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Biomedical subjects

R C Chivers

Publications and source records attributed to R C Chivers.

13 recordsLinked to original sources
PubMed1978

Ultrasonic velocity and attenuation in mammalian tissues.

A compilation, from the original papers, is presented of the data on the acoustic properties (i.e., velocity and attenuation) of mammalian tissues in the megahertz range of frequencies used in medical ultrasonics. The actual values reported have been quoted to present a clear picture of the current state of knowledge in order to enable it to be assessed and to enable future workers to compare their own results directly. In the 20 years since the last such compilation, the progress in estimating the relative contributions of the animal species, the condition of the tissues, the temperature and frequency at which measurements were made, and the method of measurement to the observed variation has been small. It is hoped that this compilation together with summarizing tables will both be of practical use to the worker in the field and also encourage the establishment of a stronger body of fundamental information for the application of ultrasonics in biology and medicine.

Absorption↗
PubMed1976

The preparation, use, and evaluation of recorded material for teaching ultrasonics in a university Master of Science course in medical physics.

The potential value of using recorded instructional material in a university Master's course module in medical ultrasonics is discussed. The procedure for preparation and evaluation of a program of slides with synchronized audio tape is reported. The evaluation indicates that the flexibility of this form of recorded material can make several unique contributions to the teaching program, in acquainting students with clinical problems, in simulating expensive equipment, and encouraging students to use the literature.

Audiovisual Aids↗
PubMed1976

Measurement of ultrasonic exposure with radiation force and thermal methods.

It is the purpose of this paper to discuss briefly the factors that influence the interaction of the ultrasonic field and medium being irradiated, and to collect together the various techniques that have been suggested for measuring energetic parameters of the ultrasonic field. The calorimetric and radiation force methods are then discussed in more detail. The former is discussed as a technique whose capabilities have not been fully exploited while the latter demands attention both because of its simplicity and its controversial theoretical basis. Areas in which further work is needed are indicated in the summary and conclusion. It is hoped that the paper will be of practical use to workers in the field.

Calorimetry↗
PubMed1975

A spectral approach to ultrasonic scattering from human tissue: methods, objectives and backscattering measurements.

The dearth of information on the physical processes involved in the propagation of ultrasound in tissue and the growing need for such information are discussed. The physical nature of the ultrasonic diagnostic process in considered in terms of a wave phenomenon and the limitations and advantages of frequency spectral analysis as a means of obtaining information are briefly analysed. A description is given of an experimental measuring system using a time-gate to select echoes scattered from a particular volume at a depth in soft tissues. The influence of attenuation by overlying tissue and the choice of the duration of the acceptance gate on the frequency spectra obtained are considered. The paper reports some backscattering measurements on formalin-fixed samples of human fat, liver and spleen in the frequency range 0-5-5-0 MHz. The results suggest that the approach may have diagnostic value in a clinical situation, in the characterization of structure in specific volumes of soft human tissue.

Adipose Tissue↗