腹部螺旋CT血管成像图像质量与辐射剂量的关系
Association between image quality and radiation dose in abdominal spiral computed tomography angiography
李伟 1龙晚生 1李卓永 1梁启堂 1胡茂清 1金志发1
作者信息
- 1. 529030 广东省江门市中心医院放射科
- 折叠
摘要
目的 探讨在行腹部CT血管成像(CTA)检查时图像质量与辐射剂量的关系,以求获得最高的质量剂量比.方法 收集2008年3月至2012年4月在本院行腹部CTA的患者270例,随机分成管电压、管电流及螺距组,每组90例.管电压组分140、120、100 kV 3级,每级30例；管电流组分400、300、200 mA 3级,每级30例；螺距组分0.5、1、1.5 3级,每级30例.采用64排螺旋CT扫描从膈顶2 cm到腹主动脉髂总动脉分叉处,在腹主动脉近端设置触发兴趣区.当造影剂CT值达到120 HU时,触发扫描并记录辐射剂量.把动脉期容积数据发送到Vitrea工作站进行最大密度投影(MIP)、容积再现(VRT)处理,通过血管的显影、饱满度、整体性、对比度、伪影等的综合得分来评估图像质量,进而对比各组的图像质量与辐射剂量.结果 管电压组中随着管电压从140 kV下降到100 kV,腹部CTA的图像质量与辐射剂量均下降,辐射剂量的下降程度更大(P＜0.05).120 kV与140 kV的图像质量均在优良以上,差异没有统计学意义(P=0.19),100、120 kV管电压下的图像质量比140kV时分别下降41.3％ (P＜0.05)、8.7％.患者采用的辐射剂量从140 kV下降到100 kV逐渐下降,3级管电压组之间辐射剂量的差异有统计学意义(均P＜0.05),120 kV的图像质量剂量比最高.管电流组中,随着管电流从400 mA下降到200 mA,腹部CTA的图像质量与辐射剂量同时下降,但辐射剂量的下降程度更大(P＜0.05),300 mA与400 mA的图像质量均在优良以上,差异没有统计学意义(P=0.21),200、300 mA管电流下的图像质量比400 mA时下降了40.4％(P＜0.05)、10.6％.患者采用的辐射剂量从400 mA到200 mA逐渐下降,3级管电流组之间辐射剂量的差异有统计学意义(均P＜0.05),300 mA的质量剂量比最高.螺距组中,随着螺距从0.5上升到1.5,腹部CTA的图像质量和辐射剂量同时下降,辐射剂量下降程度更大(P＜0.05).螺距1与0.5的图像质量均在优良以上,差异没有统计学意义(P=0.20),螺距1.5的图像质量比螺距0.5、1时下降了50.0％(P＜0.05)、10.9％.在患者采用辐射剂量上,螺距0.5、1、1.5 3级螺距组之间辐射剂量的差异有统计学意义(均P＜0.05),1的质量剂量比最高.结论 适当的降低管电压、管电流及增加螺距,图像质量虽有所下降,但能满足诊断要求,而辐射剂量下降的幅度更大,这有利于X线的全民防护.
Abstract
Objective To investigate the correlation between image quality and radiation dose in abdominal computed tomography angiography (CTA) for determination of the highest quality-dose ratio.Methods A total of 270 patients who underwent abdominal CTA in Jiangmen Central Hospital between March 2008 and April 2012 were randomly assigned to tube voltage (n=90),tube current(n=90) and pitch group(n=90),respectively.In the tube voltage group,exposure to radiation was categorized into 140 kV(n=30),120 kV (n=30) and 100 kV (n=30) subgroups.In tube current group,exposure to radiation was subdivided into 400 mA (n=30),300 mA (n=30) and 200 mA (n=30).In the pitch group,the pitch was subdivided into 0.5 (n=30),1 (n=30) and 1.5 grade (n=30),respectively.By using 64-slice spiral CT,plain abdominal scan was performed from 2 cm above the diaphragmatic dome to the bifurcation of abdominal aorta and common iliac artery.A region of interest was set in the proximal portion of abdominal aorta.The scanning was triggered for recording the radiation dose when the concentration of contrast agent reached 120 HU.The arterial phase volumetric data were sent to the Vitrea workstation for post-processing of maximum intensity projection (MIP) and volume rendering technique (VRT).The image quality was assessed by scoring of vascular fullness,developing,integrity,contrast and artifacts,thus among-group difference in image quality and radiation dose was compared.Results In the tube voltage subgroups,reduction from 140 kV to 100 kV resulted in decreased image quality and radiation dose of abdominal CTA,particularly the latter (P＜0.05).Images generated by 120 kV and 140 kV had preferable or excellent quality (P=0.19).Compared with the images generated by 140 kV,those by 100 kV and 120 kV were decreased by 41.3％(P＜0.05) and 8.7％ in the quality.Reduced voltage (from 140 kV to 100 kV) was accompanied by a progressively decreased radiation dose(P＜0.05).Image quality generated by 120 kV was the highest.In the tube current subgroups,reduction from 400 mA to 200 mA led to poorer image quality and attenuated radiation dose of abdominal CTA,particularly the latter(P＜0.05).The current of 300 mA and 400 mA had preferable or excellent image quality(P=0.21).Compared with the images generated by 400 mA,those by 200 mA and 300 mA decreased by 40.4％ (P＜0.05) and 10.6％ in the quality.Reduced current (from 400 mA to 200 mA) was accompanied by a progressively attenuated radiation dose (P＜0.05).Images generated by 300 mA possessed by the highest quality-dose ratio.In the pitch subgroups,an increased grading from 0.5 to 1.5 yielded poorer image quality and lower radiation dose of abdominal CTA,particularly the latter(P＜0.05).The grading of pitch of 0.5 and 1 had satisfactory or excellent image quality (P=0.20).Compared with the images derived by the grading of 1.5,those by 0.5 and 1 inceased by 50.0％ (P＜0.05) and 10.9％ in the quality.Images created by a pitch grading of 1 yielded the highest quality-dose ratio.Conclusion Despite poorer image quality,a comparatively reduced tube voltage and current and increased pitch may satisfy the diagnostic criteria and lead to a significantly attenuated radiation dose,which is beneficial to the universal protection from X-ray exposure.
关键词
体层摄影术,螺旋计算机/放射摄影术,腹部/图像质量/辐射剂量Key words
Tomography, spiral computed/Radiography, abdominal/Image quality/Radiation dose引用本文复制引用
出版年
2013
NETL
NSTL
维普
万方数据