• 대한방사선기술학회지:방사선기술과학
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• 제24권1호
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• pp.17-22
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• 2001

Medical X-ray examination are increased double for the last $6{\sim}8$ years. Therefore a patient exposure dose should be decrease half every 7 years. We made an experiment on copper filter thickness to decrease a patient exposure dose up to half and compared to the Image quality by MTF. The results as follow 1. A thin region like extremities needs a thicker Cu filter as compared a thick region. 2. 1/2 reduction filter must be thicker when kVp Increase. 3. Exposure factor should be increas when using 1/2 reduction filter ; extremity is 4.0 times, chest 2.9 times, skull 1.62 times, and abdomen 1.58 times 4. The MTF of using 1/2 reduction filter is lower than without filter. But no difference of visual image. 5. 1/2 reduction filter compared with double speed screen showed almost same image quality.

• 한국작물학회지
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• 제41권3호
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• pp.348-353
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• 1996

1. 돌연변이처리후 실내에서 처리된 종자의 발아율, 제 1 엽 및 뿌리의 생장율을 보면 gamma ray나 화학제 처리된 Dema M$_1$, 유묘의 경우 생존율이 l~49%정도 감소하였고 Grosso의 경우는 그 감소의 폭이 Dema보다 적어 두 품종간의 돌연변이제에 대한반응의 차가 컸으며 같은 처리농도의 화학돌연변이제를 처리할 경우 두번에 나누어 중간의 휴지기를 두고 처리하는 것이 한 번에 처리하는 것보다 식물체의 생장 저해정도가 덜하였다. 2. 포장 M$_1$식물체의 간장의 감소율을 보면 화학약제의 경우 8.5~38.5%의 범위로 간장이 줄어들었으며 특히 1.5 mM의 MNH 처리시는 두 품종 모두 파종된 식물체가 고사하였고 0.75~l.0mM의 MNH처리시 15~38%심하였다. 그러나 이중처리할 때는 1.0~l.5mM이상의 고농도로 처리하여도 간장의 생장 감소율은 단일처리보다 상대적으로 덜 하였으며 이는 두 품종 모두 비슷한 경향이었다. 3. Dema에서는 gamma ray 180Gy처리시 간장의 감소가 28% 정도로 가장 심하였고 Grosso에서는 150Gy에서 13%로 가장 심한 경향이었다. 4. M$_2$식물체의 엽록소 돌연변이 발생율을 보면 화학약제나 방사선 처리 모두 처리강도가 높을수록 albino, xantha등의 엽록소 돌연변이체가 많이 나타났으며 약제의 이중 처리시 엽록소 돌연변이의 출현률이 다른 처리보다 높았다.

• Journal of Periodontal and Implant Science
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• 제32권2호
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• pp.415-428
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• 2002

Periodontal disease is a complex infectious disease caused by bacteria in the oral mucosa, which results in gingival inflammation, breakdown of periodontal tissues, bone resorption, and finally tooth loss. Mechanical plaque control methods-scaling and root planing are effective methods to stop the progression of such periodontal disease. It was reported that subantimicrobial dose of doxycycline(SDD) regimen could improve clinical conditions of periodontal tissues without causing the overgrowth of opportunistic organisms that was a typical antibiotic side effect. Therefore pharmacological therapy, used in conjunction with mechanical therapy could be considered a useful treatment modality in the treatment of chronic periodontal disease. In this study, 30 patients diagnosed as moderate to advanced chronic periodontitis were divided into 2 groups. In this double-blind, placebo-controlled study, the patients were administered 20mg doxycycline capsule or placebo capsule b.i.d. for 4months, after scaling and root planing. Clinical parameters-bleeding on probing, pocket depth and clinical attachment level were compared and evaluated between these groups at periods of first visit, 1 month, 2 months, 3 months, 4 months. The results were as follows ; 1. In case of moderate periodontitis, pocket depth showed significant reduction after treatment in both the control & experiment groups, when compared with the baseline values(p<0.01), but in case of advanced periodontitis, only the experiment group showed significant reduction after treatment when compared with the baseline values(p<0.05). Statistically significant reduction in pocket depth was observed in the experiment group compared to the control group(p<0.05). 2. In case of moderate periodontitis, clinical attachment level showed significant reduction after treatment in both the control & experiment groups, when compared with the baseline values(p<0.01), but in case of advanced periodontitis, only the experiment group showed significant reduction after treatment when compared with the baseline values(p<0.05). Statistically significant reduction in clinical attachment level was observed in the experiment group compared to the control group(p<0.05). 3. Bleeding on probing improved after treatment in both the groups. In case of moderate periodontitis, the experiment group showed statistically significant reduction of bleeding on probing when compared with the control group at 1 and 4 months after treatment(p<0.05). In case of advanced periodontitis, treatment resulted in statistically significant reduction of bleeding on probing in both the groups(p<0.05). These results indicate that the use of subantimicrobial dose of doxycycline is a useful supplement to mechanical treatment for periodontal patients in ameliorating the clinical parameters such as periodontal pocket, attachment level, and bleeding on probing.

