- May 25, 2020
Beam Formation in Imaging
BeamFormation in Imaging
BeamFormation in Imaging
Anultrasound beam refers the area through which the sound energyemitted by a transducer travels. A sonographer needs to understandthe characteristics of a beam while using the machine to achieve theoptimal results (Chan & Perlas, 2011). It is imperative tounderstand the formation and characteristics of a beam and itformation for a sonographer because they determine the quality of animage during diagnosis.
First,the beam is three dimensional and symmetrical. This enables thesonographer to categorize it near and far fields. The near field iscylindrical in shape, and the far zone forms a cone shape. Thesonographer also needs to understand that the shape of the beamdepends on the diameter of the crystal, the frequency and wavelength,the design of the transducer used in imaging and the intensity offocusing applied on the beam (Chan & Perlas, 2011). Therefore,increasing the frequency of a wave will result in longer near fieldand lesser far field. When the sonographer changes the size of thecrystal, the beam becomes narrow. The primary rationale forunderstanding the beam formation is that the near and far fieldresults in different images. When the near field is shorter, there ismore divergence in the far field (Chan & Perlas, 2011).
Theshape of the beam affects the quality of an image. For example, ahigh wave frequency reduces the beam penetration. Therefore, toimprove the quality of the image, using high frequencies would bedesirable for low-lying organs.
Inthe Huygens principle, wavelets interact with each other to form abean that assumes the shape of an hourglass. This enables it totravel along its main axis. The transducer contains numerous crystalparticles. They produce sound waves that diverge through diffraction.The diffraction takes place because the crystals are small almost tothe size of the wavelength (Chan & Perlas, 2011). The spatialfiltering or beam formation uses directional signals. The particularangle of signals result in some of them experiencing destructive andothers constructive interference.
Conclusively,getting acquainted with the formation of a beam and itscharacteristics enables a sonographer to make the correct choice offrequency and intensity depending on the organs under study. Thecrystals in a transducer produce sound waves at different anglesresulting in constructive and destructive wavelengths. In the nearfield, the bean is cylindrical and assumes a cone shape in far field.
Chan,V., & Perlas, A. (2011). Basics of ultrasound imaging. In Atlasof ultrasound-guided procedures in interventional pain management(pp. 13-19). New York N.Y.: Springer.