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在医学、物理学和工程技术等方面,X射线技术得到了广泛的应用。本文介绍一种诊断用X线自动曝线控制器,描述了控制器电离室和电子电路的物理设计。电离室由两个平行板电极组成,中间充空气。电离室电极用高原子序数的金属制造。金属材料吸收X射后放出的电子数远远大于空气等价壁放出的电子数。电离室电离电流与吸收的X线光子能量有关(因此与X光管管电压有关)。拍X线片时,通常用的增感屏是CaWO_4,也是一种高原子序数材料。增感屏中产生可见光子的数目也是依赖X线能量的。金属室壁电离室电流依赖X线能量的关系与增感屏相似,这意味着对于一定的剂量、电离室给出的信号大小虽然依赖于KV,但其依赖方式和X线片的黑度对KV的依赖关系一样。
In medicine, physics and engineering, X-ray technology has been widely used. This article presents a diagnostic X-ray auto-exposure controller that describes the physical design of the controller’s ionization chamber and electronics. The ionization chamber consists of two parallel plate electrodes with air in the middle. Ionization chamber electrodes are made of high atomic number metals. The number of electrons emitted by the metal material after absorbing X-rays is much larger than the number of electrons emitted by the air-equivalent wall. The ionization chamber ionization current is related to the absorbed X-ray photon energy (hence the X-ray tube voltage). X-ray films taken when the commonly used sensitization screen is CaWO_4, but also a high atomic number of materials. The number of visible photons in the sensitization screen is also dependent on the X-ray energy. The dependence of the metal cell wall ionization chamber current on the X-ray energy is similar to that of the intensifier screen, which means that although the signal size given by the ionization chamber depends on the KV for a given dose, its dependence on the X-ray darkness KV’s dependencies are the same.