방사선방어학회지 [Journal of Radiation Protection and Research]

간행물 정보
  • 자료유형
  • 발행기관
    대한방사선방어학회 [Korean Association For Radiation Protection]
  • ISSN
  • 간기
  • 수록기간
  • 등재여부
    KCI 등재
  • 주제분류
    자연과학 > 기타자연과학
  • 십진분류
    KDC 431.482 DDC 540

Original Research


In Situ Gamma-ray Spectrometry Using an LaBr3(Ce) Scintillation Detector

Young-Yong Ji, Taehyung Lim, Wanno Lee

대한방사선방어학회 방사선방어학회지 VOLUME 43 NUMBER 3 2018.09 pp.85-96

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Background: A variety of inorganic scintillators have been developed and improved for use in radiation detection and measurement, and in situ gamma-ray spectrometry in the environment remains an important area in nuclear safety. In order to verify the feasibility of promising scintillators in an actual environment, a performance test is necessary to identify gamma-ray peaks and calculate the radioactivity from their net count rates in peaks. Materials and Methods: Among commercially available scintillators, LaBr3(Ce) scintillators have so far shown the highest energy resolution when detecting and identifying gamma-rays. However, the intrinsic background of this scintillator type affects efficient application to the environment with a relatively low count rate. An algorithm to subtract the intrinsic background was consequently developed, and the in situ calibration factor at 1 m above ground level was calculated from Monte Carlo simulation in order to determine the radioactivity from the measured net count rate. Results and Discussion: The radioactivity of six natural radionuclides in the environment was evaluated from in situ gamma-ray spectrometry using an LaBr3(Ce) detector. The results were then compared with those of a portable high purity Ge (HPGe) detector with in situ object counting system (ISOCS) software at the same sites. In addition, the radioactive cesium in the ground of Jeju Island, South Korea, was determined with the same assumption of the source distribution between measurements using two detectors. Conclusion: Good agreement between both detectors was achieved in the in situ gamma-ray spectrometry of natural as well as artificial radionuclides in the ground. This means that an LaBr3(Ce) detector can produce reliable and stable results of radioactivity in the ground from the measured energy spectrum of incident gamma-rays at 1 m above the ground.


Development of Diode Based High Energy X-ray Spatial Dose Distribution Measuring Device

Jeonghee Lee, Ikhyun Kim, Jong-Won Park, Yong-Kon Lim, Myungkook Moon, Sangheon Lee, Chang Hwy Lim

대한방사선방어학회 방사선방어학회지 VOLUME 43 NUMBER 3 2018.09 pp.97-106

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Background: A cargo container scanner using a high-energy X-ray generates a fan beam X-ray to acquire a transmitted image. Because the generated X-rays by LINAC may affect the image quality and radiation protection of the system, it is necessary to acquire accurate information about the generated X-ray beam distribution. In this paper, a diode-based multi-channel spatial dose measuring device for measuring the X-ray dose distribution developed for measuring the high energy X-ray beam distribution of the container scanner is described. Materials and Methods: The developed high-energy X-ray spatial dose distribution measuring device can measure the spatial distribution of X-rays using 128 diode-based X-ray sensors. And precise measurement of the beam distribution is possible through automatic positioning in the vertical and horizontal directions. The response characteristics of the measurement system were evaluated by comparing the signal gain difference of each pixel, response linearity according to X-ray incident dose change, evaluation of resolution, and measurement of two-dimensional spatial beam distribution. Results and Discussion: As a result, it was found that the difference between the maximum value and the minimum value of the response signal according to the incident position showed a difference of about 10%, and the response signal was linearly increased. And it has been confirmed that high-resolution and two-dimensional measurements are possible. Conclusion: The developed X-ray spatial dose measuring device was evaluated as suitable for dose measurement of high energy X-ray through confirmation of linearity of response signal, spatial uniformity, high resolution measuring ability and ability to measure spatial dose. We will perform precise measurement of the X-ray beamline in the container scanning system using the X-ray spatial dose distribution measuring device developed through this research.


Dosimetric Comparison of 6 MV Flattening Filter Free and 6 MV Stereotactic Radiosurgery Beam Using 4 mm Conical Collimator for Trigeminal Neuralgia Radiosurgery

Vaibhav R Mhatre, Pranav Chadha, Abhaya P Kumar

대한방사선방어학회 방사선방어학회지 VOLUME 43 NUMBER 3 2018.09 pp.107-113

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Background: The purpose of our study was to compare the dosimetric advantages of Flattening filter free (FFF) beams for trigeminal neuralgia patients using 4 mm conical collimators over previously treated patients with 6 MV SRS beam. Materials and Methods: A retrospective study was conducted for 5 TN patients who had been previously treated at our institution using frame-based, LINAC-based stereotactic radiosurgery (SRS) on Novalis Tx using 6 MV SRS beam were replanned on 6X FFF beams on Edge Linear accelerator with same beam angles and dose constraints using 4 mm conical collimator. The total number of monitor units along with the beam on time was compared for both Edge and Novalis Tx by redelivering the plans in QA mode of LINAC to compare the delivery efficiency. Plan quality was evaluated by homogeneity index (HI) and Paddick gradient index (GI) for each plan. We also analyzed the doses to brainstem and organ at risks (OARs). Results and Discussion: A 28% beam-on time reduction was achieved using 6X FFF when compared with 6X SRS beam of Novalis Tx. A sharp dose fall off with gradient index value of 3.4 ± 0.27 for 4 mm Varian conical collimator while 4.17 ± 0.20 with BrainLab cone. Among the 5 patients treated with a 4 mm cone, average maximum brainstem dose was 10.24 Gy for Edge using 6X FFF and 14.28 Gy for Novalis Tx using 6X SRS beam. Conclusion: The use of FFF beams improves delivery efficiency and conical collimator reduces dose to OAR’s for TN radiosurgery. Further investigation is warranted with larger sample patient data.


