对用于肺部自适应放疗的合成CT影像质量的对比研究OACSTPCD

Objective To evaluate the image quality of synthetic CT(sCT)with different cone beam CT(CBCT)scanning modes based on Velocity software.Methods 4D-CT simulation was performed for the CIRS lung phantom by setting the regular respiratory motion pattern.The treatment planning was completed on the average intensity projection CT,that was the planning CT(pCT),which was then transfered to the TrueBeam linac to realize 3D-CBCT and 4D-CBCT scanning and image reconstruction respectively.Then the corresponding sCT was generated based on Velocity software.Results The sCT images preserved the fine structures of the reference pCT.There was a strong correlation between the two image contours,and all Dice similarity coefficients were more than 0.85.Through direct comparison,it could be seen that the artifacts of sCT images were significantly reduced compared with the corresponding CBCT images.The CT values of different regions of interest in sCT3D/sCT4D images were significantly lower,and the noise of sCT was less.For sCT,the average CT values percentage difference for sCT3D images was 7.68%,and the average CT values percentage difference for sCT4D images was 4.65% .Compared with 3D-CBCT,the CT value of sCT images obtained based on 4D-CBCT was significantly improved.Conclusion Under constant breathing pattern,the image quality of sCT corresponding to different CBCT generated from Velocity is comparable to that of pCT,respiratory-correlated image guidance is more clinically valuable in radiotherapy for lung cancer patients.