ESTRO 2025 - Abstract Book

S2971

Physics - Image acquisition and processing

ESTRO 2025

Conclusion: In conclusion, the study showed effectiveness in using DE imaging for accurate tumour motion detection in an experimental setup mimicking lung cancer imaging.

Keywords: Dual-Energy imaging, Lung tumour tracking

1467

Digital Poster Iodine Quantification and HU Calculation Accuracy of Multiple Spectral Images in Dual Energy CT Utilizing Twin Spiral Technology Hsiang-Chi Kuo, Maria Chan, Seng Boh Lim, Usman Mahmood, Michalis Aristophanous, Jean Moran, Laura Cervino Arriba, Xiang Li Medical Physics, Memorial Sloan Kettering Cancer Center, New York, USA Purpose/Objective: To determine the accuracy of iodine quantification in iodine map and HU calculation in virtual non-contrast (VNC) images and spectral images decomposed from a dual-energy system using twin spiral technology. Material/Methods: An iodine phantom featuring a circular inner ring and an elliptical outer ring, containing iodine (0.5, 1, 2, 5, 10, and 15 mg/ml) was scanned using various scanners with head and neck (HN) and brain protocols at 80 kV/(Sn)140 kV and 100kV/(Sn)140 kV, respectively. Various reconstruction techniques were assessed, including beam hardening corrections for bone (BHb) and iodine (BHi) under the HN protocol. To evaluate the feasibility of using VNC images for dose calculations, a CT density phantom (CTDP) was scanned to produce a range of spectral images, including mixed-energy images (MEI: combination images of 60% low kV and 40% high kV) and virtual monochromatic images (VMI) at energies of 50 keV, 70 keV, 75 keV, 80 keV, 120 keV, and 190 keV. Iodine quantification accuracy was compared to nominal concentrations with a tolerance of 0.5 mg/ml or 20%, whichever is greater, and HU accuracy was compared to the treatment planning system (TPS) with a tolerance of 50 HU. Results: The evaluation of absolute errors for the HN protocol indicated that the BHi correction maintained errors below 0.5 mg/ml under all tested conditions. The BHb correction exhibited the least error at lower concentrations (0.5 and 1.0