我国CT扫描检查中受检者剂量调查结果与分析

目的 通过调查全国15个省市不同级别医疗机构的CT扫描参数并计算受检者剂量，分析我国CT检查中受检者剂量水平，为建立适合我国国民体质特征的CT诊断参考水平提供依据。方法 按照《医用辐射危害评价与控制技术研究》实施方案要求，调查临床实际CT扫描中受检者信息和CT扫描参数，根据临床受检者实际扫描参数，使用CT电离室测量CT设备的CT剂量指数（包括CTDI₁₀₀、CTDI_W和CTDI_VOL），计算代表受检者剂量的剂量长度乘积（DLP）。结果 共在全国15个省市的166家医院调查的483台次不同类型CT扫描设备上，调查了6 524例CT扫描程序。对于头颅、胸部、腹部和腰椎等不同的CT扫描部位，其加权CT剂量指数（CTDI_W）平均值分别为43、15、19和25 mGy，第75百分位数分别为50、19、23和32 mGy；相应DLP的平均值分别为540、397、503和376 mGy·cm，第75百分位数分别为659、525、632和479 mGy·cm。结论 通过此次调查基本上掌握了我国部分省市CT扫描检查中受检者剂量，本次4种部位受检者剂量的第75百分位数，与其他国家和地区的出版物中给出的诊断参考水平互有高低，提示应根据我国国民体质特征，建立适合本国或者不同地区的CT检查中受检者诊断参考水平的重要性，推动CT检查的医疗照射防护最优化。

Investigation and analysis on the dose of the subjects in CT scanning in China

Objective To investigate the CT scanning parameters in hospitals at different levels in 15 provinces and cities in China and the doses to patients undergoing CT examination, in order to provide the basis for establishing CT diagnostic reference level suitable for our country. Methods As required in the implementation program for Technical Study on Medical Radiation Hazard Assessment and Control, the information on the patients examined and the CT scanning parameters in clinical practices were investigated. The CT dose index (CTDI₁₀₀, CTDI_W, CTDI_VOL) of CT scanner was measured by using the CT ionization chamber. The dose length product (DLP) was calculated on the basis of the scan length of the patients examined. Results A total of 6 524 CT scanning procedures and 483 different types of CT scanning equipment were surveyed in 166 hospitals in 15 provinces in China. For head, chest, abdomen, and lumbar vertebrae, the average weighted CTDI_W were 43,15, 19 and 25 mGy, respectively, and the third quartile of CTDI_W were 50, 19, 23 and 32 mGy, respectively. The average DLP were 540, 397, 503 and 376 mGy·cm, respectively. The third quartile of DLP were 659, 525, 632 and 479 mGy·cm respectively. Conclusions Through this survey, the doses to CT-examined patients in some provinces were basicly ascertained. The third quartile of doses to four body parts of the examined patients are different from the diagnostic reference level given in publications in other countries and regions. It is important to establish the CT diagnostic reference level suitable for our CT-examined patients according to Chinese national physical characteristics and therefor to promote the optimization of medical radiation protection in CT examination.