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Physics is the scientific study of matter and energy, and their interaction. Energy, such as light, heat or sound, which is emitted from one source, travels through space or material, and then is absorbed by another object, is defined as radiation. Radiation physics is the branch of physics that studies the effects of radiation on matter. This field has been instrumental in providing improved manufacturing processes, nuclear energy, and advanced medical diagnostic and treatment options.
The types of radiation studied by physicists include alpha, beta, and gamma rays, neutrons and x-rays. Alphas are particles containing two protons and two elections which are emitted from the nucleus of an atom. Betas are high speed particles which appear identical to electrons. Neutrons are the neutral particles within the nucleus of all cells. Gamma rays are emitted by the nucleus, and x-rays are a result of energy changes in the nucleus.
X-ray technology is one of the most familiar applications of radiation physics, and has several manufacturing applications. For example, the automobile industry uses high energy x-rays to evaluate engine performance. X-ray microscopes are used to inspect stents and catheters during the production process, and x-ray thickness gauges measure the chemical composition of metal alloys. X-ray radiography is even used by archaeologists to examine ancient artifacts.
The oil industry has employed radiation physics applications in the treatment and production of petroleum. Oil companies use a radiation process called radiation thermal cracking (RTC) during the production of crude oil, fuel oil, tar and the treatment of the waste byproducts of oil extraction. RTC has a higher production rate, lower cost, and much lower energy consumption than tradition methods. Radiation treatment of oil contaminants provides greater environmental protection than other methods.
Nuclear energy is a growing field which is based on applied radiation physics. Through a process known as nuclear fission, energy is extracted from atoms during controlled nuclear reactions. While the United States produces the largest quantity of nuclear power, France produces the highest percentage of its nation’s electrical supply through nuclear reactors.
The field which has benefited the most from radiation physics, however, is medicine. Through the application of physics, scientists have developed methods of using ionizing radiation for diagnosing and treating medical conditions. This includes not only the traditional forms of x-rays, but also ultrasound, magnetic resonance imaging (MRI) and nuclear medicine.
The majority of nuclear medicine involves imaging and employs computers, sensors and radioactive materials called radiopharmaceuticals. X-rays, the oldest form of imaging, uses high frequency light rays to construct images. Gamma rays have even higher frequencies, and are used in nuclear imaging. Positron emission tomography (PET) and single photon emission computer tomography (SPECT) are two of the most widely used pieces of nuclear imaging equipment.
The most common use of radiation therapy is the for treatment of cancerous tumors. This usually involves depositing high energy x-rays into the cancer cells. The radiation is absorbed by the cell, causing it to die. Radiation is generally delivered to the tumor through an external source. The challenge for medical physicists is to direct the radiation in such a way that the minimum number of healthy cells are destroyed.
Radiation brachytherapy involves the internal application of radiation materials. In this treatment, radioactive “seeds” are implanted near the tumor. The release of radiation is slow, and the distance between the seeds and tumor is short enough that the radiation exposure to healthy cells is limited.
The benefits of radiation physics cross several disciplines and industries. Concerns over potential depletion of fossil fuels make the development of nuclear energy an on-going priority in many nations. The field of nuclear medicine is exploding, with new tests and treatments being developed rapidly, making radiation physics a discipline that will continue to grow.