Ultrasound Physics & Doppler
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US physics was given at KAUH under RSSA in 2007
This imaging modality involves exposing part of the body to high-frequency sound waves (mechanical waves) to produce images. So, ultrasound exams do not use ionizing radiation (x-ray).
Main differences between X-ray and US imaging modalities
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Parameter
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Diagnostic Ultrasound
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Diagnostic X-rays
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Wave type
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Longitudinal mechanical waves
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Electromagnetic waves
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Transmission medium
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Elastic medium
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No medium
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Generation method
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Stressing the medium
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Accelerating electric charges
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Velocity (speed)
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Depends on the medium through which it propagates
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It is relatively constant (speed of light)
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Similar waves
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Seismic, Acoustic
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Radio, Light
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In medicine, ultrasound is used to detect changes in appearance and function of organs, tissues, or abnormal masses, such as tumors.
}Ultrasound scanning is noninvasive (no needles or injections) and is usually painless.
}Ultrasound imaging uses no ionizing radiation.
}Ultrasound scanning gives a clear picture of soft tissues that do not show up well on x-ray images.
}Ultrasound is the preferred imaging modality for the diagnosis and monitoring of pregnant women and their unborn infants.
}For standard diagnostic ultrasound there are no known harmful effects on humans.
}A Doppler ultrasound study may be part of an ultrasound examination.
}Doppler ultrasound is a special ultrasound technique that evaluates blood as it flows through a blood vessel, including the body’s major arteries and veins of the arms, legs and neck.
}Doppler ultrasound, measures the direction and speed of blood cells as they move through vessels.
}The movement of blood cells causes a change in pitch of the reflected sound waves (called the Doppler effect). A computer collects and processes the sounds and creates graphs or pictures that represent the flow of blood through the blood vessels.
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