Two Systems for Direct Radiographic Miniaturization
The direct miniaturization of radiographic images is discussed, and two systems are analyzed in detail. The performance and relative advantages of a large, high-performance X-ray image intensifier (¿18-in or 46-cm diameter) and an optically coupled radiographic intensifier are presented. These systems are estimated to have comparable performance and costs. The X-ray image intensifier system is superior in quantum efficiency and gain, while the radiographic intensifier is superior in contrast. While, as expected, the resolution, contrast, and sensitivity of these systems are not as good as a conventional screen-film cassette system under all circumstances, their performance may be adequate for all but the most demanding radiologic applications.
High Performance Continuous Zoom X-Ray Image Intensifiers
This paper discusses the development and performance of a 9-inch X-ray Image Intensifier featuring a continuously variable magnification from a 9-inch useful input diameter to a 5-inch useful input diameter at a fixed 20mm diameter output image. The pentode electron optical structure in this device was designed through utilization of a digital computer electron optics evaluation program. A brief analysis of the design technique is presented, with particular emphasis directed towards techniques used for prediction and optimization of electron optical performance parameters from computer analysis data. The described techniques resulted in a design which not only demonstrates geometric distortion of less than 5 percent and a flat focal plane surface, but also enables a single voltage divider magnification control which continuously varies the magnification while maintaining focus. This particular result enables incorporation of an integral power supply within the intensifier housing that provides complete operating voltages and subsecond zooming between 9-inch and 6-inch modes. Performance parameters of the device are also investigated with particular atten-tion to an MTF evaluation technique which applies to all X-ray image intensifiers. In addition to superior MTF, this new device also exhibits a conversion gain in excess of 5,000 with 125 linepairs per inch limiting resolution in the 6-inch input mode. Nine-inch mode gain is at least 10,000 with a limiting resolution of 90 linepairs per inch. The high gain and resolution of this new intensifier, in conjunction with its capability of rapid zooming with entire control provided by an integral power supply render it an excellent device for use in x-ray diagnostic equipment.
Watershed road network analysis with an emphasis on fire fighting management.
The aim of this study is fire hazard zoning the Chehel-Chay watershed and analysis of road network in order to fire-fighting management. Using effective factors on fire occurrence, the fire hazard ...