Optical Sensitivity of TL Glow Peaks Separated Using Computerized Glow Curve Deconvolution for RTL Quartz

Myung-Jin Kim, Ki-Bum Kim, Duk-Geun Hong

대한방사선방어학회 방사선방어학회지 VOLUME 43 NUMBER 3 2018.09 pp.114-119

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Background: The retrospective dosimetry using RTL quartz can be improved by information for an optical sensitivity of sample connected with the equivalent dose determination. Materials and Methods: The quartz sample from a volcanic rock of Japan was used. After correcting the thermal quenching effect, RTL peaks of quartz were separated by the CGCD method cooperated with the general order kinetics. The number of overlapped glow peaks were ascertained by the Tm-Tstop method. The optical sensitivity was examined by comparing the change of intensity on RTL glow peaks measured after exposure to light from a solar simulator with various illumination times. Results and Discussion: Seven glow peaks appeared to be overlapped on the RTL glow curve. The general order kinetics model was appropriate to separate glow peaks. After exposure to light from a solar simulator from a few minutes to 416 hr, the signals for peaks P4 and P5 decayed following the form of f(t) = a1e-λ1t, while the signals for peaks P6 and P7 decayed by the form of f(t) = a1e-λ1t+a2e-λ2t+a3e-λ3t. Conclusion: For dosimetric peaks, the times taken to reduce the RTL signal to half of its initial value were 70 sec for the peak P4, 54 s for the peak P5, 9,840 sec for the peak P6 and 26,580 sec for the peak P7, respectively. We conclude that the optical sensitivity of peaks P4, and P5 gives much higher than that of peaks P6 and P7.

Technical Paper


Uranium Enrichment Comparison of UO2 Pellet with Alpha Spectrometry and TIMS

Ji-Yeon Song, Hana Seo, Sung-Hwan Kim, Jung-Youn Choi

대한방사선방어학회 방사선방어학회지 VOLUME 43 NUMBER 3 2018.09 pp.120-123

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Background: Analysis of enrichment of UO2 is important to verify the information declared by the license-holders. The redundancy methods are required to guarantee the analysis result. Korea Institute of Nuclear Nonproliferation and Control (KINAC) used to analyze it with alpha spectrometry and consign to Korea Basic Science Institute (KBSI) Thermal Ionization Mass Spectrometry (TIMS). This article evaluated the similarity of the results with two methods and derive correlation equation. It could be compared to the results measured by TIMS running by KBSI. Materials and Methods: There are not many certified materials for the uranium enrichment value. Therefore, 34 uranium pellets, which have the wide range of uranium enrichment from 0.21 to 4.69 wt%, were used for the experiments by the alpha spectrometry and the TIMS. Results and Discussion: The study shows there are the tendency of analyzed enrichment by each equipment. It shows uranium enrichment with alpha spectrometry evaluated 17% higher than that with TIMS on average. The regression equations were also derived in case the similarity between the two results with two methods is lower than predicted. Two experiments were designed to compare the effect of number of samples. The R2 was 0.9977 with 34 pellets. It shows the equation is appropriate to predict the enrichment values by TIMS with that of alpha spectrometry. The R2 was 0.9858 with four pellets for ten times. The R2 decreased while the number of samples increased. The discrepancy between the lowest and highest enrichment seems to be one of the reason for it. Conclusion: KINAC expects the first equation with 34 samples is useful to predict the result with TIMS, the redundancy method, based on the alpha spectrometry. The extra samples are necessary to collect if the enrichment value analyzed by TIMS is lower than the value predicted with the equation. Further study would be followed related to the impact of the peak counts for each uranium isotopes, sample amount and number of experiments when TIMS established in KINAC by the end of 2018.


Re-evaluation of Korean Effluent Concentration Limits and Comparative Analysis

Won Tae Hwang, Joeun Lee, Dahye Kwon, Eun Han Kim, Moon Hee Han

대한방사선방어학회 방사선방어학회지 VOLUME 43 NUMBER 3 2018.09 pp.124-129

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Background: Effluent Concentration Limits (ECLs) were re-evaluated via direct calculation using dose coefficients based on radiation protection quantity introduced in Korea and the intrinsic breathing rates of Korean residents. Materials and Methods: The re-evaluated ECLs were compared with the domestic standards given in the Notice of the Nuclear Safety and Security Commission (NSSC), as well as with ECLs specified in the Code of Federal Regulations (CFR). Results and Discussion: The relative ratios of the re-evaluated ECLs to the currently applied domestic standards differed depending on the radionuclide type, but it was clearly shown that, for tritium (3H) and radiocarbon (14C), which significantly affect radiological dose to the public during the normal operation of nuclear power plants, the re-evaluated ECLs were higher than the domestic standards. This implies that Korean standards are relatively conservative. Conclusion: The re-evaluated results for each age group showed that 131I (radioiodine), one of the significant radionuclides, had the lowest values, but nonetheless, the domestic standards for radioiodine were lower than the ECLs given in the CFR and the re-evaluated ECLs via a method given in the CFR.


Regulations for JRPR Editorial Committee 외


대한방사선방어학회 방사선방어학회지 VOLUME 43 NUMBER 3 2018.09 pp.130-140

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