33 Common Radioactive Isotopes Used in Medicine – Types and Examples

Radiation is an expenditure and energy propagation through space or a substance in the form of waves or particles. The radiation particles are composed of atoms or sub-atoms which have a moving mass and also spreads at high speeds using kinetic energy. Some examples of radiation particles are electrons, beta, alpha, photons and neutrons.
Radiation sources can occur naturally or synthetically.

Natural radiation sources such as radiation from cosmic rays, radiation from chemical elements found in the earth’s crust, radiation that occurs in the atmosphere due to the shifting trajectory of rotation of the sphere of the earth. While synthetic radiation sources are such as x-ray radiation, beta-ray radiation, alpha-ray radiation, and gamma-ray radiation.

The radioisotope is a radioactive element that emits radioactive rays. Radioactive has an important role in complementing human needs in various fields. One of them is in medicine and health. The use of radioactive isotopes in the medical field are for radiodiagnostic and radiotherapy that are also called as nuclear medicine. The nuclear technique by using radioactive isotopes in the nuclear medicine field began in the 1930s as a manifestation of the development of science and technology.

Nuclear medicine is one of the branches of medicine that utilizes open radiation sources from the disintegration of synthetic radioactive nuclei for diagnostic purposes through monitoring of physiological and biochemical processes.
On this occasion we will present more about the role of radioactive, working mechanism and its impact in the field of medicine and health.

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History of Radioisotope Development In The Medical Field

The use of radioactive isotopes in biology and medicine was actually started in 1901 by Henri Danlos using radium for the treatment of tuberculosis in the skin, but the application of radioisotope as tracers in biology and medicine was pioneered by George de Hevesy in the 1920s when radioactive isotopes were used naturally. In the next development they used synthetic radioactive isotopes. So that in 1943 George Hevesy was awarded the Nobel Prize in Chemistry. The first radioisotope used extensively in nuclear medicine is I-131, which was discovered by Glenn Seaborg in 1937.

At the first time I-131 is used as an indicator of the function of the thyroid gland by detecting the emitted beam, with a Geiger enumerator placed near the thyroid gland. Followed by its use for the treatment of hyperthyroidism in 1940. The next discovery of the Seaborg radioactive isotopes Tc-99m and Co-60, which is a milestone in the field of Nuclear Medicine. Thanks to his services, Seaborg was awarded the Nobel Prize for Chemistry in 1951. In the next period, nuclear medicine grew rapidly after the invention of gamma camera by Hal Anger in 1958. The device was able to detect the distribution of photons emitted from the body, which can describe the function An organ. This method is called nuclear imaging, which is used for in vivo diagnosis.

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Type of Radioactive Isotopes

Based on its origin Radioactive isotopes consists of 2 types, there are:

1. Natural radioactive isotopes

Based on the source, natural radioactive isotopes can be broadly divided into two types. The first is primordial radioactive isotopes, which exist in the earth’s crust since the formation of the universe, and the second is the cosmogenic radioisotope which is the result from the interaction between cosmic radiation and air. In addition to these two types, there are also radioactive isotopes that arise because of spontaneous decay of nuclides that can be split or due to the neutron catch nuclear reaction of cosmic radiation, and there are also extinct radioactive isotopes that are no longer present due to short half life, but because of the very small quantity it can be ignored.

Primordial Radioisotope” state=”closed
In a primordial radioisotope there is a radioisotope that forms a series of radioactive isotopes and that does not form a series. Among the non-generating radioactive isotopes are potassium-40 (K-40) with a half-life of 1.27 billion years old, rubidium-87 (Rb-87) with a half-life of 47.5 billion years and about 10 other nuclides that have a half-life of more than 10 billion years. Out of these radioactive isotopes, the only source of natural radiation to be reckoned with are K-40 and Rb-87.

The natural radioactive isotopes that make up the series are the thorium nucleus series with thorium-232 (Th-232) parent with a half-life of 14 billion years, the actinium radioisotope series with uranium-238 (U-238) parent with a half-life of 700 million years. The mass numbers of the series can be expressed respectively with 4n, 4n + 2, 4n-3 (n are integers). The neptunium series expressed with 4n + 1 with the neptunium-237 (Np-237) parent with a half-life of 2.14 million years, is no longer present in nature because of its short half life.

Cosmogenic Nuclides
There are a variety of nuclides including cosmogenic nuclides, most notably tritium (H-3), beryllium-7 (be-7), carbon-14 (C-14), and sodium-22 (Na-22). In addition there are also beryllium-10 (Be-10, half-life of 2.5 million years), silicon-32 (Si-32, half-life 500 years), phospor-32 (P-32, half-life 14.3 days) , Phospor-33 (P-33, half-life of 25 days), sulfur-35 (S-35, half-life 87 days); And chlor-36 (Cl-36, age of 310 thousand years).

