X射线的性质

The properties of X rays

1．穿透作用 穿透作用是指X射线通过物质时不被吸收的能力。X射线能穿透一般可见光所不能透过的物质。可见光因其波长较长，光子其有的能量很小，当射到物体上时，一部分被反射，大部分为物质所吸收，不能透过物体；而X射线则不然，因其波长短，能量大，照在物质上时，仅一部分被物质所吸收，大部分经由原子间隙而透过，表现出很强的穿透能力。X射线穿透物质的能力与X射线光子的能量有关，X射线的波长越短，光子的能量越大，穿透力越强。X射线的穿透力也与物质密度有关，密度大的物质，对X射线的吸收多，透过少；密度小者，吸收少，透过多。利用差别吸收这种性质可以把密度不同的骨骼、肌肉、脂肪等软组织区分开来。这正是X射线透视和摄影的物理基础。

The penetration of 1. penetrating action refers to the ability of X rays to not be absorbed when they pass through a substance. X rays can penetrate the material that can not be penetrated by the common visible light. Because of its long wavelength of visible light, the photon energy is very small, when the shot object, a part is reflected, for most substances absorbed, not through the object; and the X ray is not, because of its short wavelength, high energy, light on the matter, only a part is absorbed by the material. Through the gap and through most of the atomic, showed a strong penetrating ability. The ability of X - rays to penetrate the material is related to the energy of the X - ray photons. The shorter the wavelength of the X - ray, the greater the energy of the photon and the stronger the penetration. The penetration of X rays is also related to the density of the material. The large density material has more absorption of X rays, less permeation, less density, less absorption, and more permeation. Differential absorption can be used to distinguish soft tissues, such as bone, muscle and fat, with different density. This is the physical basis of X - ray fluoroscopy and photography.

2．电离作用 物质受X射线照射时，使核外电子脱离原子轨道，这种作用叫电离作用。在光电效应和散射过程中，出现光电子和反冲电子脱离其原子的过程叫一次电离，这些光电子或反冲电子在行进中又和其它原子碰撞，使被击原子逸出电子叫二次电离。在固体和液体中。电离后的正、负离子将很快复合，不易收集。但在气体中的忘离电荷却很容易收集起来，利用电离电荷的多少可测定X射线的照射量：X射线测量仪器正是根据这个原理制成的。由于电离作用，使气体能够导电；某些物质可以发生化学反应；在有机体内可以诱发各种生物效应。电离作用是X射线损伤和治疗的基础。

When 2. ionizing substances are irradiated by X rays, the electrons outside the nucleus are separated from the atomic orbitals, which are called ionization. In the photoelectric effect and scattering process, the process of photoelectrons and recoil electrons breaking away from their atoms is called one ionization. These opto-electronic or recoil electrons collide with other atoms in the process of traveling, so that the attacked atom escapes the electron and is called the two ionization. In solid and liquid. The ionized positive and negative ions will soon be complex and are not easy to collect. But the forgotten charge in gas can be easily collected. The amount of X ray can be measured by the number of ionization charges. The X ray measuring instrument is based on this principle. Because of ionization, the gas can be conductive; some substances can have chemical reactions; in organic bodies, various biological effects can be induced. Ionization is the basis of X - ray damage and treatment.