低剂量联合降低管电压、增加螺距在盆腔CT扫描中的应用

Application Of Low Dose Combined With Lower Tube Voltage And Increasing Pitch In Pelvic Ct Scan

【目的】评价低剂量联合降低管电压、增加螺距在盆腔CT扫描中的应用价值。【方法】选取120例盆腔CT扫描女性患者，将100kV管电压与螺距0．7P、0．9P搭配形成2组参数组合为A组、B组，140kV管电压与螺距0．7P、0．9P搭配也形成2组参数组合为C组、D组。记录各组剂量长度乘积（dose length product，DLP）及CT剂量指数（CTdoseindex，CTDI）值；分析辐射剂量与管电压、螺距的关系，采用主客观评价的方法对图像进行评价。【结果】C、D组DLP和CTDI均显著高于A、B组（P〈0．05），且B组DLP和CT-DI较A组、D组DLP和CTDI较C组均显著减少（P〈0.05）。各组I级显示率均较高，达到90％以上，均影像层次清晰、颗粒较均匀，膀胱、子宫、直肠清晰显示，图像质量好；且各组图像质量比较均无显著性差异（P〉0．05）。【结论】降低管电压、增加螺距是降低辐射剂量的有效的方法，参数组合100kV、0．9P，既能降低辐射剂量，同时又能保证图像质量。

[ObjectivelTo evaluate the application value of low dose, lower tuhe voltage and increasing pitch during pelvic computed tomography （CT） scanning. [Methods] A total of 120 female patients received pelvic CT scans at the tube voltages of 100 and 140 kV and the pitchs of 0.7 and 0.9 P. They were divided into 4 groups （ n =30 each）. And the values of CT dose index （CTDI） and dose length product （DLP） values were calculated. And the relationship was analyzed by subjective and objective evaluations. [Results] CT radiation dose was positively associated with tube voltage and negatively with pitch. And the pitches was 0.7 and 0.9P, tube voltages from 140 kV to 100 kV, CTDI, DLP average fell 59.9%, 68.4% ; tube voltages 100 and 140 kV and pitch 0.7～0.9, the average values of CTDI and DLP fell by 20.7 ～ and 9.1% respectively. [Conclusion] Reducing tube voltage and increasing pitch may reduce radiation dose. And 0.9 P parameter, 100 kV and lower dose reduces the radiation dose （〉 500%） and ensures image quality.