2. Synthetic radioactive isotopes

Synthetic radioisotope is a radioisotope that is formed and made by humans. Synthetic radioactive isotopes are generated from the use of nuclear energy for peaceful and military purposes. Below we will discuss the number of radioactive isotopes due to nuclear power generation as well as nuclear experiments. Artificial radioactive isotopes can be grouped into radioactive isotopes arising from nuclear power generation, radioactive isotopes produced for medicine, industry, or radioactive isotopes arising from nuclear experiments.

Radioactive material is a material that emits radiation a, b, g or neutron. In the periodic arrangement table, you can see an element that emits radiation called a radioactive element, or that does not emit a radiation called a stable element. For example, iodine with mass number 129 or 131 to 135 is a radioactive element. Radioactive elements are also called radioactive isotopes.

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Advantages of Radioisotope in Medical Field

At this time, the application of nuclear power in the medical field has made an invaluable contribution to the diagnosis and treatment of various diseases. Various medical disciplines such as the science of internal medicine, neuroscience, cardiology, and so forth have benefited from nuclear engineering. This technology is widely used in medical fields because of its various advantages in treating disease. And the advantages of this technology Radioactive Isotopes Used in Medicine are listed below:

1. To treat diseases: many cancers can be cured with radiation therapy, either with or without being combined with other treatments such as surgery and chemotherapy.
2. To control diseases: If it is not possible anymore for a disease to be healed, radiotherapy is useful for controlling the growth of cancer cells by making cancer cells become smaller and stopped spreading.
3. Reduce the symptoms of diseases: In addition to controlling cancer, radiotherapy can reduce the symptoms usually occur in cancer patients such as pain and also make patients live more comfortably.
4. Help the other treatment: mainly postoperative and chemotherapy are often referred to as “adjuvant” or additive therapy with the aim of surgical therapy and chemotherapy are given more effective.

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Effects of Radioactive Isotopes in Human Body

Medical treatment by using radio active isotopes may have some adverse effect on human body. The adverse effect of radio active isotopes may present in human tissue or organ such as:

1. Blood and Bone Marrow
   White blood is the fastest cellular component of blood undergoing changes due to radiation. The effect on this tissue is the decrease in the number of cells. The other blood cell compounds (clotted grains and red blood) prepare after the white blood cells. The bone marrow that does not get a higher dose can still produce the red blood cells, while at a sufficiently high dose it will occur a permanent damage in bone marrow and will lead to death (lethal dose 3 – 5 sv). As a result of suppression of bone marrow activity, the person that affected by radiation will suffer from tendency of bleeding and infection, anemia and stochastic hemoglobin defect and the effect of irradiation in bone marrow are leukemia and red blood cell cancer.
2. Digestive Tract
   Damage to the digestive tract provides symptoms of nausea, vomiting, indigestion and food absorption and diarrhea. These effects can lead to dehydration due to severe vomiting and diarrhea. Stochastic effects that can occur is the formation of cancer in the epithel of the digestive tract.
3. Reproductive Organs
   The non stochastic somatic effect on the reproductive organs is infertility, whereas the genetic effect (inheritance) occurs due to mutations of genes or chromosomes in the sex cells.
4. Nervous System
   Adverse effects on nervous system includes radiation resistance. Death due to nervous system damage occurs at a dose of ten sievert.
5. Eyes
   The lens of the eye is sensitive to radiation. Cataracts are a non-stochastic somatic effect (can be occurs in years).
6. Skin
   The somatic non-stochastic effects on the skin vary with dose size, ranging from redness to burns and tissue death. Stochastic somatic effect on the skin is skin cancer.
7. Bone
   The part of the bone that is sensitive to radiation is the bone marrow and the inner and outer membranes of the bone. Damage to the bone usually occurs due to stontium-90 or radium-226 accumulation in the bone. Stochastic somatic effects of this organ is cancer in epithelial cells of bone membrane.
8. Thyroid gland
   The thyroid functioning regulates general metabolism through the hormone tiroxin it produces. This gland is relatively resistant to external irradiation but is easily damaged by internal contamination by radioactive iodine.
9. Lung
   The lungs generally suffer the radiation damage from gas, vapors or particles in the form of radioactive aerosols that are inhaled through the breathing. However, that’s the radioactive isotopes used in medicine.

