Radioactive Xenon Gas Research Articles

Design and development of radioactive xenon gas purification and analysis system based on molecular sieves

The dynamic adsorption of xenon on molecular sieve packed columns was investigated. The modified Wheeler-Jonas equation was used to describe adsorption parameters such as adsorption capacity and adsorption rate coefficient. Different experimental conditions were accomplished to study their effects and to touch appropriate adsorbing circumstances. Respectable consistency was reached between experimental and modeled values. A purification and analysis setup was developed for radioactive xenon gas determination. Standard sample analysis results approved acceptable quantification accuracy.

Burn survivors' pulmonary and muscular impairment, exercise tolerance and return-to-work following medical-vocational rehabilitation: A long-term follow-up.

To follow up the long-term outcome in return-to-work (RTW) rate in burn-injury patients, and to determine the degree of impairment in pulmonary and muscular function and exercise tolerance. A prospective, longitudinal follow-up study without a control group. Twenty-five burn-injury patients referred for medical-vocational rehabilitation. Return-to-work rate was followed after completed medical-vocational rehabilitation. Pulmonary function was evaluated with spirometry, diffusing capacity and radio spirometry. Exercise capacity was determined using a bicycle ergometer. Muscle functions evaluated in the arms and legs were: isokinetic torque, isometric strength, endurance and muscular strength utilization. Return-to-work rate was 87%. During bicycle exercise tests the patients, on average, reached their expected workloads. The dominating lung func-tion abnormality observed on lung scintigraphy was delayed wash-out time of inhaled radioactive xenon gas, suggesting airway obstruction. All tests of shoulder-flexor and knee-extensor muscle function showed large minimum-maximum differences. Mean isometric endurance of shoulder flexors was lower than mean of references, and isokinetic knee extensor torques were slightly lower. High return-to-work rates can be achieved after burn injury requiring hospital-ward care. Despite measurable impairments in muscle strength/endurance and pulmonary function in a substantial proportion of these patients, overall normal bicycle exercise capacity was observed except for a few cases.

A cost-effective and versatile xenon gas dispenser

To modify a commercial xenon gas dispenser so that two xenon unit-dose vials could be combined with a modified dispenser to deliver a recommended dose. To maintain the same operating mechanism, changes were made only to the vial shield and the needle port of the original gas dispenser. The modified gas dispenser consisted of two puncture needles and two vial holders shielded with the same thickness of lead as the commercial dispenser. Our evaluation showed that the modified gas dispenser operated the same way as the commercial unit, and the average 133Xe residual activity in either one or two xenon unit-dose vials of the modified gas dispenser was not significantly different from that in one vial of the commercial xenon gas dispenser. The modified xenon gas dispenser allows the stock of xenon gas vials to be managed cost-effectively. The modified unit can be used to dispense two low-activity xenon gas vials to deliver a standard dose to a patient. Also, the modified gas dispenser can be used to combine different amounts of xenon activity in two unit-dose vials in order to customize the dose delivered to patients with special needs (e.g., obese patients). Our modified device can also function as a single-dose dispenser by placing an empty vial alongside the unit-dose vial of radioactive xenon gas.

キセノンガスによる中耳換気の研究 正常人について

The ventilation and clearance of the middle ear were measured by radioisotope imaging techniques in order to gain a clear picture of the mechanism of ventilation. Radioactive xenon gas was insufhated into the middle ear of 9 normal subjects via the Eustachian tube, and observed by scinti camera. The volume was calculated with the passage of time. Approximately 11% of the insufflated gas immediately entered into the middle ear cavity and mastoid air cells in spite of the fact that the middle ear and mastoid air cells are a closed cavity. The gas in the middle ear diminished at a rate of 6% of volume per hour and it was thought to be absorbed mainly into the middle ear mucosa at a regular rate in the resting state.

Factors affecting the trapping performance of xenon holdup--filters in nuclear medicine applications.

Activated charcoal traps are used in nuclear medicine departments to capture exhaled radioactive xenon gas. In the present study, the trapping performance of charcoal was investigated for different physical qualities in experimental and clinical situations. Various factors affecting the trapping capacity are identified, such as the charcoal mass, moisture and carbon-dioxide concentrations in the sweep gas, gas-flow rate through the trap, and temperature. Improper drying of the exhaled air prior to passage through the charcoal bed appears to be a critical factor, leading to a much earlier breakthrough of xenon. Commercial xenon traps intended for ambient temperature operation were found to be useful only for a limited number of patients due to an early breakthrough point. By refrigerating the trap, however, a much larger capacity was achieved. If correctly managed, xenon traps constitute a useful alternative for isolating radioactive xenon wastes in clinical and experimental applications.

