• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.819-824
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• 2019

In this study, we proposed a method for identifying isotopes generated from high-energy proton $^{nat}Pb$(p,xn) nuclear reactions through the difference of gamma rays generated through nuclear reactions using different proton energies. The experiment was performed by using a high energy proton generated from a 100 MeV proton linear accelerator of the Korea Atomic Energy Research Institute. Gamma rays generated by various nuclides generated through proton nuclear reactions were measured using a gamma-ray spectroscopy system composed of HPGe detectors. Gamma-ray standard sources were used for accurate energy calibration and efficiency measurements of HPGe gamma-ray detectors. For the proposed method, 100 and 60 MeV proton energy beams were used for the same natural lead samples. This method was found to be very effective in identifying nuclides produced by comparing gamma rays generated from the same sample with each other. The results of this study are expected to be very effective in obtaining other proton nuclear reaction results in the future.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.133-138
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• 2018

The measurement of gamma-ray spectrum of $^{nat}W(p,xn)$ reaction with natural tungsten were performed by using a high energy proton generated from a 100-MeV proton linear accelerator of the Korea Multi-purpose Accelerator Complex (KOMAC). Gamma rays generated by various nuclides generated through the nuclide were measured using a gamma-ray spectroscopy system composed of HPGe detector. A gamma-ray standard source was used for energy calibration and efficiency measurement of the detector. Analysis of the gamma rays observed in the measured spectra showed that the radionuclides produced were $^{167}Re$, $^{178}Re$, $^{179}Re$, $^{180}Re$, $^{181}Re$, $^{182}Re$, $^{184}Re$, $^{172}Ta$, $^{174}Ta$, $^{178}Ta$, $^{182}Ta$, $^{184}Ta$, $^{175}W$, $^{176}W$, $^{177}W$ and $^{179}W$. Nuclides were generated. The results of this study will be applied to nuclear fusion, astrophysics, and nuclear medicine applications in the future.

• The Journal of Korean Society for Radiation Therapy
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• v.29 no.2
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• pp.101-108
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• 2017

Purpose: The proton used in proton therapy has a characteristic of giving a small dose to the normal tissue in front of the tumor site while forming a Bragg peak at the cancer tissue site and giving up the maximum dose and disappearing immediately. It is very important to verify the proton arrival position. In this study, we used the off-line PET CT method to measure the distribution of positron emitted from nucleons such as 11C (half-life = 20 min), 150 (half-life = 2 min) and 13N The range and distal falloff point of the proton were verified by measurement. Materials and Methods: In the IEC 2001 Body Phantom, 37 mm, 28 mm, and 22 mm spheres were inserted. The phantom was filled with water to obtain a CT image for each sphere size. To verify the proton range and distal falloff points, As a treatment planning system, SOBP were set at 46 mm on 37 mm sphere, 37 mm on 28 mm, and 33 mm on 22 mm sphere for each sphere size. The proton was scanned in the same center with a single beam of Gantry 0 degree by the scanning method. The phantom was scanned using PET-CT equipment. In the PET-CT image acquisition method, 50 images were acquired per minute, four ROIs including the spheres in the phantom were set, and 10 images were reconstructed. The activity profile according to the depth was compared to the dose profile according to the sphere size established in the treatment plan Results: The PET-CT activity profile decreased rapidly at the distal falloff position in the 37 mm, 28 mm, and 22 mm spheres as well as the dose profile. However, in the SOBP section, which is a range for evaluating the range, the results in the proximal part of the activity profile are different from those of the dose profile, and the distal falloff position is compared with the proton therapy plan and PET-CT As a result, the maximum difference of 1.4 mm at the 50 % point of the Max dose, 1.1 mm at the 45 % point at the 28 mm sphere, and the difference at the 22 mm sphere at the maximum point of 1.2 mm were all less than 1.5 mm in the 37 mm sphere. Conclusion: To maximize the advantages of proton therapy, it is very important to verify the range of the proton beam. In this study, the proton range was confirmed by the SOBP and the distal falloff position of the proton beam using PET-CT. As a result, the difference of the distally falloff position between the activity distribution measured by PET-CT and the proton therapy plan was 1.4 mm, respectively. This may be used as a reference for the dose margin applied in the proton therapy plan.

• Journal of radiological science and technology
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• v.34 no.4
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• pp.333-339
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• 2011

The purpose of this study is to compare DNA repair characteristics of normal fibroblast cell (MRC-5) and neuroblastoma cell (SK-N-SH) induced by proton beam. Cells were irradiated with 2Gy, 5Gy and 8Gy proton beam. The rate of DNA rejoining was measured by alkaline version of the comet assay. After a repair time, tail moment was measured again. The tail moment of MRC-5 was lower than SK-N-SH. However, after 8Gy of exposure, the tail moment of MRC-5 was measured as 50.320223.17155 which represents dangerous level of DNA damage. The cells were repaired practically within 25 hours after 2 and 5Gy of exposure while they were not fully recovered after 8Gy of exposure. Especially, tail moment of MRC-5 after 25 hours was 18.15364.42849. In the distal declining edge of SOBP, the RBE value is increased by high LET. The RBE differences of SOBP in high-dose were greater than low-dose. After the high-dose exposure, MRC-5 of normal fibroblast cell could lead to lasting DNA damage as shown in this study. In conclusion, we has to pay special attention when the region of the treatment volume is close to sensitive tissues.

