Introduction: Bone density measurements around hip implants are challenged by artifacts and the complex anatomy of the acetabulum. We developed 3D segmentation software and used dual energy CT to reduce artifacts. The between-scan agreement and reliability of the software was tested and bone mineral density (BMD) measurements in single- and dual energy CT (SECT and DECT) were compared. Methods and Materials: 24 patients with total hip arthroplasty were scanned and rescanned using SECT and virtual monochromatic DECT images. 3D-ROIs were defined slice-by-slice and BMD was calculated adjacent to the acetabular cup. Results: Mean BMD for SECT was 411 mg/ccm with a between scan difference of 21 mg/ccm, p=<0.0001 in the uncemented cup. DECT showed a mean BMD of 153 mg/ccm with a difference of 10 mg/ccm, p<0.0001. Around the cemented cup the mean BMD for SECT was 523 mg/ccm with a between-scan difference of 14 mg/ccm, p=0.25 and 186 mg/ccm in DECT with a difference of 6 mg/ccm, p=0.15. ICC was >0.95 with more narrow limits of agreement in DECT compared with SECT. CTDI was 25% higher with DECT and subjective image quality was better in SECT. Conclusion: Equally reliable BMD measurements adjacent to acetabular cemented and uncemented cups can be performed using the segmentation software. The absolute between-scan agreement was better in DECT. Virtual monochromatic DECT with fast kVp switching may be beneficial in estimating BMD adjacent to metal implants, but radiation dose and image quality should be taken into consideration. BMD cannot be measured interchangeably with SECT and DECT.