Establishment of National DRL for CT in Hybrid Imaging Studies (The Second Phase of the National NM CT (PET) Dose Audit for Kuwait Population -2019)

ABSTRACT DRLs for CT part used in PET/CT examinations are limited. The aim was to execute the second phase of the national DRL for CT part of PET/CT imaging operating in KW, in support of optimisation and dose reduction as imaging technology is advancing. In this multicentre collaborative PET centers (No:8) audit, data collection was restricted to the adult oncology patients due to a limited number of the other studies and also due to the National MOH Ethical Committee recommendation. The CTDIvol, DLP and SL were recorded and the Median, Mean, SD, 75 th , 25 th percentiles as well as WB effective dose (ED) were calculated. Dose and scan length statistics for HB and WB scans (65% and 35% of total: 309) and the WB+HB presented together with the proposed NDRLs and the Achievable doses. Third quartile DLP (mGy x cm) and CTDIvol (mGy) values for the HB were (537, 5) which were higher than the UK NDRL (400, 4.3) but were lower than the Swiss NDRL (620, 6) and the France NDRL (762, 7.7). Comparatively, the Proposed NDRLs for (WB) were (684, 4.1) which were lower than Swiss National Data (720, 5.0). It is worth noted that, the Swiss had about 5000 (HB) & 706 (WB), the UK had 370 (HB) and France had 1000 (HB) entries. Calculated ED varied from 4.1 to 10.2 mSv, (mean values=6.9 mSv) for HB and from 2.6 to 7 mSv (mean value=4.6 mSv) for WB scans which were lower than the first phase (2018). Although, there was 9.1% improvement in NDRL, but the outcome suggested there is a continuous need for monitoring NDRL.