Since 2018, Central Research Institute of Korea Hydro & Nuclear Power (KHNP–CRI) has been operating an X-ray irradiation system with a maximum voltage of 160 kV and 320 kV X-ray tube to test personal dosimeters in accordance with ANSI N13.11-2009 “Personnel Dosimetry Performance- Criteria for Testing”. This standard requires that dosimeters for the photon category testing be irradiated with the X-ray beams appropriate to the ISO beam quality requirements. KHNP-CRI has implemented the fourteen X-ray reference radiation beams in compliance with ISO-4037-1, 2, and 3. When installing the X-ray irradiation system, KHNP-CRI evaluated the uncertainties of dose conversion coefficients for deep and shallow doses, based on “Catalogue of X-ray spectra and their characteristic data – ISO and DIN radiation qualities, therapy and diagnostic radiation qualities, unfiltered X-ray spectra” published by Physikalisch Technische Bundesanstalt (PTB). A CdTe detector (X-123, AMPTEK) with disk type collimators made of tungsten was used to acquire X-ray spectra. The detector was located at 1 m from the center of the target material in the Xray tubes. Six uncertainty factors for the dose conversion coefficients for the fourteen X-ray beams were chosen as follows; the minimum and maximum cut-off energies Emin and Emax, the air density (ρ), the accuracy of the high-voltage of the X-ray tube, statistics of the pulse height spectra and the unfolding method. For example, uncertainty of each quantity for a HK30 beam was calculated to be 0.3%, 2.32%, 0.19%, 1.25%, and 0.13%, and 0.18%, respectively. The combined standard uncertainty for the deep dose conversion coefficient of the HK30 beam was calculated to be 2.67%. The coverage factor corresponding to a 95 percent confidence interval was obtained as k = 1.8 using a Monte Carlo method, which is slightly lower the coverage factor of k = 1.95 for a Gaussian distribution. This seems to result from that two dominant uncertainties, the unfolding uncertainty and minimum cut-off energy uncertainty, follow a rectangular distribution.

The two spotted mite, Tetranychus urticae Koch, is a global pest, and has developed severe resistance to several types of acaricides. This study compared the development in susceptible (S) and acequinocyl, bifenazate, pyridaben, abamectin and etoxazole-resistant (AcR, BR, PR, AbR and ER) strains of T. urticae by X-ray irradiation. When eggs were irradiated with 100 Gy, the egg hatching was completely inhibited in all strains. When nymphs were irradiated with 200 Gy, their hatching was completely inhibited in all strains. When adults were irradiated, the fecundity and egg hatching was decreased at 150 Gy and above, and hatchability of F1 generation was completely inhibited at 300 Gy in all strains. Adult longevity was slightly increase at 150 Gy and above. In addition, we performed quantitative real-time PCR on several genes. To examine the difference of all strains on radiation stress-induced gene expression, we performed quantitative RT-PCR (qPCR) of several known stress-induced genes.

Spotted wing drosophila (SWD), Drosophila suzukii, is one of the most harmful pests causing serious damages to blueberries in Northern America and Europe. It is essential to seek alternatives to methyl bromide to ensure dis-infestation of this pest from agricultural products. We investigated the effect of X-ray irradiation (0, 50, 100, 200 and 300 Gy) on development and reproduction of SWD to meet this standard. When eggs were irradiated with the doses, some portion of the eggs hatched even at 300 Gy. The larvae hatched from the irradiated eggs did not pupate at 300 Gy, and they could not develop to adults even at 50 Gy. When larvae were irradiated, they developed up to pupa in some proportion. However above 100 Gy, there was no adult emergence. When pupae were irradiated, some of them emerged to adults. However, the adults could not produce eggs at all above 100 Gy. When adults were irradiated, oviposition occurred normally, but fecundity and hatchability were decreased as irradiation dose went up.

