Effect of plaque brachytherapy dose and dose rate on risk for disease-related mortality in 1238 patients with choroidal melanoma

2020 ◽  
Vol 105 (1) ◽  
pp. 57-62
Author(s):  
Maria Filì ◽  
Eric Trocme ◽  
Christina Herrspiegel ◽  
Stefan Seregard ◽  
Gustav Stålhammar
Keyword(s):  
Radiation Dose ◽  
Dose Rate ◽  
Cox Regression ◽  
Tumour Size ◽  
Choroidal Melanoma ◽  
Radiation Dose Rate ◽  
Dose Rates ◽  
Quartile Group ◽  
Iodine 125 ◽  
Related Mortality

BackgroundEpiscleral brachytherapy is the most common treatment for medium-sized choroidal melanomas. Although controversial, inadequate brachytherapy dose and dose rates have at least a hypothetical implication on patient survival.MethodsAll patients who received ruthenium-106 or iodine-125 brachytherapy for choroidal melanoma at St. Erik Eye Hospital 1996 to 2016 were included (n=1238). Cox regression hazard ratios for melanoma-related mortality across deciles, quartiles and individual integers of apex radiation doses (Gy) and dose rates (Gy/hour) were calculated, adjusted for tumour size and location.ResultsThe average radiation dose at the tumour apex ranged from 73.0 Gy in the first decile to 108.6 Gy in the tenth. Decreasing apex dose by 1 Gy increments or by decile or quartile group was not associated with melanoma-related mortality (p>0.2) The average radiation dose rate at the tumour apex ranged from 0.5 Gy/hour in the first decile to 2.8 Gy/hour in the tenth. Similarly, decreasing apex dose rate by 1 Gy/hour increments or by decile or quartile groups was not associated with melanoma-related mortality (p>0.5).ConclusionThere are no increased hazards for choroidal melanoma-related mortality after brachytherapy with decreasing doses between 108.6 and 73.0 Gy, or with decreasing dose rates between 2.8 and 0.5 Gy/hour.

scholarly journals EVALUATION OF RADIATION DOSE RATE OF RSG-GAS REACTOR

2018 ◽  
Vol 24 (3) ◽  
Author(s):  
Amir Hamzah ◽  
Hery Adrial ◽  
Subiharto Subiharto
Keyword(s):  
Radiation Dose ◽  
Radiation Exposure ◽  
Dose Rate ◽  
Nuclear Reactor ◽  
Area Measurement ◽  
Radiation Dose Rate ◽  
Safety Level ◽  
Modeling And Analysis ◽  
Dose Rates ◽  
Limit Value

EVALUATION OF RADIATION DOSE RATE OF RSG-GAS REACTOR. The RSG-GAS reactor has been operated for 30 years. Since the nuclear reactor has been operated for a long time, aging process on its components may occur. One important parameter for maintaining the safety level of the RSG-GAS reactor is to maintain radiation exposure as low as possible, especially in the working area. The evaluation results should be able to demonstrate that the radiation exposure of the RSG-GAS is still safe for workers, communities and the surrounding environments. The purpose of this study is to evaluate radiation exposure in the working area to ensure that the operation of RSG-GAS is still safe for the next 10 years. The scope of this work is confirming the calculation results with the measured radiation dose in the RSG-GAS reactor working area. Measurement of radiation exposure is done by using the installed equipments at some points in the RSG-GAS working area and a portable radiation exposure measurement equipment. The calculations include performance of a modeling and analysis of dose rate distribution based on the composition and geometry data of RSG-GAS by using MCNP.  The analysis results show that the maximum dose rate at Level 0 m working area of RSG-GAS reactor is 3.0 mSv/h with a deviation of 6%, which is relatively close to the measurement value. The evaluation results show that the dose rate in RSG-GAS working area is below the limit value established by the Nuclear Energy Regulatory Agency of Indonesia (BAPETEN) of 10 mSv/h (for the average effective dose of 20 mSv/year). Therefore, it is concluded that the dose rate in RSG-GAS working area is safe for personnel..Kata kunci: dose rates, RSG-GAS, radiation safety, MCNP.

Development of New Simulation Software System to Evaluate Radiation Dose Rates in a Wide Radioactively Contaminated Area

2012 ◽  
Author(s):  
Tomoharu Hashimoto ◽  
Masahiro Kondo ◽  
Ryuichi Tayama ◽  
Hideho Gamo
Keyword(s):  
Radiation Dose ◽  
Dose Rate ◽  
Gamma Ray ◽  
Simulation Software ◽  
Radiation Dose Rate ◽  
Dose Rates ◽  
Reduce Radiation Exposure ◽  
Radiation Sources ◽  
Reduction Effect ◽  
Contaminated Area

