Image review for COVID-19 on CBCT vs MIP's
Clough, Abigael Sanders, J Banfill, Kathryn Price, Gareth J Eccles, Cynthia L Aznar, Marianne Camille Van-Herk, Marcel
Clough, Abigael
Sanders, J
Banfill, Kathryn
Price, Gareth J
Eccles, Cynthia L
Aznar, Marianne Camille
Van-Herk, Marcel
Citations
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Abstract
Purpose or Objective
Thoracic CT features of COVID-19 include ground glass opacity or lung consolidation and can also be identified
on Cone Beam Computed Tomography (CBCT). The authors developed a reporting tool using maximum
intensity projections (MIP); enabling rapid review by therapeutic radiographers of longitudinal changes in
successive CBCT images suggestive of COVID-19 infection in asymptomatic patients during radiotherapy. The
aim of this work was to assess if the reporting tool required fewer departmental resources than standard CBCT
review process for COVID-19 related changes.
Materials and Methods
The tool - run overnight for all thoracic CBCTs - provides a single report containing sequentially positioned
lung MIP images, multiple slices of the last CBCT to show the most up-to-date anatomy in more detail.
Additionally, a longitudinal plot of the right and left lung mean density over time. Lung density values (in
mean Hounsfield Units (HU)) are also shown in the MIP images. The MIP images clearly show lung infections
and their progression (Fig. 1).
To demonstrate the efficiency of this tool and quantify the additional burden related to COVID-monitoring,
two experienced observers independently reviewed thoracic CBCTs and MIP reports from 22 patients.
CBCT images were reviewed from a single day (13.02.21) and all MIPs were reviewed for all fractions available
for each patient up to and including the day of the CBCT. The time taken to review all CBCTs and MIP reports
was recorded in seconds (sec), each observer reviewed 11 patients. The observers checked accuracy through
the review of patient’s clinical notes to confirm no symptoms of COVID-19. All reports were cross checked by
both observers for lung density changes. Results
Fig.2 shows time taken for observers to review one CBCT for typical COVID-19 lung density changes; 55 sec
(range 35-86 sec, standard deviation (SD) 12.8 sec). The mean time taken for observers to review all MIPs
together was 12 sec (range 9-16 sec, SD 1.8 sec). The MIP review included a mean of 9 fractions worth of
images per patient (range 2-25). Neither observer reported COVID-19 changes using either method for the
patients reviewed on this date. Although the observers reviewed different patient image sets, their mean
review times for CBCT were similar at 56 and 61 seconds per CBCT respectively. The mean time for MIP
reviews were also comparable at 13 and 12 seconds respectively. An additional benefit of the MIP method was
that multiple CBCT images are available in a single “snap-shot” allowing progression to be more easily
visualised Conclusion
The use of MIPs facilitates more rapid assessment of COVID-19 related lung density changes than CBCT review
resulting in less impact on clinical resource. This will provide minimal burden for screening of infections in
radiotherapy departments.
Affiliation
Description
Date
2021
Publisher
Collections
Keywords
Type
Meetings and Proceedings
Citation
Clough A, Sanders J, Banfil K, Faivre-Finn C, Price G, Eccles C, et al. Image review for COVID-19 on CBCT vs MIP's. Radiotherapy and Oncology. 2021;161:S421-S2.