多排螺旋CT五个剂量测量点位的统计学差异

目的:探讨螺旋CT五个辐射剂量测量点位(CTDI₁₀₀)值之间的差异和相关性统计学关系,以及该机器的辐射稳定性。方法:通过辐射剂量计和辐射剂量模体对螺旋CT五个测量点位进行12次重复测定,对各个点位的测量结果计算其相对偏差,然后用单因素方差分析(One-Way ANOVA)方法分析各点位测量结果之间的显著性。结果:5个点位重复测量的相对标准差分别为0.33%(中心点)、0.73%(3点位)、0.32%(6点位)、1.00%(9点位)和0.32%(12点位);3点位和9点位的平均值接近,单因素方差分析无显著性差异;12点位和6点位的平均值与3点位平均值的相对偏差在0.5%以下。结论:测试螺旋CT辐射稳定性良好,测试机型3点位和9点位在CTDI₁₀₀上测量等效。在非验收测试和状态测试场合CTDI_P可以进行简化。 

Statistics Difference of Five Radiation Gage Points for Multi-slice Spiral CT

Object: To investigate the statistic relationship between 5 clock positions of CTDI₁₀₀ and stabilization of radiation. Method: Radiation meter and phantom are used to 12 time repeating tests on the radiation dose of a spiral CT at 5 Clock positions and then one-way ANOVA method is used to character the their difference significance of those 5 clock positions. Result: The relevant standard difference of measurements at 5 test clock positions are 0.33%(center), 0.73%(3 clock), 0.32%(6 clock), 1.00%(9 clock), 0.32%(12 clock) respectively; meanwhile the average of measurements at 3 clock is much close to that at 9 clock and no significant difference is found in one-way ANOVA test;Moreover the relative deviation between mean value of 12 Clock plus 6 Clock and 3 Clock is 0.5%. Conclusion: The tested spiral CT shows good radiation stability and 3 Clock position have equal effect with 9 clock's in CTDI₁₀₀ measuring, moreover, peripheral CTDI of that can be simplified except for non-acceptance test or operational condition test.