Positron Emission Tomography (PET) scan allow doctors to scan the internal structure of a human body to see how the tissues and organs function so they can identify if an individual carrier any of the following conditions, which include cancers, heart disease and brain disorder. Beside detecting if an individual have any of the problem above, it can also assess the effectiveness of treatment plan, determine specific problem within the main problem above and determine the spread of cancer inside the body. As a result, Positron Emission Tomography is commonly used by oncologist, neurologists, neurosurgeons and cardiologists.
The way that the Positron Emission Tomography machine work is by detecting the gamma rays and send it to the computer. The computer will analyze the gamma rays into information that will be use to create the image. In order for the gamma rays to be emitted from the patient body the patient will need to consume tracer, which can either be injected, swallow or inhale into the body. Tracer is a chemical compound that have a radioactive atom attach to the chemical substance that is used by the particular organ or tissues during it metabolic process, which is a process where the cells produce energy and other substance to sustain its life. Due to this reason, there are many type of tracers because different organ or tissue require different tracer. For example: The tracer that is use for PET brain scan is fluorodeoxyglucose, which is made out of a flouride-18 and glucose because the brain use glucose during it metabolism process. The structure of this tracer is shown above. When the tracer enter the body and reach the target organ or tissue it will gather in the area with the highest levels of chemical activity because this is where the disease will take place. When this occur the radionuclide in the tracer will undergo radioactive decay process where it will break down the atomic nucleus and emit positron. Positron is a particle that has a positive charge and has the same mass as an electron. The positron will collide with an electron in the tissue to release energy in the form of gamma ray, which is an electromagnetic waves that is emitted when the nucleus change from an excited state to a ground energy state. Afterward the scanner will detect the Gamma ray and use the computer to process it into an image. The affect tissues will appear to be very bright because this is where most of the radionuclide gather up and emit the most gamma ray.
In conclusion, it show that Positron Emission Tomography scan is very important in the medical field because it is use to detect some of the most serious diseases that is hard for doctor to cure, which are cancer, heart disease and brain disorder.
Modern Chemistry by Holt McDougal
http://www.mayoclinic.org/tests-procedures/pet-scan/basics/definition/prc-20014301
http://interactive.snm.org/docs/PET_PROS/FDG_K_Zukotynski.pdf
http://199.116.233.101/images/thumb/3/35/Glucose_vs_FDG_Diagram.png/500px-Glucose_vs_FDG_Diagram.png
http://interactive.snm.org/docs/PET_PROS/FDG_K_Zukotynski.pdf
http://199.116.233.101/images/thumb/3/35/Glucose_vs_FDG_Diagram.png/500px-Glucose_vs_FDG_Diagram.png
Hi! This topic is super interesting to me, I touched on it a bit in my second discussion post :). I was wondering, why do different organs need different tracers, does it have to do with the type of chemicals already in the organs? Or is it simply due to the positioning of the organ in the body and wanting to get the best possible image?
ReplyDeleteThe reason why different organs require a different type of tracer is because there are certain parts of the body where some of the elements tend to build up and cause a high concentration of itself in that specific area. For example, phosphorous in the bones, potassium in the muscles, iodine in the thyroid etc. Due to this reason, to ensure that the tracer will arrive at that specific part of the body the tracer will need to contain the element that the tissues or organs need. The element that the target organ or tissue need will help to guide the tracer to the right place so that the PET scan can capture the image of the internal body. For instance, if the doctor want to take a picture of the thyroid gland the patient will be ask to drink a solution of sodium iodide that contain radioactive iodine-131 so the tracer will accumulate in the thyroid gland. If you want to find out more visit this website: https://www.sciencelearn.org.nz/resources/1801-using-isotopes-as-tracers
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ReplyDeleteYo, just letting you know this is some pretty cool stuff. Came to this post for the sake of creating a comment (which I am doing :P) but I actually genuinely had no clue before how they detected cancer in others, so this is pretty intriguing. Thank you for your post.
ReplyDeleteActually, going on a tangent - why is it that they use fluoride in the tracers?
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