• Clinical and Experimental Reproductive Medicine
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• v.28 no.3
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• pp.225-233
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• 2001

Objective : To evaluate the efficacy of low-dose aspirin on IVF outcome and endometrium in patients undergoing IVF-ET. Materials and Methods : From February, 2001 to Jun, 2001, 60 infertile patients were randomly divided into study group (28 cycles) and control group (32 cycles). The study group received a daily oral dose of 25 mg of aspirin for at least 2 weeks from first visiting day. Controlled ovarian hyperstimulation was initiated in all patients with the GnRH agonist starting in the midluteal phase of the previous cycle. Results: There were no significant differences in age of the patients, basal serum E2, LH, FSH level and endometrial thickness among two groups. There were no statistically significant differences between the study group and the control group respectively in dosage ($26.5{\pm}4.8$ vs $26.2{\pm}5.3$ amples) and duration ($10.4{\pm}4.2$ vs $9.8{\pm}5.3$ days) of gonadotropin administration, serum E2 level on the hCG administration day ($1823{\pm}342$ vs $1854{\pm}543$), LH ($14.5{\pm}2.7$ vs $14.8{\pm}3.1$), FSH ($16.7{\pm}3.4$ vs $18.3{\pm}4.7$), the number of follicles > 15 mm ($13.2{\pm}6.3$ vs $12.8{\pm}5.9$), the number of oocytes retrieved ($9.2{\pm}2.4$ vs $8.4{\pm}1.7$), the number of embryos transferred ($4.7{\pm}2.0$ vs $4.7{\pm}2.0$), fertilization rate (68.4% vs 64.5%), implantation rate (21.3% vs 17.6%), and clinical pregnancy rate (28.4% vs 26.2%). The endometrial thickness and the percentage of endometrial trilaminar pattern on hCG day were significantly higher in study group than control group ($12.9{\pm}3.7mm$ vs $10.4{\pm}2.8mm$, 78.3% vs 64.5%). Conclusion: Many reports suggest that low-dose aspirin improve ovarian response, implantation rate, fertilization rate, implantation rate, and pregnancy rate by increasing the blood flow, but we couldn't prove the significant effect of low-dose aspirin on the IVF outcome except on endometrium. This may be affected by dose of aspirin, duration, and number of patients studied. This trial is small, so our results highlight the need for a large randomized controlled trial to identify the effect of low-dose as pirin on IVF-ET outcome.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3398-3402
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• 2022

We fabricated a 15 m long position-sensitive plastic scintillation optical fiber (PSOF) detector consisting of a PSOF, two photomultiplier tubes, four fast amplifiers, and a digitizer. A single PSOF was used as a sensing part to estimate the gamma-ray source position, and ¹³⁷Cs, an uncollimated solid-disk-type radioactive isotope, was used as a gamma-ray emitter. To improve the sensitivity, accuracy, and measurement time of a PSOF detector compared to those of previous studies, the performance of the amplifier was optimized, and the digital signal processing (DSP) was newly designed in this study. Moreover, we could measure very low dose rates of gamma-rays with high sensitivity and accuracy in a very short time using our proposed PSOF detector. The results of this study indicate that it is possible to accurately and quickly locate the position of a very low dose rate gamma-ray source in a wide range of contaminated areas using the proposed position-sensitive PSOF detector.

• Korean Journal of Environmental Biology
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• v.19 no.3
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• pp.205-210
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• 2001

To determine the effect of low dose gamma radiation on the germination and enzyme activities, seeds of Chinese cabbage (Brassica compestris L. cv. Hanyoreum) and radish (Raphanus sativus L. cv. Chungsukoungzoung) were irradiated at the dose of 2-50 Gy. The germination rate of irradiation group was higher than that of the control. Especially it was highest at the early stage. The germination rate of Chinese cabbage was high at 2 Gy and 8 Gy irradiation group and that of radish was high at 2 Gy, 6 Gy and 10 Gy irradiation group. Growth of both seedlings of Chinese cabbage and radish increased positively in low dose irradiation group. The height of Chinese cabbage was noticeably high at 4 Gy and 10 Gy irradiation group and that of radish at 6 Gy irradiation group. The protein contents of seedlings from seeds irradiated with the low dose gamma radiation was higher than the control, especially at the early stage. The enzyme activities of seedlings from seeds irradiated with the low dose gamma radiation was high at 4 Gy and 10 Gy irradiation group. These results suggest that the germination, growth and enzyme activities of old vegetable seeds could be promoted by the low dose gamma radiation.

