Ultrasound physics

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A continuous wave primarily has three parameters. They consist ofamplitude, frequency and the initial phase. The pulsed waveparameters include pulse duration, pulse repetition period (PRP),pulse repetition frequency (PRF), spatial pulse length and dutyfactor. Despite the two waves having individual parameters, they alsoshare a few of them such as frequency, period, propagation speed andthe wavelength.

In the pulsed wave, pulse repetition frequency is the exact number ofpulses that happen in one second. It’s dependent on the pulserepetition period by being its reciprocal. That is, PRF decreases asthe imaging depth increases. However, it’s entirely unrelated tothe transducer frequency, and the depth of view determines it. PRF ismeasured in Hertz per second (Hz/sec) and the sonographer can changeit during alteration of the imaging depth. In clinical imaging, itranges from 1,000 to 10,000 Hz.

In the continuous wave, the frequency is measured in Hertz, and itreciprocates both the period (time taken to complete a cycle) and thewavelength. It increases while both the time and wavelength decreaseand vice versa. It is determined by the sound source too as in pulsewave. The rate varies in across different sounds such as inultrasound it’s above 20000Hz, infrasound is below 20Hz, audiblesound 20-20000Hz, and in the diagnostic ultrasound, it ranges from100Hz to 2000Hz.

The parameters are used during the analysis of blood by the Dopplertransducer. The pulsed wave ultrasound is preferred to thecontinuous-wave because it allows the depth of the flow site to bemeasured while the latter is unable to determine the precise locationof velocities in the beam and it can’t produce clear color flowimages. The parameters are also essential in cardiology as their datais used in detecting abnormalities related to the cardiac system(Otto, 2013). They are also indispensable in urology as they aidmeasure the rate of blood flow through the kidney, and in thedetection of kidney stone and prostate cancer. Finally, they areuseful in obstetrics and gynecology as they are crucial for themonitoring of the fetus development and detection of tumors of thebreast and ovary (Bamber et.al., 2013).


Bamber, J., Cosgrove, D., Dietrich, C. F., Fromageau, J., Bojunga,J., Calliada, F., &amp Fink, M. (2013). EFSUMB guidelines andrecommendations on the clinical use of ultrasound elastography. Part1: Basic principles and technology. Ultraschall in derMedizin-European Journal of Ultrasound, 34(02), 169-184.

Otto, C. M. (2013). Textbook of clinical echocardiography.Elsevier Health Sciences.

Ultrasound Physics

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Ultrasoundis considered painless and has thus been used in the production ofimages of internal body organs using sound waves. Sound of highfrequency is transmitted into the body and the reflected waves arecollected by the transducer where a computer creates the images(Chatterjee&amp Miller, 2010).A sonographer should thus be well versed with different frequencies.Additionally, they should also be knowledgeable with the working of atransducer.

Properselection of the right frequency is essential for the provision ofoptimal image resolutions in diagnostic procedures. Ultrasound waveswith short wavelengths produce images with a high axial resolution(Chatterjee&amp Miller, 2010).Additionally, when waves of rarefaction and compression are increasedfor a given distance, two separate structures can accurately bediscriminated.

Wavesof high frequency are more attenuated compared to those of lowfrequency. This property makes it suitable for the short wavelengthwaves to be appropriate in imaging superficial structures. On theother hand, those of long wavelengths produce images of lowresolution. However, their property of small degree of attenuationenables them to penetrate deeper in structures (Chatterjee&amp Miller, 2010).

Atransducer is considered to be a paramount element of an ultrasoundsystem. It is composed of a piezoelectric element which transformselectrical signals to mechanical oscillations. Characteristicsassociated with transducer frequencies are propagation speed andthickness of the crystal.

Frequencyincreases with the thickness of a crystal and also with increasedpropagation speed. Relationships that arise with the rate of atransducer are penetration and resolution. When the frequency of asensor is high, resolution increases (Chatterjee&amp Miller, 2010).The increase is attributed to the sending of more signals whichenables the detection of objects in various locations. On the otherhand, when it is low, resolution decreases. The reduction isattributed to the sending of fewer signals and hence fast movingstructures will not be resolved.

Differentsituations require the use of frequencies that vary. For instance,2.5MHZ is used in gynecological and profound abdomen imaging. Forbreast, pelvic and vascular imaging, a frequency of 7.5MHz is used.10.0 MHz for superficial veins, thyroid, and superficial masses(Chatterjee&amp Miller, 2010).

Inconclusion, a sonographer should be well versed with differentfrequencies. Additionally, they should also be knowledgeable withcharacteristics associated with transducer features that areessential for the provision of optimal image resolutions indiagnostic procedures. They will be in a position to apply theright frequency for various body parts.


Chatterjee,S., &amp Miller, A. (2011).&nbspBiomedicalinstrumentation systems.Clifton Park, NY: Delmar Cengage Learning.

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