Congress:
EuroSafe Imaging 2020
Keywords:
Multicentre study, Observational, Retrospective, Patterns of Care, Screening, CT, Radiation physics, Lung, Action 2 - Clinical diagnostic reference levels (DRLs)
Authors:
M. B. Chatfield, D. Golden, D. Gress, M. Simanowith, J. Burleson
DOI:
10.26044/esi2020/ESI-14402
Description of activity and work performed
We compared median (Achievable Dose) and 75th percentile (Diagnostic Reference Level) for both CTDIvol and DLP for low dose CT chest screening studies from the two data sources, DIR and LCSR. In addition to comparing data for the whole year 2018, we considered two alternative sampling methods for the LCSR data that represent reduced burden of manually collecting data – data for one month only (June 2018), and data for a random 10% of records from the year.
The analysis included 3190 LCSR facilities with manually submitted CTDIvol and DLP for 456,835 exams, for the year 2018. The analysis also included data from 748 DIR facilities with DICOM radiation dose structured reports (RDSRs) and secondary capture images for 95,537 exams for the year 2018.
Overall comparison:
The data from LCSR (potentially manually collected) have a higher standard deviation than the data collected using automated methods. The median CTDIvol ranges from 2.4 to 2.46 mGy across the methods, and the 75th percentile ranges from 3 to 3.03 mGy. The median DLP ranges from 85-86.4 mGy-cm, and 75th percentile ranges from 109-112 mGy-cm (Table 1).
Comparison at the level of facilities :
We repeated the same analysis using facility median values of CTDIvol and DLP, for facilities with at least 20 records. The median CTDIvol ranges from 2.3 to 2.44 mGy across the methods, and the 75th percentile ranges from 2.85 to 2.9 mGy. The median DLP ranges from 82.6-87.26 mGy-cm, and 75th percentile ranges from 102.08-105.83 mGy-cm (Table 2).
Looking at the entire distribution in boxplots, we find the distributions to be very similar for CTDIvol (Figure 1) and DLP (Figure 2).