  Objective: Computed Tomography (CT) has an important role to detect lung
lesion related to Covide 19. The purpose of this work is to obtain diagnostic
findings of Ultra-Low Dose (ULD) chest CT image and compare with routine dose
chest CT. Material and Methods: Patients, suspected of Covid 19 infection, were
scanned successively with routine dose, and ULD, with 98% or 94% dose
reduction, protocols. Axial images of routine and ULD chest CT were evaluated
objectively by two expert radiologists and quantitatively by Signal to Noise
Ratio (SNR) and pixel by pixel noise measurement. Results: It was observed that
the ULD and routine dose chest CT images could detect Covid 19 related lung
lesions in patients with PCR positive test. Also, SNR and pixel noise values
were comparable in these protocols. Conclusion: ULD chest CT with 98% dose
reduction can be used in non-pandemic situation as a substitute for chest
radiograph for screening and follow up. Routine chest CT protocol can be
replaced by ULD, with 94% dose reduction, to detect patients suspected with
Covid 19 at an early stage and for its follow up.
