ESTRO 2023 - Abstract Book

S1394

Digital Posters

ESTRO 2023

measured in direct comparison to the parameters provided by the vendor. Noise levels were measured with the same Catphan, and noise power spectrum (NPS) was calculated on a cylindric water phantom scaned with all clinical protocols. Results Imaging distortion and slice thickness were measured less than 0.2 mm and 2.5mm in all imaging protocols with both reconstruction modes. Imaging resolution was measured 1.35mm with iCBCTAcuros and 2.5mm with iCBCT mode. The maximum deviation in the measured Tube voltage and exposure was 1.7 kVp and 2.3 mAs, respectively. The scanning speed was measured consistently between 5.85 s and 5.86s with all clinical protocols. The congruency of imaging dose was within 2%, except for tube voltage of 80kVp, where the measured average imaging dose differed 6% from the vendor’s calculation. Uniformity was measured above 98%, between 97% and 98%, and between 95% and 97% in imaging protocols with tube voltage of 125kVp and above, 100 kVp, and 80 kVp. The contrast-to-noise ratio was 0.5 at 80 kVp and 50 mAs, but increased rapidly with tube voltage and exposure. NPS analysis showed that the imaging noise is dominated by white noise with a very weak peak at 0.25mm-1 in a magnitude of 1.8% of the white noise, indicating very weak imaging artifacts compared to current CBCT images. Conclusion The novel CBCT system met expected image quality performance and is expected to achieve acquisition in a single-breath hold. The imaging dose is 2~3 fold lower than the currently installed CBCT systems on a C-arm Linacs.