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The most important breakdown in the public’s understanding of nuclear power is in its concept of the dangers of radiation. Radiation consists of several types of subatomic particles, principally those called gamma rays, neutrons, electrons, and alpha particles. These particles shoot through space at very high speeds, something like 100,000 miles per second and they can easily penetrate deep inside the human body, damaging some of the biological cells of which the body is composed. This damage can cause a fatal cancer to develop, or if it occurs in reproductive cells, it can cause genetic defects in later generations of offspring.

However, through constant development in medical and nuclear science, especially in particle physics, scientists have come up with a revolutionary concept in using radiation as a mean of diagnosing and curing diseases. This in every way contradicts the basic understanding among people regarding radiation. In the medical field, scientists have been toiling endlessly to understand the behavior of radiation particles or to be more precise ionizing radiation. Once the secret of ionizing radiation is fully understood, it breaks open a whole new possibility and potential for nuclear medicine using radioactive substance.

So what exactly is nuclear medicine? Nuclear medicine uses radioactive substance which gives off ionizing radiation as they decay, to both diagnose and treat diseases. To put this subject into retrospective, in medical diagnostics using nuclear scans, a radioactive substance is injected, swallowed or breathed into the body and it gives off radiation (gamma rays) as it passes through or lodges in the body. These invisible rays can be tracked and used to produce images and doctors will then check the pictures to find for lumps or tumors as well as cancerous cells. Scans are the main use of nuclear medicine.

In treating diseases, radiotherapy is considered one of the best methods of combating cancer cells from spreading. Radioactive substance is able to stop cancers growing, and destroys cancer cells. It can be used to cure cancers or to ease a patient’s suffering. For example, thyroid cancers are treated by swallowing radioactive iodine. Doctors administer treatment using nuclear medicine because radiation damages cancer cells more than is harms normal cells. For example, heart and blood vessel examinations can be done with a thallium stress test .The thallium isotope is produced in a cyclotron, a type of particle accelerator. Iodine 123, which is primarily used to generate images of the thyroid, is also produced in a cyclotron.

The Medical Cyclotron

The cyclotron is an accelerator of subatomic particles. It produces a large quantity of protons (heavy particles with an electrical positive charge) and gets them moving at an accelerated rate along a circular orbit, inside a chamber controlled by powerful alternating electromagnetic fields. Thus, the particles gain energy and are smashed against a target at nearly the speed of light. The isotopes produced by the cyclotron are used for body imaging.

The Medical Cyclotron structural layout.

However, there is the common misconception that X-rays and CT Scans are classified as nuclear medicine. This is not true because they are not produced from radioactive substance. X-ray images, used to diagnose disease, are similar to photographs. A normal camera records light bouncing off the surface of objects and transmits it into the camera. Because X-rays penetrate into softer objects (like bodies, or luggage), we can use them with a special camera to make pictures of the harder objects inside our bodies or our backpacks: lumps, bones, metal. X-rays are also used in curing cancers, by focusing concentrated X-Rayson the cancer site. X-rays, however, are a type of ionizing radiation. CT Scans, like X-Rays, are not classified as nuclear medicine. CT Scans use many X-Rays to create a 3-dimensional picture. They are a greater concern as the risk of cancer for the patient is greater for Cat Scans than for X-Rays.

References:

http://nuclear-news.net/information/wastes-2/draft-august-2/

http://www.lbl.gov/Publications/Currents/Archive/Aug-27-1999.html

http://www.cerebromente.org.br/n01/pet/petcyclo.htm

Radiation is the energy that travels in waves. It includes visible light, ultraviolet light, radio waves and other forms, including particles. Each type of radiation has different properties. Non-ionizing radiation can shake or move molecules. Ionizing radiation can actually break molecular bonds, causing unpredictable chemical reactions. Humans cannot see, feel, taste, smell or hear ionizing radiation. Unavoidable exposure to ionizing radiation comes from cosmic rays and some natural material. Human exposure to natural radiation is responsible for a certain number of mutations and cancers. Additional exposure above natural background radiation is cause for concern since it may result in otherwise preventable disease.

The levels of radiation risks and danger.

Where does ionizing radiation come from?

Ionizing radiation is matter or energy that is given off by the nucleus of an unstable atom in the process of decaying and reaching a stable (ground) state. This energy is released in the form of subatomic particles (alpha and beta) or waves (gamma and x rays). Most elements and their atoms are not radioactive. A few radioactive elements, like uranium, radium, and thorium, occur in nature. Humans, through nuclear power, bomb production and testing, have created and released manmade radioactive elements (radionuclides) that were previously unknown in the environment. Through mining and industrial processing naturally radioactive elements like uranium and thorium have been released to flow through the natural systems on which life depends. These substances were, with few exceptions, geologically isolated from the environment under layers of shale and quartz before human beings dug them up by the ton and contaminated the biosphere. Because of poorly conceived and implemented nuclear technologies, such as atomic energy, bomb production and reprocessing, we and our descendants are left with a legacy of radioactive waste with no proven isolation method.

…of Alpha, Beta and Gamma

Putting into retrospective, alpha particles are perceived as high energy, large subatomic structures. They can’t travel very far and can be stopped by a piece of paper or the human skin. However, alpha particles hit hard and are capable of doing a great deal of damage to the cells they rip through. Once inhaled, ingested or otherwise taken inside the body (as through a cut in the skin), they have the power to tear through cells in organs or blood, releasing their energy to surrounding tissue and leaving extensive damage in their wake. A single track of a single alpha particle can deliver a large dose of radiation to a cell. Plutonium is an alpha emitter. Other alpha emitters include radon gas, uranium, and americium.

Beta particles are electrons. They are just a fraction of the size of alpha particles and can travel farther and are more penetrating. Betas pose a risk both outside and inside the body, depending on their energy level. External exposure can result in beta penetration through the surface to the most sensitive layers of skin. Inhalation or ingestion of a beta emitting radionuclide poses the greatest risk. Externally, a half-inch of Plexiglas or water shielding can generally stop a beta. Strontium-90 and tritium are two beta-emitting radionuclide routinely released from nuclear power reactors during normal operation. Our bodies often mistake strontium-90 for calcium, collecting it in our bones that make our new blood cells. Once there, it increases our risk of bone and blood cancers like leukemia. Every one of us has strontium-90 in our bodies as a result of nuclear bomb testing. Tritium is radioactive hydrogen, which binds where normal hydrogen does. Hydrogen is the most abundant element on the earth, and is a component of water, which cushions our genetic material (DNA). Tritium can bond in this water, irradiating our DNA at very close range.

Gamma rays are the most penetrating type of radiation and can be stopped only by thick lead blocking their path. Cesium-137 is a gamma emitter often released from nuclear reactors. It mimics potassium, collecting in muscle. Iodine-131 and Iodine

Reference: http://www.oasisllc.com/abgx/radioactivity.htm