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Ultrasound transducer physics
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Understanding transducer theory as well as function is vital in performing clinical ultrasound tests on patients. A transducer can be defined as any device that converts one form of energy into another. Transducers are not just something used in the ultrasound world. There are many different kinds of transducers in the world. Some examples of transducers that we come in contact with in the real world are microphones, speakers, lasers etc. (Miele).
Transducers used in a clinical setting are quiet complicated. “However, they share many of their design characteristics with simple, single crystal, unfocused probes.” Describing the components of a simple probe often helps people understand transducer characteristics as well as function. A basic ultrasound transducer has a case, a cylindrical tube that protects the internal components of the transducer. The electrical shield is a barrier which lines the inside of the case. This shield aids in prevention of electrical noise from interfering with diagnostic images. The acoustic insulator is also a barrier. However the insulator isolates the components of the transducer from the case. One of the most important parts of the transducer is the piezoelectric crystal itself which is involved in energy conversion. One of the more obvious components of a simple probe is the wire. The wire provides an electrical connection between PZT or active element and the actual ultrasound system. The last two components that I am going to talk about are the more important ones, the matching layer and the backing layer. The matching layer is at the face of the transducer in front of the PZT. “The matching layer is designed with impedance between that of the active element in the skin.” The ideal mat...
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...er than the natural focus is called the far field, far zone or Fraunhofer zone (Miele).
There are many different types of transducers. I am going to briefly talk about one, the linear switched array probe. This probe is used for vascular 2D imaging, Doppler and color Doppler. This probe as you may know from using it creates a rectangular image. It is a great probe for vascular because it creates a wide linear image in the near field. On the downside we are unable to steer this transducer. That is why, “most linear transducers produced now are phased linear and not switched linear arrays” (Miele).
In conclusion, a transducer can be simplistically defined as anything which converts one form of energy to another form of energy. As I said before knowledge of transducer theory as well as function is necessary for anyone to successful in the field of ultrasound.
The transducer in the assay was the Shimadzu UVmini-1240 UV-Vis Spectrophotometer. It is used to measure the absorbance of ferricyanide in solution. Ferricyanide is a yellow species that be measured and compared to the glucose concentration of the sample. Electrochemical glucometers look like the most common type of transducer for commercial use. It utilizes electrodes and flowing current measured by a voltmeter.2
... are sent through the electrodes to measure how well the nerves can send a signal to the muscle and to determine whether signals get worse when the muscle is tired.
by the internal computers of the instrument, to create an image of internal body tissues. These images were then displayed on the screen for the user,
This is a type of imaging test that uses sound waves (ultrasound) to produce an image of your heart. There are two types that may be used:
This produces a sensation of hearing, although it is not a restoration of hearing. It is done through the surgical implantation of a device in the mastoid bone behind the ear. Externally, a microphone picks up sound from the environment, and a speech processor filters the sound selectively for audible speech and sends it to a transmitter, from which the processed sound signals are sent to the internal device. Internally, a receiver and stimulator converts the signal into electric impulses which are sent to an array of electrodes, and from there to the brain through the auditory nerve system (Mackay 51). Hearing aids and cochlear implants differ from each other in many ways.
When performing an ultrasound on the aorta, patients are typically supine. Occasionally, it is necessary to roll the patient in the right lateral decubitus position in order to eliminate bowel gas from obscuring the visualization of the aorta. A 5-7 MHz transducer typically provides an optimal amount of penetration through abdominal tissue. When imaging the aorta, it is pertinent to adjust controls on the machine to provide and obtain the most accurate images possible. Adjusting such knobs as the 2D gain and time gain compensation will allow the best visualization of the aorta by showing the presence or absence of a clear aortic lumen. B2.61.
Ultrasounds use the same concepts that allow sonar on boats to see the bottom of the o...
Ultrasound Technicians are very valuable in the world of health care. Also known as Diagnostic Medical Sonographer, an Ultrasound Technician uses special machines and equipment that operates on sound waves to determine or diagnose medical problems for patients. There are specializations within this field in which some individuals explore. For instance, areas of specialization includes but not limited to; pregnancy, heart health, gynecology, and abdominal sonography. Although each specializing branch has its own distinctive function, they all involve probing the body to facilitate doctors with diagnoses.
