Introduction: Hybrid Positron Emission Tomography with Computed Tomography (PET/CT) imaging is well estab- lished in the oncology setting. However, in the current cancer diagnostic imaging approach in Malaysia patients need separate CT and PET/CT examinations for morphologic and physiologic cancer staging, respectively, as PET/CT is unable to produce images with optimum diagnostic quality. Therefore, introducing contrast media into CT atten- uation correction (CTAC) acquisition to increase image quality have raised concerns on heightened radiation expo- sure. This study aimed to verify the amount of external radiation exposure irradiated to the patient converging to the scanning protocol implemented in whole-body (WB) 18F-FDG-PET/CT examination. Methods: A retrospective study was conducted to determine the radiation dose delivered during CTAC acquisition of 18F-FDG-PET/CT examination at three hospitals providing PET/CT imaging services in Penang State. The implemented scanning protocols and parameters, and the effective dose received by the patient were analysed based on dose length product (DLP) and CTDIvol reported by the scanner. Results: CTAC of WB 18F-FDG-PET/CT imaging was executed as either non-contrast (NC-CTAC) or contrast-enhanced (CE-CTAC). CE-CTAC produced a 250% higher radiation dose compared to NC- CTAC. The scanning parameter differences that significantly contributed to increased radiation dose were the tube current and pitch value. Conclusion: CE-CTAC delivered a higher radiation dose than NC-CTAC acquisition in WB 18F-FDG PET/CT imaging due to different mAs and pitch as scanning parameters.