Diagnostic ultrasound : physical basic and interactions with tissue

Dijagnostički ultrazvuk ima široku primjenu u skoro svim granama medicine. Ultrazvučni val je zvučni val frekvencija iznad 20 kHz koji nastaje obrnutim piezoelektričnim efektom. Princip rada ultrazvuka se temelji na emisiji ultrazvučnih valova i detekciji njihovih odjeka koji nastaju refleksijom od struktura u organizmu. Snimanjem tih odjeka može se dobiti slika unutrašnjosti organizma. Slika može biti u A, B ili M-modu. Na slici mogu postojati i artefakti koji su u nekim slučajevima nepoželjni, dok u drugim upravo pojava artefakta znači dijagnozu. Iako je dijagnostički ultrazvuk raširena dijagnostička metoda koja je relativno jeftina, bezbolna i neinvazivna, može prouzrokovati neke neželjene termičke i mehaničke efekte kao što su prekomjerno zagrijavanje tkiva i pojava kavitacije. Iz tih razloga, postoje smjernice o sigurnosti upotrebe ultrazvuka.Diagnostic ultrasound is widely used in almost all fields of medicine. The ultrasound wave is a sound wave with frequency above 20 kHz which is produced by inverse piezoelectric effect. The working principle of ultrasound is based on emission of ultrasound waves and detection of their echoes that reflect from structures in the organism. By recording those echoes, the image of the inside of organism is produced. The image can be shown in A, B, or M-mode. On the picture artefacts can be present which are unwanted in some cases, while in the other cases they point towards a diagnosis. Although the diagnostic ultrasound is a widespread method that is inexpensive, painless and non-invasive, it can cause some unwanted thermal and mechanical effects such as tissue overheating and cavitation. For these reasons, there are guidelines on the safety of the use of ultrasound