Radioisotopes in Medicine - Essay Example

Radioisotopes in Medicine Every chemical element has got species of atoms which may be one or more than one with same atomic number i.e. having the same number of protons in the nucleus; same position in the periodic table; similar chemical properties but different atomic masses and physical characteristics. These species are called isotopes of the same element. These isotopes are possessed by all elements. These isotopes have been divided into stable and unstable. Unstable isotopes are those which undergo radioactive decay. In atoms of all elements, the number of protons in the nucleus determines the atomic number; these atoms have the same number of electrons as that of protons and these electrons are responsible for the chemical characteristics of these elements. In addition to the protons, there are neutrons found in the nucleus. These are the neutrons which give an element a radioactive status. Unlike the protons, these neutrons are found in different number in different atoms of the same element and based on this difference in the number of neutrons the isotope status is acquired by an element. The sum of protons and neutrons in an atom is called its atomic mass. So atomic number of all atoms of an element is the same but atomic mass could be different (Medical isotopes). Radioisotopes There are some elements which decay and are converted to isotopes that posses the properties of unstable isotopes; examples are uranium and thorium. The same isotopes can be generated artificially when it does not exist naturally in some elements. This is achieved by a combination of protons and neutrons. These radioisotopes can be obtained through a variety of ways but the most frequent way of producing radioisotopes is by neutron activation in a nuclear reactor. There are two major outcomes which give radioisotope status to an element, either by gaining a neutron and making an atom neutron rich or by gaining a proton and resulting in proton rich atom. The unstable state of a radioisotope is converted to stable one by the emission of alpha or beta particle with some energy release in the form of gamma rays. In fact, this is radioactive decay of that atom. In medicine, these radioactive products are termed as radiopharmaceuticals (Medical isotopes). History of Nuclear Medicine Around the first decade of the last century there had been some initial discussions on the issues of radioactivity and radioisotopes like thorium and ionium. Most of the radioisotopes which are in more frequent use today were discovered during the third decade of the last century. Radioactive isotopes like, iodine-131, cobalt-60, technetium-99m and others were discovered during a short period of three years (1938-1941) (Radioisotopes for diagnosis and treatment). Till mid-seventies of the last century there was not much development in the field when some newly discovered radioisotopes along with technetium-99m revolutionized the field of nuclear medicine when technetium-generator made it practical to convert inactive pharmaceuticals to be labelled on the hospital premises (Radioisotopes in medicin). In 1980s, gamma cameras performance was improved through computer integration which helped in enhancing the processes and eventually the quantification of the radioactivity emitted. (Radioisotopes in medicin). Around the last decade of the last century the image quality as well as details were made improved with the help of single photon emission computer tomography (SPECT) systems. Radioisotopes utilization in Medicine Radioisotopes have been utilized in medicine very extensively for preventive, diagnostic, therapeutic and prognostic purposes. Currently, the annual turn over of nuclear medicine activities related to diagnostic as well as therapeutic procedures has been estimated around 10-12 million each year in the United States (Radioisotopes for diagnosis and treatment; Jalilian, 2006). Preventive Radiopharmaceuticals have been utilized in research activities in the field of molecular medicine to detect any genetic diseases and eventually their treatment options. Although, this is not a very old area but promising results are expected (Immam, 2005). Hunt et al did an extensive work on the estimation of the dose of irradiation from the nursing mothers, who have got some organs with irradiation, to the infants. The authors have given an elaborative account on the dose which will be helpful in taking necessary steps for the prevention and the safety of the infants (Hunt, 2005). Diagnostic For diagnostic purposes, nuclear medicine has been utilized very extensively and almost all organs of the body have been reached and benefited with this development. For diagnostic purposes, the dose of any radiopharmaceutical used is enough for the diagnostic purpose and it does not attain levels which may become medically significant. Whatever radioisotope used should have the ability to: have a half life