Technetium has an atomic number is 43 so it has 43 protons and 55 neutrons. On periodic table, it’s located on Group 7, Period 5, and Block d. It has an atomic mass of 98. According to Aufbau Principle and Hund’s rule the full electron configuration of Technetium is 1s22s22p63523d104s24p64d55s2 and condensed electron configuration of Technetium is [Kr] 4d55s2. First lonization energy of Tc is 702 kJ mol 1 and second lonization energy is always higher so it is 1470 kJ mol 1. (Winter, M) Technetium is solid at room temperature, therefore a great superconductor at temperatures of 11 K and below.
It dissolves in nitric acid and concentrated sulfuric acid but doesn’t dissolve in hydrochloric acid (Technetium Element Facts). Technetium is an important silvery grey transition element that was discovered by Carole Perrier and Emillio Segre at the University of Palermo in 1937 in Italy (Bentor, Yinon). They were given a sample of molybdenum (99Mo) which was bombarded by deuterons. The 99Mo decays with a half life of 66 hours to the metastable state of Tc (Nave, 2004). This process allows the production of 99m Tc to be used in the medical field.
The fact that 99Mo is a fission product of 235U fission, it can be used to generate 99m Tc and be separated from other fission products (Nave, 2004). Carole Perrier and Emillio Segre found several technetium isotopes when molybdenum (99Mo) was bombarded by deuterons, and they were all radioactive. This became the first element synthesized in laboratory and produced synthetically (Technetium Element Facts). The isotope of an element has the same number of protons in their atoms, but different masses because of different number of neutrons. Technetium has 26 isotopes with the mass numbers ranging from 88 to 113.
It doesn’t have any stable isotopes. The most stable isotope is Tc 98 which has a half life of 4. 2 million years (Technetium Element Facts). The focus of research is Technetium-99m (99m Tc), which is a metastable isotope with a half life of 6. 03 hours, which is very long for an electromagnetic decay. With such a long half-life for excited state leading to this decay, it’s called metastable state, and hence the name 99m (Nave, 2004). It emits gamma rays and low energy electrons, allowing for technetium-99 to form, which has a half life of 211 000 years (Technetium Element Facts).
The physical and biological half life of Technetium-99m is short, it leads to fast clearing of body after an imaging process. Also, gamma is single energy not accompanied by beta emission allows for accurate alignment of imaging detectors (Nave, 2004). Uses: Technetium -99m is an important radioisotope used in 80% of nuclear medicine worldwide. It can help diagnose many diseases such as heart, kidney, lung, liver, thyroid and bone cancer. It is used to image the skeleton, heart muscles, brain, thyroid, lungs, and bone marrow. Technitium-99, is used as radioactive tracer which can be detected in the body by gamma cameras.
Computer processes the image when the gamma camera is rotated around the patient. It takes 15-20 seconds for each projection which are collected every three to six degrees and takes a total of 15-20 min for a total scan (Uses of Technetium-99m). Three main uses of 99m Tc will be briefly discussed in nuclear medicine. Firstly, 99m Tc is used in Myocardial perfusion imaging (MPI). MPL is a nuclear cardiology test that shows how blood flows to the heart muscle. A common diagnostic application to see if the heart is healthy, a low dose of radioactive tracer in the blood is used.
A tracer element is injected into patient’s vein through (IV line) and a radiation detector rotates around the chest of the patient, detecting gamma radiation (Nave, 2004). The detection of gamma rays produce images of blood flow in the heart muscle from different angles to assess the flow of blood (Nave, 2004). This test can show if heart is not getting enough blood flow, also called “nuclear stress test” and also show how well heart is pumping blood. This procedure can diagnose heart wall motion or heart tissue damage after a heart attack (Uses of Technetium-99m).
In the past, for the same MPI test, an isotope of thallium was used with a gamma ray of energy of about 70 keV. However, isotope of technetium is a preferred choice of scan as it has a short half-life and produces gamma of energy about 140 keV (Nave, 2004). Secondly, 99m Tc radioisotope is used in brain and bone scans. In brain scanning, it can detect strokes an illness. In bone scans, it is used directly as it heals skeletal injury (Uses of technetium-99m) Thirdly, 99m Tc radioactive properties is used to identify lymph nodes in patients with breast cancer.
Through an immunoscintigraphy (IS) procedure in an immune system protein is capable of binding to cancer cells. An injection of radioisotope combined with gamma probe camera is used to detect gamma rays emitted by the 99m Tc (Abu et al, 2004). Tumor is detected where the concentration is high. This technique is very helpful when finding cancer cell are hard to detect (Uses of Technetium-99m). Advantage and disadvantage of 99m Tc: There are some advantage and some disadvantage to 99m Tc. As mentioned above it can diagnose many medical illness including detection of heart diseases, strokes and breast cancer.
It can also prevent patient infections therefore very little or no harm to patients (Benefits and Problems of Radioisotopes). Since 99m Tc has a half-life of 6. 03 hours, it’s beneficial because it lasts long enough for doctors to get all the scans needed and it doesn’t stay in the body for a long period of time because it decays quickly (Garlow, 2012). There are also some disadvantages because after 99m Tc is used its waste requires disposal which can harm aquatic and terrestrial organism (Benefits and Problems of Radioisotopes). It can cause damage to health if not stored properly (Wagner, 2012). 99m Tc has a short half life of 6. 3 hours which makes storage difficult and transporting impossible.
Therefore, it is shipped by pharmaceutical companies directly to local market using A 99m Tc generator. It is a device that is used to take the metastable isotope 99m Tc of technetium from 99Mo which has a half-life of 66 hours which is used to transport over long distances to hospitals. This provides shield for long distance transport to minimize extraction work (Wagner, 2012). Technetium-99m Affect on Environment: Technetium-99 (Tc-99) has a long half-life, mass 98 is produced at a high level during nuclear fission, which is taken by terrestrial and aquatic organism.
Therefore, there is a long-term risk of nuclear energy (Degenkolb, et al. 1994). Since plants are important intermediate of Tc-99 food chain transfer to animals and human a study was done on photosynthesis of soybean seedlings in presence and absence of micromolar amounts of Tc-99 under different light levels. The study concluded that photosynthesis system had a significant decline of photosynthesis rate under full light condition and stomatal conductance decreased as a function of Tc-99 concentration (Degenkolb, et al. 994).
This proof the long-term risk of nuclear energy on terrestrial and aquatic organism. According to the book, “Technetium in the Environment” 99Tc waste is released to the environment from nuclear fuel cycle facilities when there is processing of spent fuel. A study showed that 99Tc is released to the environment during reprocessing, fuel fabrication, UF6 production and waste disposal. Special consideration should be given to improving techniques for removing technetium from uranyl nitrate before its converted to UF6.
In the future, this will be required as a critical step at reprocessing plants prior to conversion if 99Tc releases to the environment remain low. Technetium 99 has a unique environmental mobility; therefore, it should be given special consideration in nuclear fuel cycle assessment when there is recycling of uranium fuel. Overall, published data related to its production, concentration in recycled fuel and its release to environment is not available. Hence, further research is required in order to understand 99TC impact on environment (Desmet, 2013).
