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Group 8

Page history last edited by Steven Schmatz 9 years, 3 months ago

Medical Application of Radiation Tracking

Steven Schmatz, Rebecca Sorgenfrei, Laura Griffin and Sebastian Gentry


An Introduction


     What do you think of when you hear the term “nuclear technology?” One may think of an effective source of power. On the other hand, it is not uncommon to think of nuclear waste and atomic bombs, which both seem threatening and damaging, things that could be viewed as anything but ethical.


     However, did you know that new nuclear technology can be used to save lives?



     We are here to present to you a new technology that is widely known as nuclear tracking. We have recently completed extensive research into said topic with information from various academic databases, such as the Gale database, in addition to our own knowledge in chemistry and mathematics. We will inform you on the basics of nuclear isotopic tracking, emphasizing the benefits and problems in relation to other widely used diagnostics. We hope that you will enjoy learning and be supportive the development of this new diagnostic technology.



     A sample PET scan is shown at left. The darker red color indicates a greater amount of function in the area.




So, what even is nuclear isotope tracking?


     Nuclear tracking is used to diagnose diseases in bones or most organs, including the thyroid, liver, and heart. To begin the process of nuclear tracking,  a patient is first injected with a short-lived radioactive isotope, usually Technetium-99. The radiation emitted can be tracked throughout the body by a gamma camera. A gamma camera takes pictures of organs from many angles and builds an image for a doctor to easily view of the places radiation is being emitted from the body. The isotope is in this way like a source of light in a dark place; it can illuminate important finds that would be otherwise hidden.


A more advanced type of nuclear diagnosis is PET (Positron Emission Tomography) technology, which involves injecting a patient with a positron-emitting radionuclide. These nuclide accumulates in the diseased tissue. As it decays, it releases a positron, which combines with an electron. A PET camera detects the gamma rays given off and can pinpoint their exact source. PET is the most effective and non-invasive way of detecting cancer, as well as being used in cardiac and brain imaging. 


A sample video of this new technology is shown below.



Application of nuclear tracing in diagnostics


In one study, David A. Wolk, M.D., from the Penn Memory Center in Philadelphia, and colleagues, evaluated use of a tracer called fluorine-18, labeled flutemetamol, for imaging the brain. The study involved conducting PET scans on seven patients who were given a dose of this substance. All had previously undergone a biopsy for normal pressure hydrocephalus, a progressive condition that includes dementia and can be difficult to distinguish from Alzheimer’s Disease. Researchers found correspondence between readings of the PET scans and evidence of amyloid lesions -- the plaque associated with Alzheimer’s -- provided by microscopic evaluation of the biopsied tissue.


In layman's terms, by using fluorine-18, researchers were able to find evidence of amyloid lesions, a sign of Alzheimer’s, by using nuclear tracers. Use of nuclear tracers can replace the need for biopsies to diagnose conditions like Alzheimer’s. Since Alzheimer’s generally occurs in the elderly, who are generally more fragile, anything to reduce the number of surgeries that they have to go through is beneficial for them. Who doesn’t want to make life easier for the elderly?




     One PET scan may cost the patient anywhere from $3000 to $6000, but this price is relatively reasonable when the results of the procedure are taken into account. A patient might have to pay a few hundred dollars more for a PET scan than a more simplistic form of imaging technology, but the results of the PET scan may show a small tumor or another sign of a life-threatening disease that less advanced technology might miss. Also, PET scans can show various organ functions and provide a stream of images to a computer, whereas other imaging technologies such as x-rays only provide snapshots of the body. As a result of spending this extra money, the patient may save their own life and will get a more complete diagnosis of their disease. Save your life or save a paycheck? The options are barely comparable.


What could possibly go wrong?


Nuclear diagnosis exposes the body to radiation, which in large quantities could be damaging. However, this medical diagnostic technology only exposes the patient to about as much radiation as two x-rays. Everyone is continually exposed to radiation, from sources such as space, rocks, soil, and even potassium or carbon atoms in their own body. These sources are what cause around 85% of the annual exposure to radiation that a person receives. The diagnostician can select the most appropriate examination for a patient’s medical problem, to avoid unnecessary radiation exposure.


What about side effects?