4종 해충(복숭아혹진딧물, 점박이응애, 아메리카잎굴파리, 대만총채벌레)에 이온화에너지인 전자빔과 X-ray를 각각 조사하여 이들 해충 의 발육과 생식에 미치는 영향을 비교하여 억제선량을 결정하였다. 복숭아혹진딧물 약충에 전자빔과 X-ray 조사 시, 전자빔의 경우에는 100 Gy, X-ray의 경우에는 30 Gy에서 우화성충의 산자가 완전히 억제되었다. 복숭아혹진딧물 성충의 경우 200 Gy (전자빔)와 50 Gy (X-ray)에서 각각 F1 세대 약충의 우화가 억제되었다. 그러나 이들 두 이온화에너지 모두 성충수명에는 영향을 주지 않았다. 점박이응애의 알에서는 전자빔 150 Gy와 X-ray 50 Gy 선량에서 알의 부화가 완전히 억제되었다. 아메리카잎굴파리 번데기에서는 X-ray 조사선량이 증가할수록 우화율이 감소하 였다. 대만총채벌레 성충에 조사 시 전자빔의 250 Gy와 X-ray의 200 Gy 선량에서 F1 세대 알의 부화가 완전히 억제되었다.

In this study, we investigated the effects of X-ray irradiation to control six important insect pests of floriculture crops: Liriomyza trifolii, Spodoptera litura, Myzus persicae, Tetranychus urticae, Bemisia tabaci, and Frankliniella intonsa. We irradiated on six insect pests that were placed in different positions (top, middle, and bottom) of export flower boxes after filling the boxes with roses and chrysanthemums, respectively. When irradiated with X-ray of 150 Gy, the eggs of T. urticae, B. tabaci, F. intonsa, L. trifolii, and S. litura were prevented from hatching at every position in the boxes. The pupation and emergence of L. trifolii larvae and S. litura larvae and B. tabaci nymphs and F. intonsa nymphs were inhibited at every position in the boxes. However, the emergence of T. urticae and M. persicae nymphs was not inhibited, even at the top position in the boxes. When pupae were irradiated, the emergence of L. trifolii was inhibited at every position in the boxes, while S. litura was not inhibited completely, even at the top position in the boxes. When adult T. urticae, S. litura, and L. trifolii were irradiated, the hatching rate of the F1 generation was not completely inhibited at every position. The insect pests that were not inhibited completely at the dose of 150 Gy showed much higher inhibitory effects at the dose of 250 Gy. Therefore, the dose of X-ray irradiation required to inhibit may vary according to the types of flowers and insect pests and according to their positions within the boxes.

The effects of X-ray irradiation on development and reproduction of Spodoptera litura were examined. Eggs, larvae, pupae, and adults were irradiated at target doses of 10 - 250 Gy. When eggs were irradiated with 30 Gy, egg hatching was completely inhibited. When irradiated to the larvae, pupation was inhibited at 100 Gy and larval period was delayed. When irradiated to the pupae, emergence was inhibited at over 100 Gy. When irradiated to the adults, longevity and fecundity did not show any differences. However, egg hatching was significantly decreased at 70 Gy and above. Also, X-ray irradiation was not induced the rapid death of S. litura. Reciprocal crosses between irradiated and unirradiated moths demonstrated that males were more radiotolerant than females. The levels of DNA damage in S. litura adults were evaluated using the alkaline comet assay. Our results indicate that X-ray irradiation increased levels of DNA damage. The recovery of DNA damage in S. litura adults increased as time passed. But DNA damage hasn't recovered fully. These results indicate that X-ray irradiation induced abnormal development and reproduction by DNA damage in S. litura.

