Positron-emission tomography or PET is an imaging method aimed at visualizing different metabolic processes within the body. This technique is helpful in diagnosing various types of cancer as well as heart diseases. The application of this tool is based on the knowledge of how particles and anti-particles interact with each other (Serway and Vuille 1005). One should keep in mind that they have the same mass, but their charges are opposite (Serway and Vuille 1005). An electron and a positron represent a pair consisting of a particle and an antiparticle. The effects of their collision are critical for explaining the mechanisms of PET.
We will write a custom Essay on Physics for Future Leaders specifically for you
301 certified writers online
At first, it is important to mention some isotopes of carbon, fluorine, nitrogen, and iodine can emit large quantities of positrons. The biological substances containing these isotopes are called tracers. As a rule, tracers tend to concentrate in certain parts of the body (Muller 349). For example, glucose can accumulate in various tumors for which it serves as the source of energy (Dolgushin et al. 85). In its turn, iodine isotopes usually accumulate at the glands (Muller 349).
When tracers enter the body, isotopes begin to decay. This process is accompanied by the emission of positrons that hit electrons almost instantaneously (Waterstram-Rich and Gilmore 239). The collision of an electron and a positron leads to the annihilation of both particles (Jarnagin 288). The result of this annihilation is the creation of two photons that have the same energy and move in the opposite directions (Jarnagin 288). The knowledge of this mechanism is vital for locating isotopes and describing their distribution in the body of the patient.
PET involves the use of detectors that can register gamma rays resulting from the emission of photons. These detectors cannot pinpoint the exact place from which the photons came (Muller 349). Nevertheless, one can know with certainty that this point lies on the line that connects the two spots where the two photons hit the detectors (Muller 349; Cavedon and Rudin 135). Sometimes, photons can be scattered, and under such circumstances, one cannot determine the place of their origin.
However, there are thousands of annihilations, and this sample is sufficient for visualizing the distribution of isotopes within the body (Muller 349). As a result, medical workers have an opportunity to notice anomalies indicating at possible diseases.
PET images can help physicians determine those areas of the body where tracers flow. Moreover, they can identify those regions where the number of annihilations is higher (Northrop 331). By studying such images, healthcare professionals can make several important findings (Muller 349). For instance, they can ascertain the location of tumors in which positron-emitting isotopes tend to accumulate. In part, this tendency can be explained by the fact that tumors require these substances for their growth and reproduction (Dolgushin et al. 85). At the same time, the absence of a tracer can also be regarded as an anomaly indicating at the existence of some defects (Jardins and Burton 96).
The main disadvantage of PET is that isotopes decay very quickly; thus, medical workers may not always rely on this technique. However, despite this shortcoming, PET remains a valuable diagnostic tool that can help physicians make informed decisions. The application of this technique is made possible by the discoveries of physicists who gained valuable insights into the properties of anti-matter and anti-particles.
Magnetic Resonance Imaging
Magnetic resonance imaging or MRI is a diagnostic technique that enables medical workers to visualize the structure of organs and observe various physiological processes. This method is often useful in detecting disorders and determining the stage of different diseases like cancer (Fung et al. 286). The functioning of this technology is mostly based on the study of magnetic fields and properties of particles, especially protons. Overall, it is important to explain how this technology operates and assists healthcare professionals.
To describe the principles underlying MRI, one should first explain some issues related to the structure of the human body. It is critical to remember that the density of hydrogen varies in different parts of biological organisms. For instance, the quantity of hydrogen is significantly higher in various soft tissues whereas in bones, it tends to be much lower (Muller 347). The nucleus of hydrogen is a proton or a positively charged particle whose properties are essential for the work of MRI machines.
The nuclei of other elements can also be suitable for this technology; for example, one can speak about carbon, nitrogen, and oxygen. However, hydrogen is usually chosen because it can be found almost in every type of soft tissue (Lampignano and Kendrick 774). Additionally, unlike other elements, the nucleus of hydrogen consists of a single proton that is more strongly affected by magnetic fields. Thus, medical workers usually focus on this element while applying MRI.
