摘要
目的探讨应用64层螺旋CT(MSCT),采用适宜噪声指数的自动管电流调节技术(ATCM)获得稳定的腹部CT扫描图像,并降低射线剂量的可行性。方法选取150例需接受64层MSCT腹部扫描的患者为自动毫安组,采用自动管电流扫描技术检查;随机分为A、B、C 3组,每组50例,预设噪声指数(NI),A组为8,B组为10,C组为12,管电流设置范围为30～600mA。同期接受常规腹部MSCT(采用固定管电流扫描技术)检查的50例患者为固定毫安组,管电流520mA。其余扫描参数相同。记录各组CT辐射剂量并进行比较,对图像质量进行评分,图像的平均噪声与体重指数(BMI)的相关性采用pearson相关分析。结果各组辐射剂量差异有统计学意义(P<0.05),固定毫安组的辐射剂量大于各自动毫安组的辐射剂量。固定毫安组、自动毫安A、B、C组的图像质量评分分别为2.97±0.56、2.94±0.98、2.76±1.02、2.54±1.33,自动毫安A、B组的图像均能达到临床诊断要求。自动毫安组中,噪声指数较低时,不同组织的图像噪声较固定毫安组的图像噪声变异度小,图像更加均匀。固定毫安组图像的平均噪声与BMI呈正相关(R2=0.484 6,P<0.05)。自动毫安组图像的平均噪声与BMI无相关性(R2=0.002 3,P>0.05)。结论 ATCM应用于64层MSCT低剂量腹部扫描时可以在降低射线剂量的基础上获得稳定的图像质量,噪声指数设定在10以内较为适宜。
Objective To investigate the feasibility of application of auto-mA technique （ATCM） with adequate noise index （NI） in abdominal CT scan getting stable image quality and decreasing radiation dosage in a 64 multi-detect row CT （MDCT）. Methods A total of 150 patients applied for abdominal 64 MSCT examination were selected as group auto-mA scanned with auto-mA technique and subdivided into three groups randomly with each 50 patients. NI was 8 for group A, 10 for group B, and 12 for group C, with tube current range from 30 to 600 mA. Another 50 patients taking conventional abdominal MSCT examination with fixed tube current technique in same period of time were selected as group fixed-mA. Scan protocol was used as same as group auto-mA except the tube current being 520 mA. The radiation dosage documented and the scores of image quality of groups were compared and the correlation of the mean image noise and body weight index （BMI） was analyzed with Pearson analysis. Results There was significant difference in the radiation dosages between the groups （P〈0.05） and the dosage of fix-mA group was higher than that of auto-mA groups. The image quality score of fixed-mA, auto-mA A, B, C groups were 2.97±0.56, 2.94±0.98, 2.76±1.02, and 2.54±1.33, respectively. Images of auto-mA group A and B were diagnosable. Compared with group fixed-mA, the noise variability of different tissues of group auto-mA was lower and images looks more homogenously with smaller NI. There was significant direct correlation between mean image noise and BMI in group fixed-mA （R2=0. 484 6, P〈0.05） and in group auto-mA no relationship was found between mean image noise and BMI （R2 =0. 002 3, P〉0.05）. Conclusion Low dose abdominal 64 MDCT scan with ATCM can obtain stable image quality with decreasing radiation dosage. NI 10 or lower is adequate.
出处
《福建医药杂志》
CAS
2012年第1期109-111,共3页
Fujian Medical Journal