short but of the duration that it should not decay before the process of imaging is complete; emit gamma rays of the intensity to cross the body and be detected outside. Technitium-99m is the radioisotope which is being used for most of the organs in substantially higher proportions (Medical isotopes). The features which make technetium-99m more popular in nuclear medicine are: short half life, low gamma rays but able to escape the body, and its generator, which can be installed at the hospital and eventually technetium-99m become rightly available at the site. Fluoro-deoxy glucose (FDG) has been used in Positron Emission Tomography (PET) as an integral component. With the help of FDG-PT inflammatory process of a disease has been studied (Jalilian, 2006). Brain, breast, thyroid, bone, skin, heart, vessels, lungs, kidney and so many other organs and tissues have been studied and as a result their pathological processes have been intervened with promising outcomes. Radioimmuno assays are the procedures utilized by the pathologists to focus on blood, urine, hormones, serum and antigens. These procedures work when specific radioisotopes are incorporated. Therapeutic Although, the use of nuclear medicine in therapeutics is not as much common as diagnostics but it is still used in fairly recognizable areas. The well known radioisotopes for therapeutic purposes is that which emits beta rays with just enough gamma to produce imaging, one example is leutetium-177. Iodine-131 has been used with great success in the management of thyroid gland pathologies including hyperthyroidism and even thyroid cancer (Medical isotopes). On the other hand, phosphorus-32 has been utilized to control red blood cells production in Polycythemia vera. Use of boron-10 in tumor treatment is based on the alpha particle emission. Short term therapy (brachytherapy), has been tested with encouraging results in rheumatoid arthritis (Jalilian, 2006). Radiotherapy Tumor cells are the rapidly dividing cells and irradiation has got good affiliation with dividing cells. These cells can be targeted and damaged through irradiation process (Radioisotopes for diagnosis and treatment). Hence, radiotherapy has been used for the treatment of different tumors in the body. This radiation is of two types: external which utilizes gamma beam from cobalt-60 source while in internal radiotherapy some beta or gamma emitter is planted in the area to be irradiated and then irradiation of the area is achieved from that source. Iridium-192 has been implanted in the head and breast while iodine-131 has been used in the treatment of thyroid cancer (Radioisotopes for diagnosis and treatment). Target alpha therapy (TAT) is a new modality and being tested for the treatment of the tumors, like cystic glioma, leukemia and melanoma. Samarium-153, to a larger extent, and strontium-89, to a lesser extent, has been used as palliative agents for the relief of pain caused by various types of cancers (Radioisotopes for diagnosis and treatment). The technology started based on the discoveries in early years of the last century has made an excellent development like any other field; nuclear medicine like any other branch of medicine has made several breakthroughs. Today, most of the pathological procedures as well as other diagnostic procedures which include almost all organs and tissue in the body have been revolutionized by development in nuclear medicine. Therapeutic uses of nuclear medicine, although, are not of that level as diagnostic utilization is but there is a recognizable advancement and at the same time there is good room for new discoveries. As this century has been nominated as that of bioinformatics so future may see more advances in this field. Outline Introduction of isotopes and radioisotopes History of Nuclear Medicine Use of radioisotopes in medicine Preventive Diagnostic Therapeutic Radiotherapy Conclusion Work cited “Medical isotopes: General concepts. Nuclear Medicine.” 2003.Radiochemistry society. Science Education Training. 24 Aug. 2006. [http://www.radiochemistry.org/nuclearmedicine/radioisotopes/01_isotopes_dt.shtml] “Radioisotopes for diagnosis and treatment. Nuclear Medicine.”. Radiochemistry society. Science Education Training. 24 Aug. 2006 [http://www.radiochemistry.org/nuclearmedicine/radioisotopes/01_isotopes_dt.shtml] Immam, SK. “Molecular nuclear imaging: the radiopharmaceuticals”. Cancer Biother Radiopharm. (2005): 163-72. Hunt, JG. Nosske, D. dos, Santos DS. “Estimation of the dose to the nursing infant due to direct irradiation from activity present in maternal organs and tissues.” Radiat Prot Dosimetry. (2005): 290-9. Jalilian, AR. Bineshmarvasti, M. Sardari, S. “Application of radioisotopes in inflammation.” Curr Med Chem . (2006): 959-65. “Radioisotopes in Medicine: A history of nuclear medicine.” Royal society of chemistry, London. No. 5. [http://www.rsc.org/Membership/Networking/InterestGroups/Radiochemistry/Essays.asp] Read More