Effect of air luminescence counts on determination of 222Rn by liquid scintillation counting

Murase, Yuko; Homma, Yoshio; Takiue, Makoto

doi:10.1016/0883-2889(89)90221-9

Cited by 11 publications

(3 citation statements)

References 7 publications

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“…4,5 In modern times, air scintillation (sometimes also called air fluorescence or air luminescence) has been utilized to study cosmic showers entering the earth atmosphere [6][7][8] and as a means to count alpha emitters. [9][10][11] The application of air scintillation for dosimetry of electron beams from a van de Graaff accelerator (0.5-1.5 MeV) has also been reported 12 and kilovoltage electron beams have been photographed using this phenomenon. 13 However, to the best of our knowledge, air scintillation has never been considered in the context of the clinical use of modern medical linear accelerators.…”

Section: Introductionmentioning

confidence: 99%

“…21 Cherenkov radiation has a broad emission spectrum that spans the entire ultraviolet and visible spectrum. In air, given the low index of refraction, electrons must have energy greater than 20.3 MeV to produce Cherenkov radiation, which is beyond the range of most medical linear accelerators (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). Several studies have however utilized Cherenkov radiation generated in water and tissue for dosimetry [22][23][24][25] and molecular imaging.…”

Section: Introductionmentioning

confidence: 99%

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Seeing the invisible: Direct visualization of therapeutic radiation beams using air scintillation

et al. 2013

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Purpose: To assess whether air scintillation produced during standard radiation treatments can be visualized and used to monitor a beam in a nonperturbing manner. Methods: Air scintillation is caused by the excitation of nitrogen gas by ionizing radiation. This weak emission occurs predominantly in the 300-430 nm range. An electron-multiplication chargecoupled device camera, outfitted with an f/0.95 lens, was used to capture air scintillation produced by kilovoltage photon beams and megavoltage electron beams used in radiation therapy. The treatment rooms were prepared to block background light and a short-pass filter was utilized to block light above 440 nm. Results: Air scintillation from an orthovoltage unit (50 kVp, 30 mA) was visualized with a relatively short exposure time (10 s) and showed an inverse falloff (r 2 = 0.89). Electron beams were also imaged. For a fixed exposure time (100 s), air scintillation was proportional to dose rate (r 2 = 0.9998). As energy increased, the divergence of the electron beam decreased and the penumbra improved. By irradiating a transparent phantom, the authors also showed that Cherenkov luminescence did not interfere with the detection of air scintillation. In a final illustration of the capabilities of this new technique, the authors visualized air scintillation produced during a total skin irradiation treatment. Conclusions: Air scintillation can be measured to monitor a radiation beam in an inexpensive and nonperturbing manner. This physical phenomenon could be useful for dosimetry of therapeutic radiation beams or for online detection of gross errors during fractionated treatments.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Seeing the invisible: Direct visualization of therapeutic radiation beams using air scintillation

et al. 2013

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“…Prichard and Gesell (1977) assumed 25% of the gas phase radionuclides contributed to the observed count rate by interacting at the cocktail-air meniscus. Murase et al (1989) reported a counting efficiency of 42% for radon and its daughters in an empty LS vial as a result of air luminescence. Both imply that when a large headspace volume exists in the vial the measured count rates reflect both the radionuclides in the cocktail phase and some of the 222 Rn and daughters within the headspace.…”

Section: Methodsmentioning

confidence: 99%

Development of Radon-222 as Natural Tracer for Monitoring the Remediation of NAPL in the Subsurface

Davis¹,

Semprini²,

Istok³

2003

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EXECUTIVE SUMMARYNaturally occurring 222-radon in ground water can potentially be used as an in situ partitioning tracer to characterize dense nonaqueous phase liquid (DNAPL) saturations. The static method involves comparing radon concentrations in water samples from DNAPL-contaminated and non-contaminated portions of an aquifer. During a push-pull test, a known volume of test solution (radon-free water containing a conservative tracer) is first injected ("pushed") into a well; flow is then reversed and the test solution/groundwater mixture is extracted ("pulled") from the same well. In the presence of NAPL radon transport is retarded relative to the conservative tracer. Assuming linear equilibrium partitioning, retardation factors for radon can be used to estimate NAPL saturations. The utility of this methodology was evaluated in laboratory and field settings. Laboratory push-pull tests were conducted in both non-contaminated and trichloroethene NAPL (TCE)-contaminated sediment packs before-and after alcohol cosolvent flushing and pump-and-treat remediation; field push-pull tests were conducted in wells located in non-contaminated and light non-aqueous phase liquid (LNAPL)-contaminated portions of an aquifer at a former petroleum refinery. The laboratory and field push-pull tests demonstrated that radon retardation does occur in the presence of TCE and LNAPL and that radon retardation can be used to calculate TCE saturations. However, nonequilibrium radon partitioning and heterogeneous TCE distributions may affect the retardation factors and TCE saturation estimates. Numerical simulations were used to further investigate the influence of 1) initial radon concentration, which varies as a function of NAPL saturation and 2) heterogeneity in NAPL saturation distribution within the radius of influence of the push-pull test.A method is described for determining the partition coefficient for radon in the presence of NAPL. The method uses sequential extractions of radon into equal volume aliquots of organic solvent. The radon-laden organic liquid is then counted on a liquid scintillation analyzer with alpha-beta separation. The high quench resistance and counting efficiency of alpha particles by liquid scintillation methods are ideal for counting a variety of aromatic, aliphatic, and cyclic organic solvent and scintillation cocktail mixtures. Accurate knowledge of the instrument counting efficiency, quench, and standard solution activity are not required. Replicate measurements of the aqueous-organic radon partition coefficient on benzene, toluene, o-xylene, n-hexane, cyclohexane, trichloroethene, and perchloroethene showed excellent agreement with theoretical radon partition coefficients derived from Ostwald solubility coefficients. The method was also used to determine the aqueous-organic radon partition coefficient for several commercial liquid scintillation solutions. 4 LITERATURE REVIEW CHLORINATED ALIPHATICS AND DNAPLsChlorinated solvents have seen prolific use in the industrialized world throughout the twentieth...

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A modified integral counting method and efficiency tracing method for measuring 222Rn by liquid-scintillation counting

Homma¹,

Murase²,

Handa³

1994

Applied Radiation and Isotopes

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Effect of air luminescence counts on determination of 222Rn by liquid scintillation counting

Cited by 11 publications

References 7 publications

Seeing the invisible: Direct visualization of therapeutic radiation beams using air scintillation

Seeing the invisible: Direct visualization of therapeutic radiation beams using air scintillation

Development of Radon-222 as Natural Tracer for Monitoring the Remediation of NAPL in the Subsurface

A modified integral counting method and efficiency tracing method for measuring 222Rn by liquid-scintillation counting

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