Langevin's Ultrasonic Metrology.

This article proposes that Paul Langevin should be considered the originator of ultrasonic metrology. He established the theoretical foundation for the use of radiation pressure for the measurement of acoustic power, by considering the energy density at a target in a beam. This approach was used for calibrating the ultrasonic transducers he helped to develop for submarine detection and underwater communications during the First World War (WWI).

The origins of medical physics.

The historical origins of medical physics are traced from the first use of weighing as a means of monitoring health by Sanctorius in the early seventeenth century to the emergence of radiology, phototherapy and electrotherapy at the end of the nineteenth century. The origins of biomechanics, due to Borelli, and of medical electricity following Musschenbroek's report of the Leyden Jar, are included. Medical physics emerged as a separate academic discipline in France at the time of the Revolution, with Jean Hallé as its first professor.

Thermally-mediated ultrasound-induced contraction of equine muscular arteries in vitro and an investigation of the associated cellular mechanisms.

We have previously shown that MHz frequency ultrasound causes contraction of the carotid artery in vitro. We now extend this investigation to equine mesenteric arteries and investigate the cellular mechanisms. In vitro exposure of the large lateral cecal mesenteric artery to 4-min periods of 3.

Three-dimensional ultrasound imaging of mammary ducts in lactating women: a feasibility study.

Objective: The main function of the breast is to produce milk for offspring. As such, the ductal system, which carries milk from the milk-secreting glands (alveoli) to the nipple, is central to the natural function of the breast. The ductal system is also the region in which many malignancies originate and spread.

Ultrasound-induced contraction of the carotid artery in vitro.

Ultrasound is known to produce a range of nonlethal responses in cells and tissues. Frequencies in the kilohertz ultrasound range have been shown to produce relaxation in large arteries. The present work explores the effects of insonation at MHz frequencies, representative of those used diagnostically and therapeutically, in an in vitro preparation of the carotid artery.

Hazards, risks and safety of diagnostic ultrasound.

The safety of exposure to diagnostic ultrasound is evaluated using a structured approach to risk assessment, based on the acoustic output of present ultrasound scanners. Thermal hazard is described, the magnitude and probability of temperature rise is reviewed, and the severity of harm from any outcome is reviewed. Similar assessments are made separately for acoustic cavitation and gas-body effects, which have previously been considered together.

Fetal thermal effects of diagnostic ultrasound.

Processes that can produce a biological effect with some degree of heating (ie, about 1 degrees C above the physiologic temperature) act via a thermal mechanism. Investigations with laboratory animals have documented that pulsed ultrasound can produce elevations of temperature and damage in biological tissues in vivo, particularly in the presence of bone (intracranial temperature elevation). Acoustic outputs used to induce these adverse bioeffects are within the diagnostic range, although exposure times are usually considerably longer than in clinical practice.

Transient elastography using impulsive ultrasound radiation force: a preliminary comparison with surface palpation elastography.

The use of impulsive acoustic radiation force for transient strain imaging was investigated and compared with conventional elastography. A series of experiments were performed to evaluate the performances of the technique on gelatine phantoms containing inclusions and to determine a range of applications where radiation force elastography may be useful compared with static elastography. Slip boundaries and cylindrical inclusions of varying elastic modulus were placed in background materials.

Medical and non-medical protection standards for ultrasound and infrasound.

Protection from inappropriate or hazardous exposure to ultrasound is controlled through international standards and national regulations. IEC standard 60601 part 1 establishes requirements for the mechanical, electrical, chemical and thermal safety for all electro-medical equipment. The associated part 2 standard for diagnostic medical ultrasonic equipment sets no upper limits on ultrasonic exposure.

Elastography for breast cancer diagnosis using radiation force: system development and performance evaluation.

The use of impulsive acoustic radiation force for strain imaging was investigated. A focused ultrasound transducer was used to apply localized radiation force to a small volume of tissue mimic (100 mm3) for durations of 8 ms. A conventional real-time ultrasound imaging probe was used to obtain echo signals.

Broadband attenuation and nonlinear propagation in biological fluids: an experimental facility and measurements.

The design and construction of a versatile experimental facility for making measurements of the frequency-dependence of attenuation coefficient (over the range 1 MHz to 25 MHz) and nonlinear propagation in samples of biological fluids is described. The main feature of the facility is the ability to perform all of the measurements on the same sample of fluid within a short period of time and under temperature control. In particular, the facility allows the axial development of nonlinear waveform distortion to be measured with a wideband bilaminar polyvinylidene difluoride membrane hydrophone to study nonlinear propagation in biological fluids.

Broadband measurements of the frequency dependence of attenuation coefficient and velocity in amniotic fluid, urine and human serum albumin solutions.

The frequency dependence of attenuation coefficient in amniotic fluid, urine and 4.5% and 20% human serum albumin solutions over the frequency range 5 MHz to 25 MHz was measured at both room temperature and physiological temperature using a variable path length technique. A 15 MHz (13 mm diameter) transducer was used to produce a broadband single-cycle pulse and a 4 mm diameter bilaminar polyvinylidene difluoride membrane hydrophone was used to detect the attenuated pulse.

The cooling effect of liquid flow on the focussed ultrasound-induced heating in a simulated foetal brain.

There is a need to investigate the thermal effects of diagnostic ultrasound (US) to assist the development of appropriate safety guidelines for obstetric use. The cooling effect of a single liquid flow channel was measured in a model of human foetal brain and skull bone heated by a focussed beam of simulated pulsed spectral Doppler US. Insonation conditions were 5.

Ultrasound-induced heating in a foetal skull bone phantom and its dependence on beam width and perfusion.

The cooling effect of single and multiple perfusing channels has been measured in a model of human foetal skull bone heated by wide and narrow beams of simulated pulsed spectral Doppler ultrasound (US). A focussed transducer operating with a centre frequency of 3.5 MHz, that emitted pulses of 5.

Nonlinear acoustics in diagnostic ultrasound.

The propagation of ultrasonic waves is nonlinear. Phenomena associated with the propagation of diagnostic ultrasound pulses cannot be predicted using linear assumptions alone. These include a progressive distortion in waveform, the generation of frequency harmonics and acoustic shocks, excess deposition of energy and acoustic saturation.