【摘要】 目的通过测量患者在"深吸气"与"深呼气"不同屏气状态时腹部前后径值的改变,以及应用CT管电流自动调节技术(ATCM)时的不同CT剂量指数(CTDI)和剂量长度乘积(DLP)值,评价不同屏气状态对减小腹部前后径和照射剂量的影响作用。方法对120例成人按性别和体质量指数(BMI)等分成(超重、正常、超轻)6组,按性别和BMI分为正常值组(BMI18～25)、超重组(BMI>25)和超轻组(BMI<18),每组男、女各10例。对同组内的20例患者分别取"深吸气"与"深呼气"不同屏气状态行腹部CT扫描。分别测量CT影像上腹部前后径值和使用ATCM时腹部的照射剂量(CTDI和DLP值)。进行两种不同屏气状态的作用效果对照评估。结果患者取"深呼气"屏气状态较"深吸气"屏气状态,可不同程度地减小腹部前后径和照射剂量。在男性超重、正常、超轻3组中,腹部前后径分别平均减小了4.20、3.95、3.86 cm,照射剂量(CTDI和DLP值)依次分别平均减小了14.83%mGy、121.89mGy.cm,21.20%mGy、175.82mGy.cm,18.70%mGy、161.31 mGy.cm。在女性3组中为4.25、4.39、3.44 cm。CTDI和DLP值依次分别平均减少了15.20%mGy、180.98 mGy.cm,27.83%mGy、167.16 mGy.cm,21.10%mGy、128.57 mGy.cm。以上各对照组数值经t检验后差异均具有显著统计学意义(P<0.05)。在两种不同屏气状态下扫描所得的影像上,经测量相同部位的CT值及标准偏差均在正常允许值范围,两者影像的质量无明显差异。结论采用"深呼气"状态下的屏气方式,可起到"自我压迫"作用,能有效减小腹部前后径和降低腹部受照剂量。更多还原

【Abstract】 Objective To evaluate the effect of different breath-hold status(deep inspiration or deep expiration) on abdominal CT scan through assessing the impact of breath-hold status on anteroposterior(AP) diameter and radiation dose[computed tomography dose index(CTDI) and dose-length product(DLP)] with automatic tube current modulation(ATCM).Methods A total of 120 patients were divided into 6 groups(overweight,normal and ultra-light) according to gender and body mass index(BMI).The patients in each group were further divided into 2 subgroups,who received abdominal scanning either under deep inspiration or under deep expiration.The AP diameters and radiation doses in different groups and breath-hold status were measured and compared.Results In the male overweight,normal and ultra-light groups,deep expiration reduced AP diameters by 4.20,3.95,3.86 cm,respectively,as compared with deep inspiration.It also led to decrease in CTDI and DLP by 14.83 % mGy and 121.89 mGy·cm,21.20 % mGy and 175.82 mGy ·cm,18.70 % mGy and 161.31 mGy·cm,respectively,in comparison to deep inspiration.In the female groups,the corresponding values for AP reduction were 4.25,4.39,3.44 cm,and that for CTDI and DLP were 15.20 % mGy and 180.98 mGy·cm,27.83 % mGy and 167.16 mGy·cm,as well as 21.10 % mGy and 128.57 mGy·cm,respectively.The differences in the AP diameters and radiation doses between the deep inspiration group and the deep expiration group were statistically significant(P < 0.05).The standard deviations of the CT values of the two breath-hold status were all within normal range of allowed values.No significant difference in image quality was observed.Conclusion It is demonstrated that the deep expiratory breath-hold status could play a "self-compression" role in reducing AP diameter of abdomen and radiation dose.更多还原