Examples of magnetic resonance imaging in the following topics:
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- Magnetic resonance imaging is a medical imaging technique used in radiology to visualize internal structures of the body in detail.
- Magnetic resonance imaging (MRI), also called nuclear magnetic resonance imaging (NMRI) or magnetic resonance tomography (MRT), is a medical imaging technique used in radiology to visualize internal structures of the body in detail.
- MRI utilized the property of nuclear magnetic resonance (NMR) to image the nuclei of atoms inside the body.
- This electromagnetic field has just the right frequency (known as the resonance frequency) to become absorbed and then reverse the rotation of the hydrogen protons in the magnetic field.
- MRI shows a marked contrast between the different soft tissues of the body, making it especially useful in imaging the brain, the muscles, the heart, and cancerous tissue—as compared with other medical imaging techniques such as computed tomography (CT) or X-rays.
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- Examples include the laser , the transistor (and thus the microchip), the electron microscope, and magnetic resonance imaging (MRI).
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- Positron emission tomography is a nuclear medical imaging technique that produces a three-dimensional image of processes in the body.
- Positron emission tomography (PET) is a nuclear medical imaging technique that produces a three-dimensional image or picture of functional processes in the body.
- PET scans are increasingly read alongside CT or magnetic resonance imaging (MRI) scans, with the combination giving both anatomic and metabolic information.
- Because PET imaging is most useful in combination with anatomical imaging, such as CT, modern PET scanners are now available with integrated high-end multi-detector-row CT scanners .
- Because the two scans can be performed in immediate sequence during the same session, with the patient not changing position between the two types of scans, the two sets of images are more-precisely registered, so that areas of abnormality on the PET imaging can be more perfectly correlated with anatomy on the CT images.
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- Physics is involved in medical diagnostics, such as X-rays, magnetic resonance imaging (MRI), and ultrasonic blood flow measurements.
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- Paramagnetism is the attraction of material while in a magnetic field, and diamagnetism is the repulsion of magnetic fields.
- Paramagnetism is a form of magnetism whereby the paramagnetic material is only attracted when in the presence of an externally applied magnetic field.
- Paramagnetic materials have a relative magnetic permeability greater or equal to unity (i.e., a positive magnetic susceptibility) and hence are attracted to magnetic fields.
- Unlike ferromagnets, paramagnets do not retain any magnetization in the absence of an externally applied magnetic field, because thermal motion randomizes the spin orientations responsible for magnetism.
- Orientation in paramagnetic material when electric field is applied (right image) and removed (left image).
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- Solenoids are loops of wire around a metallic core, and can be used to create controlled magnetic fields.
- Electromagnetism is the use of electric current to make magnets.
- These temporarily induced magnets are called electromagnets.
- Electromagnets are employed for many uses: from a wrecking yard crane that lifts scrapped cars, to controlling the beam of a 90-km-circumference particle accelerator, to the magnets in medical imaging machines (for other examples see ).
- An electromagnet creates magnetism with an electric current.
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- To achieve this, the voltage frequency must match the particle's cyclotron resonance frequency,
- A magnetic field parallel to the filament is imposed by a permanent magnet.
- As electrons sweep past these openings, they induce a resonant, high-frequency radio field in the cavity, which in turn causes the electrons to bunch into groups.
- The sizes of the cavities determine the resonant frequency, and thereby the frequency of emitted microwaves.
- A cross-sectional diagram of a resonant cavity magnetron.
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- Magnetic forces can cause charged particles to move in circular or spiral paths.
- Cosmic rays will follow spiral paths when encountering the magnetic field of astrophysical objects or planets (one example being Earth's magnetic field).
- So, does the magnetic force cause circular motion?
- (If this takes place in a vacuum, the magnetic field is the dominant factor determining the motion. ) Here, the magnetic force (Lorentz force) supplies the centripetal force
- A particle experiencing circular motion due to a uniform magnetic field is termed to be in a cyclotron resonance.
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- Magnetic field lines are continuous, having no beginning or end.
- No magnetic monopoles are known to exist.
- A changing magnetic field induces an electromotive force (emf) and, hence, an electric field.
- Magnetic fields are generated by moving charges or by changing electric fields .
- Hertz used an AC RLC (resistor-inductor-capacitor) circuit that resonates at a known frequency and connected it to a loop of wire as shown in .
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- A cathode ray tube consists of a vacuum tube that contains one or more electron guns used to excite phosphors on a screen to produce images.
- It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images.
- In all modern CRT monitors and televisions, the beams are bent by magnetic deflection, which is a varying magnetic field generated by coils and driven by electronic circuits around the neck of the tube.
- In oscilloscope CRTs, electrostatic deflection is used, rather than the magnetic deflection commonly used with television and other large CRTs.
- Oscilloscopes use electrostatic rather than magnetic deflection because the inductive reactance of the magnetic coils would limit the frequency response of the instrument.