scholarly journals Calculation of the average dose rate for linear gamma-radiation sources

2010 ◽  
Vol 44 (6) ◽  
pp. 539-539 ◽  
Author(s):  
G. Z. Gochaliev
Keyword(s):  
Gamma Radiation ◽  
Dose Rate ◽  
Average Dose ◽  
Radiation Sources

scholarly journals Calculation of the Effective Energy Release Centerʼs Position of Inorganic Scintillation Detectors for Calibration at Small “Source–Detector” Distances

2021 ◽  
Vol 12 (3) ◽  
pp. 239-248
Author(s):  
R. V. Lukashevich ◽  
G. A. Fokov
Keyword(s):  
Gamma Radiation ◽  
Dose Rate ◽  
Energy Release ◽  
Radiation Field ◽  
Scintillation Detector ◽  
Radiation Source ◽  
Radiation Flux ◽  
Scintillation Detectors ◽  
Effective Energy ◽  
Radiation Sources

Inorganic scintillation detectors are widely used to measure of dose rate in the environment due to their high sensitivity to photon radiation. A distinctive feature when using such detectors is the need to take into account of the position of the effective energy release center. This peculiarity is actual when using measuring instruments with inorganic scintillation detectors as working standards during calibration at short “source–detector” distances in conditions of low-background shield or using a facility with protection from external gamma radiation background in the dose rate range from 0.03 to 0.3 μSv/h (μGy/h). The purpose of this work was to calculate the position of the effective energy release center of NaI(Tl) scintillation detectors and to take it into account when working at short “source–detector” distances.An original method of determining the position of the effective energy release center when irradiating the side and end surfaces of inorganic scintillation detector with parallel gamma radiation flux and point gamma radiation sources at small “source–detector” distances using Monte Carlo methods is proposed. The results of calculations of the position of the effective energy release center of NaI(Tl) based detectors of “popular” sizes for the cases of parallel gamma radiation flux and point sources of gamma radiation at small “source–detector” distances are presented. The functional dependences of the position of the effective energy release center of NaI(Tl) based detectors on the distance to the point gamma radiation sources and the energy of gamma radiation sources are presented.As a result of the study it was found that for scintillation NaI(Tl) detectors of medium size (for example, Ø25×40 mm or Ø40×40 mm) the point gamma radiation source located at a distance of 1 m or more, creates a radiation field which does not differ in characteristics from the radiation field created by a parallel flux of gamma radiation. It is shown that approaching the point gamma radiation source to the surface of scintillation detector leads to displacement of the position of the effective energy release center to the surface of the detector.

Comparison of Lead, Copper and Aluminium as Gamma Radiation Shielding Material through Experimental Measurements and Simulation Using MCNP Version 4c

2018 ◽  
Vol 9 (08) ◽  
pp. 20193-20206 ◽  
Author(s):  
Md. Akhlak Bin Aziz ◽  
Md. Faisal Rahman ◽  
Md. Mahidul Haque Prodhan
Keyword(s):  
Gamma Radiation ◽  
Sodium Iodide ◽  
Experimental Approach ◽  
Radiation Shielding ◽  
Test Material ◽  
Simulation Techniques ◽  
Radiation Sources ◽  
Simulation Monte Carlo ◽  
Shielding Material ◽  
Code Version

The paper compares  Lead, Copper and Aluminium as gamma radiation shielding material using both experimental and simulation techniques. Cs- 137 (662KeV), Na-22 (511KeV) and Na- 22(1274KeV) were used as gamma radiation sources and a sodium iodide (NaI) detector was used to detect the radiation. Variations were noted for detected gamma count rates by changing shielding material thickness. In the experimental approach, thickness was varied by placing sheets of a particular test material one by one. For simulation, Monte Carlo n- Particle (MCNP) code version 4c was used and the geometry of the whole experimental setup was plotted in it. The results were then compared for each test material and it was found that lead is the best shielding material for gamma radiation followed by copper and aluminium.

scholarly journals Quantitative Assessment of 3D Dose Rate for Proton Pencil Beam Scanning FLASH Radiotherapy and Its Application for Lung Hypofractionation Treatment Planning

