The dimension of a spectral reflector is greater than the wavelength of the ultrasound beam. With specular echo reflection, the sound strikes the target at perpendicular incidence and the sound is reflected back towards the receiver. Specular reflections produce bright echoes.

The third generation ultrasound contrast agents (UCA/USCA) are more echogenic and stable, and are able to enhance the echogenicity of parenchyma on B-mode images. These microbubbles may thus show perfusion, even in such a difficult region as the myocardium.

See also History of Ultrasound Contrast Agents.

(TOF) Time of flight is a ultrasound technique used for calculating of the distance to a target by using the timing of the returning echo from the target and the speed of sound in the medium between the target and the sensor. Time of flight is used in echo location and ultrasonic flowmeters.

(US) Also called echography, sonography, ultrasonography, echotomography, ultrasonic tomography.
Diagnostic imaging plays a vital role in modern healthcare, allowing medical professionals to visualize internal structures of the body and assist in the diagnosis and treatment of various conditions. Two terms that are commonly used interchangeably but possess distinct meanings in the field of medical imaging are 'ultrasound' and 'sonography.'
Ultrasound is the imaging technique that utilizes sound waves to create real-time images, while sonography encompasses the entire process of performing ultrasound examinations and interpreting the obtained images. Ultrasonography is a synonymous term for sonography, emphasizing the use of ultrasound technology in diagnostic imaging. A sonogram, on the other hand, refers to the resulting image produced during an ultrasound examination.
Ultrasonic waves, generated by a quartz crystal, cause mechanical perturbation of an elastic medium, resulting in rarefaction and compression of the medium particles. These waves are reflected at the interfaces between different tissues due to differences in their mechanical properties. The transmission and reflection of these high-frequency waves are displayed with different types of ultrasound modes.
By utilizing the speed of wave propagation in tissues, the time of reflection information can be converted into distance of reflection information. The use of higher frequencies in medical ultrasound imaging yields better image resolution. However, higher frequencies also lead to increased absorption of the sound beam by the medium, limiting its penetration depth. For instance, higher frequencies (e.g., 7.5 MHz) are employed to provide detailed imaging of superficial organs like the thyroid gland and breast, while lower frequencies (e.g., 3.5 MHz) are used for abdominal examinations.

Ultrasound in medical imaging offers several advantages including:

Diagnostic ultrasound imaging is generally considered safe, with no adverse effects. As medical ultrasound is extensively used in pregnancy and pediatric imaging, it is crucial for practitioners to ensure its safe usage. Ultrasound can cause mechanical and thermal effects in tissue, which are amplified with increased output power. Consequently, guidelines for the safe use of ultrasound have been issued to address the growing use of color flow imaging, pulsed spectral Doppler, and higher demands on B-mode imaging. Furthermore, recent ultrasound safety regulations have shifted more responsibility to the operator to ensure the safe use of ultrasound.

See also Skinline, Pregnancy Ultrasound, Obstetric and Gynecologic Ultrasound, Musculoskeletal and Joint Ultrasound, Ultrasound Elastography and Prostate Ultrasound.

Ultrasound machines, widely used in medical imaging, are essential tools in the field of diagnostic ultrasound. These devices utilize high-frequency sound waves to create real-time images of internal body structures. Ultrasound machines consist of several key components that work together to generate diagnostic images. These include:
B-mode machines represent the vast majority of machines used in echocardiology, obstetrical scans, abdominal scans, gynecological scans, etc. B-mode ultrasound machines usually produce the sector (or pie segment-shaped) scans. These ultrasound scans require either a mechanical scanner transducer (the transducer moves to produce the sector scan), or a linear array transducer operated as a phased array.


Ultrasound machines come in different types, each catering to specific clinical needs. The two primary types are stationary and portable ultrasound machines:


See also Handheld Ultrasound, Ultrasound System Performance, Equipment Preparation, Coaxial Cable, and Microbubble Scanner Modification, Environmental Protection and Ultrasound Accessories and Supplies.