A major concern in exporting agricultural commodities is the introduction or spread of exotic quarantine pests to the new area. To prevent spread of insect pests, various phytosanitary measures are used. In this study, we compared the effect of electron beam and X-ray irradiation on development and reproduction of the two-spotted spider mite, Tetranychus urticae. Eggs, nymphs, and adults were irradiated at target doses of 50, 70, 100, 150, 200, 250, and 300 Gy with electron beam and 10, 20, 30, 50, 70, 100, 150, and 200 with X-ray irradiation. When eggs were irradiated, egg hatching was completely inhibited at 150 Gy of electron beam and 50 Gy of X-ray irradiation. When irradiated to the nymphs, emergence was not affected at all target dose in both electron beam and X-ray irradiation. Hatchability of F1 generation was significantly decreased at 100 Gy of electron beam and 70 Gy of X-ray irradiation. When irradiated to the adults, longevity did not show any differences at all target dose in both electron beam and X-ray irradiation. These results suggest that the effect of X-ray irradiation was more potential than electron beam irradiation.

Radiotherapy is one of the major therapies for cancer treatment. p53 acts as a central mediator of the cellular response to stressful stimuli, such as radiation. Recently it has been known that activation of the phosphatidylinositol- 3-kinase (PI3K) pathway is associated with radioresistance. In this study, we investigated whether X-irradiation up-regulates PI3K in a p53-dependent manner in human colon cancer cells. In order to study this phenomenon, we have treated p53-wild type and p53-mutant type HCT116 cells with X-ray. Treatment of wild type HCT116 cells with 8 Gy resulted in a marked increase in PI3K (p85), which paralleled an increase in PTEN, a counterpart of PI3K. However, these effects of X-rays in the p53-mutant cells were not observed. These results suggest that the X-irradiation- induced up-regulation of PI3K/PTEN pathway is p53-dependent.

The mechanical property of a phosphore layer was investigated by measuring the resolution (LP/mm) and by positron annihilation spectroscopy and SEM. Image plate samples containing the phosphore layer were irradiated by X-rays in a hospital numerous times over a course of several years. The LP/mm values of a (Ba,Sr)FBr : Eu image plate irradiated by X-rays varied between 2.2 and 2.0 over a period of four years. Coincidence Doppler Broadening (CDB) positron annihilation spectroscopy was used to analyze defect structures. The S parameters of the samples from hospital use varied from 0.6219 to 0.6232. There was a positive relationship between the time of exposure to the X-rays and the S parameters. Most of the defects were found to have been generated by X-rays.

쇠파리의 난과 3-5일령 및 7-9일령 용에 X-선을 조사시켜 부화율, 우화율을 조사하였으며 또한 3-5일 영용에 X-선을 조사시켜 우화된 성충의 불임유기선량에 대한 실험결과를 다음과 같이 얻었다. 1. 란부화율은 약 300R 조사시 이었으며 3-5일영 및 7-9일영 번데기에 대한 사충율의 회귀직선은 Y=2.665x+2.301, Y=4.36x_0,18이고 중앙치사선량은 11.5KR과 12.6KR이었다. 2. 3KR 조사웅충과 정상자충에서 산란된 란은 약 가 미부화되었다. 그러나 2.KR 조사자충과 정상웅충 사이에서 산란된 란은 가 부화되지 않았다. 3. 불임유기선량은 자충이나 웅충과 같이 4KR이면 완전할 것으로 보며 선량을 고려할 때 충분히 이용가능할 것으로 본다.

본 연구는 고 에너지 X-선을 조사한 새싹식물 종자를 파종 및 재배하여 산도, 염도, 당도, 당산비의 변화 를 분석하고 식물의 생장에 미치는 영향을 알아보고자 하였다. 새싹식물 6종의 종자에 각 종자별로 대조군 1개군과 실험군 4개군을 구성하여 6MV X-선을 0, 2, 5, 8, 10 Gy 각각 조사하였다. 조사된 종자들을 파종하고 재배하여 식물의 액을 추출 및 성분분석을 실시하였다. 무 순과 적무의 산도는 모두 증가하였고, 청경채와 메밀은 산도가 평균적으로 감소하였다. 다른 종자의 실험 군은 대조군과 비슷한 산도로 분석 되었다 새싹식물의 염도, 당도는 평균적으로 감소하였으나, 적무의 염도는 2배 증가하였고, 수분 함량이 높은 콩 나물은 당도가 모두 증가하였다. 따라서 고 에너지 X선은 식물의 성분에서 염기성 이온을 생성하고, 수분 함량이 높은 식물은 방사선 감수성이 높아 생장에 영향을 받아 과산화물이 생성되어 식물의 성분 변화에 영향을 미친다고 판단된다. 향후 고 에너지 방사선의 조사에 따른 식물성분의 변화 원인을 알아내기 위한 지속적인 유전학적 연구가 필요할 것이다.

