Post#10

In medicine ultrasonic devices are used to examine internal organs without surgery and are safer to genetic material than X rays. The waves with which the body is irradiated are reflected and refracted; these are recorded by a sonograph for use in diagnosis. First developed in World War II to locate submerged objects, this technique is now widely used in virtually every branch of medicine.
Ultrasonic study and application of the energy of sound waves vibrating at frequencies greater than 20,000 cycles per second, beyond the range of human hearing. The application of sound energy in the audible range is limited almost entirely to communication, since increasing the pressure, or intensity, of sound waves increases loudness and therefore causes discomfort to human beings. Ultrasonic waves however, being inaudible, have little or no effect on the ear even at high intensities. They are produced commonly by a transducers containing a piezoelectric substance, a quartz-crystal ultrasonic wave.
The basic ultrasound transducer has the appearance of a cylindrical tube. A sound pulse is emitted from the front of the tube, which is placed on the skin. A wire connecting the transducer to the ultrasound system extends from the back of the cylinder.
The basic transducer has seven components which include
1. Case- the cylindrical tube constructed of metal or plastic that protects the internal components of the transducer. 2. Electrical shield- then metallic barrier lining the inside of the case, it prevents electrical signals in the air, unrelated to diagnostic information. 3. Acoustic insulator – prevent vibrations in the case form inducing an electrical voltage in the PTZ of the transducer. 4. PTZ or active elements- the piezoelectric crystal itself. 5. Wire- provides electrical connection between the PTZ and the ultrasound system. 6. Matching layer- increases the efficiency of sound energy transfer between the active element and the body and protects the active elements. 7. Backing material also called damping element- the bonding reduces the ringing of the pulse, and it is a short duration and length.
There are several types of transducers that will assist in ultrasound imaging, the Linear phased arrays is common, the footprint, or face of the transducer that comes into contact with skin, is small square 1 centimeter on each side, the beam is steered and focused using an electrical technique called phasing. The image created by a phased array transducer is fan or sector-shaped, similar to that produced by the mechanical transducer. These pulses are directed in a pattern similar to that of the sweeping of a windshield wiper or the spokes of a bicycle wheel.
Linear sequential arrays, has a large acoustic footprint and creates rectangular images. The linear sequential array has 120-250 rectangular-shaped strips of piezoelectric material arranged side by side in a line. The sound beams are parallel to each, and the image is never wider than transducer.
Vector Arrays is a combination of linear sequential and linear phased array technologies. Sloped electrical delay patterns can be introduced that steer the sound beams of the linear in variety of directions. Trapezoidal images are created by vector array transducers. At intermediate and deep depths, the images appear as a sector.

(Comparing which is safer,ultrasonic devices or X-rays)