加速器锥形束CT成像参数对空间分辨率的影响

Variations of spatial resolution with imaging parameters for kilovoltage cone-beam CT

目的分析加速器机载kV锥形束CT(CBCT)成像参数对空间分辨率的影响。方法采用CatPhan600模体的CTP528模块,分别改变管电压、管电流、准直器、扫描范围和重建精度,测量XVICBCT的空间分辨率。结果管电压从80kV增至140kV时,空间分辨率从5lp/cm增加到7lp/cm。管电流对空间分辨率影响较小。准直器型号、重建精度和机架旋转范围对空间分辨率影响较大。结论 CBCT的影像质量随成像条件变化范围很大,实际应用时需要根据条件合理选择参数,减少患者辐射剂量的同时得到最佳的影像质量。

Objective To evaluate the impact of preset imaging parameters on spatial resolution of Linac-integrated kV cone-beam CT（CBCT）unit.Methods The spatial resolution in CBCT mode was evaluated with CPT 528 module of CatPhan 600 phantom with different combinations of kV,mAs,collimator,scanning ranges and reconstruction resolution.Results The spatial resolution increased from 5 lp/cm to 7 lp/cm when the tube voltage varied from 80 kV to 140 kV.Current and exposure time per frame had little influence on the spatial resolution.The spatial resolution mainly depended on collimator,reconstruction resolution,and gantry rotation range.Conclusion The image quality of CBCT varies with the preset scanning parameters.Parameters should be reasonably chosen according to the patient＇s anatomy,so as to compromise image quality and radiation dose.