• Title, Summary, Keyword: Counting efficiency

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A Suggestion for Counting Efficiency Management of the Automation Instrument (자동화장비 계측효율 관리적 측정방법 제안)

  • Park, Jun Mo;Kim, Han Chul;Choi, Seung Won
    • The Korean Journal of Nuclear Medicine Technology
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    • v.22 no.2
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    • pp.105-111
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    • 2018
  • Purpose Quality control of instrument takes up a large part in the Radioimmunoassays. The gamma-ray instrument, which is one of the important instruments in the laboratory, observes the condition and performance of instrument and performs quality control of the instrument by measuring the Normalization, Calibration, Background and etc. However, there are some automation instruments which can't measure the counting efficiency of gamma-ray meters, resulting in insufficient management in terms of performance evaluation of gamma-ray meters. Therefore, the purpose of this paper is to manage the quality control continuously and regularly by suggesting how to measure the counting efficiency of gamma-ray instruments. Materials and Methods In case of a comparative measurement method to a gamma-ray instrument dedicated to nuclear medical examination, the CPM and counting efficiency can be obtained after the measurement of normalization by inserting the I-125 $200{\mu}L$(CPM 50,000~500,000) into the test tube. With this CPM and counting efficiency values, it's possible to calculate the measurement of the DPM value and count the CPM from the automation instrument from the same source, and enter the DPM to calculate the counting efficiency using a comparative measurement method. Another method is to calculate the counting efficiency by estimating the half life using the radiation source information of the tracer in B test reagents of company A. Results According to the calculation formula using the DPM obtained by counting the normalization of gamma-ray meters, the detection efficiency was 75.16% for Detector 1, 76.88% for Detector 2, 77.13% for Detector 3, 75.36% for Detector 4 and 73.2% for Detector 5 respectively. Using another calculation formula estimated from the shelf life, the data of the detection efficiency from Detector 1 to Detector 5 were 74.9%, 75.1%, 76.5%, 74.9% and 73.2% respectively. Conclusion Although the accuracy of counting efficiencies of both methods are insufficient, this is considered to be useful for ongoing management of quality control if counting efficiency is managed after setting the acceptable ranges. For example, if the measurement efficiency is set to 70% or higher, the allowed %difference between measurements is within 3% and the %difference with the detector wall is set within 5%.

An Intercomparison of Counting Efficiency and the Performance of Two Whole-Body Counters According to the Type of Phantom

  • Pak, Minjung;Yoo, Jaeryong;Ha, Wi-Ho;Jin, Young-Woo
    • Journal of Radiation Protection and Research
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    • v.41 no.3
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    • pp.274-281
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    • 2016
  • Background: Whole-body counters are widely used to evaluate internal contamination of the internal presence of gamma-emitting radionuclides. In internal dosimetry, it is a basic requirement that quality control procedures be applied to verify the reliability of the measured results. The implementation of intercomparison programs plays an important role in quality control, and the accuracy of the calibration and the reliability of the results should be verified through intercomparison. In this study, we evaluated the reliability of 2 whole-body counting systems using 2 calibration methods. Materials and Methods: In this study, 2 whole-body counters were calibrated using a reference male bottle manikin absorption (BOMAB) phantom and a Radiation Management Corporation (RMC-II) phantom. The reliability of the whole-body counting systems was evaluated by performing an intercomparison with International Atomic Energy Agencyto assess counting efficiency according to the type of the phantom. Results and Discussion: In the analysis of counting efficiency using the BOMAB phantom, the performance criteria of the counters were satisfied. The relative bias of activity for all radionuclides was -0.16 to 0.01 in the Fastscan and -0.01 to 0.03 in the Accuscan. However, when counting efficiency was analyzed using the RMC- II phantom, the relative bias of $^{241}Am$ activity was -0.49 in the Fastscan and 0.55 in the Accuscan, indicating that its performance criteria was not satisfactory. Conclusion: The intercomparison process demonstrated the reliability of whole-body counting systems calibrated with a BOMAB phantom. However, when the RMC-II phantom was used, the accuracy of measurements decreased for low-energy nuclides. Therefore, it appears that the RMC-II phantom should only be used for efficiency calibration for high-energy nuclides. Moreover, a novel phantom capable of matching the efficiency of the BOMAB phantom in low-energy nuclides should be developed.