The functioning of this technology requires the knowledge of how protons move when they are placed in a strong magnetic field. It should be noted that these particles orient themselves towards a powerful external magnet. In particular, they can line up almost in the same direction. When a rotating magnetic field is created, protons begin to wobble (Stippich 16). The rate of their precession is directly proportionate to the strength of the magnetic field (Lampignano and Kendrick 774).
If a rotating magnetic field is removed, protons realign themselves to the original magnetic field (Fossum 169). During this transition, they emit radio signals that can be detected and measured by the receiver (Fossum 169). These mechanisms lie at the core of MRI machines; furthermore, they are essential for the creation of visual images used by medical workers.
One of the tasks is to ascertain the locations from which the signal is emitted. This goal can be achieved by changing the strength of the magnetic field and the frequency of radio waves (Muller 347). By identifying the location of protons, healthcare workers can visualize the organs and physiological processes. In this way, they get deeper insights into the problems affecting the body. Very often, they have to apply contrast agents to make the internal structure of organs more visible (Kaushal and Sheba 114).
To a great extent, the work of MRI relies on the knowledge of quantum physics, especially the concept of spin. This notion is used to describe the angular momentum that subatomic particles have (Mangrum et al. 2; Roth and Deshmukh 2). The design of MRI machines is premised on the assumption that particles with spin respond to the magnetic field in a predictable way.
Get your first paper with 15% OFF
The main advantage of MRI is that it does not produce harmful effects on the human body. In this case, there is no ionizing radiation that damages soft tissues (Schnapp and Feghali-Bostwick 123). Moreover, it does not require any form of surgery. This is why physicians prefer to use this technique on a regular basis when they have to diagnose different disorders.
Cavedon, Carlo, and Stephen Rudin, editors. Cardiovascular and Neurovascular Imaging: Physics and Technology. CRC Press, 2015.
Dolgushin, Michail, et al. Brain Metastases: Advanced Neuroimaging. Springer, 2018.
Fossum, Theresa. Small Animal Surgery. 5th ed., Elsevier Health Sciences, 2018.
Fung, Ellen, et al. Bone Health Assessment in Pediatrics: Guidelines for Clinical Practice. 2nd ed., Springer, 2016.
Jardins, Terry D., and George G. Burton. Clinical Manifestations and Assessment of Respiratory Disease. 7th ed., Elsevier Health Sciences, 2016.
Jarnagin, William R., editor. Blumgart’s Surgery of the Liver, Pancreas and Biliary Tract E-Book. 7th ed., Elsevier Health Sciences, 2016.
Kaushal Rege, and Goklany Sheba, editors. Cancer Therapeutics and Imaging: Molecular and Cellular Engineering and Nanobiomedicine. World Scientific, 2017.
Lampignano, John, and Leslie Kendrick. Bontrager’s Textbook of Radiographic Positioning and Related Anatomy. 9th ed., Elsevier Health Sciences, 2017.
Mangrum, Wells, et al. Duke Review of MRI Physics: Case Review Series. 2nd ed., Elsevier Health Sciences, 2018.
Muller, Richard. Physics and Technology for Future Presidents: An Introduction to the Essential Physics Every World Leader Needs to Know. Princeton University Press, 2010.
Northrop, Robert. Non-Invasive Instrumentation and Measurement in Medical Diagnosis. 2nd ed., CRC Press, 2018.
Roth, Christopher, and Sandeep Deshmukh. Fundamentals of Body MRI. 2nd ed., Elsevier Health Sciences, 2016.
Schnapp, Lynn, and Carol Feghali-Bostwick. Acute Lung Injury and Repair: Scientific Fundamentals and Methods. Humana Press, 2017.
Serway, Raymon, and Chris Vuille. College Physics. 10th ed., Cengage Learning, 2014.
Stippich, Christopher, editor. Clinical Functional MRI: Presurgical Functional Neuroimaging. 2nd ed., Springer, 2015.
Waterstram-Rich, Kristen M., and David Gilmore, editors. Nuclear Medicine and PET/CT: Technology and Techniques. 8th ed., Elsevier Health Sciences, 2017.