ESTRO 2025 - Abstract Book

S3054

Physics - Image acquisition and processing

ESTRO 2025

Results: Both DL-DECT at 140 kVp and PCCT had low beam hardening but minimized at different VMI energies (Figure 1B). For DL-DECT(140 kVp), the lowest beam hardening (2.1 HU) was obtained at a VMI energy of 140 keV, while for PCCT, the minimal beam hardening (2.3 HU) was achieved at 90 keV. For VMI energies lower than 80 keV, beam hardening was in general substantially increased. Good VMI CT number accuracies were achieved for all scan modes but at different VMI energy ranges (Figure 2A). Again, DL-DECT(140 kVp) and PCCT showed the best VMI accuracy, with an optimum of 9.4 HU for both, but at 150 keV for DL-DECT(140 kVp) and at 110 keV for PCCT. Summed over the full energy range, DL-DECT(140 kVp) had the overall best VMI accuracy. Looking at the VMI energy with the lowest beam hardening (see Figure 1B), DL-DECT(140 kVp) had the best VMI accuracy of 9.7 HU at 140 keV, followed by PCCT with a VMI accuracy of 11.5 HU at 90 keV (Figure 2B).

Conclusion: Comparing the scanning modes, DL-DECT(140 kVp) and PCCT showed reduced beam hardening and good VMI accuracy. Generally, DL-DECT(140 kVp) performed the best at high VMI energies, while at intermediate VMI energies, PCCT had the best performance.

Keywords: proton therapy, dual- and photon-counting CT