Objective To discuss the application value of sinogram-affirmed iterative reconstruction (SAFIRE) technique in reducing the chest radiation dose. Methods 80 patients who received chest CT examination in our hospital in November 2013 were divided into two groups (control group and low-dose group) randomizedly with each group of 40 people. In control group, the tube voltage was 130 kV and FBP (Filtered Back Project) reconstruction technique was used; while in low-dose group, the tube voltage was 80 kV and SAFIRE (Strength 3) technique was used. Then the CT values, standard deviations (SD), signal to noise ratios (SNR) and contrast to noise ratios (CNR) of descending aorta and muscle at the level of tracheal bifurcation in two groups were measured. CT dose indexes (CTDI) and dose lengths product (DLP) of two groups were recorded, effective doses (ED) were estimated. Then two radiologists assessed the image quality according to 5-level scale, and the consistency between two radiologists was evaluated with Kappa test. ResuIts CTDI, DLP and ED of control group were (6.71±1.06) mGy, (237.75±45.76) mGy·cm and (3.33±0.64) mSv, while those of lowdose group were (2.08±0.28) mGy, (78.53±11.35) mGy·cm and (1.10±0.16) mSv. And these differences between the two groups were signi昀cant (P<0.05). SNR and CNR of control group were (6.84±1.83) and (2.25±1.05), while those of low-dose group were (6.43±1.32) and (1.99±1.41), those differences between the two groups were not significant (P>0.05). All images could satisfy diagnosis requirements, and the consistency of scores among two radiologists was good (Kappa=0.764). ConcIusion Low dose chest CT scan combined with SAFIRE technique can effectively reduce radiation dose without affecting diagnosis effect.%目的：探讨正弦图确定迭代重建（SAFIRE）技术在降低胸部扫描剂量中的应用价值。方法选取2013年11月于我院作胸部CT检查的80例患者，将患者随机分成两组（对照组和低剂量组），每组各40人。对照组采用管电压130 kV和滤波反投影（FBP）重建技术，低剂量组采用管电压80 kV和SAFIRE（Strength 3级）技术。分别测量两组气管分杈层面降主动脉和同层背部肌肉的CT值及其标准差（SD）、信噪比（SNR）、对比噪声比（CNR）；记录两组患者的CT剂量指数（CTDI）、剂量长度乘积（DLP），并估算有效剂量（ED）。由两名医师对图像质量采用5分制进行评估，并用Kappa检验评价医师评分结果的一致性。结果对照组的CTDI为（6.71±1.06）mGy，DLP为（237.75±45.76） mGy·cm，ED为（3.33±0.64） mSv；低剂量组的CTDI为（2.08±0.28） mGy， DLP为（78.53±11.35） mGy·cm，ED为（1.10±0.16） mSv；两组差异均有统计学意义（P＜0.05）。对照组的SNR为（6.84±1.83），CNR为（2.25±1.05）；低剂量组的SNR为（6.43±1.32），CNR为（1.99±1.41），两组差异均无统计学意义（P＞0.05）且图像质量均能满足临床诊断要求，医师间的评估结果具有较好的一致性（Kappa=0.764）。结论胸部低剂量CT结合SAFIRE技术，可在不影响诊断效果的情况下，显著降低辐射剂量。
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