Ultrasound Imaging, Research Paper Example

Ultrasound is a type of mechanical wave like sound that occupies a frequency range exceeding human limits of hearing. Frequency ranges comprise of;

• Audile sound 15 Hz-20 kHz
• Medical ultrasound 1-15 MHz

Imaging device normally used today is Ultrasound. Ultrasound can easily carried, free of radiation risk and cost effective as compared with other imaging devices such as; magnetic resonance and computed tomography, Non-ionizing emission that is sound intensities used at diagnostic imaging are known to be safe and used in place of x-ray used techniques in many crucial imaging cases. It can allowed structural and functional ideas and ultrasound interacts with tissue and can come up with biological changes. In most incidences, therapeutic and surgical applications of ultrasound depend on that property.

Ultrasound images are created by sending an ultrasound wave towards the facility to be imaged and then holding the signal that is reflected by the intended tissue.

Modern medical ultrasound is conducted using a pulse-echo approach with a brightness mode show. It involves projection of small pulses of ultrasound echo from the transducer into the body. As the ultrasound waves passes body tissues of different acoustic impedances along the channel of transmission, a number of them become reflected right back into the transducer. However, there are some that are able to infiltrate deeper. Ultrasound transducer works as a speaker as well as device receiving sound waves. The ultrasound pulse are always short, it usually traverse in a straight path which is referred to as ultrasound beam (Kossoff, 2011).

Ultrasound transducer

Ultrasound transducers have several piezoelectric crystals which are interconnected electronically and pulsate in response to applied electric current. To get a better picture of how this transducer is created, we give the details of the amplitudes, frequencies and wavelengths of sound waves.

Ultrasound wavelength and frequency

Ultrasound of high frequency has a short wavelength and vice versa meaning that the wavelength and frequency of ultrasound is inversely related. Ultrasound waves are known to have frequencies that outweigh the upper limit for audible human hearing. The frequencies exceed 20 kHz. Majorly medical ultrasound devices use sound waves in the range of 1-20MHz.

Appropriate selection of transducer frequency is of significant since it provide optimal image resolution in diagnostic and procedural ultrasound. High frequency ultrasound wave’s produces images of high axial resolution. In the case where the number of waves come together and dispersed a certain magnitude is increased. It results to discrimination between two different structures along the axial plane of wave length. Waves baring high frequencies are susceptible to a high reduction degree as compared to those with low frequencies. This difference in distance relating to reduction is what makes the waves with greater frequencies to be put to use in imaging shallow body areas. Elongated wavelength offers low resolution images. Nonetheless, they bare an advantage and that is the capability of penetrating into deeper structures. This is brought about by their low reduction mark. From the above description, it is appropriate to use high-frequency transducers to image superficial structures and low-frequency transducers for imaging the lumbar neuraxial structures that are deep in the majority of adults (Elder, 2009)

 Ultrasound waves

Ultrasound waves are constructed in pulses that normally comprise of sound cycles mostly two or three of the same frequency. The amount of pulses emitted by the transducer at a time is what is referred to as pulse repetition frequency (PRF). Emitting the waves in pulses is very vital to ensure that these signals are able to arrive at the intended areas. They can also manage to go back to the transducer right in advance and early than sendoff of the next pulse.

 The interaction between the tissue and ultrasound

Tissues are penetrated by the waves after transmission, targeting deeper areas. There are some that are echoed back while others are converted into heat. To perform imaging activity the important factor is the echoes reflected back to the transducer. Acoustic impedance is a tissue that determines the amount of echo returned after coming in contact with tissue interface.

Refraction is important in construction of ultrasound transducer. Refraction is a term used to denote a redirection of the conveyed sound waves. It occurs after these waves have been able to come into contact with two different tissue interfaces, provided that the waves have a dissimilar amount of speed. If the frequencies of the sound waves are continuous, then the wavelengths have to diverge in order to maintain a variation in the sound broadcasting speed targeted at two tissues. The redirection of sound pulses is based on this phenomenon. Refraction is important as it acts as one of the important causes of wrong position of a structure on an ultrasound image (Sidney, 2004)

 Conclusion

Ultrasound is cost effective, portable, safe and real time in nature. These qualities and everyday improvements in the image quality and resolution have increased use of ultrasound to a large area in medicine. Some of the areas of growth includes; Regional anesthesia and pain medicine procedures. People need to grasp the above fundamental principles which will go a long way in helping the medical practitioner in the field of pain as well as the anesthesiologists in service provision after becoming proficient in the above mentioned instrument.

References

Edler I, Lindstrom K. (2009)The History of Echocardiography. Ultrasound Medical Biology. 2004; 30:130-260

Kossoff G. (2011) Basic physics and imaging characteristics of ultrasound. World J Surg. 2000; 24:98-108

Sidney Edelman, (2004) Understanding ultrasound physics, 4th edition