Figure 3.

Example of COVID-19 positive patient report (retrospective cohort). Patient MIP's reviewed retrospectively demonstrating COVID-19 like lung density changes, start of change shown by orange symbol. Patient was asymptomatic and therefore not RT-PCT tested. Part of the observed HU variation demonstrated in the graph is due to differences in imaging systems used, as the patient was moved between treatment units. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)