THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

17Commercial and MedicalUltrasound Applications17.1 The Growth of Ultrasonic ApplicationsIt is recognized among technologists that the field of ultrasonics is still in its infancy,and many new uses for ultrasound will continue to accrue in commercialand medical fields. Ultrasound is proving its continued worth in diagnostics, as it isgenerally nondestructive at lower intensities and does not engender the deleteriouseffects on materials and living tissues that X-rays do. At higher levels of operation,ultrasound is used in manufacturing operations in cleaning, cutting, and weldingmaterials and to provide therapeutic treatment and alleviate the trauma of surgeryby making possible increased precision in incisions, targeting of tumors and infectedtissues for selective ablation, and stanching bleeding. Improvements havebeen made and are still continuing; as the results of better imaging, more versatiletransducer arrays, and more powerful analytical algorithms are rendered possibleby more powerful computers and larger data storage systems. In this chapter asurvey is conducted of the uses of ultrasound in manufacturing and agriculturalprocesses, quality control, and in medical (including dentistry) diagnostics andtherapeutic procedures. In addition to manufacturing, the petroleum, chemical,and pharmaceutical sectors also make use of ultrasound to monitor and facilitateproduction. The safety of ultrasound also constitutes an important topic in thissection.17.2 Industrial Applications of UltrasoundUltrasonic CleaningUltrasonic cleaning is the oldest industrial application of power ultrasound. Applicationsspan a wide variety of industries ranging from castings to semiconductors.Ultrasonic cleaning works best on relatively hard materials such as metals, glass,ceramics, and plastics, which reflect rather than absorb sound.Both cavitation and the agitation of the fluid by the waves are entailed inthe process of ultrasonic cleaning. At lower frequencies, cavitation acts as the479