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)

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, 75th, 25th 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. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This project has been supported by a grant from Kuwait Foundation for the Advancement of Sciences ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This project has been approved by The Ethical Committee, Ministry of Health, Kuwait. All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All presented data in this article are original and are available on request