床旁胸部CR摄影曝光指数应用探讨  

Explore of the Exposure Index at Bedside Computed Radiography

作　　者：史卓[1] 宋俊峰[1] 周纯武[1] 刘金启[1] 

机构地区：[1]中国医学科学院肿瘤医院影像诊断科,北京100021

出　　处：《实用放射学杂志》2010年第7期1019-1021,共3页Journal of Practical Radiology

摘　　要：目的 探讨计算机X线摄影（computed radiography,CR）床旁胸片曝光指数（exposure index,EI）与相关因素（kVp、mAs、SID、体厚）的变化规律性,指导胸部CR床旁摄影参数的合理应用.方法 分别固定影响EI的3个可变参数kVp、mAs和SID中的某一项,然后对水模正后方的IP板进行同参数多次曝光,测得在某一固定体厚（水模）下曝光指数随另外2个条件的变化规律.而后固定前3个物理条件,再用层厚可变的亚克力板（acrylic,俗名特殊处理有机玻璃）模拟人体胸部正位的体厚,测量曝光指数随亚克力板厚度的变化规律.结果 在固定15 cm厚水模的情况下,为使曝光指数基本不变,测得的3组数据表明：①当管电压被固定为某一定值时,摄影距离增加的同时,应按曲线参数增加管电流.②当摄影距离被固定时,增加管电压的同时,应按曲线参数降低管电流.③当管电流固定时,延长摄影距离的同时,应按曲线参数增加管电压.当这3个物理条件（kVp、mAs、SID）都固定,曝光指数值随着亚克力板厚度的增加呈现出直线递减的规律. 结论适当的曝光指数的应用既能保证数字床旁摄影图像质量,又能达到控制床旁摄影的照射剂量,相对降低受检者群体的辐射剂量的目的 .Objective To study the change law of exposure index （EI） and relative factors（kVp, mAs, SID, body thickness） at bedside CR,in order to guide reasonable application of radiographic factors. Methods IP plate below the water model underwent explosure many times in the same exposure parameters and one of the three variable physical factors kVp, mAs and SID was fixed. The change law of the EI values with the other two individual exposure factors in certain body thickness（water model）. After that, using the alterable--thickness Acrylic board to imitate the patients＇ body thickness and exposured,the change law that the El values with the Acrylic boards＇ thickness change were measured. Results In 15 cm thickness water model＇s condition,to keep no change of EI, the three groups＇ data measured indicated ： ①when the kVp was fixed as a certain value,the mAs had to increase based on the curved shape parameter table with SID increase;②when the SID was fixed, the mAs had to decrease based on the curved shape parameter ta- ble with kVp inerease;③when mAs was fired, the kVp had to increase based on curved shape parameter table with SID increase. When three physical factors（ kVp, m As, SID）fixed, the El value was straight descending law with the Acrylic boards＇ thickness increased. Conclusion At bedside radiography, using El suitably can control both the image quality and radiation dose.

关 键 词：床旁计算机X线摄影 曝光指数 摄影参数 辐射防护 

分 类 号：R323.2[医药卫生—人体解剖和组织胚胎学] R814.42[医药卫生—基础医学]