• Title, Summary, Keyword: Scintillation detector

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Comparison of Image Uniformity with Photon Counting and Conventional Scintillation Single-Photon Emission Computed Tomography System: A Monte Carlo Simulation Study

  • Kim, Ho Chul;Kim, Hee-Joung;Kim, Kyuseok;Lee, Min-Hee;Lee, Youngjin
    • Nuclear Engineering and Technology
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    • v.49 no.4
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    • pp.776-780
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    • 2017
  • To avoid imaging artifacts and interpretation mistakes, an improvement of the uniformity in gamma camera systems is a very important point. We can expect excellent uniformity using cadmium zinc telluride (CZT) photon counting detector (PCD) because of the direct conversion of the gamma rays energy into electrons. In addition, the uniformity performance such as integral uniformity (IU), differential uniformity (DU), scatter fraction (SF), and contrast-to-noise ratio (CNR) varies according to the energy window setting. In this study, we compared a PCD and conventional scintillation detector with respect to the energy windows (5%, 10%, 15%, and 20%) using a $^{99m}Tc$ gamma source with a Geant4 Application for Tomography Emission simulation tool. The gamma camera systems used in this work are a CZT PCD and NaI(Tl) conventional scintillation detector with a 1-mm thickness. According to the results, although the IU and DU results were improved with the energy window, the SF and CNR results deteriorated with the energy window. In particular, the uniformity for the PCD was higher than that of the conventional scintillation detector in all cases. In conclusion, our results demonstrated that the uniformity of the CZT PCD was higher than that of the conventional scintillation detector.

Feasibility study of SiPM based scintillation detector for dual-energy X-ray absorptiometry

  • Park, Chanwoo;Song, Hankyeol;Joung, Jinhun;Kim, Yongkwon;Kim, Kyu Bom;Chung, Yong Hyun
    • Nuclear Engineering and Technology
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    • v.52 no.10
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    • pp.2346-2352
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    • 2020
  • Dual-energy x-ray absorptiometry (DXA) is the noninvasive method to diagnose osteoporosis disease characterized by low bone mass and deterioration of bone tissue. Many global companies and research groups have developed the various DXA detectors using a direct photon-counting detector such as a cadmium zinc telluride (CZT) sensor. However, this approach using CZT sensor has some drawback such as the limitation of scalability by high cost and the loss of efficiency due to the requirement of a thin detector. In this study, a SiPM based DXA system was developed and its performance evaluated experimentally. The DXA detector was composed of a SiPM sensor coupled with a single LYSO scintillation crystal (3 × 3 × 2 ㎣). The prototype DXA detector was mounted on the dedicated front-end circuit consisting of a voltage-sensitive preamplifier, pulse shaping amplifier and constant fraction discriminator (CFD) circuit. The SiPM based DXA detector showed the 34% (at 59 keV) energy resolution with good BMD accuracy. The proposed SiPM based DXA detector showed the performance comparable to the conventional DXA detector based on CZT.

A scintillation detector configuration for pulse shape analysis

  • Van Chuan, Phan;Hoa, Nguyen Duc;Hai, Nguyen Xuan;Anh, Nguyen Ngoc;Dien, Nguyen Nhi;Khang, Pham Dinh
    • Nuclear Engineering and Technology
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    • v.50 no.8
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    • pp.1426-1432
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    • 2018
  • This paper presents a neutron detector configuration using EJ-301 scintillation liquid, a R9420 photo-multiplier and a homemade preamplifier. The detector qualities which include the energy linearity, efficiency response and neutron/gamma discrimination are guaranteed for neutron detection in the energy range from 0 to 3000 keVee. Regarding the neutron/gamma discrimination capability, four pulse shape discrimination (PSD) methods which are the threshold crossing time (TCT), pulse gradient analysis (PGA), charge comparison (CC) and correlation pattern recognition (CPR), were evaluated and discussed; among of these, the CPR method provides the best neutron/gamma discrimination.

