Purpose: This work presents the first attempt to explore the potential of the combination of the spectral modulator and flying focal spot technology for material decomposition and scatter estimation in fast-kV switching cone-beam CT(CBCT)system.
Methods: A preliminary simulation experiment was performed to investigate how the spectral modulator and flying focal spot affected the energy separation in fast-kV switching CBCT. Three sets of experimental configuration were used for kV switching: 80/140kV, 80/140kV+spectral modulator and 80/140kV+spectral modulator+flying focal spot. The Molybdenum and Copper are selected as the materials of the spectral modulator, and the thickness is set to 0.1mm and 0.4mm respectively taking the similar level of dose into consideration.The material decomposition simulation study was conducted in the three sets cases. The water phantom that we used has a size of 24 cm in diameter in which there are four rods of iodine solutions with concentrations at 5, 10, 15, 20 mg/cc.
Results: In the simulation case with only spectral modulator applied, the energy separation can be improved from 23 keV to [23,27.5] keV for fast-kV switching CBCT system. In the other case combined with the flying focal spot technology, the spectral modulator can change the energy separation from [23,24] keV to [18,32] keV, while the energy separation of 24% pixels gets worse due to the flying focal spot. In material decomposition study, the CNR of water and iodine was improved in the case of using spectral modulator and flying focal spot.
Conclusion: The preliminary simulation experiment shows that the spectral modulator and flying focal spot can improve energy separation for the most pixels, which is beneficial for material decomposition. In the future, the algorithms of material decomposition and scatter estimation will be developed for the fast-kV CBCT system combined with spectral modulator and flying focal spot.
Funding Support, Disclosures, and Conflict of Interest: This project was supported in part by grants from the National Natural Science Foundation of China (No. U20A20169 and No. 12075130).
Not Applicable / None Entered.