计算机X射线摄影条件与影像质量相关性的研究  

Studies on the correlation between photograph condition and image quality on computed radiography

作　　者：丁文洪[1] 章伟敏[1] 丁信法[1] 

机构地区：[1]浙江大学医学院附属第二医院放射科,杭州310009

出　　处：《中华放射医学与防护杂志》2007年第6期590-592,共3页Chinese Journal of Radiological Medicine and Protection

基　　金：浙江省医药卫生科技基金资助项目（2004A039）

摘　　要：目的通过比较计算机X射线摄影（computed radiography，cR），不同kV、曝光剂量及曝光等级的组合对对比．细节检出指数和影像质量的影响，探讨CR摄影中合理使用曝光剂量及曝光等级组合的原则。方法根据阈值对比度．细节检测能力（TCDD）技术，用55、65和75kv，分别结合3种不同的曝光剂量与曝光等级组合对体模TO．16进行摄影，请3位观察者采用双盲法对所得影像进行观察评分，计算阈值检测指数HT（A）；同时结合临床分别对膝关节、胸部、腰椎进行不同组合的投照，请3位放射专家进行双盲阅片，评价影像质量。结果相对低的kV采用增加曝光剂量、减小曝光等级的组合所得探测指数提高幅度高于高的kV；在kV值相同的情况下，对比度好的部位可明显降低曝光剂量，提高曝光等级。结论根据疾病诊断需要和受检部位对比度情况，合理使用曝光等级既能明显降低患者的辐射，又不影响疾病的诊断。Objective To evaluate how to use reasonably the combination of exposure dose and speed class on the base of imaging quality on computed radiography （CR）. Methods Based on threshold contrastdetail detectability （TCCD）technique, phantom TO. 16 photography was done with 55, 65 and 75 kV, and combination with three kinds of different exposure dose and speed class respectively. Three radiologists scored each image sequence using double blind method and calculated the threshold detection index （HT） . The imaging quality of knee joint, chest and lumbarspine was also evaluated by these radiologists on the base of diagnostic quality and the different combination of exposure dose and speed class. Resets Exposure dose was increased by using lower kV value, and HT value was increased by lower exposure grade rather than higher kV value. Exposure dose was decreased obviously and speed class was increased in the good contrast location at the same kV value. Conclusions Based on the demand of diagnostic quality and the contrast of the checked location, the speed class should be carefully selected to decrease the radiation dose exposure to patients, without any decrease of the diagnostic quality.

关 键 词：计算机X射线摄影 曝光等级 影像质量 阈值对比度-细节检测能力(TCDD) 

分 类 号：R686[医药卫生—骨科学]