下颈部横径调节管电压技术颈部增强MDCT的图像质量和辐射剂量

目的探讨基于下颈部横径的低辐射剂量颈部增强MDCT的可行性。方法对临床拟诊为颈部病变的患者行颈部CT检查,根据患者下颈部横径的大小分为三组,分别采用120kV、100kV和80kV管电压行螺旋CT扫描。对三组不同辐射剂量扫描图像进行评价,记录三组不同扫描方案的剂量长度乘积(DLP)和CT容积剂量指数(CTDIvol)。比较三组辐射剂量及图像质量的差异。结果三组患者的下颈部横径差异有统计学差异(F=137.92,P0.01),差异有统计学意义(F=571.62,P0.01);CTDIvol分别为(9.30±1.82)mGy,(5.77±2.70)m Gy,(2.88±0.00)m Gy,差异亦有统计学意义(F=1.856E+32,P0.01)。三组之间两两比较DLP及CTDIvol差异均有统计学意义(P均0.01)。Kappa一致性检验示两名医师对颈部图像质量的评分一致性较高(三组Kappa值均0.70),中等横径组与小横径组分别与大横径组比较图像质量评分差异均无统计学意义(F=1.036,P0.05),三组的图像对比噪声比差异无统计学意义。结论根据患者下颈部横径的大小采用不同管电压并结合自动管电流调制行颈部增强CT扫描可以明显降低患者的辐射剂量,而不影像图像的诊断质量,该扫描方案在显示颈部结构是可行的。

The Effect of Lower Neck Transverse Diameter Adjusting Tube Voltages Technique on Image Quality and Radiation Dose at Neck Enhancement MDCT

Objective To explore the feasibility of low-dose neck enhancement MDCT based on the lower neck transverse diameter.Methods According to the lower neck transverse diameter the patients suspected of cervical disease were divided into 3 groups at large diameter (group A,diameter≥40cm) or medium diameter(group B,35cm≤diamete＜40cm) or small diameter(group C,diameter＜35cm),undergoing 64-MDCT with 120,100,80kV,respectively.The dose-length product (DLP) and CT dose index volume (CTDIvol) of 3 groups were recorded.The image quality and radiation dose were evaluated and compared among 3 groups.Results There was significant difference in lower neck transverse diameter among three groups(F=137.92,P＜0.01).The DLP of the three groups were (217.35 ±24.30) mGy· cm,(137.42± 14.47)mGy · cm,(63.37 ± 7.00) mGy · cm(F=571.62,P＜0.01),and the CTDI vol were (9.30± 1.82)mGy,(5.77±2.70)mGy,(2.88±0.00) mGy(F=1.856E+32,P＜0.01).There was significant difference between arbitrary two of the three groups,respective(all P＜0.01).Kappa conformance test showed that the image quality scores determined by two physicians were highly consistent with each other (all Kappa value＞0.70).No significant difference in image quality and contrast to noise of three groups(F=1.036 (P＞0.05).Conclusion Based on Based on patient's lower neck transverse diameter,neck enhancement MDCT with different suitable tube voltage and automatic tube current modulation can effectively reduce the radiation dose,while high quality image of neck structure can still be ensured.