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  • Title/Summary/Keyword: Proton accelerator

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Improvement of accuracy in radioactivity assessment of medical linear accelerator through self-absorption correction in HPGe detector

  • Suah Yu;Na Hye Kwon;Sang-Rok Kim;Young Jin Won;Kum Bae Kim;Se Byeong Lee;Cheol Ha Baek;Sang Hyoun Choi
    • Nuclear Engineering and Technology
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    • v.56 no.6
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    • pp.2317-2323
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    • 2024
  • Medical linear accelerators with an energy of 8 MV or higher are radiated owing to photonuclear reactions and neutron capture reactions. It is necessary to quantitatively evaluate the concentration of radioactive isotopes when replacing or disposing them. HPGe detectors are commonly used to identify isotopes and measure radioactivity. However, because the detection efficiency is generally calibrated using a standard material with a density of 1.0 g/cm3, a self-absorption effect occurs if the density of the measured material is high. In this study, self-absorption correction factors were calculated for tungsten, lead, copper, and SUS-303, which are the main materials of medical linear accelerator head parts, for each gamma-ray energy using MCNP 6.2 code. The self-absorption effect was more pronounced as the energy of the emitted gamma rays decreased and the density of the measured materials increased. These correction factors were applied to the radioactivity measurements of the in-built and portable HPGe detectors. Furthermore, compared to the surface dose rate measured by the survey meter, the accuracy of the measurements of radioactivity improved by an average of 124.31 and 100.53 % for inbuilt and portable HPGe detectors, respectively. The results showed a good agreement, with an average difference of 3.70 and 5.24 %.

Analysis of Light Elements by PIGE (양성자 유발 감마선 발생법에 의한 경원소 분석)

  • Kim, Y.S.;Choi, H.W.;Kim, D.K.;Woo, H.J.;Kim, N.B.;Park, K.S.
    • Analytical Science and Technology
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    • v.13 no.1
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    • pp.12-21
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    • 2000
  • The PIGE (Proton Induced Gamma ray Emission) method was applied for the measurement of light elements Li ~ K. A test measurement has been performed for geological, biological, environmental and material samples by using a standard sample for each element. The measurement was performed for the two proton energies of 2.4 and 3.4 MeV, and 3.4 MeV was found to yield better result for multielemental analysis. The result shows a fair agreement within 15% for all elements with standard values. The detection limits of Li, B, F and Na are less than 100 ppm, while those of the other elements are from a few hundred ppm to a few percents.

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A Study on the Measurement of Half-life for the 179Re Isotope Produced by a 100 MeV Proton Nuclear Reaction (100 MeV 양성자 핵반응에 의해 생성된 179Re 동위원소의 반감기 측정에 관한 연구)

  • Lee, Samyol
    • Journal of the Korean Society of Radiology
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    • v.14 no.4
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    • pp.447-453
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    • 2020
  • This study accurately measured the half-life of the 179Re radioactive isotope using the 100 MeV proton and high-purity HPGe gamma ray measurement system generated from a high-energy proton linear accelerator at the Korea Atomic Energy Research Institute. The result obtained is 19.64 ± 0.26 min. Compared with the past results of the half-life of the 179Re radioisotope known to date, the results of B. Harmatz published in 1960 and B. J. Meijer published in 1975 measured the median value higher than the results obtained in this study. In the case of K. J. Hofstetter, published in 1966, a very large error is also characteristic. This result showed a tendency that the center value was very consistent with the result of this study. The results of Coral M. Baglin's 19.5 min published in 2009 are very consistent with the error range. The obtained measured result was compared with the result of ENSDF (Evaluated Nuclear Structure Data File). Through this study, more reliable values were measured for the results of the half-life of the 179Re, which was previously incorrect, and the validity of the recently published results of Coral M. Baglin was confirmed.

The first private-hospital based proton therapy center in Korea; status of the Proton Therapy Center at Samsung Medical Center

