Osamu Matsuoka

Retention of 133Ba in the Trachea of Rabbits, Dogs, and Monkeys Following Local Administration As133BaSO4 Particles

AbstractThe retention of 133Ba in the trachea from intratracheally administered 133BaSO4 particles was determined in rabbits, dogs, and monkeys. A significant retention of Ba in the trachea was observed with two peaks in these three animal species 1 week after administration. The first peak in the cranial region of the trachea corresponded to the approximate position of the tracheostomy and the second peak in the caudal trachea corresponded to the approximate position of the tip of the cannula. The amount of 133Ba retained 1 week after injection in the caudal region of trachea, which indicated the physiological retention of particles in the airway wall, was 0.145, 0.044, and 0.043% of the initial injection dose for rabbits, dogs, and monkeys, respectively. These retention rates were much lower than those measured in a previous rat study. If experimental conditions of anesthesia and relative injection dose (e.g., the amount of 133BaSO4 per surface area of the tracheal lumen) did not affect particle retenti...

An investigation to assess which component in the air is concerned with the vacuum effect on plastic track detector sensitivity

Abstract It has recently been found that the storage of plastic track detectors in vacuum prior to irradiation decreases the track registration sensitivity. We tested the main gases composing the air: nitrogen, oxygen and water vapour, to assess whether they could recover the sensitivity of the detector once decreased after it had been stored in a vacuum, adopting as intermediate criterion of detector sensitivity the diameters of etch pits left by normally-incident α-particles. The present results demonstrate that oxygen itself is concerned with the vacuum effect on plastic track detectors.