Nuclear diagnostic procedures have been used for around 50 years, and there are no known long-term side effects. Some allergic reactions to the radiotracer may occur, but they are extremely rare and usually mild. Some pain and redness may occur around the injection site of the radioactive isotope, which will quickly go away. Infants can be harmed by the radiation, so women should inform their doctor if they are pregnant or breastfeeding. Because children can be harmed by the nuclear radiation, this method of diagnosis is not ideally used on them. However, when used on the average adult patient, the vast benefits involved with nuclear diagnostic procedures greatly outweigh the few risks.


The radiation doesn't stay in your body altogether that long, either. 


Decay of Tracers (Technetium-99m)


One of the most common nuclear tracers is Technetium-99m. What does the "m" mean? It signifies a metastable nuclear isomer, which means that the Tc atom is in a high nuclear energy state. The energy is released in the form of gamma rays, a high-energy form of electromagnetic radiation. As shown on the right, the half-life of Technetium-99m is around six hours. 


Also, knowing that radiation becomes negligible when 15.625g remain in the body, and that 4000g are initially injected, the amount of time that the radiation affects your body can be determined.


Given the half-life equation is:

We can substitute and initial amounts.


By dividing both sides by 4000, we get:

By taking the quotient of the natural logarithms of both 0.5 and 1/256, the amount of halving periods can be found.

Thus, there are 8 halving periods of 6 hours necessary before the amounts of the daughter element, Technetium-99, to be produced.


This amounts to 48 hours, or two days. Therefore, radiation from nuclear tracking of Technetium-99m only affects your body for two days after the injection.









    The effectiveness of nuclear isotope tracking arises from the amount of benefits over risks. For the small price of a minimal dose of radiation, radiative beacons can give information to physicians about the health and function of the organ. The science behind all of it is near to optimal, by choosing elements with short half-lives and minimal damage to the body.



     These new technologies can save many lives each year by making an accurate and effective diagnosis, and since the technology is relatively affordable for hospitals, it can be adopted in medical centers worldwide. Diseased children and adults alike can get a new lease on life. It is evident that this technology can save lives. It is shown that this technology has many more benefits than risks. Hence, it is clear that we must fund this new and advanced technology to save the lives of millions of people across the globe.


     Tracers are very important for diagnostic purposes. Many diseases and disorders are identified much sooner than they would have been if radioactive tracers didn’t exist. Just think of the ethics of it! How many friends, how many family members, how many citizens of the world, people who have lives and family members of their own, would have to live with the consequences of a slower diagnosis? In many illnesses, the intensity of the symptoms and permanent damages are largely affected by the stage of the disease in which it is identified. People could die if radioactive tracers did not exist. That is something worth having. It is something worth working for. It is something we should be very thankful for.


     Thank you for carefully considering our presentation. We hope that it has helped you to better understand the benefits, and the problems, of using nuclear technology in diagnostics. We know this interesting and intriguing invention will help the advancement of the medical field as a whole.



Works Cited


JAMA and Archives Journals. "Positron emission tomography may help identify the presence of Alzheimer's disease lesions in the brain." ScienceDaily, 12 Jul. 2011. Web. 7 Dec. 2011.

"Patient Care." Stanford School of Nuclear Medicine. Web. 5 Dec. 2011. <http://nuclearmedicine.stanford.edu/patient_care/>.

"Positron Emission Technology-Computed Tomography (PET/CT)." Radiologyinfo.org. 24 May 2011. Web. 3 Dec. 2011. <http://www.radiologyinfo.org/en/info.cfm?pg=pet#part_nine>.

"Radioisotopes in Medicine." World Nuclear Association. Oct. 2011. Web. 5 Dec. 2011. <http://www.world-nuclear.org/info/inf55.html>.

"Technetium 99m." Cyberphysics.co.uk. Web. 5 Dec. 2011. <http://www.cyberphysics.co.uk/topics/radioact/Tc99m.htm>.

"Radioactive Tracers." Science Clarified. 2011. Web. 5 Dec. 2011. <http://www.scienceclarified.com/Qu-Ro/Radioactive-Tracers.html>.

"Radioactive Tracers." HyperPhysics. Web. 4 Dec. 2011. <http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/tracer.html>.

"Health Effects." U.S. Environemtal Protection Agency. 8 July 2011. Web. 6 Dec. 2011. <http://epa.gov/radiation/understand/health_effects.html>.

All pictures used in this presentation are available free on wikimedia.org



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