• Progress in Medical Physics
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• v.20 no.3
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• pp.180-190
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• 2009

Depth of prostate volume from the skin can vary due to intra-fractional and inter-fractional movements, which may result in dose reduction to the target volume. Therefore we evaluated the feasibility of automated depth determination-based adaptive proton therapy to minimize the effect of inter-fractional movements of the prostate. Based on the center of mass method, using three fiducial gold markers in the prostate target volume, we determined the differences between the planning and treatment stages in prostate target location. Thirty-eight images from 10 patients were used to assess the automated depth determination method, which was also compared with manually determined depth values. The mean differences in prostate target location for the left to right (LR) and superior to inferior (SI) directions were 0.9 mm and 2.3 mm, respectively, while the maximum discrepancies in location in individual patients were 3.3 mm and 7.2 mm, respectively. In the bilateral beam configuration, the difference in the LR direction represents the target depth changes from 0.7 mm to 3.3 mm in this study. We found that 42.1%, 26.3% and 2.6% of thirty-eight inspections showed greater than 1 mm, 2 mm and 3 mm depth differences, respectively, between the planning and treatment stages. Adaptive planning based on automated depth determination may be a solution for inter-fractional movements of the prostate in proton therapy since small depth changes of the target can significantly reduce target dose during proton treatment of prostate cancer patients.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.257-263
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• 2021

This study derives the relative cross-section for the natW(p,xn)176Re nuclear reaction by measuring the gamma rays generated from the nuclear reaction with natural tungsten using a 100 MeV linear accelerator of the Korea Multi-purpose Accelerator Complex in the Korea Atomic Energy Research Institute. In general, research on isotopes with a short half-life always shows a tendency that the intensity of radioactivity decreases rapidly within a short period of time, making it very difficult to measure itself. In particular, 176Re is one of the relatively short radionuclides with a half-life of 5.3 minutes. In this study, 109.08 keV gamma rays generated from the 176Re isotope having such a short half-life were measured using a high-purity Ge detector(HPGe detector). The obtained relative measurements were the results in the 8 to 14 MeV proton energy domain published by Richard G. in 1967, and the TENDL-2019 value, which was the result of A. J. Koning in 2019, which evaluated the nuclear reaction cross-section by calculation based on this comparative analysis was performed. The results of this study are expected to be usefully applied to the design of nuclear fusion reactor which is known as future energy sources, elements ratio for the nuclear synthesis of astrophysics.

• 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 $\Delta$V/ V=5.2$\times$10$^{-3}$ without ion beam and 7.2$\times$10$^{-3}$ 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 $\Delta$V/V=2.45$\times$10$^{-4}$ and the energy stability with $\Delta$E/E=2.44$\times$10$^{-4}$ was steadily maintained at the 247.3kV terminal voltage, and the stabilization factor was deduced to be 29.4.

• 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.

• Journal of the Korean Vacuum Society
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• v.10 no.3
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• pp.380-386
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• 2001

A nuclear microprobe system with adjustable precision object slits and a magnetic quadrupole doublet was designed by the beam optics simulation using a first order matrix formalism, and installed in a $30^{\circ}$ beam line connected with KIGAM 1.7 MV Tandem VDG Accelerator. Demagnification factors for x and y axis are calculated to be 25 and 4.9, respectively, and a minimum beam spot side is expected to be about 5 $\mu\textrm{m}$ for 3 MeV proton beams with a current of about 1 nA. A multi-purpose octagonal target chamber has been built to facilitate MeV ion-beam analytical techniques of PIXE, RBS, ERDA, and ion beam micro-machining. It contains X-ray and particle detectors, a zoom microscope, a Faraday cup, a 4-axis sample manipulator and a high vacuum pumping system. The system performance of the nuclear microprobe is now being tested, and automatic manipulator control and data acquisition system will be installed for routine applications of micro ion-beam analytical techniques.

• Nuclear Engineering and Technology
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• v.22 no.2
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• pp.101-107
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• 1990

The PIXE (Proton Induced X-ray Emission) method is applied to the quantitative analysis of trace elements in tap water, red wine, urine and old black powder samples. Sample irradiations are performed with a 1.202 MeV proton beam from the SNU 1.5-MV Tandem Van de Graaff accelerator, and measurements of X-ray spectra are made by the Si(Li) spectrometer To increase the sensitivity of analysis tap water is preconcentrated by evaporation method. As an internal standard, Ni powder is mixed with black powder sample and yttrium solution is added to the other samples. The analyses of the PIXE spectra are carried out by using the AXIL (Analytical X-ray Analysis by Iterative Least-squares) computer code, in which the routine for least-squares method is based on the Marquardt algorithm. The elements such as Mg, Al, Si, Ti, Fe and Zn are analyzed at sub-ppm levels in the tap water sample. In the red wine sample prepared without preconcentration. the element Ti is detected in the amount of 3ppm. In conclusion, the PIXE method is proved to be appropriate for the analysis of liquid samples by relative measurements using the internal standard. and is expected to be improved by the use of evaluated X-ray production cross-sections and the development of sample preparation techniques.