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Results for “RADIATION MONITORING”

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At least 145 records · Page 8Linked to original sources
PubMed2000

The effects of internal radiation exposure on cancer mortality in nuclear workers at Rocketdyne/Atomics International.

We examined the effects of chronic exposure to radionuclides, primarily uranium and mixed-fission products, on cancer mortality in a retrospective cohort study of workers enrolled in the radiation-monitoring program of a nuclear research and development facility. Between 1950 and 1994, 2,297 workers were monitored for internal radiation exposures, and 441 workers died, 134 (30.4%) of them from cancer as the underlying cause. We calculated internal lung-dose estimates based on urinalysis and whole-body and lung counts reported for individual workers. We examined cancer mortality of workers exposed at different cumulative lung-dose levels using complete risk-set analysis for cohort data, adjusting for age, pay type, time since first radiation monitored, and external radiation. In addition, we examined the potential for confounding due to chemical exposures and smoking, explored whether external radiation exposure modifies the effects of internal exposure, and estimated effects after excluding exposures likely to have been unrelated to disease onset. Dose-response relations were observed for death from hemato- and lymphopoietic cancers and from upper aerodigestive tract cancers, adjusting for age, time since first monitored, pay type, and external (gamma) radiation dose. No association was found for other cancers, including cancers of the lung. Despite the small number of exposed deaths from specific cancer types and possible bias due to measurement error and confounding, the positive findings and strong dose-response gradients observed suggest carcinogenic effects of internal radiation to the upper aerodigestive tract and the blood and lymph system in this occupational cohort. However, causal inferences require replication of our results in other populations or confirmation with an extended follow-up of this cohort.

California↗
PubMed2005

Neutron radiation area monitoring system for proton therapy facilities.

A neutron radiation area monitoring system has been developed for proton accelerator facilities dedicated to cancer therapy. The system comprises commercial measurement equipment, computer hardware and a suite of software applications that were developed specifically for use in a medical accelerator environment. The system is designed to record and display the neutron dose-equivalent readings from 16 to 24 locations (depending on the size of the proton therapy centre) throughout the facility. Additional software applications provide for convenient data analysis, plotting, radiation protection reporting, and system maintenance and administration tasks. The system performs with a mean time between failures of >6 months. Required data storage capabilities and application execution times are met with inexpensive off-the-shelf computer hardware.

Equipment Design↗
PubMed2003

[Summing up the 5-year monitoring of morphology and function of the stomatognathic system in children exposed to radiation].

Monitoring of the maxillodental system in children born and living in regions contaminated by radiation as a result of the Chernobyl accident was carried out in 1997-2002 within the framework of Federal Program "Children of Russia", section "Chernobyl Children". Analysis of 5-year changes in the maxillodental morphology and function showed a trend to improvement: the prevalence of normal-for-age status increased and the parameters of maxillodental function normalized.

Child↗
PubMed1999

Robotic recovery of highly radioactive resin.

As the ALARA coordinator at Waterford 3 Nuclear Steam Electric Station, I have seen radiological challenges in many forms. Some are handled as routine with little effort, while others can severely challenge even the finest Health Physics staff. One such event occurred on 26 December 1997, during a routine recirculation of the Spent Resin Tank, when contents of an unknown origin spilled from the tank. Technicians performing initial actions to contain the spill monitored radiation levels of 5-20 rem h21 (50-200 mSv) at waist level. Based on photographs and visual accounts it was estimated that approximately 30-40 ft3 (0.57-1.12 m3) of resin had spilled into the pump room. A sample of the resin indicated that dose rates at the floor would exceed 100 rem h21 (1 Sv h21). It was clear, given the volume of material spilled and dose rates in the room, that robots would be required for any type of recovery effort. This presented another problem in that Waterford 3 did not own a robot, and we had no experience in this area.

Cost-Benefit Analysis↗
PubMed2006

Self-indicating radiation alert dosemeter (SIRAD).