  • Chung, Kwangzoo;Han, Youngyih;Kim, Jinsung;Ahn, Sung Hwan;Ju, Sang Gyu;Jung, Sang Hoon;Chung, Yoonsun;Cho, Sungkoo;Jo, Kwanghyun;Shin, Eun Hyuk;Hong, Chae-Seon;Shin, Jung Suk;Park, Seyjoon;Kim, Dae-Hyun;Kim, Hye Young;Lee, Boram;Shibagaki, Gantaro;Nonaka, Hideki;Sasai, Kenzo;Koyabu, Yukio;Choi, Changhoon;Huh, Seung Jae;Ahn, Yong Chan;Pyo, Hong Ryull;Lim, Do Hoon;Park, Hee Chul;Park, Won;Oh, Dong Ryul;Noh, Jae Myung;Yu, Jeong Il;Song, Sanghyuk;Lee, Ji Eun;Lee, Bomi;Choi, Doo Ho
    • Radiation Oncology Journal
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    • v.33 no.4
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    • pp.337-343
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    • 2015
  • Purpose: The purpose of this report is to describe the proton therapy system at Samsung Medical Center (SMC-PTS) including the proton beam generator, irradiation system, patient positioning system, patient position verification system, respiratory gating system, and operating and safety control system, and review the current status of the SMC-PTS. Materials and Methods: The SMC-PTS has a cyclotron (230 MeV) and two treatment rooms: one treatment room is equipped with a multi-purpose nozzle and the other treatment room is equipped with a dedicated pencil beam scanning nozzle. The proton beam generator including the cyclotron and the energy selection system can lower the energy of protons down to 70 MeV from the maximum 230 MeV. Results: The multi-purpose nozzle can deliver both wobbling proton beam and active scanning proton beam, and a multi-leaf collimator has been installed in the downstream of the nozzle. The dedicated scanning nozzle can deliver active scanning proton beam with a helium gas filled pipe minimizing unnecessary interactions with the air in the beam path. The equipment was provided by Sumitomo Heavy Industries Ltd., RayStation from RaySearch Laboratories AB is the selected treatment planning system, and data management will be handled by the MOSAIQ system from Elekta AB. Conclusion: The SMC-PTS located in Seoul, Korea, is scheduled to begin treating cancer patients in 2015.

Evaluation on the Radiation Exposure of Radiation Workers in Proton Therapy (양성자 치료 시 방사선 작업 종사자에게 미치는 방사선 피폭에 대한 평가)

  • Lee, Seung-Hyun;Jang, Yo-Jong;Kim, Tae-Yoon;Jeong, Do-Hyung;Choi, Gye-Suk
    • The Journal of Korean Society for Radiation Therapy
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    • v.24 no.2
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    • pp.107-114
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    • 2012
  • Purpose: Unlike the existing linear accelerator with photon, proton therapy produces a number of second radiation due to the kinds of nuclide including neutron that is produced from the interaction with matter, and more attention must be paid on the exposure level of radiation workers for this reason. Therefore, thermoluminescence dosimeter (TLD) that is being widely used to measure radiation was utilized to analyze the exposure level of the radiation workers and propose a basic data about the radiation exposure level during the proton therapy. Materials and Methods: The subjects were radiation workers who worked at the proton therapy center of National Cancer Center and TLD Badge was used to compare the measured data of exposure level. In order to check the dispersion of exposure dose on body parts from the second radiation coming out surrounding the beam line of proton, TLD (width and length: 3 mm each) was attached to on the body spots (lateral canthi, neck, nipples, umbilicus, back, wrists) and retained them for 8 working hours, and the average data was obtained after measuring them for 80 hours. Moreover, in order to look into the dispersion of spatial exposure in the treatment room, TLD was attached on the snout, PPS (Patient Positioning System), Pendant, block closet, DIPS (Digital Image Positioning System), Console, doors and measured its exposure dose level during the working hours per day. Results: As a result of measuring exposure level of TLD Badge of radiation workers, quarterly average was 0.174 mSv, yearly average was 0.543 mSv, and after measuring the exposure level of body spots, it showed that the highest exposed body spot was neck and the lowest exposed body spot was back (the middle point of a line connecting both scapula superior angles). Investigation into the spatial exposure according to the workers' movement revealed that the exposure level was highest near the snout and as the distance becomes distant, it went lower. Conclusion: Even a small amount of exposure will eventually increase cumulative dose and exposure dose on a specific body part can bring health risks if one works in a same location for a long period. Therefore, radiation workers must thoroughly manage exposure dose and try their best to minimize it according to ALARA (As Low As Reasonably Achievable) as the International Commission on Radiological Protection (ICRP) recommends.

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A Numerical Analysis on the Characteristics of Flow in the 20 MeV DTL Cooling System (20 MeV DTL 냉각계통의 유동 특성에 관한 수치해석)

  • Kim, Kyung-Ryul;Park, Jun;Kwon, Sei-Sin;Kim, Hyung-Gyun;Kim, Hee-Sub;Hwang, Woon-Ha;Yoon, Jong-Cheol
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2907-2912
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    • 2007
  • The cooling water system for the PEFP 20 MeV proton accelerator was established and tested to obtain the precise resonance frequency of DTL through the temperature control of cooling water. The water temperature in the main flow loop was manipulated by adjusting the proportion of hot water returning from the DTL structures through the heat exchanger loop. Due to low duty factor operation and insufficient cooling loop installation of the DTL tanks, the manual mode operation was applied to maintain the DTL temperatures close to their resonance temperatures. The optimized process conditions with flow balancing and pressure drop in the DTL cooling systems are reported.