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3549
Author(s):  
Minglei Kang ◽  
Shouyi Wei ◽  
J. Isabelle Choi ◽  
Charles B. Simone ◽  
Haibo Lin
Keyword(s):  
Dose Rate ◽  
Treatment Planning ◽  
Organs At Risk ◽  
Patient Treatment ◽  
Average Dose ◽  
Clinical Implementation ◽  
Flash Intensity ◽  
Dose Threshold ◽  
Rate Calculation ◽  
The Impact

To quantitatively assess target and organs-at-risk (OAR) dose rate based on three proposed proton PBS dose rate metrics and study FLASH intensity-modulated proton therapy (IMPT) treatment planning using transmission beams. An in-house FLASH planning platform was developed to optimize transmission (shoot-through) plans for nine consecutive lung cancer patients previously planned with proton SBRT. Dose and dose rate calculation codes were developed to quantify three types of dose rate calculation methods (dose-averaged dose rate (DADR), average dose rate (ADR), and dose-threshold dose rate (DTDR)) based on both phantom and patient treatment plans. Two different minimum MU/spot settings were used to optimize two different dose regimes, 34-Gy in one fraction and 45-Gy in three fractions. The OAR sparing and target coverage can be optimized with good uniformity (hotspot < 110% of prescription dose). ADR, accounting for the spot dwelling and scanning time, gives the lowest dose rate; DTDR, not considering this time but a dose-threshold, gives an intermediate dose rate, whereas DADR gives the highest dose rate without considering any time or dose-threshold. All three dose rates attenuate along the beam direction, and the highest dose rate regions often occur on the field edge for ADR and DTDR, whereas DADR has a better dose rate uniformity. The differences in dose rate metrics have led a large variation for OARs dose rate assessment, posing challenges to FLASH clinical implementation. This is the first attempt to study the impact of the dose rate models, and more investigations and evidence for the details of proton PBS FLASH parameters are needed to explore the correlation between FLASH efficacy and the dose rate metrics.

scholarly journals Terrestrial Gamma Radiation Dose Rate of West Sarawak

2017 ◽  
Vol 156 ◽  
pp. 00006
Author(s):  
A. Izham ◽  
A.T. Ramli ◽  
W.M. Saridan Wan Hassan ◽  
H.N. Idris ◽  
N.A. Basri
Keyword(s):  
Radiation Dose ◽  
Gamma Radiation ◽  
Dose Rate ◽  
Radiation Dose Rate ◽  
Gamma Radiation Dose

scholarly journals Изменение характеристик переизлучающих волокон Y-11 и O-2 под действием гамма облучения

2020 ◽  
Vol 128 (12) ◽  
pp. 1973
Author(s):  
А.Ю. Афанасьев ◽  
А.Ю. Бояринцев ◽  
И.А. Голутвин ◽  
Э.М. Ибрагимова ◽  
А.И. Малахов ◽  
...  
Keyword(s):  
Gamma Radiation ◽  
Dose Rate ◽  
Room Temperature ◽  
Low Dose ◽  
Low Dose Rate ◽  
60Co Gamma ◽  
60Co Gamma Radiation

The effect of 60Co gamma radiation on the intensity of the reemitted light at the exit from WLS-fibers of Y-11 M and O-2 M type WLS fibers and the subsequent restoration of the characteristics of irradiated fibers after exposure to room temperature are investigated. Irradiation of a low dose rate (0.048 Mrad / h) to a dose of 1 Mrad leads to a slight decrease in the intensity of the reemitted light at the exit of both types of fibers, and with a further increase in the dose, the curve does not change. When irradiated with a dose rate of 0.158 Mrad / h, the characteristics of both types of fibers deteriorate significantly. When the irradiated samples are held at room temperature, fiber characteristics are restored.

scholarly journals High Terrestrial Radiation Level in an Active Tin-Mine at Jos South, Nigeria

2020 ◽  
Vol 24 (3) ◽  
pp. 435-442 ◽  
Author(s):  
M. Atipo ◽  
O. Olarinoye ◽  
B. Awojoyogbe ◽  
M. Kolo
Keyword(s):  
Gamma Radiation ◽  
Dose Rate ◽  
Technological Development ◽  
Absorbed Dose ◽  
Ground Level ◽  
Absorbed Dose Rate ◽  
Lifetime Cancer Risk ◽  
Radiation Level ◽  
Background Gamma Radiation ◽  
The Mean

