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Biomedical subjects

A J Cousin

Publications and source records attributed to A J Cousin.

16 recordsLinked to original sources
PubMed1987

The case for radioprotective eyewear/facewear. Practical implications and suggestions.

Numerous eyeglass lens materials have been recommended for protection of radiologists' eyes from the cataractogenic effect of radiation during fluoroscopic procedures. For the most part, these lenses coincidentally attenuate x-ray beams because they contain elements of high atomic number that are added to increase refractive index. With a bean hardened to simulate scatter, direct transmission ratios were measured for 32 commercially available lens materials. Scatter to the eye, both through and around the glass lenses and secondary scatter to the eye from the radiologist's head, was determined with lenses mounted on a head phantom and a 1-cm3 ion chamber in the position of the eye. Transmission ratios for the various lenses ranged from 3% to 98% for an 80 kVp x-ray beam (HVL = 4.5 mm Al). Measurements with the head phantom in place show that secondarily scattered radiation from the fluoroscopist's head contributes significantly to ocular exposure. Optimal radiation protection of the eyes during fluoroscopy depends not only on eyeglasses with leaded glass, but also on shielding of sufficient size and shape to reduce exposure to the surrounding head.

Cataract↗
PubMed1986

New cineradiographic methods for assessment of Bjork-Shiley valve integrity.

The Bjork-Shiley prosthesis has been used extensively for valvular replacement since 1969. Despite its widespread use, it is subject to complications that can be assessed with cineradiography. New methods are presented for assessment of incomplete closing and opening angles that occur with valvular malfunction. Alternative methods of cineradiographic measurement are compared with each other and with the new method. The new method is an appropriate alternative when the conventional double-profile method cannot be used and distributes the burden of performance and complexity between the technologist and radiologist. This new method is shown to be accurate to within 1 degree.

Aortic Valve↗
PubMed1983

Ultrasonic measurement of rate and depth of human fetal breathing: effect of glucose.

A recently developed ultrasonic tracking device was used to determine the effect of maternal intravenous glucose infusion on amplitude and frequency of breathing movements in six healthy human fetuses at 38 to 40 weeks' gestation. Following a 2-hour observation period, an intravenous injection of either 25 gm of a 50% glucose solution or an equal volume of saline was given to the mother. Observations were continued for a further 4 hours. Fetal rib cage and abdominal diameters were measured continuously with the ultrasonic tracking device and the information was recorded on a strip chart recorder for later analysis. Breath interval and incidence measurements were highly correlated with data obtained by an independent technique (r greater than or equal to 0.90). During the first 80 minutes after glucose injection, total fetal trunk movement recorded during breathing movements increased from 1.5 +/- 0.2 to 2.9 +/- 0.4 mm (P less than 0.05). There was no significant change in the frequency or variability of fetal breathing movements after glucose infusion.

Blood Glucose↗
PubMed1980

Rhythmic fetal movements.

In recent years, studies have confirmed that rhythmic movement of the fetal torso occurs. These movements have been investigated with respect to a large number of factors, but no conclusive evidence of their significance has been documented. Much effort has been directed at developing better methods of measuring these movements. In this paper, examples of preliminary clinical results utilizing an advanced real-time B-scan phase-locked tracking scheme are presented. These traces represent a significant advancement in our ability to record rhythmic fetal torso movements and should enable us to enhance our knowledge of the physiology and clinical significance of this phenomenon.

Adult↗