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KOMAC RFQ Vacuum System

  • Han, J.M.d;S.H.Jeong;Cho, Y.S.;Park, B.H.
    • Proceedings of the Korean Vacuum Society Conference
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    • 1999.07a
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    • pp.33-33
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    • 1999
  • The design of a vacuum pumping system for the KOMAC (Korea Multipurpose Accelerator Complex) RFQ(Radio-Frequency Quadrupole) linac is described. [Fig] Resulted from the lost proton beam, gas streaming from the LEBT (Low Energy Beam Transport) and out-gassing from the surfaces of the RFQ cavity and vacuum plumbing, the total gas load will be on the order of 7.2×10-4 Torr-liters/sec, consisting mainly of hydrogen. The system designed to pump on a continual basis with redundancy to ensure that the minimal operating vacuum level of 1.0×10-6 Torr is maintained even under abnormal conditions. Details of the design, performance analysis and the preliminary test results of the cryogenic pumps are presented.

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Response Function of HPGe Detector using 23Na(p, γ)24Mg and 27Al(p, γ)28Si Reaction (23Na(p, γ)24Mg27Al(p, γ)28Si반응을 이용한 HPGe 검출기의 응답함수)

  • Park, Sang-Tae
    • Journal of Radiation Protection and Research
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    • v.35 no.2
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    • pp.85-90
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    • 2010
  • In the present work, peak relative efficiency for the energy was obtained and response function was worked out. This study was carried out using the high resolution high efficiency HPGe detector(diameter 78.7 mm, length 86.5 mm) and NaI(Tl) detector for anti-compton. The anti-coincidence of the signals from the two detectors could be used to lessen the Compton effect signal; thus, the γ-ray energy resolution could be improved. The γ-ray spectrum was measured at 55 to the direction of the incident proton beam. Reaction spectrum was obtained from the 23Na(p, γ)24Mg reaction at Ep = 1424 keV and 27Al(p, γ)28Si reaction at Ep = 992 keV. To accelerate the incident proton which creates the (p, γ) capture reaction, the 3 MeV Pelletron accelerator at the Tokyo Institute of Technology was used. Response function was worked out by a noble technique. We worked out a response function from 1.2 to 9.4 MeV at intervals of 0.75 MeV.

Secondary Neutron Dose in Carbon-ion Radiotherapy: Investigations in QST-NIRS

  • Yonai, Shunsuke;Matsumoto, Shinnosuke
    • Journal of Radiation Protection and Research
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    • v.46 no.2
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    • pp.39-47
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    • 2021
  • Background: The National Institutes for Quantum and Radiological Science and Technology-National Institute of Radiological Sciences (QST-NIRS) has continuously investigated the undesired radiation exposure in ion beam radiotherapy mainly in carbon-ion radiotherapy (CIRT). This review introduces our investigations on the secondary neutron dose in CIRT with the broad and scanning beam methods. Materials and Methods: The neutron ambient dose equivalents in CIRT are evaluated based on rem meter (WENDI-II) measurements. The out-of-field organ doses assuming prostate cancer and pediatric brain tumor treatments are also evaluated through the Monte Carlo simulation. This evaluation of the out-of-field dose includes contributions from secondary neutrons and secondary charged particles. Results and Discussion: The measurements of the neutron ambient dose equivalents at a 90#x00B0; angle to the beam axis in CIRT with the broad beam method show that the neutron dose per treatment dose in CIRT is lower than that in proton radiotherapy (PRT). For the scanning beam with the energy scanning technique, the neutron dose per treatment dose in CIRT is lower than that in PRT. Moreover, the out-of-field organ doses in CIRT decreased with distance to the target and are less than the lower bound in intensity-modulated radiotherapy (IMRT) shown in AAPM TG-158 (American Association of Physicists in Medicine Task Group). Conclusion: The evaluation of the out-of-field doses is important from the viewpoint of secondary cancer risk after radiotherapy. Secondary neutrons are the major source in CIRT, especially in the distant area from the target volume. However, the dose level in CIRT is similar or lower than that in PRT and IMRT, even if the contributions from all radiation species are included in the evaluation.

SNU 1.5 MV Van de Graaff Accelerator (V) -on the Operation of the High Voltage Stabilization System- (NU 1.5MV 반데그라프 가속기 (V) -고전압 안정화 계통의 동작-)

  • Bae, Y.D.;Bak, H.I.;Chung, K.H.;Woo, H.J.;Choi, B.H.
    • Nuclear Engineering and Technology
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    • v.19 no.2
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    • pp.115-121
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    • 1987
  • A high voltage stabilization system for the SNU 1.5MV Tandem Van do Graaff accelerator was set up and its operational characteristics were examined and optimized. The optimum parameters of beam transport system were experimentally determined, and under the proper condition the accelerated proton beam current of 350nA was obtained at the target chamber. Without the high voltage stabilization the observed magnitude of voltage fluctuation was ΔV/ V=5.2×103 without ion beam and 7.2×103 with ion beam, respectively, and its apparent ripple frequency for voltage fluctuations was about 3Hz or less. Through the optimized operation of the high voltage stabilization system, the terminal voltage fluctuation was reduced to ΔV/V=2.45×104 and the energy stability with ΔE/E=2.44×104 was steadily maintained at the 247.3kV terminal voltage, and the stabilization factor was deduced to be 29.4.

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