This study characterized the acoustic properties of an International Electromechanical Commission (IEC) agar-based tissue mimicking material (TMM) at ultrasound frequencies in the range 10–47 MHz. A broadband reflection substitution technique was employed using two independent systems at 21°C ± 1°C. Using a commercially available preclinical ultrasound scanner and a scanning acoustic macroscope, the measured speeds of sound were 1547.4 ± 1.4 m∙s−1 and 1548.0 ± 6.1 m∙s−1, respectively, and were approximately constant over the frequency range. The measured attenuation (dB∙cm−1) was found to vary with frequency f (MHz) as 0.40f + 0.0076f2. Using this polynomial equation and extrapolating to lower frequencies give values comparable to those published at lower frequencies and can estimate the attenuation of this TMM in the frequency range up to 47 MHz. This characterisation enhances understanding in the use of this TMM as a tissue equivalent material for high frequency ultrasound applications.
Non-invasive detection, localization and characterization of an arterial stenosis (a blockage or partial blockage in the artery) continues to be an important problem in medicine. Partial blockage stenoses are known to generate disturbances in blood flow which generate shear waves in the chest cavity. We examine a one-dimensional viscoelastic model that incorporates Kelvin-Voigt damping and internal variables, and develop a proof-of-concept methodology using simulated data. We first develop an estimation procedure for the material parameters. We use this procedure to determine confidence intervals for the estimated parameters, which indicates the efficacy of finding parameter estimates in practice. Confidence intervals are computed using asymptotic error theory as well as bootstrapping. We then develop a model comparison test to be used in determining if a particular data set came from a low input amplitude or a high input amplitude; this we anticipate will aid in determining when stenosis is present. These two thrusts together will serve as the methodological basis for our continuing analysis using experimental data currently being collected.Mathematics Subject Classification: 62F12; 62F40; 65M32; 74D05.
Introduction For many patients, audio-visual appointments have provided a timely and efficient way of seeking advice, assessment and treatment for their hand injuries during the NHS response to COVID-19. This study aimed to explore the experience of hand units across the UK in determining the safe and judicious use of audio-visual outpatient care for the management of acute upper limb trauma. Methods An online cross-sectional survey was sent to the therapy leads of hand units across the UK. Questions focused on the experience of using audio-visual technology in the management of upper limb trauma, and the relevant factors in determining its appropriate use. A deductive mixed methods analysis was used to identify both common themes and capture community experience and characteristics. Results A total of 51 out of 76 hand therapy units completed the survey; a response rate of 67%. Of these, 82% (42/51) reported using audio-visual technology to manage upper limb trauma during the UK COVID-19 lockdown. When determining patient suitability for audio-visual consultations, 73% (37/51) of respondents reported the use of COVID-19 guidelines, but only 35% (18/51) reported the use of a clinical decision-making tool. In agreement with our experience at Salisbury Hospital Foundation Trust, 92% (47/51) had concerns relating to the use of audio-visual care. Conclusion The choice of safely managed remote care or in-person consultation has, to date, largely relied on the discretion of the clinician. A carefully designed clinical decision-making tool for the management of upper limb trauma is needed for use both in clinical practice and in future service planning.
The output energies from a range of cutaneous laser systems have been shown to vary considerably between a representative test patch and a full treatment, and over the course of an entire simulated clinic list.
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