The Japanese government plans to conduct decontamination tasks in radioactively contaminated areas. For such a situation, we developed a system that evaluates radiation dose rates in a wide radioactively contaminated area by utilizing our radiation dose evaluation technology. This system can not only generate present maps of radiation dose rate in the air based on the dose rate measured at the surface of the contaminated areas, but can also quickly calculate the reduction effect of dose rate due to decontamination tasks by entering decontamination factors. The system can then formulate decontamination plans and make it possible to plan measures to reduce radiation exposure for workers and local residents. Radioactive nuclides that contribute to gamma-ray dose rate are mainly Cs-134 and Cs-137 in soil, on trees, buildings, and elsewhere. Shapes of such radiation sources are assumed to be 10m square or 100m square. If it is unsuitable that the radiation sources assume to squares, the radiation sources can assume to point. The relation between distance from the surface or point source and the radiation dose rate is calculated using MCNP5 code (A General Monte Carlo N-Particle Transport Code - Version 5), and approximated using four-parameter empirical formula proposed by Harima et al. In addition, the system can consider shielding such as soil, concrete, and iron. When setting such shielding, the skyshine dose rate is taken into account in dose rate calculation.

scholarly journals Chernobyl-level radiation exposure damages bumblebee reproduction: a laboratory experiment

2020 ◽  
Vol 287 (1937) ◽  
pp. 20201638
Author(s):  
Katherine E. Raines ◽  
Penelope R. Whitehorn ◽  
David Copplestone ◽  
Matthew C. Tinsley
Keyword(s):  
Radiation Dose ◽  
Radiation Exposure ◽  
Dose Rate ◽  
Colony Growth ◽  
High Dose ◽  
Radiological Protection ◽  
Negative Consequences ◽  
Exclusion Zone ◽  
Radiation Dose Rate ◽  
Dose Rates

The consequences for wildlife of living in radiologically contaminated environments are uncertain. Previous laboratory studies suggest insects are relatively radiation-resistant; however, some field studies from the Chernobyl Exclusion Zone report severe adverse effects at substantially lower radiation dose rates than expected. Here, we present the first laboratory investigation to study how environmentally relevant radiation exposure affects bumblebee life history, assessing the shape of the relationship between radiation exposure and fitness loss. Dose rates comparable to the Chernobyl Exclusion Zone (50–400 µGy h −1 ) impaired bumblebee reproduction and delayed colony growth but did not affect colony weight or longevity. Our best-fitting model for the effect of radiation dose rate on colony queen production had a strongly nonlinear concave relationship: exposure to only 100 µGy h −1 impaired reproduction by 30–45%, while further dose rate increases caused more modest additional reproductive impairment. Our data indicate that the practice of estimating effects of environmentally relevant low-dose rate exposure by extrapolating from high-dose rates may have considerably underestimated the effects of radiation. If our data can be generalized, they suggest insects suffer significant negative consequences at dose rates previously thought safe; we therefore advocate relevant revisions to the international framework for radiological protection of the environment.

scholarly journals Uncertainties in the assessment of the radiation impact on biota in the vicinity of nuclear facilities

2021 ◽  
Vol 30 (3) ◽  
pp. 112-123
Author(s):  
S.I. Spiridonov ◽  
◽  
V.E. Nushtaeva ◽  
Keyword(s):  
Radiation Dose ◽  
Dose Rate ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Facilities ◽  
Radiation Dose Rate ◽  
Radiation Background ◽  
Dose Rates ◽  
Radioactive Release ◽  
The Impact

Evaluation of radiation impact on biota inhabiting near nuclear facilities of radioactive release to atmosphere from reactors of different types (WWER-1200, BN-600, BN-800, UVV-2M) is consid-ered in the paper. Radiation dose rates to reference groups of terrestrial biota species (annelids, insects, large and small mammals, grasses and conifers) vary from 0.01 to 0.2 µGy/day. The im-pact of the NPP using up-to-date reactor WWER-1200 is shown to be not exceeding 1% of the to-tal radiation impact. To compare correctly radiation impacts on the biota species from radioactive release and from exposure to established radiation dose rate limits, it is necessary to take into account contribution of all constituents of radiation background. Impacts on biota species from the total exposure to radioactive release or the exposure to established radiation dose rate limits were evaluated. Estimated radiation impact from exposure to the radioactive release did not ex-ceed 0.1; the impact from the established dose rate limits was 0.9. Obtained information allows making the following conclusion: uncertainty of quantitative evaluation of radiation impact on bio-ta in planned radiation situations is mainly caused by uncertainty of established dose rate limits. There is a need to establish dose criteria for emergency, it will allow creating “weighty” radioeco-logic justification of “nuclear power plants with account for potential emergency conditions.

scholarly journals Investigation of Background Radiation Level Within X-ray Machine Environment

2015 ◽  
Vol 6 ◽  
pp. 145-149
Author(s):  
F Gbaorun ◽  
D Terver
Keyword(s):  
Radiation Dose ◽  
Dose Rate ◽  
Background Radiation ◽  
Background Level ◽  
Maximum Level ◽  
Radiation Dose Rate ◽  
Radiation Level ◽  
X Ray ◽  
Dose Rates ◽  
Machine Room

