Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Xenon Radioisotopes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

The measurement of arterial perfusion of the liver in man using the radioisotope xenon-133.

The washout from the liver of xenon-133 injected into the thoracic aorta of human subjects undergoing cardiac investigation was monitored externally with a sodium iodide scintillation detector. The washout curve displayed an initial peak of activity, followed by a brief decline, and then a second, slower rise. The initial peak was thought to be due to isotope arriving in the liver via the hepatic artery, and the second rise due to isotope arriving via the portal vein. A method of analysis is presented which uses the height of this arterial peak to calculate arterial perfusion of the liver.

Hepatic Artery↗

[Dynamic radioisotope studies of the regional functions of the lung (a preliminary report)].

A critical analysis on the non-isotope method potentiallities is presented in the paper as well as the radioisotope xenon mode for examinations of gas ventilation and diffusion. The advantages of 133xenon are listed, the main being as follows: regional investigation parallelly in four zones, completely safe for the patient without loading procedures, precision and availability for mass investigations. The authors recommend its wider application in practive, based on a great many radioisotope investigations of healthy and sick individuals.

Bronchial Spasm↗

Atmospheric xenon radioactive isotope monitoring.

The Comprehensive Nuclear Test Ban Treaty (CTBT) organisation is implementing a world-wide monitoring network in order to check that the State Signatories comply with the treaty. One of the monitoring facilities consists of an atmospheric noble gas monitoring equipment. According to the requirements annexed in the treaty, the French Atomic Energy Commission (CEA) developed a device, called SPALAX, which automatically extracts xenon from ambient air and makes in situ measurements of the activities of four xenon radioisotopes (131mXe, 133mXe, 133Xe, 135Xe). The originality of this device is noticeable essentially in the gas sample processing method: thanks to the coupling of a gas permeator and of a noble gas specific adsorbent, it can selectively extract and concentrate xenon to more than 3 x 10 E6. This process is carried out continuously without cryogenic cooling, without any regeneration time. The detection of the xenon radioactive isotopes is done automatically by high spectral resolution gamma spectrometry, a robust technology well-suited for on-field instrumentation. In the year 2000, a prototype was involved in an international evaluation exercise directed by the CTBT organisation (CTBTO). This exercise demonstrated that the SPALAX equipment perfectly met the requirements of the CTBTO for such systems. On the basis of the continuous 24-h resolution record of the atmospheric xenon radioactive isotopes concentrations, the SPALAX system also demonstrated that ambient levels of 133Xe can fluctuate quickly from less than the detection limit to over 40 x 10(-3) Bq m(-3). In order to build an industrial version of this equipment, the CEA entered into a partnership with a French engineering company (S.F.I., Marseille, France), which is now able to produce an industrial version of SPALAX, i.e. more compact and more efficient than the prototypes. The 133Xe minimum detectable concentration is 0.15 x 10(-3) Bq m(-3) air per 24 h sampling cycle.

Air Pollutants, Radioactive↗

Chernobyl retrospective.

On April 28, 1986 heavy radioactive fallout from an unknown source was reported from Sweden. Later, it was discovered that two days earlier, a nuclear power reactor at Chernobyl, in the Soviet Union, had exploded releasing an enormous cloud of effluent containing 40 million Ci of 131I, 3 million Ci of 137Cs, and 50 million Ci of xenon radioisotopes. This far exceeded the 15 Ci of 131I escape in the notorious Three Mile Island accident. Chernobyl reactor IV, of an antiquated design, was a graphite-moderated reactor which suffered a steam explosion when the operating staff attempted an experiment involving preservation of safety functions during a planned shutdown. Following the explosion, a fire started in the graphite core which required ten days to control. Thirty-one persons died, two in the initial explosion and 29 of various combinations of thermal and radiation burns, and gamma irradiation. Existing emergency plans were invoked involving treatment on the scene and evacuation of seriously injured patients to a special hospital in Moscow, as well as to nearby Kiev. Later, 135,000 residents of the immediate neighborhood were surveyed and evacuated after fallout radiation levels began to rise. Fallout patterns around Europe and the northern hemisphere were closely tracked. Consequences of the accident in human and monetary terms will require years of evaluation. Although the United States has no power reactors of the Chernobyl type, the country does have a radiation disaster management plan, often rehearsed at the state level. As a consequence of Chernobyl certain international agreements dealing with radiation disaster information and management have been forged.

Accidents↗

The release rate of 37Ar from human subjects following intravenous injection.

Two measurements of the exhalation rate of 37Ar following an intravenous bolus injection have been made on a volunteer, and compared with the exhalation rate of 133Xe for the same subject. The results are also compared with a previously reported pilot 37Ar injection study on a second volunteer. During the first 100 min following injection, the 37Ar washout rate was shown to resemble closely the 133Xe washout rate. This result shows that for short time periods after injection, the behaviour of 133Xe may be used to predict 37Ar behaviour.

Argon↗

A Monte Carlo program to calculate the exposure rate from airborne radioactive gases inside a nuclear reactor containment building.

A program was developed to calculate the exposure rate resulting from airborne gases inside a reactor containment building. The calculations were performed at the location of a wall-mounted area radiation monitor. The program uses Monte Carlo techniques and accounts for both the direct and scattered components of the radiation field at the detector. The scattered component was found to contribute about 30% of the total exposure rate at 50 keV and dropped to about 7% at 2000 keV. The results of the calculations were normalized to unit activity per unit volume of air in the containment. This allows the exposure rate readings of the area monitor to be used to estimate the airborne activity in containment in the early phases of an accident. Such estimates, coupled with containment leak rates, provide a method to obtain a release rate for use in offsite dose projection calculations.

Accidents↗

Placental transfer of radiopharmaceuticals and dosimetry in pregnancy.

The calculation of radiation dose estimates to the fetus is often important in nuclear medicine. To obtain the best estimates of radiation dose to the fetus, the best biological and physical models should be employed. In this paper the most recent data available on the placental crossover of many radiopharmaceuticals are presented. This information was used with standard kinetic models describing the maternal distribution and retention and with the best available physical models to obtain fetal dose estimates for these radiopharmaceuticals at all stages of pregnancy (presented in a separate paper). The literature yielded information on placental crossover of 15 radiopharmaceuticals, from animal or human data. From these data, radiation dose estimates were developed in early pregnancy and at 3, 6, and 9 mo gestation for these radiopharmaceuticals, as well as for many others used in nuclear medicine (the latter considering only maternal organ contributions to fetal dose).

Adult↗

Methods for assessment of the effect of drugs on cerebral blood flow in man.

The cerebral circulation is not an unimportant vascular bed but it is difficult one to investigate. Methodological difficulties are the main reasons for the paucity of clinical pharmacology studies to date. Of the methods currently available those of the McHenry (1964) and Wyper et al. (1976) appear to be the most useful to the clinical investigator. Increasing use of multiple detectors even with inhalation techniques may give evidence of regional drug effects upon the cerebral circulation. Improvements in methodology in the last few years, particularly the development of atraumatic methods are likely to act as an important spur to research in this field.

Cerebrovascular Circulation↗