In an event of a nuclear or dirty bomb explosion and a radiological accident, there is a need for self-indicating instant radiation dosemeter for monitoring radiation exposure. The self-indicating instant radiation alert dosemeter (SIRAD) is a credit card size radiation dosemeter for monitoring ionising radiation from a few hundredths of a Gray to a few Gray. It is always active and is ready to use. It needs no battery. The dosemeter develops colour instantly upon exposure, and the colour intensifies with dose. It has a colour chart so that the dose on the active element may be read by matching its colour with the chart that is printed next to it on the card. However, in this work, the dose is measured by the optical density of the element. The dosemeter cannot be reset. The response changes by <1% per degrees C from -20 to +60 degrees C. The shelf-life is >3 y at room temperature. It contains no hazardous materials. The dosemeter would meet the requirements of instantly monitoring high dose in an event of a nuclear or dirty bomb explosion or a radiation accident.

Colorimetry↗
PubMed1991

Monitoring underground radiation fields using powdered calcium sulfate thermoluminescent dosimeters.

Powered thermoluminescent dosimeters, CaSO4:Dy, were used to monitor underground radiation fields. Methods of monitoring at selected sites in Taiwan are described; exposure rates above ground at the monitoring sites are also included for comparison. Differences in exposure rates between above ground at 1 m and underground at -2 m may reach 0.516 nC kg-1 h-1. The key factor affecting exposure rates underground is the water content in soil or precipitation that may reduce the diffusion of Rn. The difference in exposure rates between rainy days and sunny days may reach 0.774 nC kg-1 h-1. An example of applying this monitoring technique at a radwaste repository is given.

Calcium Sulfate↗
PubMed2003

OMINEX: survey of internal dose monitoring programmes for radiation workers.

Monitoring of the workforce in the nuclear industries is carried out primarily in order to demonstrate compliance with European Union (EU) legislation and the Basic Safety Standards for the protection of the health of workers against the dangers arising from ionizing radiation recommended by the International Atomic Energy Agency (IAEA). There is, however, no common strategy for internal dose monitoring programmes currently in use in the EU countries. Surveys have been carried out in which organisations were asked to provide information on the design of their internal dose monitoring programmes and on the costs of these programmes. Information was requested from both EU countries and Associated States. Databases for storage and reporting of all gained information were constructed, and results from the surveys have been compiled. This work was carried out within the EC 5th Framework Programme project, OMINEX, which aims to provide advice and guidance on designing and implementing internal dose monitoring programmes in the workplace in such a way that best use is made of available resources, while minimising costs.

Data Collection↗
PubMed1981

[Monitoring of radiation via CT (author's transl)].

The results presented in this article lead to the conclusion that it would be appropriate to demand control or monitoring of radiation via CT whenever complicated exposure to radiation is required. Such control appears mandatory in order to guarantee a sufficiently high tumour dosage and satisfactory protection or minimum burdening of the surrounding tissue. At first sight, it may seem that such CT operations are relatively costly. However, once the teamwork has been properly established, both the time required and the cost involved remain within reasonable limits and will probably not be greater than control via therapy simulator. The decisive factor is that computerised tomography should offer sufficient possibilities of translating such control into reality by effecting the necessary dosage adjustments in accordance with given requirements.

Esophageal Neoplasms↗
PubMedDate not supplied

[The ID-03 X-ray dosimeter for monitoring the radiation parameters of X-ray equipment in roentgenography].

The paper presents an [symbol: see text]-03 X-ray dosimeter designed by the Research Institute of Introscopy, Spektr Moscow Research-and-Production Association, for monitoring the radiation parameters of X-ray plants at roentgenography. A Si(Li)-based semiconductor detector with the p-i-n structure is used as a detector of X-ray radiation. The technical data of the dosimeter are given.

Equipment Design↗
PubMed2006

Thermoluminescent detectors applied in individual monitoring of radiation workers in Europe--a review based on the EURADOS questionnaire.