Enhanced Coulomb Counting Method for State-of-Charge Estimation of Lithium-ion Batteries based on Peukert's Law and Coulombic Efficiency

  • Xie, Jiale;Ma, Jiachen;Bai, Kun
    • Journal of Power Electronics
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    • v.18 no.3
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    • pp.910-922
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    • 2018
  • Conventional battery state-of-charge (SoC) estimation methods either involve sophisticated models or consume considerable computational resource. This study constructs an enhanced coulomb counting method (Ah method) for the SoC estimation of lithium-ion batteries (LiBs) by expanding the Peukert equation for the discharging process and incorporating the Coulombic efficiency for the charging process. Both the rate- and temperature-dependence of battery capacity are encompassed. An SoC mapping approach is also devised for initial SoC determination and Ah method correction. The charge counting performance at different sampling frequencies is analyzed experimentally and theoretically. To achieve a favorable compromise between sampling frequency and accumulation accuracy, a frequency-adjustable current sampling solution is developed. Experiments under the augmented urban dynamometer driving schedule cycles at different temperatures are conducted on two LiBs of different chemistries. Results verify the effectiveness and generalization ability of the proposed SoC estimation method.

A Study of Counting Efficiency according to the Window-width on Radionuclides $^{131}I\;and\;^{198}Au$ (방사성핵종(放射性核種) $^{131}I$$^{198}Au$에서 Window 폭(幅)에 따른 계수측정(計數測定)에 관(關)한 연구(硏究))

  • Park, Soung-Ock
    • Journal of radiological science and technology
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    • v.7 no.1
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    • pp.85-92
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    • 1984
  • It is a esperimental report to investigation for optimum window-width on radionuclides $^{131}I\;and\;^{198}Au$ The obtained results were as follow; 1. In case of $^{131}I$, 1) The lowest counts produced at the window-width of 10KeV and 20KeV. 2) The count rate, more increased, when the window-width more opened, but the counting efficiency is very good between 70KeV and 130KeV window-width (19.23% -35.71% about the peak energy). 3) The heighest counting rate per KeV of window appeared at 130KeV window-width. 4) BKG counts increased proportionally to the wider window as 5.473 + 0.016 cpm. 2. In case of $^{198}Au$ 1) The lowest counts appeared at 10KeV and 20KeV window. 2) Count rate more increased, when window-width more opened, but the counting efficiency is very good between 80KeV and 140KeV window (19.46% - 34.06% about the peak energy). 3) The highest counting rate per KeV of the window appeared at 140KeV window. 4) BKG counts increased proportionally to the wider window-width as 4.74 + 1.09 cpm.

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Quality Control of Radiation Counting Systems and Measurement of Minimum Delectable Activity (방사선 계측기의 품질관리 및 최소검출방사능 측정)

  • 송병철;한성심;김영복;지광용;손세철
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • pp.419-424
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    • 2004
  • Various radiation counters have been using to determine radioactivity of radwastes for disposal. A radiation counting system was set up using a radiation detector chosen in this study and its stability was investigated through the periodic determination of background and counting efficiencies in accordance with a quality control program to increase the confidence level. The average background level for the $\gamma$-spectrometer was 1.59 cps and the average counting level for the standard sample was 45248 Ops within $2{\sigma}$ confidence levels. The average alpha background level for the low background ${\alpha}{\beta}$ counting system was 0.31 cpm and the efficiency for alpha counting was 34.38%. The average beta background level for the ${\alpha}{\beta}$ counting system was 1,30 cpm and the efficiency for beta counting was 46.5%, The background level in the region of 3H and 14C for the liquid scintillation counting system was 2.52 and 3.31 cpm and the efficiency for alpha counting was 58.5 and 95.6%, respectively. The minimum detectable activity for the$\gamma$-spectrometer was found to be 3.2 Bq/$m\ell$ and 3.8 Bq/$m\ell$ for the liquid scintillation counter, and 20.5 and 23.0 Bq/$m\ell$, respectively for the $\alpha$ and $\beta$ counting system.

