CT探测器宽度和信号采集位置对影像质量的影响  

The effect of CT detector width and signal acquisition positions on image quality

作　　者：郭森林[1] 任悦[1] 张永县[1] 康天良[1] 刘云福[1] 朱蕾[1] 牛延涛[1] Guo Senlin;Ren Yue;Zhang Yongxian;Kang Tianliang;Liu Yunfu;Zhu Lei;Niu Yantao(Department of Radiology,Beijing Tongren Hospital,Capital Medical University,Beijing 100730,China)

机构地区：[1]首都医科大学附属北京同仁医院放射科,北京100730

出　　处：《中华放射学杂志》2023年第6期684-688,共5页Chinese Journal of Radiology

摘　　要：目的探讨宽体探测器CT不同扫描模式、不同探测器宽度及信号采集位置对CT值及噪声的影响,为临床实践中合理选择扫描模式和相关参数提供依据。方法使用GE Revolution CT对体部剂量模体进行扫描。逐层扫描模式时,分别选择40、80、160 mm探测器宽度,用探测器的中心、边缘和两圈扫描的毗邻区域对模体同一层面进行成像;螺旋扫描模式时,探测器宽度/螺距组合分别为40 mm/0.516、40 mm/0.984、80 mm/0.508、80 mm/0.992,对位于扫描野边缘和中心的模体同一层面进行成像。对所得影像的几何形状进行主观评价,测量CT值和标准差(SD),比较不同成像参数时各测量值之间的差异。逐层扫描模式不同扫描参数下CT值和SD的比较均采用多组间Friedman检验,螺旋扫描时不同扫描参数下CT值和SD的比较均采用两相关样本非参数Wilcoxon检验。结果任意扫描参数组合所得影像的几何外形均无明显改变。逐层扫描模式使用不同探测器宽度时CT值差异有统计学意义(χ^(2)=14.00,P=0.001),40 mm时CT值和160 mm时CT值均大于80 mm,差异具有统计学意义(P<0.05)。不同信号采集位置的CT值差异有统计学意义(χ^(2)=12.04,P=0.002),边缘和毗邻的CT值均大于中心,差异具有统计学意义(P<0.05)。螺旋扫描80 mm时CT值大于40 mm,差异具有统计学意义(Z=-2.10,P=0.036)。逐层扫描模式使用不同探测器宽度时CT值的SD差异有统计学意义(χ^(2)=8.17,P=0.017),160 mm时SD大于80 mm,差异具有统计学意义(P<0.05)。不同信号采集位置的SD差异有统计学意义(χ^(2)=13.50,P=0.001),边缘SD大于中心,差异具有统计学意义(P<0.05)。螺旋扫描螺距为0.984、0.992时SD大于螺距为0.516、0.508(Z=-2.66,P=0.008),其余组间差异均无统计学意义(P>0.05)。结论宽体探测器CT选择不同扫描模式、探测器宽度及信号采集位置会对影像的CT值和SD产生一定影响。Objective To evaluate the influence of different detector widths and signal acquisition positions of wide-detector CT in different scanning modes on CT number and noise,and to provide a basis for reasonable selection of scanning modes and related parameters in clinical practice.Methods The body dose phantom was scanned by GE Revolution CT.The scan was performed with detector widths of 40,80 and 160 mm in sequential scanning mode and with detector width/pitch combinations of 40 mm/0.516,40 mm/0.984,80 mm/0.508 and 80 mm/0.992 in spiral scanning mode.The phantom was placed at the central and peripheral of the selected detector widths,and the adjacent positions between two axial scans.The images of the phantom were evaluated subjectively and the CT numbers and SDs were measured.The differences between the measured values at different imaging parameters were compared.The multi-group Friedman test was used to compare CT numbers and SD under different scanning parameters in sequential scanning mode,and the Wilcoxon test was used to compare CT numbers and SD in spiral scanning mode.Results There was no statistically significant difference in the geometric shapes of the phantom images obtained at any combination of parameters.In sequential scanning mode,the differences at different detector widths were statistically significant(χ^(2)=14.00,P=0.001)with CT numbers at 40 mm and 160 mm greater than CT numbers at 80 mm(P<0.05).The differences at different signal acquisition positions were statistically significant(χ^(2)=12.04,P=0.002)with CT numbers at peripheral and adjacent greater than CT numbers at central(P<0.05).In spiral scanning mode CT numbers at detector width at 80 mm were greater than CT numbers at 40 mm(Z=-2.10,P=0.036).For SD,the differences at different detector widths were statistically significant in sequential scanning modes(χ^(2)=8.17,P=0.017)with SD at 160 mm greater than SD at 80 mm(P<0.05).The differences at different signal acquisition positions were statistically significant(χ^(2)=13.50,P=0.001)wi

关 键 词：体层摄影术 X线计算机 宽体探测器 图像质量 

分 类 号：R814[医药卫生—影像医学与核医学]