辐射剂量和管电压对CT图像质量的影响：基于任务的图像质量评价

杨政君; 张昂; 陈勇; 姜江; 王凌云; 张勇; 张璇; 齐晓凤

doi:10.15953/j.ctta.2021.060

辐射剂量和管电压对CT图像质量的影响：基于任务的图像质量评价

杨政君^1,,
张昂¹,
陈勇¹,
姜江¹,
王凌云¹,
张勇²,
张璇²,
齐晓凤^1, ,

1.
上海交通大学医学院附属瑞金医院放射科, 上海200025
2.
通用电气医疗CT研发部, 上海201203

详细信息

作者简介:
杨政君: 女，上海交通大学医学院附属瑞金医院放射科主管技师，主要从事放射技术工作，擅长X线及钼靶、CT及MR的操作技术和各类CT及MR的重建技术，E-mail：234074482@qq.com

齐晓凤: 女，上海交通大学医学院附属瑞金医院放射科主管技师，主要从事放射科技术及带教工作，擅长平片、CT及MR的机器操作与图像后处理工作， E-mail：qxf40373@rjh.com.cn

中图分类号: R 814；R 144
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出版历程
- 收稿日期: 2020-12-05
- 录用日期: 2022-01-11
- 网络出版日期: 2022-01-18
- 发布日期: 2022-03-31

The Effect of Radiation Dose and Tube Potential on Image Quality of CT: A Task-based Image Quality Assessment

1.
Department of Radiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China
2.
Computed Tomography Research Center, GE Healthcare, Shanghai 201203, China

摘要

摘要: 目的：通过基于任务的图像质量评价参数，研究对比不同辐射剂量和管电压对CT图像的影响。方法：使用GE Revolution Apex扫描美国放射学会（ACR）质量控制体模Gammex 464。采用3种剂量（5、10和20 mGy）和3种管电压（80、100和120 kVp）的扫描方案并重建9组CT图像。选取体模module 1中骨和丙烯酸测量各组图像的任务传递函数（task-based transfer function，TTF，代表空间分辨率）并记录其TTF_50％。选取体模module 3测量噪声功率谱（noise power spectrum，NPS，代表噪声）并记录噪声值、空间频率（f-peak）和 NPS peak值。在图像TTF和NPS的基础上进一步计算图像的可检测能力指数（${d}'$，代表对病灶的可检出能力）。剂量和管电压对图像的影响采用单因素方差分析，P值的多重比较采用 FDR校正。结果：管电压较剂量对TTF_50％的影响较为明显，但两者在骨和丙烯酸物质中的差异均无统计学意义。噪声和NPS peak随着剂量上升而显著减小；随着管电压的增加而减小，但差异不具有统计学意义。剂量较管电压对f-peak的影响较大，但两者差异均无统计学意义。图像的检出能力随着剂量的增加而显著升高；各管电压下图像的检出能力差异无统计学意义。结论：剂量相比管电压更能影响CT图像质量；随着剂量的增加，图像噪声显著改善，对病灶的检出能力显著提升。基于任务为基础的评价指标可以较为全面地反映CT图像质量。
- CT图像质量 /
- 辐射剂量 /
- 图像质量评价
Abstract: Purpose: To compare the effect of radiation dose and tube potential on image quality of CT through the task-based image quality assessment parameters. Methods: We scanned Gammex 464 (the ACR quality assurance phantom) with GE Revolution Apex CT. Three radiation doses (5, 10, 20 mGy) and three tube potentials (80, 100, 120 kVp) were used to reconstruct nine sets of image. Bone and acrylic inserts from module 1 of the phantom was selected for the measurement of task-based transfer function (TTF, representing spatial resolution) and TTF_50% was recorded for each set of images. Module 3 was selected for the measurement of noise power spectrum (NPS, representing image noise) and noise value, spatial frequency (f-peak) and NPS peak value were recorded for each set of images. Detestability index (${d}'$ representing lesion detestability) was furtherly calculated based on TTF and NPS of images. The effect of radiation dose and tube potential on image quality was evaluated by One-way Anova analysis. Multiple comparisons for P value were corrected by FDR. Results: Compared with radiation dose, the effect of tube potential on TTF_50% was more obvious, but there was no significant difference between them in bone and acrylic substances. Noise and NPS peak significantly decreased with the increase of both radiation dose and tube potential but no statistical difference was found. Compared with tube potential, radiation dose showed greater impact on f-peak, but no statistical difference was found. d’ was significantly improved as radiation dose increased; while no statistical difference was found under different tube potentials. Conclusion: Image quality is predominantly influenced by radiation dose rather than tube potential. Image noise and lesion detestability is signifcantly improved as radiation dose elevates. Image quality could be comprehensively inflected by the task-based image quality assessment.
- CT image quality /
- radiation dose /
- image quality assessment

HTML全文

图 1 任务传递函数TTF和噪声功率谱NPS的测量图示

Figure 1. Diagram for task-based transfer function and noise power spectrum

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图 2 9组图像的噪声功率谱NPS结果

Figure 2. NPS for nine sets of images

下载: 全尺寸图片幻灯片

表 1 本研究CT扫描参数

Table 1 CT Scanning parameters in this study

分组	管电压/kVp	管电流/mA	剂量/mGy	旋转时间/s	螺距
A	80	285	5	0.8	0.984
B	80	570	10	0.8	0.984
C	80	795	20	0.6	0.516
D	100	145	5	0.8	0.984
E	100	290	10	0.8	0.984
F	100	405	20	0.6	0.516
G	120	90	5	0.8	0.984
H	120	180	10	0.8	0.984
I	120	215	20	0.7	0.516

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表 2 各组图像基于任务的图像质量评价参数结果

Table 2 Assessment results for images based on task-based image image quality assessment

分组	骨TTF_50％/mm^-1	丙烯酸TTF_50％/mm^-1	噪声/HU	f-peak/mm^-1	NPS peak /HU²mm²	${d}'$
A	0.43	0.46	24.2	0.28	678.5	13.07
B	0.43	0.40	23.0	0.30	607.8	15.45
C	0.43	0.40	22.8	0.30	586.3	16.85
D	0.42	0.42	17.2	0.25	316.2	16.73
E	0.44	0.42	16.2	0.27	297.6	19.57
F	0.43	0.40	16.1	0.28	314.7	21.63
G	0.42	0.42	11.6	0.27	158.9	24.01
H	0.44	0.43	10.9	0.27	137.3	27.95
I	0.43	0.40	10.8	0.28	132.5	32.09

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