Doppler Effect

The Doppler Effect is the phenomenon in which blood in veins or arteries for example are moving towards or away from the probe with different frequencies. This is mainly applied to laminar and turbulent flow within a vascular structure. When the source moves toward the listener, the perceived frequency is higher than the emitted frequency, creating a higher pitched sound. If the sound moves away from the listener, the perceived frequency is lower than the transmitted frequency, and the sound will have a lower pitch. 

:)

I haven't been updating lately. I have been slacking on my blog. Trying to figure what is the best way for me to take in all the information that I need to learn. I found a good website that I have been studying from called Quizlet.com it provides me with almost every subject you can think of. One thing I must do is get back on Blogger, I loved writing on here but I haven't had the time really with studying and work.
Another thing that has been distracting me a bit is the Kindle App I recently downloaded I am obsessed
with it.

I'll be back soon with the next topic. TTYL

Propagation Speed

Propagation Speed is the maximum speed an acoustic wave moves through a medium. Propagation speed increases proportionally with the stiffness ( the stiffer the medium the faster the wave will travel).

Wavelength

Wavelength is the length measured from one crest of one wave to the other crest of the wave.

Wavelength is measured in units of distance: mm, cm, m, nano meters, micro meters, etc.

Sound Waves

A wave is a propagation of energy that moves back and forth or vibrates at a steady rate. Sound waves are mechanical oscillations that are transmitted by particles in a gas, liquid, or solid medium. Generated by an external source, ultrasound is the transmission of high frequency mechanical vibrations greater than 20 kilohertz (kHz) through a medium.

Waves are generated over a period of time. The time required to produce each cycle depends on the frequency of the transducer. Frequency is equal to the number of cycles per second by the sound source and the particles of the medium. The speed of the wave depends on the property of the medium. There are many forms of energy that travel in the forms of waves such as a sound.There are two types of waves. Mechanical waves and electromagnetic waves.

Mechanical waves are characterized by physical motion of particles in the medium and cannot travel through a vacuum. Electromagnetic waves on the other hand travel through a vacuum.

Waves are further classified as Longitudinal and Transverse waves.
Example:  

A Longitudinal wave is considerded when the particles in the medium vibrate parallel to the direction that the sound wave is traveling. 

Transverse waves means the particles in a medium vibrate perpendicular to the direction the sound wave is traveling.

Introduction to Basic Ultrasound principles

To get a good image free of artifacts, sonographers need to have a firm understanding of the basic ultrasound principles. This inculdes ultrasound physics, including common terminology, measurement units, and the fundaments of sound generation.

Sound is generated by a sound source, for exapmle a tuning for or a violin string. When their source vibrates, adjacent partices are displaced.These particles push against other adjacent particles. This constant pushing is known as particle vibration.

Ultrasound refers to sound waves beyond the human audiable range. Diagnostic applications of ultrasound use frequencies of 1 to 10 million cycles/sec, or 1 to 10MHz. Ultrasound is used to examine soft tissue anatomic structures within all areas of the body.

In medical ultrasound, the vibrating source is a ceramic element that vibrates in response to an electrical signal. The vibrating motion of the ceramic elements in the transducer causes the particles in the surrounding tissue to vibrate. As the source vibrates, it periodically presses against and pulls away from the adjacent medium with resultant particle compression and expansion (rarefaction) in the medium. This movement of energy through structures is called a wave. Patients are examined with a transducer that converts electrical energy into mechanical energy. As the sound beam is directed into the body at various angles to the organs, reflection, absorption, and scatter cause the returning signal to be weaker than the initial impulse. Over a short period of time, multiple anatomic images are acquired in a real-time format.