Examples of Radioactive isotopes Used In Medical Science

1. Teknetum-99 (Tc-99) were injected into a blood vessel will be absorbed mainly by the damaged tissue in certain organs, like the heart, liver and lungs. In contrast, TI-201 will primarily be absorbed by healthy tissue in the heart’s organs. Therefore, the two radioactive isotopes are used together to detect the heart damage.
2. Iodine-131 (I-131) is absorbed primarily by the thyroid, liver and certain parts of brain. Therefore, I-131 can be used to detect damage to the thyroid, liver, and to detect a brain tumor.
3. Iodine-123 (I-123) is another radioisotope of iodine. I-123 that emits gamma rays are may be used to detect brain diseases.
4. Sodium-24 (Na-24) is used to detect the presence of circulatory disorders. A NaCl solution which are composed of stable Na-24 and Cl is injected into the blood and the blood stream can be followed by detecting the emitted beam, so it can be known if there is a blockage of blood flow.
5. Xenon-133 (Xe-133) is used to detect lung diseases.
6. Phosphorus-32 (P-32) is used to detect eye diseases, tumors, and others. And can also used to treat polycythemia rubavera disease, which is the excessive formation of red blood cells. In its application, the isotope P-32 is injected into the body so that the radiation will be emitting the beta rays and can inhibit the red blood cell formation on the spinal cord.
7. Sr-85 to detect the disease in the bones.
8. Se-75 for the detection of pancreatic disease.
9. Cobalt-60 (Co-60) is a source of gamma radiation for tumor and cancer therapy. Because cancer cells are more sensitive (more susceptible to radioisotope radiation than normal cells), the use of this radioactive isotopes is to kill cancer cells by regulating the direction and dose of radiation.
10. Cobalt-60 (Co-60) and Scandium-137 (Cs-137), the radiation is used to sterilize medical instruments.
11. Pu-238 is the electrical energy from the pacemaker for heart.
12. Fe-59 is used for studying the formation of red blood cells.
13. Cr-51 is used for detecting damage the spleen.
14. Ga-67 is used for checking lymph damage.
15. C-14 is used for detecting diabetes and anemia.
16. Ferum-59 (Fe-59) can be used to study and measure the rate of formation of red blood cells in the body and to determine whether the iron in the diet can be used properly by the body.
17. Radiation from radium can be used for cancer treatment. Therefore, radium-60 can kill cancer cells and healthy cells would require a specific technique that places around cancer received radiation to a minimum.
18. Gamma radiation can kill living organisms, including bacteria. Therefore, gamma radiation is used for the sterilization of medical devices.
19. X-Rays
    soft X-rays are used to take still images, known as radiographs. X-rays may penetrate the human body but are absorbed by the more bone-like parts of the bone. X-ray photographs are used to detect bone defects, to detect broken bones and to examine the state of the internal organs
    hard X-rays are used to kill cancer cells. This is known as radiotherapy.
    x-rays can be used to view the condition of the bones, teeth and other body organs without perform a surgery directly on the patient’s body. Usually, the common people call it as the ”Rontgen Photo”.
20. Gamma Rays
    Gamma rays are widely used in the medical field, such as to treat cancer and sterilize hospital equipment.

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Radioactive Isotopes Mechanism of Action

Broadly speaking, in the world of radioisotope medicine there are 2 mechanism of action for this technology to be used in medical field. There are radiodiagnostic and also radiotherapy. Here are the explanation of these mechanisms.

1. Radiodiagnostic

I-131 is used as a treatment therapy for overactive thyroid conditions or we call hyperthyroidism. I-131 itself is an isotope made up of iodine which always emits radiation rays. If I-131 is inserted into the body in small doses, then I-131 will enter the blood vessel of the gastrointestinal tract. I-131 then will pass through the thyroid gland which will then destroy the glandular cells. This will slow the activity of the thyroid gland and in some cases may alter the thyroid condition.

2. Radiotherapy

When the tissue is exposed to radiation irradiation, then the tissue will absorb radiation energy and will cause ionization of atoms. Such ionization may lead to chemical and biochemical changes that will eventually cause biological damage. Cell damage can occur in the form of chromosomal damage, mutations, slowing of cell division and loss of ability to produce.

Ionizing radiation is a beam of energy or a particle which when it comes to an atom will cause a bounce of electrons out of the electron’s orbit. The emission of energy can be electromagnetic waves, which can be gamma rays and X-rays. The emission of particles can be either electron beam (beta rays) or emission of neutron, alpha, proton particles.

By giving each therapy, the more cancer cells will die and the tumor will shrink. The cells that die will be destroyed, carried by the blood and excreted out of the body. Most healthy cells will be able to recover from the effects of radiation. However, damage to healthy cells is responsible for the side effects of radiation. As a result, that’s the radioactive isotopes used in medicine.

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