Ultrasonography is a valuable diagnostic tool widely used in medicine. During the last three decades, this non-invasive skin imaging method has been extended to dermatology. High-frequency ultrasonography with higher than 20MHz scanners is well-established for measuring tumour thickness and skin thickness when treating inflammatory skin diseases such as scleroderma or psoriasis. High-frequency ultrasonography has become extremely helpful for the preoperative assessment of skin melanoma. The correlation between ultrasonic and histological measurements of melanomas thickness is significantly similarly good using transducers of 20, 75 or 100MHz frequency (r range from 0.895 to 0.99) and better compared with transducers of 7.5MHz frequency (r=0.76). The preoperative sonographically estimated thickness of skin melanoma is sometimes overestimated, because of an underlying inflammatory infiltrate and other reasons. Assessment of skin melanoma thickness using transducers of 100MHz frequency has better agreement with histology, compared with ultrasonography with 20MHz transducers. However, the ultrasonic penetration depth is limited to 1.5mm in case of 100MHz. The newer ultrasonic techniques such as high-frequency ultrasonography and colour Doppler sonography could be used for assessment of the tumour vascularization and its metastatic potential. The wide variety of diagnostic information provided by high-frequency ultrasonography undoubtedly improves the management of oncological and inflammatory skin conditions and underlines its essential position in dermatological practice.

The problems of development of high-temperature ultrasonic transducers for modern science and technology applications are analysed. More than 10 piezoelectric materials suitable for operation at high temperatures are overviewed. It is shown that bismuth titanate based piezoelectric elements are most promisable. Bonding methods of piezoelectric elements to a protector and backing are discussed. Thermosonic gold-to-gold bonding is most modern and possesses unique features. Our achievements in this field are analysed in the context of world progress. In sol-gel and chemical vapour deposition technology bonding and sometimes coupling problems are avoided at all. Design peculiarities of the transducers are reviewed. Commercial sensors in the meanwhile are often characterized with poor performance in extreme conditions.In conclusions recommendations for high temperature ultrasonic transducers design are formulated.

No abstract

No abstract

No abstract