目的:探索平静呼吸状态下正常肾脏在三维方向的运动幅度及其相关的影响因素。方法:收集2018—2019年间行四维CT且能够平静呼吸的28例患者数据，肿瘤类别包括肝肿瘤、胰腺肿瘤或肺肿瘤。腹窗条件下逐层、逐呼吸时相勾画肾脏外轮廓并找到几何中心及三维方向坐标数值；计算左、右肾各个方向及三维方向位移。记录周围脏器体积及患者年龄、性别、身高、体重指数。采用n t检验或非参数检验比较差异。n 结果:左、右肾脏上下方向运动幅度大，分别为(8.39±3.18)、(7.71±3.55) mm。男性双肾在左右、上下及三维方向平均运动幅度均大于女性(n P165 cm者亦大于≤165 cm者(n P0.05)。n 结论:肾脏运动主要表现在上下方向，男性、身高高者运动幅度大，需格外注意使用控制呼吸运动的相关装置以降低正常组织损伤。“,”Objective:To explore the amplitude of normal kidney motion in the 3D direction and its influencing factors under free-breathing condition.Methods:Clinical data of 28 patients with a KPS score≥80 who received 4D CT scan from March 2018 to March 2019 were collected. All patients were diagnosed with liver, pancreatic or lung tumors. The kidney was outlined and the geometric center and 3D coordinate values were recorded. The motion of bilateral kidneys in each direction and the 3D direction was calculated. The volume of kidney and surrounding organs, age, sex, height and body mass index (BMI) were recorded. Clinical data were statistically compared by n t-test or nonparametric test.n Results:The motion of the left and right kidneys in the the sup-inf (SI) direction were the largest up to (8.39±3.18) mm and (7.71±3.55) mm. The motion amplitudes of bilateral kidneys in male patients were significantly larger than those of the female counterparts in the left-right (LR), SI and 3D directions (all n P0.05).n Conclusions:Kidney motion mainly occurs in the SI direction. The kidney motion amplitudes in male and taller patients are larger. Special attention should be paid to the use of breath motion control device to decrease the normal tissue damage.