Physics of ultrasound Dr. Madhav Swaminathan, Dr. Aashish Jain Abstract: Medical practice of ultrasound is constantly expanding. It is now used for not only screening and diagnosis of various diseases, but also to enhance care in the field of anaesthesia and intensive care. Ultimately, the quality of care depends on imaging quality. Practitioners of ultrasound therefore need to understand the physics and principles behind the technology in order to create optimal images. In this article, we will remain focused on the basic principles of physics and their applications in the relevant clinical practice. Key words: ultrasound, image, physics and principles. ----------------------------------------------------------------------------------------------------------------------------- …show more content…
The mechanical vibrations transmitted through a medium; solid, liquid or a gas generates a sound wave. The sound is an energy, which deflects the particles of a medium in the same direction, and itself travel as a longitudinal waveform with areas of compression and rarefactions. The image generated by ultrasound is essentially based on similar principle by means of a machine, which includes an ultrasound transducer and a screen. The transducer contains a piezoelectric crystal made up of lead zirconite, which generates an ultrasound beam on applying an electrical current to the transducer. These signals travel through a medium in the body and after striking with various tissues, return back to the transducer. Then the returned signals are processed and displayed on the screen, as either a real image or different artefacts. Using an ultrasound, this is a simplified way of understanding an image acquisition. In the following text, the principles of ultrasound generation from a piezoelectric crystal and physical properties governing image creation are discussed, with appropriate examples. The principle: The ultrasound works on Doppler Effect, which is based on work by Austrian physicist Johann Christian Doppler. The Doppler Effect says that there is an apparent change in received frequency due to relative motion between a sound source and sound