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The application of dual energy subtraction technique to sialography

双能减影技术在唾液造影中的应用

基本信息

批准号：
02670890
负责人：
KATOH Tsuguhisa
金额：
$ 1.34万
依托单位：
Tokyo Medical and Dnetal University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

(1) Grade up of the image processing systemRandom access memories and a magnetic optical disk unit were added to the image processing computer. The processing speed and capacity of image file storage were advanced. The soft ware system for the dual energy subtraction to suppress the bone image. It took within 10 minutes to process all the procedure for subtraction including input scan of x-ray film.(2) Simulation for optimizationThe optimum selection of x-ray filter materials, tube potential and intensifying screen was searched for by means of computer simulation, and found that the combination of gadrinium or tungsten for dichromizing x-ray filter, Gd_2O_2S and CaWO_4 for the screen and copper or tin for in-cassette-filter and 1OOkVcp for tube potential were expected to have high performance.(3) Phantom experimentPhantoms were made of polyethyrene tube of various diameter filled with contrast agents and bone phantom wedge and a water bath. In the images of these phantoms produced by this method, codes of contrast media thicker than 0.5mm were recognized. The remarkable reduction of contrast of the contrast media and increment of the noise were, however, observed.(4) DiscussionIt was theoretically proved that reduction of the iodine contrast was due to the similarity of the energy dependency of attenuation coefficient among the bone and the iodine. The increment of the noise was caused by the statistically additive nature of the granuality of the film-screen systems. Especially, the noise in the high edergy image, which was produced by high speed screen place behind the copper/tin filter, magnified by factor 4 or 5. It was concluded, therefore, that the present dual energy subtraction technique was not suitable for improvement of image quality of the sialography.

(1)图象处理系统的升级图象处理计算机增加了随机存取存储器和磁光盘装置。提高了图像文件的处理速度和存储容量。双能量减影骨像抑制软件系统。在10分钟内完成了所有减影程序，包括X线片的输入扫描。(2)通过计算机模拟，对X射线滤光片材料、管电位和增感屏的最佳选择进行了探索，发现用钆或钨作X射线滤光片的渗铬处理，用Gd_2O_2S和CaWO_4作增感屏，用铜或锡作盒式滤光片，用100 kVcp作管电位的组合，可望获得较好的性能。(3)体模实验装置由不同直径的聚乙烯管、骨模楔和水浴制成。在用这种方法产生的这些体模的图像中，识别出厚度大于0.5mm的造影剂代码。然而，观察到造影剂的对比度显著降低和噪声增加。(4)讨论从理论上证明了碘对比度的降低是由于碘与骨之间衰减系数的能量依赖性相似。噪声的增加是由胶片-屏幕系统的粒度的统计加性性质引起的。特别是高速屏幕产生的高能量图像中的噪声位于铜/锡滤波器之后，被放大4或5倍。因此，可以得出结论，目前的双能量减影技术不适合改善涎腺造影的图像质量。