Among the activities of EURADOS Working Group 2 formed by experts from several European countries is the harmonisation of individual monitoring as part of radiation protection of occupationally exposed persons. Here, we provide information about thermoluminescent detectors (TLDs) applied by the European dosimetric services and the dosimetric characteristics of dosemeters in which these detectors are applied. Among 91 services from 29 countries which responded to the EURADOS questionnaire, 61 apply dosemeters with TLDs for the determination of personal dose equivalent H(p)(10) for photons and beta radiation, and 16 services use TLDs for neutron albedo dosemeters. Those most frequently used are standard lithium fluoride TLDs (mainly TLD-100, TLD-700, Polish MTS-N and MTS-7, Russian DTG-4), high-sensitive lithium fluoride (GR-200, MCP-N) and lithium borate TLDs. Some services use calcium sulphate and calcium fluoride detectors. For neutron dosimetry, most services apply pairs of LiF:Mg,Ti TLDs with (6)Li and (7)Li. The characteristics (energy response) of individual dosemeters are mainly related to the energy response of the detectors and filters applied. The construction of filters in dosemeters applied for measurements of H(p)(10) and their energy response are also reviewed.

Europe↗
PubMed2004

Intraoperative radiation therapy in liver tissue in a pig model: monitoring with dual-modality PET/CT.

PURPOSE: To assess, in a pig model, the value of dual-modality positron emission tomography (PET)/computed tomography (CT) for monitoring radiation therapy. MATERIALS AND METHODS: Central bile duct resection followed by creation of a biliodigestive anastomosis was performed in nine pigs. Six of these pigs were also treated with intraoperative radiation therapy (IORT) (20 Gy) in the area of the anastomosis. Two, 4, and 8 weeks postoperatively, contrast material-enhanced fluorine 18 fluorodeoxyglucose (FDG) PET/CT of the liver was performed in all of the animals. The radioactive tracer concentration in the region of the anastomosis was quantified, and the values were compared intraindividually with the values at the liver periphery. Histologic evaluation of the liver was performed 8 weeks postoperatively. The PET/CT images were assessed for changes in liver volume and bile duct diameter over time. RESULTS: In all nine pigs, the region of the anastomosis could be clearly defined on the fused PET/CT images. PET/CT revealed a decreased concentration of FDG in the irradiated field 2 and 4 weeks after IORT. At 8 weeks, however, the distribution of the tracer in the irradiated pigs did not differ from that in the nonirradiated pigs. Homogeneous tracer uptake in all liver regions was observed in the nonirradiated animals. The CT images showed an increase in liver volume in all pigs and bile duct dilatation that increased over time in the irradiated pigs. CONCLUSION: The morphologic and functional changes due to IORT in liver tissue can be accurately monitored with dual-modality PET/CT. By enabling the integration of functional and morphologic data, PET/CT may have an important role in monitoring radiation treatment.

Anastomosis, Roux-en-Y↗
PubMed2001

Modeling the extrafocal radiation and monitor chamber backscatter for photon beam dose calculation.

A simple analytical approach has been developed to model extrafocal radiation and monitor chamber backscatter for clinical photon beams. Model parameters for both the extrafocal source and monitor chamber backscatter are determined simultaneously using conventional measured data, i.e., in-air output factors for square and rectangular fields defined by the photon jaws. The model has been applied to 6 MV and 15 MV photon beams produced by a Varian Clinac 2300C/D accelerator. Contributions to the in-air output factor from the extrafocal radiation and monitor chamber backscatter, as predicted by the model, are in good agreement with the measurements. The model can be used to calculate the in-air output factors analytically, with an accuracy of 0.2% for symmetric or asymmetric rectangular fields defined by jaws when the calculation point is at the isocenter and 0.5% when the calculation point is at an extended SSD. For MLC-defined fields, with the jaws at the recommended positions, calculated in-air output factors agree with the measured data to within 0.3% at the isocenter and 0.7% at off-axis positions. The model has been incorporated into a Monte Carlo dose algorithm to calculate the absolute dose distributions in patients or phantoms. For three MLC-defined irregular fields (triangle shape, C-shape, and L-shape), the calculations agree with the measurements to about 1% even for points at off-axis positions. The model will be particularly useful for IMRT dose calculations because it accurately predicts beam output and penumbra dose.

Biophysical Phenomena↗