Ultrasound physics for the physician a brief review

Carlsen, Ernest N.

doi:10.1002/jcu.1870030115

Cited by 24 publications

(7 citation statements)

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“…Color-coding has been criticized because there is acoustical shadowing and because tissues may act as an iregular diffuse reflector (8). Since color-coded isodensitometry is based on grayscale ultrasonography, the tissue characteristics that degrade color-coding act in an identical fashion in a gray-scale system.…”

Section: Discussionmentioning

confidence: 99%

The need for color coding in ultrasound mammography

Baum

1978

J of Clinical Ultrasound

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The correct interpretation of echo amplitude patterns of high-resolution gray scale ultrasonograms of the breast requires the use of calibrated color-coded isodensitometry, standardized operation of the ultrasound system, amplitude stability of 1 per cent or better, and a constant velocity water-coupled electro-mechanical scanner. The same conditions may be required for correct interpretation of the ultrasonograms of the parenchyma of the liver, spleen, ovaries, testes, uterus, thyroid, and tumors. Color coding is not required and may actually be detrimental in the study of gross ultrasonography anatomy and in disease states that can be identified by simple anatomical distortions. To be of value, rigid standardization and control of the amplitude characteristics and scanning velocity of the system are imperative.

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Section: Discussionmentioning

confidence: 99%

The need for color coding in ultrasound mammography

Baum

1978

J of Clinical Ultrasound

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“…8 shows an acoustic wave represented as a sinusoid with a wavelength (λ), a frequency (1/T) and a speed which is the product of frequency and wavelength. In most soft tissues, the velocity of US is about 1540 m/sec [166,167,174,179,180].…”

Section: The Physics Of Ultrasoundmentioning

confidence: 99%

“…Let the impedance of the first material be Z1 and that of the second be Z2. In the case of normal incidence, the amplitude reflection coefficient, R, can be derived as follows [170,171,173,180]:…”

Section: = *mentioning

confidence: 99%

Review on Triggered Liposomal Drug Delivery with a Focus on Ultrasound

Moussa¹,

Martins²,

Husseini

2015

CCDT

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Chemotherapy is widely used for cancer treatment; however, it causes unwanted side effects in patients. To avoid these adverse effects, nanocarriers have been developed, which can be loaded with the chemotherapeutic agents, directed to the cancer site and, once there, are exposed to stimuli that will trigger the drug release. Liposomes can be chemically modified to increase their circulation time, their stability, and their sensitivity to specific stimulus. Additionally, ligands can be conjugated to their surface, allowing for their specific binding to receptors overexpressed on the surface of cancer cells and the subsequent internalization via endocytosis. Using a triggering mechanism, including temperature, ultrasound, enzymes or a change in pH, the release of the drug is controlled and induced inside the cells, hence avoiding drug release in systemic circulation, which in turn reduces the undesired side effects of conventional chemotherapy. Ultrasound has been widely studied as a drug release trigger from liposomes, due to its well-known physics and previous uses in medicine. This review focuses on liposome-based drug delivery systems, using different trigger mechanisms, with a focus on ultrasound. The physical mechanisms of ultrasound release are also investigated and the results of in vitro and in vivo studies are summarized.

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“…Medical diagnostic ultrasound emits and receives in the range of 1 to 15 megahertz (mHz) or 1 to 15 million cycles per second. 4 This energy is generated and received by piezoelectric crystals which become distorted as electrical signals are passed across the crystal with megahertz frequency.…”

Section: Physicsmentioning

confidence: 99%