Comparison of Image Quality Parameter between Conventional Radiotherapy CT Simulator Imaging and Dual Energy Imaging on the GE Revolution Apex Elite
Abstract
Purpose
Dual Energy Computed Tomography (DECT) is readily available in some clinical settings, enabling image visualization at multiple energy levels to extract material-dependent attenuation differences. This ability enables improved tissue differentiation and contrast manipulation compared to single-energy CT (SECT). However, despite these advantages, DECT remains underutilized in radiation oncology. This study compares the performance of DECT and SECT to evaluate quantitative performance and investigate whether DECT provides imaging properties like those of SECT on the same system.
Methods
Electron density (ED) and quality control (Catphan) phantoms were scanned using both DECT (50keV, 70keV, 120 kVp-like) and SECT (120kVp). DECT data were reconstructed at multiple energy levels to evaluate energy-dependent attenuation in lung, soft tissue, and bone. These scans were compared with SECT data using the Pylinac 3.40.0 analysis framework to evaluate HU, spatial linearity and image uniformity.
Results
Both imaging techniques demonstrated consistent spatial linearity (50mm measured). DECT images showed increased non-uniformity with deviations of up to 30 HU versus SECT 5–10 HU in a uniform region. HU linearity analysis revealed that DECT reconstructions exhibited expected material-dependency (120–150 HU) compared to SECT (20–30 HU). The DECT and SECT (120kVp-like) data agreed for lung and soft-tissue-equivalent materials. For lung inserts, the mean difference (SECT-DECT) remained within ±6 HU. For soft tissues, differences were below ±5 HU at both 70 keV and 120 kVp-like reconstructions. Bone-like material showed pronounced energy dependence, with differences of up to 500 HU at 50 keV.
Conclusion
These results demonstrate that DECT offers quantitative constancy comparable to SECT for lung and soft-tissue imaging, while providing an advantage in material characterization and contrast in high-density tissues such as bone.