Sounds are produced by the vibrations of material objects, and travel as a result of
Pure Tone Audiometry is the key hearing test used to identify hearing threshold levels of an individual, in order to determine the degree, type, and place of hearing loss. The threshold level is the lowest amplitude (at a fixed pitch) that is responded to three times. It is a subjective and objective measurement of an individual’s threshold, as it relies on the patient’s response to the pure tone provided. However, it is necessary for the materials to function, as well. a material (i.e. headphones) is not working, it becomes an objective problem and unrelated to the patient’s hearing abilities (Huizing 2009).
An electrocardiograph (ECG) is a common test that tracks impulses through the heart. Sensors are placed on the body to pick up impulses and the ECG will illustrate the time each impulse takes to get from the upper chambers to the lower chambers of the heart by showing three waves. The "P wave" is the first wave that originates from the atria, followed by the "QRS complex" that comes from the ventricles, and lastly the "T wave" that shows when the ventricles are at rest again (Electrocardiogram, 2015). Doctors will time the waves to see if the timing is correct or if they are too fast or too slow (Figures 3 and 4). They will also measure the impulse to see if one part of the heart has too much electrical activity than it is able to handle. This test can also be done with a miniature portable ECG recorder that can be worn for a period of time to actually catch an episode of SVT, which is usually more successful because episodes are so unpredictable. These portable ECGs can also be called Holt monitors and event recorders and also have sensors that get tape on specific areas of the chest (Electrocardiogram, 2015). Another more specialized test for those already diagnosed with SVT but want to locate the exact cause of abnormal heart beats is an electrophysiologic test. Doctors insert catheters with electrical sensors on them in a vein in the arm or upper thigh. The doctor moves the catheter around in the heart, with the help
A sound wave is a longitudinal, mechanical wave that transfers energy whilst compressing and refracting through a uniform medium. Therefore, as sound waves move through a uniform medium, the wave will experience a gradual reduction in it’s power. When sound waves pass through the medium it interacts with the molecules and the energy is transferred to the uniform medium, as heat is generated from the molecules vibrating back forth. The heat generated from the transfer of energy reduces the power of the wave. In particular, medium uniforms which are solid gradually remove the power, whereas dense mediums result in a rapid loss of energy (Henderson, 1996).
Diagnostic Medical Sonography uses high-frequency sound waves to produce images of inside the body. The sonographer uses an instrument called an ultrasound transducer on the parts of the patient’s body that are being examined. Of course, as with any profession, there are educational requirements needed to be a sonographer.
Ultrasound or ultrasonography is a medical imaging technique that uses high frequency sound waves. It is a high pitch frequency that cannot be heard by the human ear. In ultra sound the following happens: High frequency sound pulses (1-5megahertz) are transmitted from the ultrasound machine into your body using a probe. The sound wave will travel into your body until it hits an object such as soft tissue and bone. When the sound wave hits these objects some of the wave will be reflected back to the probe. While some waves may carry on further till they hit another object and then reflected back. The probe picks up these reflected sound waves and relays them to the machine. The distance and time from the probe, to where the sound wave was reflected, to when the echo is received back is calculated by the machine. A two dimensional image like below is produced displaying the distances on the screen.
CTscans stands for “Computed Tomography”. It is a way of looking inside your body using a special camera. It is an advanced scanning x-ray and computer system that makes detailed pictures of horizontal cross-sections of the body, or the part of the body that is x-rayed. A CT scan is a diagnostic test that combines the use of x-ray with computer technology. A series of x-beams from many different angles are used to get these cross-sectional images of the patient’s body. In a computer, these pictures are assembled into a 3-dimentianal picture that can display organs, tissues, bones, and any such thing. It can even show ducts, blood vessels and tumors. One of the advantages of CT is that it clearly shows soft tissue structures (such as brain), as well as dense tissue structure (such as bone). The pictures of a Ctscanner are a lot more detailed than the pictures of a regular X-ray machine. It can make pictures of areas protected or surrounded by bones, which a regular X-ray machine can not. Because of this, a CT scanner is said to be 100 times as affective and clever as an ordinary X-ray, and can therefore diagnose some diseases a lot earlier and quicker. It is recent technology that has made it possible to accurately scan objects into a computer in three dimensions, even though the machines and ideas were developed in the 1970s. In the 70s doctors started to use this new type of machine that could give detailed pictures of organs that the older type of x-ray, machine could not give.