Room: Karl Dean Ballroom B1
Purpose: We present the advantages of using dual-source Dual-energy (DE) CT for RT planning based on our clinical experience.
Methods: Dual-source DECT acquires two scans simultaneously using 80 and Sn140 kVp X-ray beams (Drive, Siemens). Using the simultaneously acquired images, we can compute mono energetic images (MEI) from 40 to 190 keV, virtual contrast free images, maps of the electron density, effective Z, and fat can be derived to exploit the energy dependence of X-ray scattering. Advantages of these study sets on a phantom and representative patients for RT planning are presented.
Results: Soft tissue contrast in patients and a phantom was typically enhanced by a factor of 2 to 3 in 40 keV MEI in comparison to conventional 120 kVp CT. Contrast between the tumor and surrounding tissue was increased by 96 HU and contrast to noise ratio increased by as much as 60% comparing MEI to 120 kVp CT for a patient with cholangiocarcinoma. Dual-source DECT preserves spatial resolution in comparison to sequential DECT protocols as evidenced by the identification of vasculature around the pancreatic head for a patient. Volume of artifacts for 5 patients with titanium implants was reduced by over 95% with 190 keV MEI compared to 120 kVp images. A 367 cc region of photon starvation as identified by low CTN in soft tissue of a mantle patient was eliminated in a 190 keV MEI. Virtual non-contrast CT can be created from contrast CTs, removing Iodine contrast and restoring CT number similar to conventional CT, thus eliminating the need for additional non-contrast scans (improving workflow and registration). For pancreas cases with stents, effective Z-maps decrease the perceived diameter of stents, reducing artifacts.
Conclusion: Dual-source DECT is an emerging RT simulation technology offering clinically meaningful advantages, improving RT simulation workflow and enhanced structure delineation for planning.
Funding Support, Disclosures, and Conflict of Interest: partially supported by Siemens Healthcare
Dual-energy Imaging, CT, Energy Dependence