摘要
目的观察肺间质病变不同剂量扫描的高分辨CT图像,分析其对图像质量的影响。方法对92例肺间质病变的患者接受胸部高分辨CT扫描,分别进行常规剂量(A剂量组,管电压140kV,管电流250mAs)和低剂量(B剂量组,管电压140kV,管电流150mAs);超低剂量(C剂量组,管电压140kV,管电流75mAs)扫描。采用盲法对图像质量分别进行主观评价和客观评价,其中主观评价采用图像诊断接受率评分和主观噪声评分法进行评分,以肺窗和纵隔窗分别进行观察,采用5分制,并用Kappa检验评价观察者的一致性;图像质量客观评价指标包括CT值和噪声值,ROI取左心室、背部竖脊肌和胸椎锥体中央,面积1.0cm2,测量其CT值和噪声值,层面设定为左心室层面。三组均采用同一层面。窗宽400HU、窗位40HU。结果两名医师在诊断接受率和图像噪声评估分值方面有很好的一致性(Kappa值分别为0.73和0.76)。三组剂量在图像诊断接受率评分及主观噪声评分方便差异有统计学意义(P均<0.05)。而对于客观测量的左心室、背部竖脊肌、椎体的CT值,3组差异均无统计学意义(P均>0.05);对于噪声值,3组差异均有统计学意义(P均<0.05)。结论随着高分辨CT扫描剂量减低,图像质量逐渐降低,但在获得稳定图像质量的前提下,采取适当的低剂量高分辨CT扫描即可保证图像质量,又不影响临床诊断分析。而不论剂量大小,CT值的变化不明显。
Objective To analyze the effects of image quality by observing different dose of high resolution CT image of interstitial lung disease. Methods A tolal of 92 patients with interstitial lung disease underwent thoracic high resolution CT scanning in conventional dose （group A, tube voltage 140 kV, tube current 250 mAs ） and low dose （group B, tube voltage 140 kV, tube current 50 mAs, and group C, tube voltage 140 kV, tube current 75 mAs）. The image quality was evaluated subjectively and objectively. Image diagnosis acceptance rate score and subjective noise score were used in subjec-tive evaluation, and lung and mediastinal window were observed, 5 points were adopted. Consistency of the observer was evaluated using Kappa test. Image quality objective evaluation indexes included CT value and noise value. CT value and noise value were measured in ROI of the left ventricle, back erector spinae and thoracic pyramidal central, and the area of ROI was 1.0 cm2. Left ventricular level was setted, and the same level was used on three kinds of doses. The width of window was 400 HU, the level of window was 40 HU. Results Two physicians had a good consistency in the diagnostic acceptance rate and image noise evaluation values （Kappa 0.73 and 0.76）. Subjective evaluation of image in three groups had significantly differences （all P 〈0.05）. CT value of left ventricular, back erector spinae, vertebral in three groups had no significantly differences （all P 〈0.05）, while, noise value of which in three groups had significantly difference （all P 0.05）. Conclusion On the premise of obtaining stable image quality, taking low doses of appropriate high resolution CT scan （150 mAs） can ensure the quality of the image, and does can not affect the clinical diagnostic analysis. Irrespective of dose size, CT value of the lesion was not obvious.
出处
《医学影像学杂志》
2014年第1期40-43,共4页
Journal of Medical Imaging
基金
2010年河北省科学技术研究与发展计划项目(102761123)
关键词
肺间质病变
低剂量
高分辨
体层摄影术
X线计算机
图像质量
Low dose
High resolution, Tomography, X ray computer Diagnosis acceptance rate Noise image quality
