Research On Measuring Device Of X-ray Source’s Effective Focal Size

X-ray source is the core component of the industrial CT/DR radiation imaging system. The effective focal size of X-ray source, dose rate and dose stability are the main parameters that affect radiation imaging system especially the effective focal size of the X-ray source, is one of the main factors of the spatial resolution and geometric unsharpness and other key indicatorsNow, there are two types of X-ray source which are used in the industrial CT/DR, one is low energy X-ray machine, the power ranges from 10 to 450 k V; the other is high energy electron linear accelerator, the electron energy ranges from 2 to 15 Me V.There many traditional measurements methods in the low energy X-ray machine, which are called scanning method and pinhole method and so on. There are many methods, such as sandwich method and the modulation transfer function method in the high energy electron linear accelerator. But because of the complex process, low accuracy and poor reliability of traditional measuring methods test, what’s more human factors often influence. Especially for high energy electron linear accelerator, due to the high energy of ray, strong penetrating power, small focal spot and accurately measure its X-ray effective focus, as a result, there is a lot of difficulties in measuring the X-ray effective focus accurately.Therefore, the research focus of the influence on geometric unintelligibility and spatial resolution, which is caused by spatial resolution in the industrial CT/DR system. This is very important for the further optimize the design of the system and improving the system performance index.In this paper, Basing on the analysis of the research the research situation in the modern world about the measure methods about the ray source effective focal size gamma ray source, I put forward a new method of measuring angle-translation, and complete the design of measure device, and implemented by this method. At last I do the measure experiment to measure the ray source effective focal size. The main research content is as follows:1. Put forward a new measurement method of X-ray source effective focal size: Angle of translation method. Study deeply and analysis measurement principle of the angle-translation method, and according to this method completed the construction of the ray source effectively focus size measurement device.2. Complete design and type selection of effective focus measurement device hardware. complete signal acquisition circuit, complete system, motor control circuit, ray source trigger and the synchronous control circuit and the RS-485 bus interface circuit design; Complete the collimator, detectors, linear slide block, stepper motor selection of components. The measuring device master control chip FPGA, I choose Cyclone series models called EP1C3T144C8;Stepper motor select 57BYG250-7, matching with DV245 motor drive; the type of Linear slider is HTB65 P05C5- Z200.3. Complete the measuring device PC communication software and data processing, the programming of display software. And I use software VC6.0 development, C++ programming language, and RS-485 bus communication technology to complete the development of measuring system PC software. The software combines the computer technology, with communication technology in the measurement system, in order to receive data from the underlying transport circuit, and store, display and handle the real-time data.4. Complete installation and debugging of measurement device. Moreover, I do an experiment to measure effective focal size on the 4 Me V electron linear accelerator. Initially verify the angle-translation method to measure the gamma ray source effectively focus method is feasible. The experimental results show that the angle-translation method is intuitive, good repeatability, small artificial factors influence.