• Title/Summary/Keyword: Pulse radiation

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Performance evaluation of an adjustable gantry PET (AGPET) for small animal PET imaging

  • Song, Hankyeol;Kang, In Soo;Kim, Kyu Bom;Park, Chanwoo;Baek, Min Kyu;Lee, Seongyeon;Chung, Yong Hyun
    • Nuclear Engineering and Technology
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    • v.53 no.8
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    • pp.2646-2651
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    • 2021
  • A rectangular-shaped PET system with an adjustable gantry (AGPET) has been developed for imaging small animals. The AGPET system employs a new depth of interaction (DOI) method using a depth dependent reflector patterns and a new digital time pickoff method based on the pulse reconstruction method. To evaluate the performance of the AGPET, timing resolution, intrinsic spatial resolution and point source images were acquired. The timing resolution and intrinsic spatial resolution were measured using two detector modules and Na-22 gamma source. The PET images were acquired in two field of view (FOV) sizes, 30 mm and 90 mm, to demonstrate the characteristic of the AGPET. As a result of in the experiment results, the timing resolution was 0.9 ns using the pulse reconstruction method based on the bi-exponential model. The intrinsic spatial resolution was an average of 1.7 mm and the spatial resolution of PET images after DOI correction was 2.08 mm and 2.25 mm at the centers of 30 mm and 90 mm FOV, respectively. The results show that the proposed AGPET system provided higher sensitivity and resolution for small animal imaging.

A study on the UWB Antenna Design Techniques for Improving Pulse Fidelity (펄스 충실도 개선을 위한 UWB 안테나 설계기법 연구)

  • Kim, Jung-Min;Kang, Eun-Kyun
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.8
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    • pp.299-307
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    • 2013
  • In this paper, design of UWB Antenna which propagate impulse by pulse fidelity and distortion equation was induced and applied. UWB Antenna which has directional characteristic in UWB band should have low radiation loss and impulse radiation distortion. As a result, the paper designed wide band impedance transformer and microstrip slotline transit region structured antenna feeder line. By using the fabricated UWB antenna, the radiation pattern was measured in the radio anechoic chamber. Pulse fidelity of impulse radiation show good results more than 93% within ${\pm}30^{\circ}$ beam width.

Development of a real-time gamma camera for high radiation fields

  • Minju Lee;Yoonhee Jung;Sang-Han Lee
    • Nuclear Engineering and Technology
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    • v.56 no.1
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    • pp.56-63
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    • 2024
  • In high radiation fields, gamma cameras suffer from pulse pile-up, resulting in poor energy resolution, count losses, and image distortion. To overcome this problem, various methods have been introduced to reduce the size of the aperture or pixel, reject the pile-up events, and correct the pile-up events, but these technologies have limitations in terms of mechanical design and real-time processing. The purpose of this study is to develop a real-time gamma camera to evaluate the radioactive contamination in high radiation fields. The gamma camera is composed of a pinhole collimator, NaI(Tl) scintillator, position sensitive photomultiplier (PSPMT), signal processing board, and data acquisition (DAQ). The pulse pile-up is corrected in real-time with a field programmable gate array (FPGA) using the start time correction (STC) method. The STC method corrects the amplitude of the pile-up event by correcting the time at the start point of the pile-up event. The performance of the gamma camera was evaluated using a high dose rate 137Cs source. For pulse pile-up ratios (PPRs) of 0.45 and 0.30, the energy resolution improved by 61.5 and 20.3%, respectively. In addition, the image artifacts in the 137Cs radioisotope image due to pile-up were reduced.

The Study of the Photo Diode Output Signal for Pusle Radiation Detection (펄스방사선 탐지를 위한 Photo Diode 출력특성 연구)

  • Hwang, Young-Gwan;Lee, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2012.05a
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    • pp.869-871
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    • 2012
  • In this paper, we make silicon photodiodes for the detection of pulsed radiation that affects electronics devices and study the output characteristics of photodiodes using circuit design. We conducted the simulation for pulse sensing circuit and experimented the photodiode output characteristics using a high luminance light emitting diode. The results can be used for the design of the input sensor that is trigger of additional module for protecting a electoronics circuit from high energy pulse radiation.

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Modeling and Simulation for Transient Pulse Gamma-ray Effects on Semiconductor Devices (반도체 소자의 과도펄스감마선 영향 모델링 및 시뮬레이션)

  • Lee, Nam-Ho;Lee, Seung-Min
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.9
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    • pp.1611-1614
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    • 2010
  • The explosion of a nuclear weapon radiates a gamma-ray in the form of a transient pulse. If the gamma-ray introduces to semiconductor devices, much Electron-Hole Pairs(EHPs) are generated in depletion region of the devices[7]. as a consequence of that, high photocurrent is created and causes upset, latchup and burnout of semiconductor devices[8]. This phenomenon is known for Transient Radiation Effects on Electronics(TREE), also called dose-rate effects. In this paper 3D structure of inverter and NAND gate device was designed and transient pulse gamma-ray was modeled. So simulation for transient radiation effect on inverter and NAND gate was accomplished and mechanism for upset and latchup was analyzed.

