Randeep Guleria also warned against use of steroids in the early stages of infection (File) New Delhi: The computerized tomography scan (CT scan) cannot properly detect mild coronavirus cases, AIIMS Director Randeep Guleria said at a press conference today, as he warned against its misuse. The top doctor, who is also a member of the national pandemic task force, added that blood tests can't always prove Covid infections as other underlying diseases can also trigger a spike in biomarkers. The CT scan machine takes cross-sectional images of the body using computers and rotating X-ray machines. They are being used to detect Covid infections by detecting signs of pneumonia or white patches in lungs. More people are relying on the expensive scan than last year as reports suggest the mutant variants of the virus can go undetected in the gold standard RT-PCR test.