Background

Thoracic CT is vital in the early diagnosis of patients with COVID-19. Typical appearances include patchy ground glass shadowing or lung consolidation.

Modern radiotherapy for cancer patients includes daily Cone Beam Computed Tomography (CBCT), allowing daily assessment of lung appearance by radiographers. Observation of changes, if efficient, may facilitate early diagnosis of COVID-19, aid testing and improve patient management whilst protecting clinical staff.

Method

CBCT images for lung or oesophageal radiotherapy patients between January-June 2020 were collected. A tool was developed that creates overview reports for each patient, containing coronal maximum intensity projections of all CBCTs and a plot of right and left lung density over time. The development of our real-time clinical screening process occurred in two stages. First, an off-line audit reviewed 150 patient datasets (75 treated during the pandemic and 75 treated pre-2020) for tool optimisation. A single therapeutic radiographer assessed images blindly. Medical and radiotherapy records were reviewed and compared to image findings. Second, this process was repeated retrospectively on the 485 thoracic patients treated between January-June to assess the efficiency of the tool and process.

Results

Within the initial optimisation cohort 3 patients had confirmed COVID-19; two of which were independently retrospectively detected by image assessment alone. The third was not detected by the observer due to minimal lung changes on CBCTs.

Preliminary results of the larger audit cohort, 13 patient reports were identified that if seen prospectively would require further investigations; through medical record assessment none had confirmed COVID-19. The cohort included 4 confirmed cases; all were independently detected by retrospective CBCT screening.

Conclusion

The preliminary results indicate that the presence of COVID-19 can be detected on CBCT by therapeutic radiographers. This process has now been extended to clinical service with daily assessments of all thoracic CBCTs. Changes noted by radiographers are referred for oncologist review; the amount of false positives was acceptable.

Impact statement

Changes found on lung and oesophagus radiotherapy patients CBCTs could facilitate early diagnosis of COVID-19, aid testing and improve patient management whilst protecting clinical staff.