Investigation of Influence of Pulse-periodical Laser Radiation Power on Stability of Liquid-metal Contacts between Powder Particles during Selective Laser Sintering

  • Beljavin, K.E.;Minko, D.V.;Bykov, R.P.;Kuznechik, O.O.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.518-519
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    • 2006
  • A connection between pulse-periodical laser radiation power and stability of liquid-metal contacts between powder particles during selective laser sintering (SLS) is determined based on analysis solving the problem of stability of liquid column in the gravity and capillary forces field. On the grounds of obtained relationships the optimization of pulse-periodical laser radiation power and SLS-process duration is realized, that allows to produce voluminous powder porous materials with pre-determined physical and mechanical properties and surface geometry. Results of metallographic investigations of powder porous materials of titanium powder produced with technological regimes calculated by means of obtained relationships are given in the work

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A Study on Electronic Circuit for Liwe-Time Correction in Multi-Channel Analyzer : Survey and Analysis (방사선 스펙트럼 계측기 (Multi-Channel Analyzer)의 Live-Time 보상회로에 관한 연구)

  • Hwang, I.K.;Kwon, K.H.;Song, S.J.
    • Nuclear Engineering and Technology
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    • v.27 no.5
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    • pp.784-791
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    • 1995
  • This paper describes the counting-loss problem for radiation measurement Multi-channel analyzers and spectrometers adopt various techniques for compensation for counting-losses in process-ing the radiation pulses from a detector. Researchers hate tried to seek the best solution for the problem. However, any absolute solution has not been reached and vendors of radiation instruments use their own algorithms individually. This survey explains the various compensation algorithms with electronic implementation approach. Shortcomings and merits of each algorithm are also reviewed and a direction is suggested of the recommendable development strategy for counting-loss compensation.

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A Method to Suppress the Spurious Radiation due to the Current Pulse on the Cable using the Frequency Selective Metamaterial Structure (주파수 선택도를 가지는 메타재질구조를 이용한, 선로상의 전류펄스에 의한 불요방사 억제기법)

  • Kahng, Sungtek;Yang, Inkyu;Kim, Hyeong-Seok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.4
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    • pp.517-522
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    • 2013
  • The spurious electromagnetic radiation is generated due to the RF unbalanced current on a conductive cable connecting an electronic device to another. A metamaterial-based filtering geometry with frequency selectivity is suggested to reduce the radiation with a bandgap structure, where the right-handed inductance and capacitance stem from the transmission-like configuration between the cable and the metal protrusion, and the left-handed components come from the narrow cavities. The effect of the structure on the unbalanced current pulse and its spurious radiation is presented in the FDTD-method frame work.

Betatron Radiation of an Off-axis Injected Electron in a Laser Wakefield Accelerator

  • Hwang, Seok-Won;Lee, Hae-June
    • Journal of the Optical Society of Korea
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    • v.13 no.1
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    • pp.86-91
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    • 2009
  • The electrons injected into a laser wakefield undergo betatron oscillation and give rise to the emission of intense X-ray radiation. To investigate the generation conditions of the X-rays, the relativistic motion of an electron injected in an off-axis position has been simulated with wakefield profiles which are pre-calculated with a two-dimensional particle-in-cell code. The wakefield with a plasma density of $1.78{\times}10^{18}\;cm^{-3}$ is generated by the laser with an intensity of $1.37{\times}10^{18}\;W/cm^2$ and a pulse width of 30 fs. From the calculation of the single particle motion, the characteristics of the betatron radiation are investigated in the time domain. As the transverse injection position increases, the power and the duration time of the radiation increase, but the width of each pulse decreases.

Development of Measurement System for Industrial Transportable Gamma Ray CT (이동 형 산업용 단층측정 장치를 위한 감마선 검출시스템 개발)

  • Kim, Jong-Bum;Jung, Sung-Hee;Moon, Jin-Ho
    • Journal of Radiation Industry
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    • v.6 no.3
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    • pp.231-237
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    • 2012
  • This paper introduces a gamma-ray measurement system for a transportable tomography which is applicable for an industrial process diagnosis. The gamma-ray measurement system consists of pulse mode operating 72 channel CsI detectors, main AMP-pulse shaper, single channel analyzer, counter and control PC. The CsI crystal is coupled with a PIN diode which is connected to an amplifier and pulse shaper. For a compact design, the amplifier and pulse shaping circuit are included in a single package. 36 sets of CsI detectors are connected to a multi-channel counter through single channel analyzers. A computer controls and collects data from two multi-channel counters. This configuration results in 72 channel counting system in total. The CT rotator and radiation measurement system are controlled by a PC with LabVIEW program. Tomographic data were measured for a phantom by the measurement system and transportable gamma-ray CT. From the experimental data image reconstructions were performed by ML-EM algorithm. The result showed that the CsI detector system can be a suitable component for transportable gamma-ray CT system.