• Journal of Radiation Protection and Research
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• v.44 no.1
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• pp.1-7
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• 2019

Background: To monitor proton beam in proton therapy, prompt gamma imaging systems are being developed by several research groups, and these systems are expected to improve the quality of the treatment and the patient safety. To apply the prompt gamma imaging systems into spot scanning proton therapy, the systems should be able to monitor the proton beam range of a spot with a small number of protons ( <$10^8$ protons), which is quite often not the case due to insufficient prompt gamma statistics. Materials and Methods: In the present study, we propose to improve prompt gamma statistics by merging the prompt gamma distributions of several individual spots into a new distribution. This proposal was tested by Geant4 Monte Carlo simulations for a multi-slit prompt gamma camera which has been developed to measure the proton beam range in the patient. Results and Discussion: The results show that the proposed method clearly enhance the statistical precision of beam range measurement. The accuracy of beam range verification is improved, within ~1.4 mm error, which is not achievable before applying the developed method. Conclusion: In this study, we tried to improve the statistics of the prompt gamma statistics by merging the prompt gamma distributions of multiple spots, and it was found that the merged distribution provided sufficient prompt gamma statistics and the proton beam range was determined accurately.

• Journal of Microbiology and Biotechnology
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• v.17 no.6
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• pp.1041-1044
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• 2007

To assess the effects of a proton beam on oyster mushrooms (Pleurotus ostreatus), the genetic diversity and phylogenetic relationships among strains induced by a proton beam were investigated based on a clustering analysis. According to an AFLP DNA polymorphism analysis, the induced strains were divided into four groups that coincided with the dose. When applying proton-beam radiation, the dissimilarity among the induced strains increased when increasing the dose. When using more than 400 Gy, the genetic dissimilarity of the irradiated strains was 46-58%. Thus, evaluating the induced strains using the AFLP technique was effective in revealing the mutation effect of the proton beam.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.38-41
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• 2019

Proton beam writing is a direct writing lithography technique for semiconductor fabrication process. The advantage of this technique is that the proton beam does not scatter as they travel through the matter and therefore maintain a straight path as they penetrate into the resist. The experiment has been carried out at Accelerator Mass Spectrometry facility. The focused proton beam with the fluence of $100nC/mm^2$ was exposed on the PMMA coated silicon sample to make a pattern on a photo resist. The results show the potential of proton beam writing as an effective way to produce semiconductor fabrication process.

• Journal of Radiation Industry
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• v.6 no.3
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• pp.223-229
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• 2012

In this study, we investigated the biological damage and stress responses induced by ion beam (proton beam) irradiation as a basis for the development of protective measures against space radiation. We examined the biological effects of proton beam produced by MC-50 cyclotron at KIRAMS on the cultured cells and mice. The proton beam energy used in this study was 34.9 MeV and the absorption dose rate for cells and mice were $0.509Gy\;sec^{-1}$ and $0.65Gy\;sec^{-1}$, respectively. The cell survival rates measured by plating efficiency showed the different sensitivity and dose-relationship between CHO cells and Balb/3T3 cells. HGPRT gene mutation frequency in Balb/3T3 was $15{\times}10^{-6}Gy^{-1}$, which was similar to the reported value of X-ray. When stress signaling proteins were examined in Balb/3T3 cells, $I{\kappa}B-{\alpha}$ decreased markedly whereas p53, phospho-p53, and Rb increased after proton beam irradiation, which implied that the stress signaling pathways were activated by proton beam irradiation. In addition, cellular senescence was induced in IMR-90 cells. In the experiments with C57BL/6 mouse, the immune cells (white blood cells, lymphocytes) in the peripheral blood were greatly reduced following proton beam irradiation whereas red blood cells and platelets showed relatively little change. These results can be utilized as basic data for studying the biological effects of proton beam using MC-50 cyclotron with respect to proton therapy research as well as space radiation research.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.533-538
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• 2019

The mechanical-collimation imaging is the most mature technology in prompt gamma (PG) imaging which is considered the most promising technology for beam range verification in proton therapy. The purpose of the present study is to compare the performances of two mechanical-collimation PG cameras, knife-edge (KE) camera and multi-slit (MS) camera. For this, the PG cameras were modeled by Geant4 Monte Carlo code, and the performances of the cameras were compared for imaginary point and line sources and for proton beams incident on a cylindrical PMMA phantom. From the simulation results, the KE camera was found to show higher counting efficiency than the MS camera, being able to estimate the beam range even for $10^7$ protons. Our results, however, confirmed that in order to estimate the beam range correctly, the KE camera should be aligned, at least approximately, to the location of the proton beam range. The MS camera was found to show lower efficiency, being able to estimate the beam range correctly only when the number of the protons is at least $10^8$. For enough number of protons, however, the MS camera estimated the beam range correctly, errors being less than 1.2 mm, regardless of the location of the camera.