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Comparative Study of Tritium Analysis Method with High-Volume Counting Vial

  • Yoon, Yoon Yeol;Kim, Yongcheol
    • Journal of Radiation Protection and Research
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    • v.45 no.3
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    • pp.142-146
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    • 2020
  • Background: Tritium (3H) analysis in groundwater was difficult because of its low activity. Therefore, the electrolytic enrichment method was used. To improve the detection limit and for performing simple analysis, a high-volume counting vial with the available liquid scintillation counter (LSC) was investigated. Further, it was compared with a conventional 20-mL counting vial. Materials and Methods: The LSC with the electrolytic enrichment method was used 3H analysis in groundwater. A high-volume 145-mL counting vial was compared with a conventional 20-mL counting vial to determine the counting characteristics of different LSCs. Results and Discussion: When a Quantulus LSC was used, the counting window between channels 35 and 250 was used. The background count was approximately 1.86 cpm, and the counting efficiency increased from 8% to 40% depending on the mixing ratio of the volume of sample and cocktail solution. For LSC-LB7, the optimum counting window was between 1 and 4.9 keV, which was selected by the factory (Hitachi Aloka Medical Ltd., Japan) by considering quenching using a standard external gamma source. The background count of LSC-LB7 was approximately 3.60 ± 0.29 cpm when the 145-mL vial was used and 2.22 ± 0.17 cpm when the 20-mL vial was used. The minimum detectable activity (MDA) of the 20-mL vial was greater for LSC-LB7 than for Quantulus. The MDA with the 145-mL vial was improved to 0.3 Bq/L when compared with the value of 1.6 Bq/L for the 20-mL vial. Conclusion: The counting efficiency when using the 145-mL vial was 27%, whereas it was 18% when using the 20-mL vial. This difference can be attributed to the vial volume. The figure of merit (FOM) of the 145-mL vial was four times greater than that of the 20-mL vial because the volume of the former vial is approximately seven times greater than that of the latter. Further, the MDA for 3H decreased from 1.6 to 0.3 Bq/L. The counting efficiency and FOM of LSC-LB7 was slightly less than those of Quantulus when the 20-mL vial was used. The background counting rate of the Quantulus was lower than that of the LSC-LB7.

A Study of Counting Efficiency according to the Window-width on Radionuclides $^{131}I$ and $^{99m}Tc$ (방사성(放射性) 의약품(醫藥品) $^{131}I$$^{99m}Tc$에서 window폭(幅) 변화(變化)에 따른 계수(計數)의 변화비교(變化比較)에 관(關)한 검사(檢討))

  • Park, Soung-Ock
    • Journal of radiological science and technology
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    • v.9 no.1
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    • pp.65-71
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    • 1986
  • It is an experimental report about optimum window-width on radionuclides $^{99m}Tc$ and $^{131}I$ and obtained results as follows; 1. In case of $^{99m}Tc$, a) The difference of counting rate in each window-width is greater at the below 20% window than above 20% window-width. b) BKG counting is proportionated to the window-width. 2. In case of $^{131}I$, a) The counting rate increased according to the window-width but the increasing course is not equal in all window. The difference of counting rate is greater at the below of 20% window-width than above 20% window. b) BKG counting is proportionated to the window-width.

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An Improved Movable 3 photomultiplier (3PM)-γ Coincidence Counter Using Logical Sum of Double Coincidences in β-Channel for Activity Standardization