• 한국방사선학회논문지
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• 제15권7호
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• pp.957-964
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• 2021

PET/CT 검사 시 사용되는 F-18은 양전자를 방출하는 방사성동위원소이며, 높은 에너지의 소멸감마선과 베타선은 방사선작업종사자의 피폭을 초래하는 원인이 된다. 본 연구에서는 핵의학과에서 근무하는 방사선작업종사자의 피폭선량 저감방안의 일환으로, F-18에 대한 Apron의 낮은 차폐 효율의 원인을 규명하고, 아크릴로 이중 차폐한 Apron의 실효성을 평가하였다. L-Block, Apron+아크릴, Apron, 아크릴+Apron, 아크릴 다섯 개의 차폐체를 이용하여 선량을 측정하고, 몬테카를로 시뮬레이션을 수행하여 경향성을 비교하였다. 그 결과, 아크릴로 이중 차폐한 Apron의 차폐율이 Apron 단독 차폐한 경우보다 약 4~8% 높은 차폐효과가 있는 것으로 나타났다. 사용자의 활동성에 크게 영향이 가지 않는 범위 안에서 적절한 두께의 아크릴로 이중 차폐한 개인방호복은 방사선 작업종사자의 피폭저감화에 도움을 줄 수 있을 것이다.

• Journal of Radiation Protection and Research
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• 제46권4호
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• pp.160-169
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• 2021

Background: Dual-energy X-ray images (DEI) can distinguish or improve materials of interest in a two-dimensional radiographic image, by combining two images obtained from separate low and high energies. The concepts of DEI performance describing the performance of double-exposure DEI systems in the Fourier domain been previously introduced, however, the performance of double-exposure DEI itself in terms of various parameters, has not been reported. Materials and Methods: To investigate the DEI performance, signal-difference-to-noise ratio, modulation transfer function, noise power spectrum, and noise equivalent quanta were used. Low- and high-energy were 60 and 130 kVp with 0.01-0.09 mGy, respectively. The energy-separation filter material and its thicknesses were tin (Sn) and 0.0-1.0 mm, respectively. Noise-reduction (NR) filtering used the Gaussian-filter NR, median-filter NR, and anti-correlated NR. Results and Discussion: DEI performance was affected by Sn-filter thickness, weighting factor, and dose allocation. All NR filtering successfully reduced noise, when compared with the dual-energy (DE) images without any NR filtering. Conclusion: The results indicated the significance of investigating, and evaluating suitable DEI performance, for DE images in chest radiography applications. Additionally, all the NR filtering methods were effective at reducing noise in the resultant DE images.

• 상하수도학회지
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• 제19권1호
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• pp.53-60
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• 2005

Ferrous cement hydrates made from hydrating Portland cement doped with Fe (II) were reported to reductively dechlorinate chlorinated organics and to reduce Cr (VI) to Cr (III). In this study, kinetics of nitrate removal by ferrous cement hydrates were investigated. Nitrate removal kinetics were characterized by experimental variables such as cement hydration, amount of cement addition, Fe (II) dose, pH, and byproducts. As a result, hydrated cement showed better performances than non-hydrated cement due to the formation of LDH (layered double hydroxide). Doping of Fe (II) into the cement was found to improve removal efficiency at high pHs by association with Fe (II) sorbed on cement hydrates as a reactive reductant. Reduction of nitrate produced ammonium as a major product, which accounted for 63.5% of the final products, and nitrite (0.15%) as a minor product. These results indicate that the developed media are effective as sorbent/reducing agents in the nitrate removal and the reaction mechanisms of nitrate removal are sorption and reduction.

• Journal of Periodontal and Implant Science
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• 제27권4호
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• pp.701-722
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• 1997

It was reported that low dose doxycycline(LDD) regimen could inhibit pathologically elevated collagenase activity in the gingival crevicular fluid of petients with adult periodontitis without producing typical antibiotic side effects. The purpose of this study was to evaluate the effects of LDD regimen(20mg) administered during non-surgical therapy on clinical index and gingival crevicular fluid enzyme activity in diabetics who are at high risk for periodontal disease. Forty-nine subjects having at least two sites with probing pocket depths greater than 4mm were selected. In this double-blind, placebo-controlled study, the patients were administered 20 mg doxycycline capsule or placebo capsule b.i.d. for 2 weeks. Clinical parameters of dental plaque, gingival inflammation, probing pocket depth and probing attachment level were assessed at week 0, 2, 4, and 8. Gingival crevicular fluid samples were collected at the same time to evaluate the activities of collagenase and elastase. Clinical parameters and elastase activity were significantly reduced in all groups compared to the baseline value after treatment. Significantly greater reduction in pocket depth and gain in attachment level was shown in the LDD-administered group compared to placebo group in both adult periodontitis and diabetic patients. Total collagenase activity was also reduced significantly in all groups after treatment, but the greater reduction was seen in the LDD-administered diabetics group compared to relevant placebo group(at 4, 8week). Significantly greater reduction in active collagenase activity was also seen in the LDD-administered group compared to placebo group in diabetic patients(at 2, 4, 8week). These results indicated that use of low dose doxycycline could be aueseful adjunct to instrumentation therapy in the management of diabetic patient with periodontitis as well as adult periodontitis patient.

