Doppler sonography/medical applications

Introduction
Doppler Sonography is the practice of using high frequency waves to produce images for medical analysis. These high frequency waves used in Doppler sonography are called ultrasound. A Doppler ultrasound is a non-invasive test. Doppler ultrasound can be used to estimate the blood flow through blood vessels by bouncing high frequency sound waves off circulating red blood cells.

Ultrasounds are sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound devices operate with frequencies from 20KHz up to several gigahertz.

History
Doppler sonography was discovered 12 years before the X ray but the ultrasound is a much later found application in medicine. The ultrasound was first used in medicine in the fifties of the last century. Ultrasound was first introduced in obstetrics and gynaecology to view images of the female reproductive system and the developing fetus, and after that in almost all the fields of medicine. The Doppler ultrasound became the widely accepted method soon after.

Advantages of Doppler Ultrasound
The medical ultrasound provides several advantages some of them including:

•	Non invasion

•	Good visualization characteristics

•	Easy management

Working
The ultrasound device consists of a transducer, transmitter pulse generator, compensating amplifiers, the control unit for focusing, digital processors and systems for display. Sonographers typically use a hand held probe (called a transducer) that is placed directly on and moved over the patient. A water-based gel is used to couple the ultrasound between the transducer and patient.

Importance in Clinical Medicine
Doppler ultrasound is widely used in the medical field to obtain images of different parts of the body for differential diagnosis. Being a noninvasive test, medical ultrasound is a widely preferred method for diagnosis of medical conditions. It is used in the cases of abdominal, cardiac, maternity, gynaecological, urological, and cerebrovascular examination, breast examination and small pieces of tissue as well as in pediatric and operational review.

Disadvantages in the ultrasonic device
Some disadvantages of the ultrasound include:

1. Ultrasound cannot be used to study any part of the body containing gas, so it isnt useful for diagnosing problems of the lungs and digestive system.

2. Some ultrasound devices are said to produce false positives, causing patients to undergo more invasive procedures and biopsies that are not required for their diagnosis.

3. Ultrasound is also unable to detect calcification of the breast tissue, making it less useful for diagnosis of breast tumors and cancer.

Different modes of ultrasonic devices
There are 3 different modes of ultrasonic devices:

A-mode
A-mode is the easiest kind of ultrasound. A solitary transducer filters a line through the body with the echoes plotted on screen as an element of profundity. Therapeutic ultrasound aimed at a specific tumor or calculus is also A-mode, to allow for pinpoint accurate focus of the destructive wave energy.

B-Mode
In B-mode ultrasound, a straight cluster of transducers all the while filters a plane through the body that can be seen as a two-dimensional picture on screen.

M-Mode
M stands for movement. In m-mode a fast grouping of B-mode filters whose pictures take after one another in succession on screen empowers specialists to see and measure scope of movement, as the organ limits that create reflections move with respect to the test.

Color Doppler
Color Doppler (otherwise called Color Flow) moving so as to image uses the Doppler moved frequencies produced red platelets (RBCs). At the point when red platelets go through the Doppler pillar, the development of the cells causes a movement in the recurrence of the transmitted sound shaft to a higher or lower recurrence, contingent upon whether the cells are moving towards or far from the sound bar's hub. The contrast between the transmitted recurrence and the got recurrence is the Doppler movement recurrence, which is more often than not in the kilohertz range. Once the ultrasound framework has decided the Doppler recurrence shifts, different shading maps can be utilized to shading code the Doppler flags and show them as stream in connection to the hub of the Doppler pillar. Most machines will overlay the shading stream show on a B-mode picture of the life systems. Different shades of red and blue are the most widely recognized hues showed on a shading Doppler picture. In any case, impressive debate exists in the matter of what shading ought to be utilized to signify stream toward and far from the pillar pivot. Not at all like stargazing where stars moving far from the spectator are "red moved" and stars moving toward the eyewitness are "blue moved", in drug there are no guidelines for the shading showcase. Some utilization red to speak to supply routes and blue to speak to veins, others use red to speak to stream toward the transducer and blue to speak to stream far from the transducer, and still others take after the lead of the 150 years of space science writing. In today's pharmaceutical, there is no standard for the Doppler shading presentation and bearing; one must comprehend the life systems, physiology, and the sonographic instrumentation and showcase to precisely translate the pictures.

Conclusion
The eventual fate of Doppler sonography is solid.

The expansion of miniaturized scale air pocket contrast operators, which are infused into the circulation system, improves the returning Doppler signs, which makes vastly improved pictures of stream in the heart and little veins. This new system additionally conveys the likelihood of utilizing embodied cytotoxins for conveying disease chemotherapy specifically to tumors. The administrator watches with Doppler for the bubble's landing in the tumor, then blasts them inside of the tumor utilizing particular consonant heartbeats.

Another new therapeutic use of Doppler ultrasound is thrombolysis of blood clots in the brain. While thrombolysis does not rely upon the Doppler effect, color Doppler is used to guide the application of the ultrasonic energy to specific blood vessels within the brain. The sonic vibrations appear to enhance the thrombolytic actions of anticoagulants. The first 50 years of the application of ultrasound through sonography and Doppler imaging has been an amazing period in modern medicine. As the Baby Boomers start turning geriatric, there will only be an expansion of these techniques to improve the health of all people from before birth to old age.