Understanding Medical Imaging Technology
July 26, 2012
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Medical imaging is an important phase in the detection and treatment of a wide host of diseases and conditions. Medical imaging is the process of generating an optical representation of a part of the human body. There are several means for obtaining images. These can be divided into optical and electronic.
Optical devices use natural photons in the visible spectrum of light that pass through a lens to create an image in the users’ eye. Examples of such include a microscope and an endoscope. In a microscope, combinations of lenses magnify an image many times. In an endoscope, optical fibers transmit an image along a flexible tube. This allows visualization of internal structures of the ear, esophagus, or colon.
Electronic devices convert particles in the invisible frequency of the spectrum of light, most commonly x-rays and sound waves. There are numerous derivatives of this technology that use computer technology to perform complex calculations and compile images that would be impractical for humans to do on their own.
Sonography includes the diagnostic fields of ultrasound and echocardiology. High frequency sound waves are projected into the area to be studied. Sound waves reflect and scatter differently depending on the density of the tissue. A transducer senses vibrations in the ultrasound range, and converts the vibrations into electronic signals, which are then processed by a computer to produce an image of the tissue.
Radiography is the use of x-rays to produce images. An x-ray is a high frequency particle and passes readily through soft tissues, but not as easily through hard tissues, such as bone. Use of liquid contrast media, such as iodine or barium in liquid form, injected or imbibed, allows image to be taken of the vascular or gastro-enteric systems, respectively. Computed tomography (CT) scans use a rotating x-ray generator and detector to create cross-sectional images.
Magnetic resonance imaging uses a strong magnetic field to excite hydrogen particles throughout the body. Excited particles then return to their resting state. This is observed by an antenna and interpreted by a computer into an image.