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Quantitative ultrasound
Published in C M Langton, C F Njeh, The Physical Measurement of Bone, 2016
Christian M Langton, Christopher F Njeh
The majority of clinical applications of ultrasound are related to the imaging of soft tissue structures using a pulse–echo technique, illustrated in figure 14.15. The ultrasound waves are generated and received by the same transducer, placed upon the surface of the skin with a water-based gel to facilitate coupling of the ultrasound into the tissues. An ultrasound pulse is propagated into the tissues and is reflected at interfaces. For conventional medical ultrasonography, it is the dimensions of the tissues that are generally of interest, for example, the bi-parietal diameter (head width) for prediction of gestation age. The standard equation for velocity is
High-intensity focused ultrasound in the treatment of glaucoma: a narrative review
Published in Expert Review of Ophthalmology, 2021
Michele Figus, Francesco Sartini, Giuseppe Covello, Chiara Posarelli
Ultrasound is defined as any sound higher in pitch than that detectable by the human ear, ~25 kHz (thousands of cycles per second). However, medical ultrasonography relies on frequencies in the MHz (millions of cycles per second) range. Like light, ultrasound can be focused, opening the possibilities to therapeutic applications [1]. Initially proposed to treat different central nervous system diseases [2,3], high-intensity focused ultrasound (HIFU) technology was also introduced in oncology to produce prolonged hyperthermia (elevation of tissue temperature to 43°C for 1 h) in the entire cancer volume, obtaining a regression of the disease [4]. Nowadays, many pathologies are treated with HIFU, such as prostatic cancer [5], liver cancer [6], placenta accreta spectrum [7], and benign thyroid nodules [8].