The Study of CsI(Tl) Scintillation Detector Design and Signal Processing for the Measurement of the Radiation Distribution (방사선 분포측정용 CsI(Tl) 검출기 설계 및 신호처리에 관한 연구)

  • Hwang, Young-gwan;Lee, Nam-ho;Kim, Jong-yeol;Jeong, Sang-hun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.778-779
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    • 2016
  • In This paper, We designed the scintillation detector for measuring radiation signals in units of pixels for a radiation source that is distributed in the space. And we carried out a study to design a radiation imaging by the module for obtaining the detection signal. For measuring radiation distribution we configure a radiation detector combining CsI(Tl) scintillator and a photodiode. In addition, its performance was verified via gamma irradiation test.

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Measurement of the X-ray Energy by Using YSO and LYSO Scintillation Crystals (YSO와 LYSO섬광결정체를 이용한 X-선 에너지 측정)

  • Lee, Hye Young;Jeon, Jin-A;Park, Il Hung;Lee, Jik
    • New Physics: Sae Mulli
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    • v.67 no.3
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    • pp.372-376
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    • 2017
  • Scintillation crystals are the most widely used detector components for radiation detection, especially for X-ray detection, in the fields of nuclear and particle physics and for space and medical applications. We measured the X-ray energy by using a detector that consisted of a Ce-doped silicate scintillation crystal and a photosensor. The silicate scintillation crystal is either a Yttrium Silicon Oxide (YSO) crystal or a Lutetium Yttrium Silicon Oxide (LYSO) crystal, and the photosensor is a silicon photomultiplier with its photon-detection efficiency optimized for the emission spectrum of the scintillation crystals. We used the detector to observe the full-energy distribution of X-rays in the range of 11.9 and 26.3 keV with an average energy of 17.1 keV, as well as the full-energy distribution of X-rays with an energy of 59.5 keV from an $^{241}Am$ source. We fitted the full-energy distribution to a Gaussian function and determined the mean and the width of the full-energy distribution from the function. We present the energy dependence of the response of the detector to X-rays and a comparison of the scintillation light yields of the YSO and the LYSO crystals.

Fabrication and Performance Evaluation of a Scintillating Film-based Gamma Imaging Detector to Measure Gamma-ray Distribution (감마선 분포 측정을 위한 섬광필름 기반의 감마 영상 검출기 제작 및 성능평가)

  • Shin, Sang Hun;Yoo, Wook Jae;Jang, Kyoung Won;Cho, Seunghyun;Lee, Bongsoo
    • Journal of Sensor Science and Technology
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    • v.24 no.3
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    • pp.202-207
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    • 2015
  • As a feasibility study on development of a gamma imaging probe, we developed a scintillating film-based gamma imaging detector that can obtain scintillation images with information of gamma-ray distribution. The scintillating film-based gamma imaging detector was composed of a sensing probe, an image intensifier, and a beam profiler. To detect and transmit scintillation image, the sensing probe was fabricated by coupling a scintillating film, a fiber-optic image conduit, and a fiber-optic taper, consecutively. First, the optical images of USAF 1951 resolution target were obtained and then, modulation transfer function values were calculated to test the image quality of the sensing probe. Second, we measured the scintillation images according to the activity of the 137Cs and the distance between the surface of 137Cs and the distal-end of sensing probe. Finally, the intensities of scintillating light as functions of the activity and the distance were evaluated from the region of interest in the scintillation image. From the results of this study, it is expected that a fiber-optic gamma imaging detector can be developed to detect gamma-rays emitted from radiopharmaceuticals during radioimmunoguided surgery.

Design of Stack Monitoring System with Improved Performance (성능이 향상된 Stack Monitoring System의 설계)

  • Jang, Kyeong-Uk;Lee, Joo-Hyun;Lee, Seong-Won;Lee, Seung-Ho
    • Journal of IKEEE
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    • v.20 no.3
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    • pp.299-302
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    • 2016
  • In this paper, we designed the stack monitoring system with improved performance. To block the incoming pulse noise to the amplifier, shield and the power supply impedance are reduced and the power circuit is isolated. The control unit is developed with variable high voltage, adaptive gain, offset and threshold in order to match the scintillation detector characteristic to the apparatus. 300-1500V variable high voltage power circuit is configured applicable to various scintillation detector. Stack monitoring system with improved performance guarantee the efficiency and the reliability by considering the characteristic of various scintillation detector. Developed stack monitoring system is evaluated with certified testing equipment and shows excellent performance with respect to the uncertainty of the sensor test results.

