Preliminary
X-rays are a type of ionizing radiation that can provide benefits and also exposure to radiation can provide threats that harm humans. X-ray is one form of electromagnetic radiation with a wavelength ranging from 10 nanometers to 100 picometers and has energy in the range of 100 eV to 100 KeV.
The Process of Forming X-Rays
To produce x-rays must go through several processes, namely:
- The first step is to heat the cathode more than 20,000 degrees Celsius until it lights up with flowing electricity from the transformer.
- Because the cathode heats up, the electrons from the cathode will be released.
- When connected to a high voltage transformer, the electrons arising from the heat of the cathode will accelerate their movement towards the anode and focus on the target (tungsten)
A simplified diagram of a water-cooled X-ray tube - The cathode is made relatively negative towards the target by choosing high potential.
- The electron clouds suddenly stop at the target so that heat is formed> 99% and x ray is <1%
- The lead shield (shield) will prevent the x-ray from being released, so that the x-ray formed can only come out through the window.
- High heat on the target due to collision of electrons can be removed with a cooling radiator.
A summary of the major concepts associated with x-ray production
Terms of X-ray occurrence
In the process of x-rays, must meet several conditions, namely:
- A Vacuum
X-ray formation also requires vacuum. If there is no vacuum, when the electrons move there will be other particles that block the path of the electron to the target, so that the electron is not on target, or the speed of the electron is reduced because it is blocked so that the energy that should be emitted is small.
Typical rotating anode X-ray tube - Potential Difference
After free electrons are collected, the electrons need to be moved quickly towards the target. To move electrons, what is needed is a high potential difference. Basically, electrons are negatively charged particles, so the target of the anode needs to be given a high positive voltage in order to attract electrons. This works like a magnet, two different poles attract each other. Likewise with the attractiveness of the charge, if the charge is different, there will be attraction between the particles. With this, we can adjust how fast the electrons move by adjusting the tube voltage. The higher the voltage, the faster the electrons will move, and the stronger the penetrating power. - Electron Source
Every material consists of atoms, and each atom has electrons that surround the nucleus. In this case, the filament is an electron source. Generally metals are chosen as filaments because metal elements have many electrons orbiting their atomic skin. What needs to be done is to release the electrons orbiting them to become free electrons. By flowing an electric current into the filament, there will be a thermionist emission effect that causes electrons to escape the atomic skin. - Target of Collision
The anode works as a material to interact with electrons and as an electron-attracting material because it is given a high voltage. When the free electrons hit the anode target, the x-ray will be generated. In general, when electrons hit a target, electrons will emit x-ray photons. The target at the anode is generally made of tungsten, because of its high mechanical resistance, and supported by several other materials such as Rhenium, Molybnemum and Graphite to improve the target mechanical resistance.
Two high Voltage rectifier tubes capable of producing X-rays
X-Ray Properties
X-rays are electromagnetic waves with the Main properties as follows:
- Penetrating Power
X-rays can penetrate the material, with very large penetrating power for radiographically. The higher the tube load (kilo voltage) is, the greater the penetrating power. The lower the atomic weight or objects, the greater the permeability of the x ray - Dispersion
If the X-ray beam through the materials used, it will scatter spread in all directions, causing scattering radiation to the material / substance that is passed through. This can produce radiograph images. - Absorption
X-rays are absorbed by materials or substances according to the atomic weight or density of the material / substance. The higher the density or atomic weight, the greater the absorption. - Photography Effect
X-rays can blacken the film emulsion (silver-bromide emulsion) after being processed by chemical in the dark room. - Fluorescence
X-rays cause certain substances such as calcium-sulfate or Zink-sulfide tolight shine (luminance), when these materials are subjected to X-ray radiation. There are two types of luminance:
• Fluorescence, which is: will spread light when there is X-ray radiation only.
• Phosphorescence, namely: light exposure will last a few times when X-ray radiation has been turned off. - Ionization
The primary effect when X-rays of a substance or substance will cause ionization of the particles of the material or substance. - Biological Effects
X-rays will make changes to the network. This effect is used in radiotherapy treatment.
Effect of Radiation on Humans
The influence of radiation on humans needs to be considered carefully, because the composition of the human body is very complex. In addition, most of the human body consists of water which is very easy to react when subjected to radiation.
Some effects that appear on the human body due to exposure to X-ray radiation are immediately visible. Harmful effects of hair loss and skin damage. Any form of health disorder with the body and human tissues.Because of this interaction, cells can experience structural changes from their original normal structure.
According to the International Commission on Radiological Protection (ICRP) the effects of ionizing radiation on the human body are divided into two, namely as follows:
- Stochastic Effect
The stochastic effect is exposure to a low dose of radiation that can appear in the human body, where its appearance can not be ascertained. These effects include cancer and genetic effects. - Deterministic Effect
The deterministic effect is the most tissue cells experience due to high radiation doses. Determined by exposure to high exposure of radiation exposed to radiation. These effects can appear immediately up to several weeks after irradiation. If humans are exposed to continuous radiation, exposure to radiation can cause levels of molecules, cells, tissues or organs. This deterministic effect has a threshold dose, which generally arises shortly after receiving the radiation dose, its severity depends on the dose of radiation received, and its recovery can be done spontaneously
This deterministic effect is characterized by weakness and lethargy, the appearance of fever complaints, nausea and wanting vomiting, reduced appetite, headaches, excessive sweating and causing shock. The effects of radiation that can arise subsequently in the form of damage to the skin such as epilation (temporary hair loss) and other complaints can be caused by reddened skin like burns which will occur several minutes in early erythema.
Deformity of hand due to an X-ray burn
References:
www.slac.stanford.edu
www.books.google.co.id
www.wikipedia.org
www.physics.info
www.britannica.com
www.icrp.org
