P. N. T. Wells

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The growth of a malignant tumour depends on vascularisation. The ultrasonic Doppler method can detect the blood flow associated with malignant breast tumours, the signals differing qualitatively from those due to benign lesions. Several descriptors of the Doppler signals were tested; benign and malignant lesions are best separated by the difference between(More)
The feasibility of studying ovarian arterial blood flow has been demonstrated, using an ultrasonic method combining real-time imaging and pulsed Doppler (the 'duplex' method). Results using a percutaneous full-bladder technique were validated by comparison with use of an ultrasound probe applied directly to the arteries at laparotomy. The ovarian arteries(More)
After X-radiography, ultrasound is now the most common of all the medical imaging technologies. For millennia, manual palpation has been used to assist in diagnosis, but it is subjective and restricted to larger and more superficial structures. Following an introduction to the subject of elasticity, the elasticity of biological soft tissues is discussed and(More)
Ultrasonic imaging is a mature medical technology. It accounts for one in four imaging studies and this proportion is increasing. Wave propagation, beam formation, the Doppler effect and the properties of tissues that affect imaging are discussed. The transducer materials and construction of the probes used in imaging are described, as well as the methods(More)
Ultrasonic pulsed-Doppler signals from deep-lying vessels in the normal abdomen and pelvis are described. The signal characteristics combine to produce a Doppler "signature" that is specific for each vessel. The clinical potential of this method of deep flow detection is considered in relation to three areas of Doppler signal analysis: first, qualitative(More)
Real-time ultrasonic colour flow imaging, which was first demonstrated to be feasible only about a decade ago, has come into widespread clinical use. Ultrasound is scattered by ensembles of red blood cells. The ultrasonic frequency that gives the best signal-to-noise ratio for backscattering from blood depends on the required penetration. The frequency of(More)
The history of the development of the applications of physics and engineering in medicine provides an insight into contemporary practice and can help to mould the future. Physics and engineering form a continuum, and, in the present context, engineering is indistinguishable from applied physics. The modern scientific era, which extends over 500 years, is(More)
Optical experiments are described for measuring the attenuation characteristics of breast tissues at visible and near-infrared wavelengths. Total attenuation coefficients post mortem were measured directly in thin tissue sections. They are usually within the range from 10 to 30 mm-1, are rather higher in fat than in fibroglandular specimens and decrease(More)