AAPM/RSNA Physics Tutorial for Residents: Topics in US

Abstract

Ultrasonography (US) has been used in medical imaging for over half a century. Current US scanners are based largely on the same basic principles used in the initial devices for human imaging. Modern equipment uses a pulse-echo approach with a brightness-mode (B-mode) display. Fundamental aspects of the B-mode imaging process include basic ultrasound physics, interactions of ultrasound with tissue, ultrasound pulse formation, scanning the ultrasound beam, and echo detection and signal processing. Recent technical innovations that have been developed to improve the performance of modern US equipment include the following: tissue harmonic imaging, spatial compound imaging, extended field of view imaging, coded pulse excitation, electronic section focusing, three-dimensional and four-dimensional imaging, and the general trend toward equipment miniaturization. US is a relatively inexpensive, portable, safe, and real-time modality, all of which make it one of the most widely used imaging modalities in medicine. Although B-mode US is sometimes referred to as a mature technology, this modality continues to experience a significant evolution in capability with even more exciting developments on the horizon.

Future of the Renal Biopsy: Time to Change the Conventional Modality Using Nanotechnology

“…Nevertheless, in spite of safety of these modalities, low imaging depth of penetration and/or poor resolution limits their applications. Theoretically, there is a tradeoff between imaging depth of penetration and spatial resolution in mechanical [140] or electromagnetic [141] based imaging modalities. In other words, the resolution of optical imaging modalities will be degraded at higher depth due to light scattering [106, 107].…”

Clinical ultrasound physics

“…Brightness mode (B mode) is the basic mode that is usually used. [2] The B mode gives a two dimensional (2D) black and white image that depends on the anatomical site of the slice. The body can be imaged in different planes depending on the position of the probe.…”

“…[1] Ultrasound frequency is defined as the number of ultrasound waves per second, and medical ultrasound machines use waves with a frequency ranging between 2 and 15 MHz. [2] The velocity of ultrasound in a specific medium equals the frequency of ultrasound multiplied by its wave length. [1]…”

Basic Ultrasound Beam Formation and Instrumentation

“…3C and 6). [2][3][4] means of presenting images in real-time, like a movie. Sectors, vectors, linear, curvilinear, and convex describe the shape of the line of piezoelectric elements.…”