In this study, a Geiger Muller ionization counter has been used to investigate the variation of background radiation dose level with time in a typical x-ray machine room and its environment. This is to monitor the effect of x-ray exposure on the background ionizing radiation level. The results showed that within a period of 3 hours, the cumulative background radiation dose in the x-ray room grew from s s Gy to around 84 . 90 ́ 10 - 10 - an initial level of 38 . 78 ́ Gy compared with nearby rooms where the s cumulative radiation grew from almost zero to a maximum value of about 46 . 9 ́ Gy within the 10 - same period. It was observed that after a radiation exposure from the machine, the background s radiation dose rate took about 25 minutes to decay from a maximum level of around 45 ́ Gy/hr to 10 - - s 17 . 47 ́ 10 the background level about Gy/hr which was found to be higher than the background dose rates in other nearby locations. While the dose rate in the x-ray machine room was higher than the s 10 - maximum dose limit of 12 ́ Gy/hr recommended for members of the public by the International Committee for Radiation Protection (ICRP), the dose rates in the other locations studied in the neighbourhood of the x-ray machine were within the limit.

scholarly journals Effect of Commercial Off-The-Shelf MAPS on γ-Ray Ionizing Radiation Response to Different Integration Times and Gains

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4950 ◽  
Author(s):  
Shoulong Xu ◽  
Jaap Velthuis ◽  
Qifan Wu ◽  
Yongchao Han ◽  
Kuicheng Lin ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Ionizing Radiation ◽  
Dose Rate ◽  
Radiation Response ◽  
High Dose ◽  
Good Precision ◽  
Radiation Dose Rate ◽  
Dose Rates ◽  
Γ Ray ◽  
Commercial Off The Shelf

We report the γ-ray ionizing radiation response of commercial off-the-shelf (COTS) monolithic active-pixel sensors (MAPS) with different integration times and gains. The distribution of the eight-bit two-dimensional matrix of MAPS output frame images was studied for different parameter settings and dose rates. We present the first results of the effects of these parameters on the response of the sensor and establish a linear relationship between the average response signal and radiation dose rate in the high-dose rate range. The results show that the distribution curves can be separated into three ranges. The first range is from 0 to 24, which generates the first significant low signal peak. The second range is from 25 to 250, which shows a smooth gradient change with different integration times, gains, and dose rates. The third range is from 251 to 255, where a final peak appears, which has a relationship with integral time, gain, and dose rate. The mean pixel value shows a linear dependence on the radiation dose rate, albeit with different calibration constants depending on the integration time and gain. Hence, MAPS can be used as a radiation monitoring device with good precision.

scholarly journals Radiation Awareness for Endovascular Abdominal Aortic Aneurysm Repair in the Hybrid Operating Room: An Instant Operator Risk Chart for Daily Practice

2021 ◽  
pp. 152660282110074
Author(s):  
Quirina M. B. de Ruiter ◽  
Frans L. Moll ◽  
Constantijn E. V. B. Hazenberg ◽  
Joost A. van Herwaarden
Keyword(s):  
Radiation Dose ◽  
Dose Rate ◽  
Effect Size ◽  
Radiation Risk ◽  
Dose Limit ◽  
Access Site ◽  
Femoral Access ◽  
Dose Rates ◽  
Rate Prediction ◽  
Operator Dose

Introduction: While the operator radiation dose rates are correlated to patient radiation dose rates, discrepancies may exist in the effect size of each individual radiation dose predictors. An operator dose rate prediction model was developed, compared with the patient dose rate prediction model, and converted to an instant operator risk chart. Materials and Methods: The radiation dose rates (DRoperator for the operator and DRpatient for the patient) from 12,865 abdomen X-ray acquisitions were selected from 50 unique patients undergoing standard or complex endovascular aortic repair (EVAR) in the hybrid operating room with a fixed C-arm. The radiation dose rates were analyzed using a log-linear multivariable mixed model (with the patient as the random effect) and incorporated varying (patient and C-arm) radiation dose predictors combined with the vascular access site. The operator dose rate models were used to predict the expected radiation exposure duration until an operator may be at risk to reach the 20 mSv year dose limit. The dose rate prediction models were translated into an instant operator radiation risk chart. Results: In the multivariate patient and operator fluoroscopy dose rate models, lower DRoperator than DRpatient effect size was found for radiation protocol (2.06 for patient vs 1.4 for operator changing from low to medium protocol) and C-arm angulation. Comparable effect sizes for both DRoperator and DRpatient were found for body mass index (1.25 for patient and 1.27 for the operator) and irradiated field. A higher effect size for the DRoperator than DRpatient was found for C-arm rotation (1.24 for the patient vs 1.69 for the operator) and exchanging from femoral access site to brachial access (1.05 for patient vs 2.5 for the operator). Operators may reach their yearly 20 mSv year dose limit after 941 minutes from the femoral access vs 358 minutes of digital subtraction angiography radiation from the brachial access. Conclusion: The operator dose rates were correlated to patient dose rate; however, C-arm angulation and changing from femoral to brachial vascular access site may disproportionally increase the operator radiation risk compared with the patient radiation risk. An instant risk chart may improve operator dose awareness during EVAR.

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