Measurement of the rate of diffusion of radioactive xenon in human dental plaque in vitro

The diffusion characteristics of dental plaque from four different subjects were examined. An estimate of the diffusion coefficient of radioactive xenon gas, 133Xe, in plaque was found by monitoring the clearance of this gas from a thin layer of plaque. The mean value for the diffusion coefficient, ± standard error, was (7.2 ± 0.2) × 10 −6cm 2 s −1, with no apparent subject-to-subject variation. It is concluded that plaque does not present a significant physical barrier to the diffusion of small uncharged species.

The autofluoroscope and 133-Xe in dynamic studies of pulmonary perfusion and ventilation.

Abstract Rapid serial images of the lungs were obtained during the intravenous administration of a 123Xe solution. Areas of retarded inflow were indicated even though the eventual perfusion level was normal. Further serial images during breathing showed ventilatory washout of radioactive xenon gas from the perfused areas. Four cases of the 17 studies are illustrated.

A device for dispensing radioactive xenon gas.

A number of technics have been described for extracting radioactive xenon gas from glass shipping vials and quantitatively dispensing and dissolving it in physiological saline (1, 2). In large institutions, where 133Xe is widely used as an indicator of blood flow and regional ventilation, the quantity of gas which can be obtained in a single glass shipping vial is usually insufficient. Curie quantities of 133Xe can be obtained from the Oak Ridge National Laboratories, Tenn., in cylinders which have internal volumes from 10 to 50 cc at a gas pressure of approximately 10 mm Hg. This communication describes a device which has been designed and constructed to readily dispense 133Xe from these gas cylinders. High purity CO2 is used to fill the 133Xe cylinder to a pressure of three atmospheres. This enables a small quantity of the 133Xe-CO2 gas mixture to be readily withdrawn from the cylinder through a micrometer needle valve. Carbon dioxide is used as the pressurizing gas since a Xe-CO2 mixture can be more readily dissolved in saline for intravenous injection than can a Xe-air mixture. A circuit diagram of the device is illustrated in Figure 1, and the actual unit is shown in Figure 2. A full cylinder of 133Xe is rigidly held in a large metal ring by means of three positioning screws. Before this cylinder is attached to the dispensing unit, air is flushed out of the unit with CO2 The xenon cylinder is then attached to the dispensing device by means of the Swagelok connector, and the system is sealed. Opening of the tank shut-off valve and the filling valve allows gas from the CO2 cylinder to fill the 133Xe cylinder to a pressure of three atmospheres. After closure of the filling valve, the circuit is ready for dispensing radioactive gas. To extract 133Xe from the unit, a syringe and stopcock are attached to the stopcock on the unit, and a bubble of radioactive gas is slowly expelled into the syringe by opening the micrometer needle valve. The amount of 133Xe dispensed can be measured by placing the syringe inside a calibrated well-type ionization chamber. Radioactive xenon gas which is to be used in a closed-circuit spirometer system can be taken up into a Hamilton gas-tight syringe for transfer. For intravenous injection, a bubble of the 133Xe-CO2 mixture can be taken up into a 20-cc syringe containing a volume of sterile saline, in which most of the gas will readily dissolve. Aliquots of xenon-saline for injection can be taken out of the syringe through the three-way stopcock. The physical layout of the dispensing unit is shown in Figure 2. The xenon gas cylinder and the dispensing syringe are mounted behind a lead and stainless-steel barrier.

Postural effect on regional ventilation.

Postural effects on regional ventilation were studied in nine normal subjects using radioactive xenon gas. Two scintillation detectors were mounted on two precordial spots on the right and left lungs, and regional ventilation was assessed on the same spots in the supine position and the right and left lateral decubitus positions. Regional total lung capacity (TLCr) and regional turn-over rate increased in the dependent lung in the lateral decubitus positions, whereas regional functional residual capacity (FRCr) decreased in the dependent lungs. Regional 50% wash-out time was always shorter in the dependent lung than that in the superior lung, although there was no appreciable difference in the right and left lungs in the supine position.