X-Ray Tube/ X-Ray Production

X-Ray Tube/ X-Ray Production

Introduction

The X-ray tube is the set which produces the radiation supplied by a material bombarded by electrons. The naming took place after the German physicist Wilhelm Conrad Roentgen. The electrons coming from the cathode and are accelerated by a high voltage to the anode. The electrons move in an enclosure where the vacuum is further possible in order to support a large potential difference for high-speed electrons (Zink, 1997). In its simplest form it consists of a cathode and an anode, which was formerly referred to as anti-cathode in a vacuum were melted in a sealed glass body. The temperature of the cathode manages the number of electrons and hence the current through the X-ray tube.

Discussion

An X-ray tube is a narrow cylinder where a vacuum provided at each end an electrode rule, one negatively charged (the cathode) and the other positively (anode). An electric current heats the cathode ?at the same time that a potential difference is created between the cathode and the anode. The cathode by heating emits an electron beam which is accelerated by the potential difference between the two electrodes and bombards the anode (Sprawls, 1993). The anode then renders a small part of the energy supplied by the electrons in the form of an invisible electromagnetic radiation. Quantity of X-rays emitted is thus proportional to the current (in amperes) of the cathode heating current and the value of the difference of potential (in volts) between the anode and the cathode (Zink, 1997).

Design of X-Ray Tube

The basic x-ray tubes are made up of the common design which includes cathode, anode, envelope, focal spot and housing.

Cathode

The cathode comprises a filament (filament), which usually consists of a tungsten wire is. This hot cathode is heated by current flow to approximately 2000 ° C so that thermal emission of electrons from the metal occurs. The electrons form a negatively charged electron cloud which opposes the exit of further electrons (Sprawls, 1993). Only through the application of a positive voltage to the anode, the electrons are accelerated to it.

Anode

The anode is the material that receives the electron beam. These electrons come with great speed and will be able to change the composition of the material at the atomic level. It is this interaction that will produce an electromagnetic wave in the spectrum of X-ray composition (Sprawls, 1993). The anode is made ??of materials which withstand high temperatures, with thousands of atoms, the atoms and have many electrons whose energy levels between the various layers are compatible with the envisaged use radiation. The anode is usually made ??of alloys tailored to the application, or x-ray mammography and rhenium tungsten molybdenum are mainly used.

Focal spot

Most of the x-ray tubes have two focal point sizes i.e. large and small. The operator selects the appropriate one according the imaging process. At the time of selecting x-ray tube for some specific application, there is a need to consider the focal spot size. If high image visibility ...