Abstract: Sustainable computed tomography (CT) imaging aims to minimize environmental impact while preserving diagnostic efficacy and ensuring patients' and workers' safety. This study aims to assess the impact of optimization using the national diagnostic reference level (NDRL) on achieving social, environmental, and economic sustainability, besides work environment safety in CT imaging.technical From September 2020 to September 2021, radiation dose indices and technical parameters were collected from 42% of CT scanners in Bahrain to establish NDRLs based on the third quartile of median dose values for each scanner across eight clinical indications (CIs). Next, the image quality (IQ) of CT exams on General Electric (Revolution) and Siemens (Somatom Definition As) scanners was assessed by three radiologists using modified CI-based scoring criteria and a Likert scale (0 to 4). Based on that, the acceptable quality doses (AQDs) were established as the median of the dose indices values for optimal IQ (average score=3) and compared to the NDRLs. AQDs in the GE scanner for abdominal pain and diverticulitis/appendicitis were higher than NDRLs; therefore, optimization was applied by the vendor specialist on these imaging protocols, and radiation dose indices and collected thermoluminescent dosimeters were positioned in the CT work environment for 60 days pre- and post-optimization to assess radiation dose. The main limitations of this study are the manual data collection and the radiologists' unavailability to assess the IQ. parameters were post-optimization. Additionally, five The NDRLs/volume CT dose index (CTDIvai) resulting from 1665 CT exams analyzed were as follows: 67, 66, 67, 13, 14, 17, 19, and 15 mGy for headache, trauma, stroke, flank pain, renal colic, abdominal pain, diverticulitis/appendicitis, and oncologic follow-up, respectively. In the GE scanner, the established AQDs/CTDIvol exceeded the NDRLs in abdominal pain (16 vs. 15 mGy) for medium patients and (34 vs. 27 mGy) for large patients, and diverticulitis/appendicitis (15 vs. 12 mGy) for medium patients and (33 vs. 30 mGy) for large patients, pinpointing the need for optimization. A significant reduction in the dose index of abdominal pain and diverticulitis/appendicitis CIs post- optimization led to a total reduction of 300±6 kWh, 128+4 kg, and $20±4 in electrical energy, carbon dioxide equivalent emissions, and annual cost savings, respectively. Furthermore, the radiation dose range in the CT work environment reduced from 2±11%- 27±10% mSv to 1±11%-23±10% mSv after optimization. These findings suggest further studies in NDRLs and ongoing optimization for sustainable CT practice and a safe CT working environment in Bahrain.