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目的:探讨不同病灶体积、靶本比及校正方式对n 99Tcn m SPECT/CT定量分析结果的影响。n 方法:将美国电气制造商协会(NEMA)国际电工委员会(IEC)体模中6个不同直径的小球(37、28、22、17、13和10 mm)填充入放射性浓度0.54 MBq/ml的n 99Tcn m与碘克沙醇混合液(含碘量135 mg，占约0.3%)，改变罐体放射性浓度形成不同的靶本比(32∶1、16∶1、8∶1、4∶1)。对不同靶本比体模行SPECT/CT，以CT阈值法自动勾画各小球感兴趣体积(VOI)并对图像行定量分析。选择相同有序子集最大期望值迭代法(OSEM)参数及校正方式分别定量4种靶本比模型下各小球放射性浓度，并与球内真实放射性活度比较，计算准确性。采用Pearson相关分析小球体积、靶本比与定量准确性的关系。对靶本比为32∶1、直径37 mm的小球分别行CT衰减校正(CTAC)＋散射校正(SC)＋分辨率恢复(RR)、CTAC＋SC和CTAC＋RR 3种校正方式重建，采用单因素方差分析和最小显著差异n t检验比较不同校正方式对定量结果及图像对比度的影响。n 结果:小球体积、靶本比与定量准确性呈正相关(n r值：0.757和0.409,均n P<0.05)。3种校正方式间，小球的定量误差及图像对比度差异均有统计学意义(n F值：139.665和38.905,均n P<0.001)，其中CTAC＋SC＋RR的定量误差小于CTAC＋SC[(9.63±8.82)%和(38.89±2.17)%；n P0.05]；CTAC＋RR的定量误差小于CTAC＋SC(n P<0.001)。CTAC＋SC＋RR图像对比度高于CTAC＋SC[(93.45±0.91)%和(92.41±0.25)%；n P<0.001]，CTAC＋SC图像对比度高于CTAC＋RR[(91.37±0.87)%；n P<0.001] 。n 结论:小球体积越大、靶本比越高，定量越准确；小球体积与定量准确性的相关性更强；合适的校正方式可明显提高图像对比度及定量的准确性，建议后处理时常规选用CTAC＋SC＋RR。“,”Objective:To evaluate the effects of different sphere volumes, target background ratio (T/B) and post-processing correction techniques on the quantitative results of n 99Tcn m SPECT/CT.n Methods:Six spheres with different diameters (37, 28, 22, 17, 13, 10 mm) in National Electrical Manufacturers Association International Electrotechnical Commission (NEMA IEC) models were filled with a mixture of 0.54 MBq/ml n 99Tcn m and iodixanol. The mixture iodine content was about 0.3%(135 mg), which led to different T/B (32∶1, 16∶1, 8∶1, 4∶1) by changing the radioactivity concentration of the cylinder. Routine imaging was performed on different T/B phantoms which were scanned by SPECT/CT. The CT threshold method was used for the delineation of volume of interest (VOI). Then the same processing correction technique and ordered-subsets expectation maximization (OSEM) parameters were used to calculate the radioactivity concentrations of different spheres, and further compared with the true values, and the accuracies were calculated. Pearson correlation analysis was applied to evaluate the relationships between sphere volume, T/B and quantitative results. The sphere with T/B of 32∶1 and diameter of 37 mm were processed by 3 correction techniques (CT attenuation correction (CTAC)+ scatter correction (SC)+ resolution recovery (RR); CTAC+ SC; CTAC+ RR). One-way analysis of variance and the least significant difference n t test were used to analyzed the effects of 3 correction techniques on the quantitative results and image contrasts.n Results:There were significant relationships between the sphere volumes, T/B and the quantitative accuracy (n r values: 0.757, 0.409, both n P<0.05). There were significant differences of 3 correction techniques on the quantitative results and image contrast (n F values: 139.665 and 38.905, both n P<0.001). Among them, the quantitative error of CTAC+ SC+ RR was lower than that of CTAC+ SC ((9.63±8.82)%n vs (38.89±2.17)%; n P0.05). The quantitative error of CTAC+ RR was lower than that of CTAC+ SC (n P<0.001). The image contrast of CTAC+ SC+ RR was higher than that of CTAC+ SC ((93.45±0.91)%n vs (92.41±0.25)%; n P<0.001) and the image contrast of CTAC+ SC was higher than that of CTAC+ RR ((91.37±0.87)%;n P<0.001).n Conclusions:The larger sphere volume and the higher T/B, the more quantitative accuracy. The volume has a more significant effect on quantitative accuracy than T/B. Choosing the appropriate correction technique is helpful to quantitative accuracy improvement. It is suggested to use CTAC+ SC+ RR in quantitative processing.