Principles of Positron Emission Tomography (PET) Scanning BE908: Biomedical Instrumentation
Assignment 2
By Alazar Tesfay Tekie
How does PET scan works?
Positron emission tomography (PET) is a nuclear imaging technology (molecular imaging) that works in the principle of radio tracer injected into the human body that enables visualization of metabolic processes in the human body. A radio tracer is a radioactive medicine used in conjunction with a natural chemical such as glucose, water, or ammonia. PET systems have sensitive detector panels to capture gamma ray emissions, creating 3-D computed PET images in the areas where the radioactive tracer concentrations are rich enough with in the body. The unique features of PET Scan are not into the
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Radioisotopes can be produced by separation of the by-product produced using fission; they can be produced from neutron irradiation in a reactor; or they can be produced from the bombardment of a target material by changed particles from accelerator. First, the cyclotron bombards non-radioactive elementinthetargetwithacceleratedparticlesthe followingradioactiveisotopes produced C-11, N-13, O-15, and F-18 are excited by charged particles bombardment. F-18 thus produced is delivered to the chemical synthesis unit where it will be incorporated to produce a final product, the label sugar molecule fluorodeoxyglucose (FDG). The entire process can take place in hospital settings in side cyclotron laboratory.
References:
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The careful familial and patient history is imperative for this exam and procedure. And as the video indicated, is this really an effective screening tool for a healthy person more so than seeing the primary care physician. According to the research in the Indian Journal of Medical Research, the “PET/CT doses were found to be higher than many other conventional diagnostic radiology examinations suggesting that all efforts should be made to clinically justify and carefully weigh the risk-benefit ratios prior to every 18FDG whole body PET/CT investigation” (Kaushik et al,
Other testing procedures that are commonly employed, in order to gain a better visual image of the excitatory activity in the brain are the PET scan and the MRI. According to Kalat (2004), these methods are non-invasive, meaning that they don’t require the insertion of objects into the brain, yet they yield results that allow researchers to record brain activity. The PET scan (positron emission tomography) involves the researcher injecting a radioactive chemical into the patient’s body, which is then absorbed mainly by the brain’s most active cells. With the use of radioactive detectors, placed around the patient’s head, a map is produced that shows which areas of the brain are most active.
One might ask, what is Spectral Computed Tomography (CT)? Spectral CT is a way for us as health professionals to add diagnostic value to our exams by using the full spectrum of an x-ray beam. To summarize, “Spectral CT acquires data sets at both low- and high-kVp settings” (Lentz 2014). Spectral CT was first studied back in the 1980’s, but Stefan Ulzheimer, PhD, said, “Because of various hurdles, it never made it into clinical practice” (Lentz 2014). John W. Steidley, PhD, states in his article Exploring the Spectrum, “While these exercises were of academic interest, CT detector technology at the time wasn’t yet advanced enough to separate the x-ray beam into its component spectrum” (Steidley 2008).
The description of PET scans in detail requires the understanding of the radioactive substance injected into the subject. First, a small amount of a biochemical substance is tagged with a positron-emitting radioisotope. A positron is an “anti-electron.” Positrons are given off during the decay of the nuclei of the radioisotope. When the positron emitted collides with an electron in the tissue of the subject, both the positron and the electron are annihilated. When this happens, the collision produces two gamma rays having the same energy (511 KeV), but going in opposite directions.
A Growing Concern." Internet Journal of Radiology 5.2 (2007): 4. Academic Search Premier. Web. 23 Nov. 2013.
Computed Tomography (CT) is a biomedical imaging technique which produces cross-section images also called "slices" of anatomy of the human body. Radiographic beams are made incident on the human body. The reflected radio beams create a detailed computerized picture taken with a specialized X-ray machine. CT is more precise than a standard X-ray, and provides a clearer image. Fig.1 shows a CT scan of transverse view of the brain. The cross-sectional images are used for a variety of diagnostic and therapeutic purposes.
What Is Polio? What Causes Polio?. (n.d.). Medical News Today. Retrieved October 23, 2013, from http://www.medicalnewstoday.com/articles/
Harris, T. (n.d.). how body armor works. Retrieved March 3, 2014, from How stuff works: http://schienc.howstuffworks.com/body-armor.htm
One of the most recently new advances in radiology is the use of magnetic resonance imaging (MRI). MRI has been around for the past century. It was at first called Nuclear Magnetic Resonance (NMR) and then it changed to MRI once there was an available image. Walter Gerlach and Otto Stern were the first scientists to start experimenting with the magnetic imaging. Their very first experiment was looking at the magnetic moments of silver by using some type of x-ray beam. The scientists then discovered this was by realizing that the magnetic force in the equipment and in the object itself. In 1975, the first image was finally created using and MRI machine. The scientists used a Fourier Transformation machine to reconstruct images into 2D. The first images ever use diagnostically was in 1980. This is when hospitals began to use them. At first the images took hours to develop and were only used on the patients that needed it most. Even though MRI has been around for a long time, it has advanced and has been one of the best imaging modalities recently (Geva, 2006).
As a starting point in CT diagnostic imaging the form of radiation used to provide an image are x-rays photons , this can also be called an external radiation dose which detect a pathological condition of an organ or tissue and therefore it is more organ specific. However the physics process can be described as the radiation passes through the body it is received by a detector and then integrated by a computer to obtain a cross-sectional image (axial). In this case the ability of a CT scanner is to create only axial two dimensional images using a mathematical algorithm for image reconstruction. In contrast in RNI the main property for producing a diagnostic image involves the administration of small amounts of radiotracers or usually called radiopharmaceutical drugs to the patient by injection or oral. Radio meaning the emitted of gamma rays and pharmaceutical represents the compound to which a nuclide is bounded or attached. Unlike CT has the ability to give information about the physiological function of a body system. The radiopharmaceutical often referred to as a nuclide has the ability to emit ga...
The technology that I have selected to discuss is handheld radiological monitoring. There are several new equipment models being marketed. One of the most recognizable and well-respected names in radiological monitoring is Canberra. One of Canberra’s latest offerings for handheld devices is the Radiagem™ 4000. The device provides the capability of monitoring dose rates and contamination levels. There are a variety of probes available for use with the meter itself. The unit is waterproof and lightweight.
Nuclear Medicine is the use of radioisotopes for diagnosis, treatment, and research. Radioactive chemical tracers emit gamma rays which provides diagnostic information about a person's anatomy and the functioning of specific organs. Radioisotopes are also utilizes in treatments of diseases such as cancer. It is estimated that approximately one in two people in Western countries are likely to experience the benefits of nuclear medicine in their lifetime.
Radiology is one of the few so-called “physical-science”-based fields of medicine, making it a challenging and rewarding application of an academic interest in science. It combines advanced knowledge of human physiology with principles of atomic physics and nuclear decay, electricity and magnetism, and both organic and inorg...
Davis, Jeanie L. "What Are the Health Benefits of Owning a Pet." WebMD - Better Information. Better Health. WebMD. Web. 30 Nov. 2011.
e) Ghosh, P. & Kelly, M. (2010). Expanding the power of PET with PERCIST. [Siemens Healthcare White Paper]. URL http://usa.healthcare.siemens.com/siemens_hwem-hwem_ssxa_websites-context-root/wcm/idc/groups/public/@us/@imaging/@molecular/documents/download/mdaw/nduz/~edisp/white_paper_10_percist-00309714.pdf