  • Hwang, Han Yull;Lee, Jong Man
    • Journal of Radiation Protection and Research
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    • v.45 no.2
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    • pp.76-80
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    • 2020
  • Background: To improve the measurement accuracy of liquid-scintillation counting for activity standardization, it is necessary to significantly reduce the background caused by thermal noise or after-pulses. We have therefore improved a movable 3 photomultiplier (3PM)-γ coincidence-counting method using the logical sum of three double coincidences for β events. Materials and Methods: We designed a new data-acquisition system in which β events are obtained by counting the logical sum of three double coincidences. The change in β-detection efficiency can be derived by moving three photomultiplier tubes sequentially from the liquid-scintillation vial. The validity of the method was investigated by activity measurement of 134Cs calibrated at the Korea Research Institute of Standards and Science (KRISS) with 4π(PC)β-γ(NaI(Tl)) coincidence counting using a proportional counter (PC) for the β detector. Results and Discussion: Measurements were taken over 14 counting intervals for each liquidscintillation sample by displacing three photomultiplier tubes up to 45 mm from the sample. The dead time in each β- and γ-counting channel was adjusted to be a non-extending type of 20 ㎲. The background ranged about 1.2-3.3 s-1, such that the contributions of thermal noise or after-pulses were negligible. As the β-detection unit was moved away from the sample, the β-detection efficiencies varied between 0.54 and 0.81. The result obtained by the method at the reference date was 396.3 ± 1.7 kBq/g. This is consistent with the KRISS-certified value of 396.0 ± 2.0 kBq/g within the uncertainty range. Conclusion: The movable 3PM-γ method developed in the present work not only succeeded in reducing background counts to negligible levels but enabled β-detection efficiency to be varied by a geometrical method to apply the efficiency extrapolation method. Compared with our earlier work shown in the study of Hwang et al. [2], the measurement accuracy has much improved. Consequently, the method developed in this study is an improved method suitable for activity standardization of β-γ emitters.

Variation of the Detection Efficiency of a HPGe Detector with the Density of the Sample in the Radioactivity Analysis (방사능 분석에서 밀도에 따른 HPGe 검출기의 검출효율 변화)

  • Seo, Bum-Kyoung;Lee, Kil-Yong;Yoon, Yoon-Yeol;Jung, Ki-Jung;Oh, Won-Zin;Lee, Kune-Woo
    • Analytical Science and Technology
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    • v.18 no.1
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    • pp.59-65
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    • 2005
  • When the low level radioactivity sample is measured, it is required to have many samples. For increase of the sample volume, a scattering and absorbing probability of the emitted gamma-ray in the sample are to be increased. In order to correct the self-absorption effect, the counting efficiency must be calibrated according to a geometrical condition and sample density. But, it is impossible to determine efficiency for counting sample using standard source with the same geometrical condition and density. In this study, the measuring efficiencies were determined with various counting containers and densities. In order to compare the self-absorption effect with the sample density in the various sample container, the variation of the counting efficiency with the densities was investigated by adding NaI, which has high solubility and density. Also, they were compared with Monte Carlo simulation. The self-absorption effect was found to be significant in the low energy region below 0.5 MeV.

Measurement of the Photon Fluence for the Evaluation of Photon Detection Efficiency of Photon Counting Sensor (광계수형 센서의 포톤계수효율 평가를 위한 포톤플루엔스 측정)

  • Park, Ji-Koon;Heo, Ye-Ji;Kim, Kyo-Tae;Noh, Si-Cheol;Kang, Sang-Sik
    • Journal of the Korean Society of Radiology
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    • v.10 no.1
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    • pp.1-6
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    • 2016
  • Recently, the various digital X-ray imaging devices using CCD and TFT LCD-based flat panel digital X-ray sensor are being used. In particular, a number of studies on photon counting sensor technique have been reported. In this study, the incident X-rays fluence on the photon counting sensor material was measured to estimate photon detection efficiency which is the quantitative performance evaluation factor of photon counting sensor. The result of measuring the photon fluence by using RQA-M2 Radiation beam quality of IEC 61223-1-2 recommendations, the incident photon fluence could be defined as about $4 photons/(0.01mm)^2{\cdot}{\mu}Gy$ within $10{\mu}m$ pin-hole area, and about $50photons/(0.03mm)^2{\cdot}{\mu}Gy$ within $30{\mu}m$ pin-hole area, and about $698photons/(0.1mm)^2{\cdot}{\mu}Gy$ within $100{\mu}m$ pin-hole area. Consequently, with the previously setup of the incident fluence, the measuring of actual photon counting efficiency by observing the output waveform of the photon counting sensor material was considered possible.