杭州市CT检查中医疗照射与职业照射水平的研究

Level of medical and occupational exposures in CT examination in Hangzhou

    摘要
  • 摘要:
    目的 了解杭州市CT检查中的医疗照射与职业照射水平，为建立CT诊断参考水平提供依据。
    方法 2018年7至12月，收集2017年杭州市内16家医用辐射防护监测点医院的CT设备信息及与CT操作相关的放射工作人员个人年剂量当量，并利用医院影像归档和通信系统收集2742名受检者的容积CT剂量指数（CTDIvol）和剂量长度乘积（DLP）。同时使用CT长杆电离室测量头部CT标准剂量模体的CTDIvol和DLP，并比较实测值与显示值的差别。基于调查数据计算儿童（<5岁、5~<10岁、10~<15岁组，共1158名）和成人（≥15岁组，共1584名）受检者不同检查部位CTDIvol和DLP的最大值、最小值、平均值、四分位数，并将CTDIvol（P75）和DLP（P75）与国外其他国家的数据进行比较。组间比较采用非参数Kruskal-Wallis H检验。
    结果 16家医用辐射防护监测点医院共有40台CT设备进口设备占92.5%（37/40）。杭州市内省级、市级、县级监测点医院放射工作人员的平均个人年剂量当量分别为0.12、0.24、0.47 mSv。儿童组中，CT受检者的头部、胸部、腹部的CTDIvol（P75）分别为48.8、11.3、13.1 mGy，DLP（P75）分别为655.5、269.2、348.5 mGy·cm；成人组中，CT受检者的头部、胸部、腹部的CTDIvol（P75）分别为54.8、10.5、12.9 mGy；DLP（P75）分别为757.0、308.0、724.9 mGy·cm，2组各部位CTDIvol（P75）、DLP（P75）间的比较，差异均有统计学意义（χ2=4.998~39.529，均P<0.05）。杭州市CT受检者各年龄组间（<5岁、5~<10岁、10~<15岁和≥15岁组）头部、胸部和腹部的CTDIvol（χ2=24.334、10.573、22.723）、DLP（χ2=62.981、51.640、57.983）差异均有统计学意义（均P<0.05）。其他国家儿童CT受检者的头部、胸部、腹部的CTDIvol和DLP分别为20~40、1.5~6.5、2.5~6.0 mGy和240~650、12~115、27~800 mGy·cm；其他国家成人CT受检者的头部、胸部、腹部CTDIvol和DLP分别为30~85、9~22、12~31 mGy和935.6~1360、346.5~610、600~1325 mGy·cm。与其他国家相比，中国杭州成人CT受检者的CTDIvol（P75）和DLP（P75）整体处于较低水平，但儿童CT受检者的CTDIvol（P75）和DLP（P75）则处于较高水平。
    结论 杭州市CT检查所致放射工作人员职业照射水平符合国家标准要求。儿童CT受检者医疗照射水平较其他国家偏高。

     

    Abstract:
    Objective To understand the level of medical and occupational exposures caused by CT examination in Hangzhou and provide basis for the establishment of CT diagnostic reference level.
    Methods CT equipment information and individual annual dose equivalent of radiation workers related to CT operation of 16 medical radiation protection monitoring point hospitals in Hangzhou in 2017 were collected from July to December 2018. Volume CT dose index (CTDIvol) and dose length product (DLP) of 2742 subjects were collected using the hospital image archiving and communication system. At the same time, CTDIvol and DLP of CT equipment of head CT standard dose phantom were measured with a CT long rod ionization chamber, and the difference between measured and displayed values was compared. Maximum, minimum, average, and quartile CTDIvol and DLP in children (<5, 5−<10, 10−<15 years group, 1158 cases in total) and adults (≥15 years group, 1584 cases in total) were calculated on the basis of survey data, and CTDIvol (P75) and DLP (P75) were compared with that of other countries. Kruskal–Wallis H test, a nonparametric approach, was used to compare groups.
    Results Forty sets of CT equipment were found in 16 hospitals of medical radiation protection monitoring points (imported equipment accounts for 92.5% (37/40)). Average individual annual dose equivalent of radiation workers in provincial, municipal, and county hospitals in Hangzhou was 0.12, 0.24, and 0.47 mSv, respectively. CTDIvol (P75) and DLP (P75) of head, chest, and abdomen in the children group were 48.8, 11.3, 13.1 mGy and 655.5, 269.2, 348.5 mGy·cm, respectively. CTDIvol (P75) and DLP (P75) of head, chest, and abdomen in the adult group were 54.8, 10.5, 12.9 mGy and 757.0, 308.0, 724.9 mGy·cm, respectively, and there were significant differences in CTDIvol (P75) and DLP (P75) between the two groups in different parts (χ2=4.998−39.529, all P<0.05). CTDIvol (head χ2=24.334, chest χ2=10.573, and abdomen χ2=22.723; all P<0.05) and DLP (head χ2=62.981, chest χ2=51.640, and abdomen χ2=57.983; all P<0.05) among age groups (<5, 5-<10, 10-<15 and ≥15 years) were statistically significant in the CT examination. CTDIvol and DLP ranges of the head, chest, and abdomen of children with CT in other countries were 20–40, 1.5–6.5, 2.5–6.0 mGy and 240–650, 12–115, 27–800 mGy·cm, respectively. CTDIvol and DLP ranges of the head, chest, and abdomen of adult CT subjects were 30–85, 9–22, 12–31 mGy and 935.6–1360, 346.5–610, 600–1325 mGy·cm, respectively. Compared with other countries, the CTDIvol(P75) and DLP (P75) of adult CT patients were at a lower level as a whole. However, CTDIvol (P75) and DLP (P75) were at a high level in children CT patients. Compared with other countries, the CTDIvol(P75) and DLP (P75) of adult CT patients were at a lower level as a whole. However, CTDIvol (P75) and DLP (P75) were at a high level in children CT patients.
    Conclusions The occupational exposure level of radiation workers caused by CT examination in Hangzhou meets the requirements of national standards. The medical exposure level of children with CT examination was higher than that of other countries.

     

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