Radiation therapy is the treatment using penetrating x-rays, gamma-rays, or particles such as protons or neutrons on the affected region of the body to destroy the cancer cells. To produce the high energy radiation, particle accelerators such as Cobalt-60 radiation therapy unit or clinac 2100 accelerator are used. Radiation therapy is a mordern treatment technique where the results are faster with fewer side effects than other more traditional forms of treatment. Depending upon the position of the radiation source, different types of treatments are used.
External beam radiotherapy is one of the kind of radiation therapy used for destroying cancer cells. In this therapy the external beam is directed towards the affected part of the patient's body. This beam comprising of high energy particles, destroys the cancer cells. The energy of X-rays and Gamma rays produced by these beams are expressed in terms of KV or MV, in this case the voltage is the maximum electric potential used by the LINAC to produce the photon beam. External beam radiotherapy is also called as teletherapy.
Proton therapy is an advanced facility used for the treatment of cancer. A positively charged particle in the atomic nuclei is called a proton and these are used in proton beam therapy. Proton beam therapy uses a machine called cyclotron which is used to energize protons. Protons are extracted from the cyclotron and directed with magnetic fields to the tumor. How deeply the radiation penetrates is calculated based on the tumor's location. Protons lose only a small amount of energy when they enter the body. Their remaining energy is released when they reach the tumor, delivering the most effective dose of radiation. Proton beams have no exit dose unlike conventional radiation therapy.
X-rays are a type of radiation used for medical diagnosis. X-rays are like any electromagnetic radiation, consisting of energetic particles called photons. X-rays pass through the skin but are resistant to bones; this property of x-rays helps in finding any fractures in the patient's body. X-rays are produced in a X-ray machine which has a X-ray tube where the electron gun shoots electrons which hit the target material (tungsten is most widely used as a target element)with a very high velocity. X-rays result from the atomic processes which occur when the target is being hit. The first atomic process is called Bremsstrahlung, a process where the change in velocity of electrons hitting the tungsten produces X-rays. These electrons slow down after swinging around the nucleus of a tungsten atom and lose energy by radiating x-rays. The second atomic process is K-shell emission, here an electron shot from the electron gun hitting the tungsten atom has enough energy to kick the electron from the k-shell (lowest energy state) of the atom. The electron from the outer shell will fall into the K-shell, and this falling electron gives rise to x-rays which are photons of a specific energy. X-rays are not only used in medicine but also in industry, at airports to check customers and baggage, and by art historians to see if a picture has been painted on top of an older one.
Gamma rays are electromagnetic radiation like X-rays, but they have higher energy. Gamma rays are energetic photons or a light wave in the same electromagnetic family as light and x-rays, but much more energetic and so, potentially harmful. These waves are generated by radioactive atoms and by nuclear explosions. Gamma rays can be produced in labs through the process of nuclear collision and also through the artificial radioactivity that accompanies these interactions. The high-energy nuclei needed for the collisions are accelerated by devices such as the cyclotron and synchrotron. By using these accelerators Gamma rays are produced using Bremsstrahlung process. Gamma-rays can kill living cells, a fact which medicine uses to its advantage, using gamma-rays to kill cancerous cells.
There are certain processes in nature that produce many of the naturally occurring radioactive isotopes. Other radioactive isotopes are only available by artificial production. These can be produced from nuclear reactors and high energy particle accelerators like Jefferson Lab. Radioactive isotopes are produced by bombarding a target with charged particles that are boosted in energy by an accelerator. Cyclotrons are one of the most common accelerators used for this purpose. Cyclotrons accelerate protons to hit a target to produce positron emitting radioisotopes, e.g. fluorine-18.