A Study on Efficiency Error in Distance Inverse Square Law using Cylinder NaI(Tl) Scintillation Detector (원통형 NaI(Tl) 신틸레이션 검출기를 이용한 거리의 역자승 법칙에서 효율 오류에 대한 연구)

  • Lee, Samyol;Yoon, Jungran;Ro, TaeIk
    • Journal of the Korean Society of Radiology
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    • v.7 no.5
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    • pp.333-338
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    • 2013
  • Generally, it's known fact that intensity of radioactivity satisfies inverse-square law. However, the law was dissatisfied with practical experiment because of limited shape of scintillation detector. Especially, in the case of near distance between the surface of detector and the radioactive source, the difference grows larger. In the present study, reason of this difference was confirmed by experiment with $2^{{\prime}{\prime}}{\times}2^{{\prime}{\prime}}{\phi}$ NaI(Tl) scintillation detector and $^{60}Co$(1.174 MeV, 1.333 MeV)and $^{137}Cs$(0.662 MeV) gamma ray sources. From the experiment, the correction coefficient was obtained with gamma ray detection efficiency and geometrical volume. In the result of the present study, the efficiency difference of the detector was corrected with the coefficient. In the present result, we obtained that the inverse-square law experiment have to consider the efficiency and geometrical value of the detector.

Sensitivity of GAGG based scintillation neutron detector with SiPM readout

  • Fedorov, A.;Gurinovich, V.;Guzov, V.;Dosovitskiy, G.;Korzhik, M.;Kozhemyakin, V.;Lopatik, A.;Kozlov, D.;Mechinsky, V.;Retivov, V.
    • Nuclear Engineering and Technology
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    • v.52 no.10
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    • pp.2306-2312
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    • 2020
  • Here we report on the first results of sensitivity evaluation of the gadolinium-aluminum-gallium- garnet (GAGG) scintillation detector with SiPM readout to fast and slow neutrons and, to the natural background and Co-60 γ-radiation as well. Data on sensitivity were obtained using certified dosimetry benches, so it can be utilized in the calculation of detection limits of neutron flux with such type of detectors. It was concluded that use of GAGG scintillator has a good prospect for neutron monitoring in different parts of nuclear research reactors and power plants.

Digital Position Acquisition Method of PET Detector Module using Maximum Likelihood Position Estimation (최대우도함수를 이용한 양전자방출단층촬영기기의 검출기 모듈의 디지털 위치 획득 방법)

  • Lee, Seung-Jae;Baek, Cheol-Ha
    • Journal of the Korean Society of Radiology
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    • v.15 no.1
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    • pp.1-7
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    • 2021
  • In order to acquire an image in a positron emission tomography, it is necessary to draw the position coordinates of the scintillation pixels of the detector module measured at the same time. To this end, in a detector module using a plurality of scintillation pixels and a small number of photosensors, it is necessary to obtain a flood image and divide a region of each scintillation pixel to obtain a position of a scintillation pixel interacting with a gamma ray. Alternatively, when the number of scintillation pixels and the number of photosensors to be used are the same, the position coordinates for the position of the scintillation pixels can be directly acquired as digital signal coordinates. A method of using a plurality of scintillation pixels and a small number of photosensors requires a process of obtaining digital signal coordinates requires a plurality of photosensors and a signal processing system. This complicates the signal processing process and raises the cost. To solve this problem, in this study, we developed a method of obtaining digital signal coordinates without performing the process of separating the planar image and region using a plurality of flash pixels and a small number of optical sensors. This is a method of obtaining the position coordinate values of the flash pixels interacting with the gamma ray as a digital signal through a look-up table created through the signals acquired from each flash pixel using the maximum likelihood function. Simulation was performed using DETECT2000, and verification was performed on the proposed method. As a result, accurate digital signal coordinates could be obtained from all the flash pixels, and if this is applied to the existing system, it is considered that faster image acquisition is possible by simplifying the signal processing process.