• 한국방사선학회논문지
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• 제8권6호
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• pp.333-338
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• 2014

최근 의료 분야에서의 불필요한 피폭을 체계적으로 관리해야 한다는 사회적 요구 증가와 더불어 차폐의 중요성이 대두되고 있는 실정이다. 하지만 현재 상용화된 제품은 다양한 의료방사선 분야보다 세분되어 있지 않다. 이에 본 연구에서는 최적화된 차폐재의 구조를 몬테카를로 시뮬레이션을 활용하여 제시하고자 하였다. 모의 추정 결과, 유방촬영 에너지(30 kVp) 스펙트럼에 대하여 단일 차폐재의 경우 $30{\mu}mPb$, 2 mmAl에서 90% 이상의 차폐율을 확인하였고, 이중차폐 구조에서는 0.03 mmPb와 1 mmAl의 설계 시 효율적인 것으로 판단되었다. 또한, 일반촬영 에너지(80 kVp) 스펙트럼에 대해서는 $340{\mu}mPb$, 30 mmAl에서 90% 이상의 차폐율을 확인하였으며, 이중차폐 구조에서는 0.3 mmPb와 1 mmAl의 설계가 유용할 것으로 사료된다. 이러한 결과는 향후 피폭저감을 위한 맞춤형 상용화 제품 개발에 대한 기초자료로 활용될 수 있을 것으로 기대된다.

• Radiation Oncology Journal
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• 제34권1호
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• pp.18-25
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• 2016

Purpose: Radiotherapy of the neck is known to cause carotid artery stenosis. We compared the carotid artery dose received between volumetric modulated arc therapy (VMAT) and conventional fixed-field intensity-modulated radiotherapy (IMRT) plans in patients with early glottic cancer. Materials and Methods: Twenty-one early glottic cancer patients who previously underwent definitive radiotherapy were selected for this study. For each patient, double arc VMAT, 8-field IMRT, 3-dimensional conformal radiotherapy (3DCRT), and lateral parallel-opposed photon field radiotherapy (LPRT) plans were created. The 3DCRT plan was generated using lateral parallel-opposed photon fields plus an anterior photon field. VMAT and IMRT treatment plan optimization was performed under standardized conditions to obtain adequate target volume coverage and spare the carotid artery. Dose-volume specifications for the VMAT, IMRT, 3DCRT, and LPRT plans were calculated with radiotherapy planning system. Monitor units (MUs) and delivery time were measured to evaluate treatment efficiency. Results: Target volume coverage and homogeneity results were comparable between VMAT and IMRT; however, VMAT was superior to IMRT for carotid artery dose sparing. The mean dose to the carotid arteries in double arc VMAT was reduced by 6.8% compared to fixed-field IMRT (p < 0.001). The MUs for VMAT and IMRT were not significantly different (p = 0.089). VMAT allowed an approximately two-fold reduction in treatment delivery time in comparison to IMRT (3 to 5 minutes vs. 5 to 10 minutes). Conclusion: VMAT resulted in a lower carotid artery dose compared to conventional fixed-field IMRT, and maintained good target coverage in patients with early glottic cancer.

• 한국식품영양학회지
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• 제35권6호
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• pp.464-472
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• 2022

The present study was designed to investigate the antiproliferative activity and molecular mechanisms of Bibimbap in HT-29 human colorectal adenocarcinoma cells. Bibimbap extract inhibited the proliferation of HT-29 cells by 50% at a concentration of 10.1±0.17 mg/mL for 48 h. The population of live cells decreased slightly, and the morphology changed with a reduction in cell volume (pyknosis) with Bibimbap. Treatment with 5 mg/mL of Bibimbap resulted in slight cell shrinkage. Furthermore, as the Bibimbap dose increased to 10 mg/mL, these characteristics were more evident, and HT-29 cells exhibited partial detachment by staining with the DNA-binding dye Hoechst 33342. Flow cytometric analysis by Annexin V and PI double staining showed that Bibimbap increased the levels of apoptosis. Analysis of the mechanism of these events showed that Bibimbap-treated cells exhibited a mitochondria-dependent apoptotic pathway through the modulation of caspase-3, caspase-8, caspase-9, and poly-ADP ribose polymerase, as well as Bax and Bcl-2 expression in dose- and time-dependent manners. Consequently, Bibimbap exerts a significant antiproliferative effect on HT-29 human colorectal adenocarcinoma cells.