본 연구에서는 후춧가루의 위생화를 위해 감마선, 전자선 및 X-선을 조사한 후 이에 따른 미생물학적 및 관능적 품질변화를 평가하였다. 후춧가루에 감마선, 전자선 및 X-선을 2, 4, 6, 8 및 10 kGy로 각각 조사한 후 미생물 변화와 관능품질 변화를 평가한 결과, 미생물의 경우 선종에 관계없이 흡수선량이 증가할수록 미생물 제어 효과가 증가하는 것으로 나타났으며, 선종별 D10값의 경우 2.24-2.75 kGy범위를 보였으며 방사선 선종에 따른 유의차가 없는 것으로 나타났다. 색도의 경우 명도, 적색도 및 황색도 모두 방사선 선종에 따른 변화가 없는 것으로 판단하였다. 관능적 품질 역시 방사선 선종에 관계없이 흡수선량에 따라 품질저하가 발생되는 것으로 나타났다. 이상의 결과를 종합하여 볼 때 방사선 선종에 따른 후춧가루의 품질변화 차이가 없는 것으로 판단하였으며, 이상의 결과는 X-선의 상업적 이용을 위한 기초 연구 자료로 활용될 수 있을 것으로 사료되었다.

방사선과 paraquat에 의해서 유도된 간 손상에 대한 홍삼추출물의 보호효과를 비교 연구하였다. ICR계 생쥐에게 X선의 5Gy조사와 paraquat투여 7일 전부터 홍삼추출물(200mg/kg/day)을 투여하였다. 대조군은 생리적 식염수를 투여하고 방사선조사군은 생리적 식염수를 투여하면서 5Gy를 조사하였다. 홍삼추출물 투여군은 7일 전부터 홍삼추출물(200mg/kg/day)을 투여하면서 5Gy를 조사하였다. Paraquat투여군은 7일 전부터 홍삼추출물(200mg/kg/day)을 투여하면서 paraquat(30mg/kg/day)를 투여하였다. 그리고 각각의 실험군에서 간조직의 H2O2, catalase, MDA를 측정하였다. 그 결과 방사선조사군과 paraquat투여군보다 홍삼추출물 투여군에서 catalase함량이 유의성 있게 증가하여 간의 보호효과가 있었으며 H2O2와 MDA함량도 유의성 있게 감소하였다. 홍삼추출물은 간 조직에 대한 방사선조사 및 paraquat투여로부터 매우 우수한 방호제라고 할 수가 있다.

Geant4와 DICOM 파일의 연동을 이용한 몬테카를로 시뮬레이션을 통해 실제 환자의 흡수선량을 산출하는 새로운 방법을 제시하고, Geant4 계산코드의 검증을 위해 MOSFET 선량계를 이용하여 PMMA 모의 팬텀 깊이에 따른 중심에 서의 흡수선량 실측값과 Geant4 시뮬레이션 결과값을 비교하였다. PMMA slab의 불완전한 압착으로 인해 발생한 불 균등한 간격의 공기층이 존재하지 않은 부분에서는 X선 조사야 15 × 15 cm2 와 20 × 20 cm2 에서 각각 0.46 ± 4.69% 와 -0.75 ± 5.19%로 나타났다. PMMA 모의 팬텀의 불완전한 압착에 의해 나타난 오차를 제외하면 Geant4와 DICOM 파일의 연동을 통한 몬테카를로 시뮬레이션에 의한 계산값이 잘 일치함을 알 수 있다.