc., without having to have the patients return for a new scan in case of a bad acquisition. This avoids an overexposure of the staff to the risk of infection by the SARS-CoV-2 virus.

The main objective of this retrospective study is to evaluate the diagnostic performance of ULD vs. LD for the accurate diagnosis of COVID-19 pneumopathy which presents a particular ground glass pattern

Our study will demonstrate that the ULD scanner can be used in the search for COVID-19 pneumopathy and thus limit the exposure of patients to X-rays, especially since thoracic scans are often repeated.