The speed of sound in soft tissue, which is measured as an average of 1,540 m/s or 1.54 mm/us, should be simulated by tissue equivalent phantoms. Phased array transducers are assessed using tissue equivalent phantoms for proper soft tissue texture and grayscale imaging. To assure instrument identification of cystic versus solid masses within soft tissues, features of variable echogenicity are included in a tissue equivalent phantom.
The relationship between pulse repetition frequency (PRF) and pulse repetition period (PRP) is reciprocal and inverse. Thus, the PRP would be the longest for the PRF with the lowest value, 7 Hz.
Pulsed sound is defined by its duty factor, pulse duration, spatial pulse length, PRP, and PRF. The seven acoustic parameters of period, propagation speed, frequency, wavelength, power, intensity, and amplitude define non-pulsed acoustic waves.
Bone has a sound speed of 3,500 m/s, which is the highest of the mentioned biologic tissues. While the liver and blood both have a sound speed of 1,560 m/s, fat has an average sound speed of 1,450 m/s. In soft tissue, sound travels at an average speed of 1,540 m/s. Metallic implants show a significant increase in the speed of sound, from 2,000 to 7,000 m/s.
Over 75% of sonographers have pain from musculoskeletal injuries at some point in their careers. For the safety of sonographers, sonographic equipment has improved in terms of ergonomic design. Cable braces, articulation of the sonographic display and control panel, including extension and swivel characteristics, and lightweight transducers are a few examples of adaptive devices implemented into sonographic equipment. Although they are not part of the sonographic machine, additional ergonomic devices also exist, such as support cushions, wrist braces, and adjustable ergonomic chairs.
The use of phantoms, such as tissue equivalent, slice thickness, and Doppler phantoms, is one method for ensuring the quality of sonography. Options for a different response deal with phantoms utilized in other imaging modalities. To ensure that imaging in a medical context is of diagnostic quality and to minimize downtime and repeat scans, quality assurance is required. Changes in equipment may be noticed through routine, periodic QA testing observation, enabling for the necessary alterations to be made for proper system operation.
Temporal resolution is determined by frame rate, or the number of images (frames) per second. Temporal resolution increases with frame rate and decreases with frame rate. Imaging depth, pulses per frame, the speed of sound in the medium, single vs. multi-focus, line density, and sector size are all factors that affect frame rate. In essence, frame rate and temporal resolution are reduced by every alteration that demands the display of more information or provides additional detail. Although temporal resolution has to do with how "fast" an image is, spatial, elevational, and lateral resolution are also types of sonographic imaging.
