by Group 7
Radioactivity and Health
Radioactivity is also used in medicine but to what extent do we use it, that's the real question behind it. An extremely dangerous science that can take a life or ruin one, we tend to forget about that, we do an X-ray when we break a bone or simply need one but we never stop to think “isn’t this kinda dangerous?”
First let's talk about where we use radioactivity.
We can use Radioactivity in:
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Examination;
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X-Rays;
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Radiotherapy;
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Sterilization of medical equipment;
But let's think about the downsides.
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Things that we have to be cautious about:
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Big quantities of ionizing radiation can cause an acute illness, that can slow the production of blood cells, and the functionality of our digestive system
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Can also permanently damage the cardiovascular system, the brain and the skin
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Someone can contract cancer by being exposed to a large quantity of it
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If the reproductive system gets affected by a considerable amount of it, the baby can either have genetic problems or contract cancer in some time
If someone gets affected by a considerable amount of radiation the injuries that come with it are called “tissue reactions” because it starts to show in the tissue that has been exposed, muscular, intestinal and so on.
The importance of Radioactivity in Medicine
Radioactivity has revolutionized life sciences during the last century, and it is still an indispensable tool. Nuclear medicine today is a well established branch of medicine. Radionuclides and radiopharmaceuticals play a key role both in diagnostic investigations and therapy. Both cyclotron and reactor produced radionuclides find application, the former more in diagnostic studies and the latter in therapy. With the advent of emission tomography (PET and SPECT), new ways for probing biochemistry in a living being have been opened. The radiochemist faces an everincrising challenge of designing new tracers for diagnostic and therapeutic applications. Rapid, efficient and automated methods of radionuclide and precursor production, labeling of biomolecules, and quality control need to be developed.
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Without radioactivity we weren't able to make such accurate diagnoses, and that's where CT, PET and SPECT are so useful.
Let's start by explaining what is a CT or Computer Tomography, is a X-ray in 3D for short, how it works is exactly how that analogy suggests, there is a motor that goes around the patient in this donut looking like thing, it takes different pictures of different angles that permit a bunch of layered photos, something that in an X-ray is not possible since everything is jammed together. This machine helped a lot in making the doctors job easier.
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Now let's explain what is a PET or Positron Emission Tomography and a SPECT or Single Photon Emission Computed Tomography. Both of these are used for enlightening our vessels, organs, bones and so on. What happens is that we inhale, consume or get injected by a small quantity of radioactive substance that will make our internals glow with different colors depending in the quantity or the zone we put it, what it helps is identifying deficiencies in some parts of the body by doing a X-ray or CT scan, with this the doctors can be more accurate.
Radium and Medicine
An interesting story about the discovery of the possibility of using radioactivity in medicine is the story of Perrie Curie, he used to show is friends a little vessel with Radium that glowed in the night with a beautiful blue-green color, however every time he showed it, his fingers started to hurt, and sometime after he involuntarily made a injury in his arm, because he had over exposed is body to the radiation, the injury persisted for 52 days without signs of recovery and he thought “if this can damaged good tissues why not used in bad ones like tumors”.
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Radium is an emitter of alpha particles, beta particles and gamma radiation. It's an element that doesn't possess a stable isotope. The 226Ra is the most abundant radioisotope to this day, with 1602 years of expectancy life. The main radioisotope that comes from it is the radon (222Rn), that is also used for therapeutic purposes. To this day there have been identified 33 isotopes of radio, with different masses between 202 and 234.
In 1914, when Marie Curie started directing one of the departments from the Institute of Radium, now known as the Institute Curie, the 1st World War started. Since the first instance Marie Curie used her influences to equip ambulances with X-ray machines that would be used as mobile radiography stations. In the same year Marie and her daughter went to the battle front to teach the doctors on how to use their equipment. With the help of the military health Marie gave a lot of hospitals a bunch of radium fume tubes, a gas that sometime after was identified as 222Rn. Marie Curie provided itself with radium only to help other people. Another notable human gesture that guaranteed her 2 gold nobel prizes for helping support the war.