• Korean Journal of Plant Resources
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• v.18 no.3
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• pp.462-469
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• 2005

Effects of proton beam irradiation on seed germination and growth pattern of tobacco (Nicotiana tabacum L. cv. BY-4; N. plumbaginifolia) and rice (Oryasativa L.) plants were estimated to develop the efficient conditions of irradiation. Seed germination rate was decreased by increasing the proton beam the current and the beam irradiation time in both tobacco and rice seeds. The beam irradiation conditions showing $50\%$ germination were over 60 sec at 10 nA, approximately 5 sec at 100 nA and at 500 nA beam current in tobacco seeds. And the conditions of $50\%$ germination were 60 sec at 10 nA, and 100 nA and 30 sec at 500nA in rice (cv. Dongjin 1) seeds. The growth of irradiated plants was decreased, but significant difference in morphological changes was not observed by the proton beam treatment. The proton beam is able to use as a mutagen, but some of the factors including beam size and beam detector-system must be established for efficient usage of the beam.

• Korean Journal of Plant Resources
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• v.24 no.3
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• pp.304-308
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• 2011

The survival rate and thermal, crystal, and physicochemical properties of starches in chinese yam tubers irradiated to proton beam were determined. Survival rate was decreased with increased proton beam irradiation. Amylose content of D. opposita starches from different proton beam ranged from 13.2% to 17.8%. D. opposita starch at 5 Gy showed the highest ${\Delta}H_{gel}$ values (12.0 J/g) while D. opposita starch at 25 Gy showed the lowest values (10.1 J/g). Several parameters such as PKV (peak viscosity), HPV (Hot peak viscosity) and CPV (Cooling peak viscosity) decreased with the increase in irradiation dose. The degrees of crystallinity of the D. opposita starches at 5, 10, 15, 20 and 25 Gy were 37.2, 38.3, 38.9, 39.2 and 39.9%, respectively. It might be deduced that proton beam irradiation causes changes of starch, especially at high dose irradiation.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.418-425
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• 2009

To get the stable and optimized proton beam in the KIRAMS-13 cyclotron which installed in the regional cyclotron center, it is necessary to measure the transverse profile of proton beam. Beam Induced Fluorescence monitor is one of the non-destructive methods to measure the beam profiles, and it has many advantages such as a simple structure, real-time measurement, and minimum energy loss. The objective of this research is the design and development of Beam Induced Fluorescence monitor to measure the proton beam profiles in the KIRAMS-13 cyclotron.

• Progress in Medical Physics
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• v.30 no.4
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• pp.112-119
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• 2019

Purpose: The advantages of ocular proton therapy are that it spares the optic nerve and delivers the minimal dose to normal surrounding tissues. In this study, it developed a solid eye phantom that enabled us to perform quality assurance (QA) to verify the dose and beam range for passive single scattering proton therapy using a single phantom. For this purpose, a new solid eye phantom with a polymethyl-methacrylate (PMMA) wedge was developed using film dosimetry and an ionization chamber. Methods: The typical beam shape used for eye treatment is approximately 3 cm in diameter and the beam range is below 5 cm. Since proton therapy has a problem with beam range uncertainty due to differences in the stopping power of normal tissue, bone, air, etc, the beam range should be confirmed before treatment. A film can be placed on the slope of the phantom to evaluate the Spread-out Bragg Peak based on the water equivalent thickness value of PMMA on the film. In addition, an ionization chamber (Pin-point, PTW 31014) can be inserted into a hole in the phantom to measure the absolute dose. Results: The eye phantom was used for independent patient-specific QA. The differences in the output and beam range between the measurement and the planned treatment were less than 1.5% and 0.1 cm, respectively. Conclusions: An eye phantom was developed and the performance was successfully validated. The phantom can be employed to verify the output and beam range for ocular proton therapy.

• Journal of Korean Neurosurgical Society
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• v.61 no.3
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• pp.386-392
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• 2018

Radiation therapy is highly effective for the management of pediatric malignant central nervous system (CNS) tumors including embryonal tumors. With the increment of long-term survivors from malignant CNS tumors, the radiation-related toxicities have become a major concern and we need to improve the treatment strategies to reduce the late complications without compromising the treatment outcomes. One of such strategies is to reduce the radiation dose to craniospinal axis or radiation volume and to avoid or defer radiation therapy until after the age of three. Another strategy is using particle beam therapy such as proton beams instead of photon beams. Proton beams have distinct physiologic advantages over photon beams and greater precision in radiation delivery to the tumor while preserving the surrounding healthy tissues. In this review, I provide the treatment principles of pediatric CNS embryonal tumors and the strategic improvements of radiation therapy to reduce treatment-related late toxicities, and finally introduce the increasing availability of proton beam therapy for pediatric CNS embryonal tumors compared with photon beam therapy.