Objective To compare the radiotherapy treatment accuracy between 4D-CT and DIBH follow-ing liver SBRT,and to illustrate the relevant factors.Methods A retrospective analysis was conducted on the clinical data of 28 liver cancer patients who underwent SBRT from November 2020 to July 2024,all of whom exhib-ited and localizedmorphological changes on magnetic resonance imaging(MRI).Among them,8 patients used DIBH,and 17 patients used 4D-CT.The areas of localized MRI-morphologic alterations(MMA)were delineated on post-therapeutic MRI.Different isodose structures were generated on the planning CT,and after performing de-formation registration based on the liver's region of interest(ROI),the most suitable isodose structure and MMA contours were compared to obtain quantitative accuracy indices.Correlations between factors such as GTV,PTV,liver volume,and volume changes,and the accuracy indices were analyzed.Results The DSC accuracy for the DIBH group was(0.66±0.17),range 0.32～0.90,while the DSC accuracy for the 4D CT group was(0.69±0.10),range 0.49～0.80.T-test analysis showed no significant statistical differences in accuracy indices between the DIBH and 4D CT groups(P<0.05).Correlation analysis revealed that,in both groups,distance-based indices(HD,MDA,3D-CoMD)were more strongly correlated with accuracy indices than conformality indices(DSC,CIMI).Conclusion There was no significant difference in treatment accuracy between the DIBH and 4D-CT groups,although the maximum accuracy in the DIBH group was higher than that in the 4D-CT group.This method can serve as an bench-markingtool for evaluating the accuracy of liver SBRT.It is recommended to prioritize the use of conformality indices,DSC and CIMI,when assessing the treatment accuracy of liver cancer SBRT using this approach.

Objective To compare the radiotherapy treatment accuracy between 4D-CT and DIBH follow-ing liver SBRT,and to illustrate the relevant factors.Methods A retrospective analysis was conducted on the clinical data of 28 liver cancer patients who underwent SBRT from November 2020 to July 2024,all of whom exhib-ited and localizedmorphological changes on magnetic resonance imaging(MRI).Among them,8 patients used DIBH,and 17 patients used 4D-CT.The areas of localized MRI-morphologic alterations(MMA)were delineated on post-therapeutic MRI.Different isodose structures were generated on the planning CT,and after performing de-formation registration based on the liver's region of interest(ROI),the most suitable isodose structure and MMA contours were compared to obtain quantitative accuracy indices.Correlations between factors such as GTV,PTV,liver volume,and volume changes,and the accuracy indices were analyzed.Results The DSC accuracy for the DIBH group was(0.66±0.17),range 0.32～0.90,while the DSC accuracy for the 4D CT group was(0.69±0.10),range 0.49～0.80.T-test analysis showed no significant statistical differences in accuracy indices between the DIBH and 4D CT groups(P<0.05).Correlation analysis revealed that,in both groups,distance-based indices(HD,MDA,3D-CoMD)were more strongly correlated with accuracy indices than conformality indices(DSC,CIMI).Conclusion There was no significant difference in treatment accuracy between the DIBH and 4D-CT groups,although the maximum accuracy in the DIBH group was higher than that in the 4D-CT group.This method can serve as an bench-markingtool for evaluating the accuracy of liver SBRT.It is recommended to prioritize the use of conformality indices,DSC and CIMI,when assessing the treatment accuracy of liver cancer SBRT using this approach.