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In her first visit to the US in 1921 she was awarded with a gram of radium, this metal was being produced in large quantities in US industries. Since Marie was so humanistic that she gave the US the complete description of the procurement process.
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Since then the application of radium started to be a commun thing, so commun that they used it in toothpastes, shampoo and food! Using a substance that could kill for normal things. They sealed some containers with radium and placed them beside the tumor, brachytherapy and intern radiotherapy. It was used in the treatment of breast cancer, skin cancer and cancer of the cervix, this persisted until the 70s. The technique is still used to this day but with a more accurate dosage and more optimized distribution.
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Then the usage of needles with a really small quantity started to be used, it proved to be really effective so much that it originated the oncological radiation therapy. Marie Curie had a fundamental job in this procedure.
Radiotherapy and Radiodiagnostic
This concept takes into account the biological effects produced by radiation. Later developments in dosimetry have made very high gamma radiation emitters, obtained from nuclear fission products and / or nuclear reactions, making it possible to drastically reduce the irradiation time of the patient. For an effective cancer treatment with gamma emitters, like 60Co, or with beta particles, precision dosimetry is essential. Optimizing tumor irradiation allows most of the planned radiation to reach the tumor, minimizing the irradiation of healthy tissues.
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Current three-dimensional imaging techniques, such as computed axial tomography (CAT) and magnetic resonance imaging (MRI) allows for even more optimal irradiation. At three-dimensional irradiation radiosurgery techniques, such as stereotactic radiosurgery (gamma knife - developed by Lars Leksell in 1967), are non-invasive treatment processes, very effective for certain types of tumors and metastases. Proton beam therapy is also a recent advance. With this technique, the radiation dose distribution is close to the theoretically optimal, but its high cost is inconvenient.
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The discovery of artificial radioactivity by Frédéric Joliot and Irène Joliot-Curie and the split 235U controlled nuclear reactors, have now allowed a wide variety of radioisotopes for use in radiotherapy and radiodiagnosis. The call these radioisotopes to molecules with affinity for certain tissues and organs generated a category of compounds called radiopharmaceuticals.
Nuclear Medicine is a medical specialty that emerged in the course of the development of clinical instrumentation that allows the detection and monitoring of radiopharmaceuticals in the body. The positron emission tomography (PET, positron emission tomography) is today a very powerful asset of this area of ​​Medicine. So-called bookmarks, in this case positron-emitting radioisotopes (the anti-electron particle), are introduced into the body of the patient, linked to biologically active molecules. The annihilation of positrons by electrons generates the release of gamma radiation, which can be monitored in space and allowing the image of its distribution in the body to be obtained. The most used in PET has, to date, been a glucose derivative (18 F-fluorodeoxyglucose), which is rapidly captured by cancer cells, allowing the detection and localization of tumors and metastases. It also makes it possible to know the metabolic activity of tissues, so it can be used to investigate and diagnose a variety of processes physiological and pathological. In recent decades, vectorized radiation therapy has shown very promising results in oncology, with fewer side effects than the conventional radiotherapy.
The concept is based on the use of a radioisotope linked to a biomolecule that directs radioactivity to the places where cancer cells exist. For this purpose, radioactive radioactives emit alpha particles, beta particles or Auger electrons. If the vectorizing molecule is an antibody, the process is called immunotherapy. In this case, the binding to tumor cells occurs through mechanisms of genetics. When the vector molecule is a peptide, its binding occurs in specific receptors, which are usually overexpressed in tumor cells (peptide receptor-mediated therapy).
Conclusion
A century after Marie Curie's discoveries, radiation therapy is one of the main weapons to fight cancer. According to available statistics, between 1991 and 1996, five million patients were treated annually with ionizing radiation. Unfortunately, this possibility of treatment, due to the costs and the lack of equipment and specialized professionals, is not yet available to a large part of the world population.