Mineral mining and milling can be a source of national economic and technological development. However, mining of minerals has been confirmed to disturb the natural distribution of radioisotopes in the soil, air and water bodies in the biota. In an attempt to evaluate the radiological burden resulting from tin mining activities at Rayfield-Du area of Jos, the background gamma-radiation level in the mine was measured via a well calibratedhand-held dosimeter placed at 1 m above ground level. The mean absorbed dose rate, annual effective dose rate and excess lifetime cancer risk for the mine was 0.83 μSvh-1; 1.44 mSv-1 and 0.005 respectively. Generally, dose rates were higher in the mine pits and processing areas as compared to administrative areas of the mine. The mean measured dose rate and calculated dose parameters for the mine were all high when compared to the regulatory limit for public exposure. The potential of developing radiation-induced health defects as a result of high radiation absorbed dose rate by the miners and dwellers around the mine is highly probable.  Keywords: Gamma-radiation; mine; absorbed dose rate; radiation exposure.

The rain induced gamma-radiation dose rate enhancement at Järvselja SMEAR station

2021 ◽  
Author(s):  
Urmas Hõrrak ◽  
Xuemeng Chen ◽  
Kristo Hõrrak ◽  
Uko Rand ◽  
Kaupo Komsaare ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Gamma Radiation ◽  
Dose Rate ◽  
Atmospheric Aerosol ◽  
Aerosol Particles ◽  
Aerosol Formation ◽  
Radiation Dose Rate ◽  
Air Mass ◽  
Rate Enhancement ◽  
Gamma Radiation Dose

&lt;p&gt;The SMEAR Estonia station (58.277663 N, 27.308266 E, 36 m a.s.l.) was established in south-east of Estonia at the J&amp;#228;rvselja Experimental Forestry in 2012 to investigate the atmosphere-biosphere interactions and atmospheric aerosol formation and growth.&lt;/p&gt;&lt;p&gt;In summer 2019, the gamma-radiation monitor GammaTRACER XL2-3 (Saphymo GmbH) was set up at J&amp;#228;rvselja station and the rain sensor DRD11A (Vaisala Oyj) in autumn 2019. These devices enable to measure the gamma-radiation dose rate and precipitation intensity, which affect the ionization rate of atmospheric air close to ground, with high accuracy and time resolution, and complement our measurement system of atmospheric ions and aerosol particles.&lt;/p&gt;&lt;p&gt;The gamma-radiation dose rate measurements at about 1.2 m above the ground reveled on relatively steady background about 70 nSv/h occasional events with increase up to about 110 nSv/h, which correlated well with rainfall intensity. Commonly such events last 3-4 hours, but in specific meteorological situation with continuous long-lasting rain and air mass movement from southerly directions the effect can last 2-3 days, resulting in gradual increase in gamma-radiation dose rate level during about 24 h.&lt;/p&gt;&lt;p&gt;Such a phenomenon is known to occur due to wet deposition of radioactive aerosol particles during rain, namely due to the radon (&lt;sup&gt;222&lt;/sup&gt; Rn) short-lived daughter progeny products (Po-218, Pb-214, Bi-214) attached to atmospheric aerosol particles. The radon (&lt;sup&gt;222&lt;/sup&gt; Rn) daughter progeny involvement is confirmed by simultaneous gamma-spectrometric measurements with SARA AGS711F (Envinet GmbH) at T&amp;#245;ravere station (58&amp;#176; 15' 52,9&quot; N, 26&amp;#176; 27' 42,1&quot;, 72 m), located about 50.3 km west from the J&amp;#228;rvselja SMEAR station. The gamma dose rates showed very similar temporal behavior when both stations were affected by the same air mass with precipitation zone passing over the stations.&lt;/p&gt;&lt;p&gt;To our best knowledge, the details of rain-induced enhancement of gamma-radiation dose rate and atmospheric processes behind the phenomenon are not well known and are worth future investigations. The events of rain induced gamma-radiation dose rate enhancement at J&amp;#228;rvselja SMEAR and T&amp;#245;ravere station are analyzed and discussed in more detail in the presentation and the spatial representativity of the phenomenon is estimated based on the gamma-radiation monitoring network data of Estonian Early Warning System.&lt;/p&gt;

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