水模管电流-噪声与管电流-辐射剂量曲线对确定腹部迭代重建低剂量CT扫描参数的价值

发布时间：2018-07-26 20:50

【摘要】：目的探讨应用水模管电流-噪声与管电流-辐射剂量曲线确定腹部迭代重建低剂量CT扫描参数的可行性。方法在西门子二代双源CT上用多组不同的参数扫描水模,分别用FBP和SAFIRE(3)重建CT图像,测量图像噪声,记录各组的辐射剂量,绘制管电压为120 k V、100 k V、80 k V时不同重建方法的参考管电流-噪声曲线与不同扫描方法的参考管电流-辐射剂量曲线。搜集80例拟行腹部CT增强扫描的患者,随机纳入对照组和实验组,对照组采用常规扫描和重建方法,实验组扫描条件从上述SAFIRE(3)曲线上读取,要求其噪声水平与对照组相近的同时辐射剂量最低。由两名放射科医师采用盲法对所得两组图像质量进行主观评分,并测量兴趣区(ROI)的图像噪声(SD)、信噪比(SNR)及对比噪声比(CNR),记录两组的容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP),计算有效辐射剂量(ED)。用两个独立样本t检验和非参数检验对两组患者各评价指标进行统计学分析。结果实验组与对照组相比,主观图像质量评分、各ROI的SD、SNR、和CNR均无统计学差异(P0.05)。实验组CTDIvol显著低于对照组[(9.38±2.12)m Gy比(16.29±2.85)m Gy,P0.05]。结论应用水模管电流-噪声与管电流-辐射剂量曲线可以准确、有效地确定腹部迭代重建低剂量CT的扫描条件。
[Abstract]:Objective to study the feasibility of iterative abdominal reconstruction of low dose CT scan parameters by using the current-noise curve of water model tube and the current-radiation dose curve of water model tube. Methods Water models were scanned with different parameters on Siemens second generation dual-source CT. The CT images were reconstructed by FBP and SAFIRE (3) respectively. The noise of the images was measured and the radiation doses of each group were recorded. The reference tube current-noise curves of different reconstruction methods and the reference tube current-radiation dose curves of different scanning methods were plotted at a voltage of 120 kV ~ 100 kV ~ (80 kV). Eighty patients with abdominal CT enhanced scanning were randomly enrolled in the control group and the experimental group. The control group was examined by conventional scanning and reconstruction methods. The scanning conditions of the experimental group were read from the above SAFIRE (3) curve. The noise level was the lowest at the same time when the noise level was close to that of the control group. Two radiologists used blind method to evaluate the image quality of the two groups. The image noise (SD), SNR (SNR) and contrast noise ratio of (ROI) were measured. The volume CT dose index (CTDIvol), dose length product (DLP), was used to calculate the effective radiation dose (ED). In the two groups. Two independent samples t-test and non-parametric test were used to analyze the evaluation indexes of the two groups. Results compared with the control group, the subjective image quality scores, SDS-SNR and CNR of each ROI in the experimental group were not significantly different (P0.05). CTDIvol in the experimental group was significantly lower than that in the control group [(9.38 卤2.12) m Gy vs (16.29 卤2.85) m Gy (P0.05)]. Conclusion the curve of current-noise and current-radiation dose of water model tube can be used to determine the scanning conditions of abdominal iterative reconstruction of low dose CT.
【作者单位】：第四军医大学放射医学教研室;第四军医大学西京医院放射科;武警山西总队医院
【分类号】：R816.5;R572

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