旋转DSA技术在肺栓塞诊疗中应用的研究

目的研究旋转DSA技术在肺栓塞(pulmonary embolism，PE)诊疗中的应用。方法建立小型猪肺栓塞模型13头，进行常规肺动脉造影并应用旋转DSA技术，对造影结果进行分析、评价和研究。结果将每头猪的肺分为相应的15条血管，共有195条血管。以病理阳性结果为标准，评价肺动脉造影及旋转。DSA技术诊断PE的价值。肺动脉造影及旋转。DSA共有47个血管阳性(24．1％)，敏感性为98％，特异性为99％，诊断准确性98％；有2个血管数字减影肺动脉造影阳性，病理阴性，假阳性率为1％；有1个血管数字减影肺动脉造影阴性，病理阳性，假阴性率为2％。结论旋转DSA技术有助于肺栓塞诊断，尤其对疑似病变有一定临床意义。

A comparative study of energy responses of computed radiography system and screen-film system

Objective To investigate the relationships between CR image pixel values and exposure factors (kVp,mAs), thickness of exposed subject, and those between conventional screen-film optical density and exposure factors (kVp,mAs), thickness of exposed subject. The relationships of these two kinds of energy response were compared. The feasibility of using CR image pixel values and measure values of IP mean incident exposure as parameters for setting up phototimer was studied. Methods Homogeneous acrylic phantoms 10, 15 and 20 cm thick were imaged with a traditional X-ray system and a CR system at 50-90, 70-120, 90-140 kVp and AEC density grade -2. Automatic exposure responses of the two systems at various tube voltages, same exposed subject thickness and grade selection were compared. Grid were used simultaneously for all radiography. Incident IP exposures were measured with an ionization chamber. Results Under the conditions of meeting clinical diagnostic requirements, the exposure of CR system was two times of that of rare earth screen-film system approximately. Tube voltages vs pixel value curves were similar to those of tube voltages vs exposure curves in CR system. When the thickness of the projected subject remained 10 cm, the screen- film density difference in 50-90 kVp was 1.21, and the pixel value difference was 270. When 20 cm thick, the density difference in 90-130 kVp was 0.30, and the pixel value difference was 100. When 15 cm thick, they were 0.62 and 160 seperately. Conclusion The speed value of Kodak CR 900 system is closely similar to that of medium screen-film systems. The exposure index value in flat field image and IP mean incident exposure could be used as factors to setup phototimer of AEC. The regularities between film density and kVp, pixel value and kVp, as well as differences in them, are important to the callibration of AEC system.