Figure 2.

Examples of COVID-19 positive patients (optimisation cohort). Top – these images show lung density changes identified by the observer at fraction 9 of 25 (arrow). This patient became symptomatic on fraction 11 of 25 with a cough and received a RT-PCR test. The results were established on fraction 12 of 25 as positive. Bottom - CBCT images were acquired in this patient for whom COVID-19 was not detected through CBCT analysis. The changes in lung density over time are minimal. Treatment has paused for this patient following COVID-19 diagnosis until longer symptomatic (for 17 days) in line with Trust COVID response protocols at the time. Density changes may have occurred during the pause in treatment where no CBCTs were made. This is an unavoidable limitation of retrospective evaluation.