• Journal of radiological science and technology
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• v.11 no.1
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• pp.33-41
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• 1988

This study was measured the radiation-induced current - X-ray dose, dose rate, X-ray quality, time, temperature, electric field characteristics and the dependence of gap length in insulating oil under of D.C. Voltage before, during and after X-ray irradiation. The obtained results can be summarized as following. 1. The radiation - induced current is more the dependence of X-ray quality (tube voltage) than quantity (tube current), the dependence of quantity is appeared at the high than low X-.ay tube voltage. 2. The dependence of dose rate is appeared at the more dose rate, and ${\triangle}\;=\;0.64{\sim}0.74$. 3. The higher temperature of insulating oil and X-ray tube voltage (X-ray quality) is increased, at the low electric field, the more radiation-induced current. 4. $G_{eq}-G_{o}(={\triangle}G)$ is increased at the low than high temperature, high than low X-ray quality. 5. The dependence of temperature is appeared before than during X-ray irradiation. 6. The RIC saturation region is appeared at the high than low insulating oil temperature during (1000 V/cm above) than before (4000 V/cm above) X-ray irradiation.

• Radiation Oncology Journal
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• v.14 no.2
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• pp.123-128
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• 1996

Purpose : This is a retrospective study to compare the Palliation rates, survival rates and complications of low dose rate and high dose rate endobronchial brachytherapy in the management of malignant airway obstruction. Materials and methods : Forty three consecutive patients with malignant airway compromise from primary or metastatic lung tumors were treated with low dose rate(LDR) endobronchial Iridium-192 insertion(21 patients) between October 1988 and June 1992, and high dose rate(HDR) endobronchial brachytherapy(22 patients) between August 1992 and April 1994 with palliative aim Flexible fiberoptic bronchoscopy under fluoroscopic control was utilized in all 91 procedures. Twenty seven LDR Procedures delivered a dose of 5-7.5 Gy to a 1.0 cm radius respectively. Results : Subjective and objective responses to treatments were evaluated on follow-up examinations by clinical examination, chest x-rays and CT scan of the chest on some patients. Fifteen of 21 LDR patients and 19 of 22 HDR Patients showed subjective improvement in terms of better breathing and less Productive cough as well as complete disappearance of hemoptysis. Objective improvement on chest x-rays and CT scan of the chest had been demonstrated on 8 LDR Patients and 10 HDR patients. Conclusion : The technique of LDR and HDR endobronchial brachytherapy is simple and well tolerated procedure with minimal morbidity It Provides excellent palliation by keeping airway Patent in these short life-spanned patients.

• Radiation Oncology Journal
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• v.16 no.4
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• pp.357-366
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• 1998

Brachytherapy is an essential part of radiotherapy for uterine cervical cancer. The low dose rate (LDR) regimen has been the major technique of intracavitary therapy for cervical cancer. However, there has been an expansion in the last 20 years of high dose rate (HDR) machines using Ir-192 sources. Since 1979, HDR brachytherapy has been used for the treatment of uterine cervical cancer in Korea. The number of institutions employing HDR has been increasing, while the number of low dose rate system has been constant. In 1995, there was a total 27 HDR brachytherapy units installed and 1258 cases of patients with cervical cancer were treated with HDR Most common regimens of HDR brachytherapy are total dose of 30-39 Gy at point A with 10-13 fractions in three fractions per week. 24-32 Gy with 6-8 fractions in two fractions per week, and 30-35 Gy with 6-7 fractions in two fractions per week. The average fractionation regimen of HDR brachytherapy is about 8 fractions of 4.1 Gy each to Point A. In Korea, treatment results for HDR brachytherapy are comparable with the LDR series and appears to be a safe and effective alternative to LDR therapy for the treatment of cervical carcinoma. Studies from the major centers report the five-year survival rate of cervical cancer as. 78-86$\%$ for Stage 1, 68-85$\%$ for stage 11, and 38-56$\%$ for Stage III. World-wide questionnaire study and Japanese questionnaire survey of multiple institutions showed no survival difference in any stages and dose-rate effect ratio (HDR/LDR) was calculated to be 0.54 to 0.58. However the optimum treatment doses and fractionation schemes appropriate to generate clinical results comparable to conventional LDR schemes have yet to be standardized. In conclusion, HDR intracavitary radiotherapy is increasingly practiced in Korea and an effective treatment modality for cervical cancer. To determine the optimum radiotherapy dose and fractionation schedule, a nation-wide prospective study is necessary in Korea. In addition, standardization of HDR application (clinical, computer algorithms, and dosimetric aspects) is necessary.

• Journal of radiological science and technology
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• v.37 no.1
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• pp.21-28
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• 2014

Cultured pancreatic beta cells and nerve cells, it is given normal condition of 10% FBS (fetal bovine serum), 11.1 mM glucose and hyperglycemia codition of 1% FBS, 30 mM glucose. For low LET X-ray irradiated with 0.5 Gy/hr dose-rate(total dose: 0.5 to 5 Gy). Survival rates were measured by MTT assay. When non irradiated, differentiated in the pancreatic beta cells experiment is hyperglycemia conditions survival rate compared to normal conditions survival rate seemed a small reduction. However increasing the total dose of X-ray, the survival rate of normal conditions decreased slightly compared to the survival rate of hyperglycemia conditions, the synergistic effect was drastically reduced. When non irradiated, undifferentiated in the nerve cells experiment is hyperglycemia conditions survival rate compared to normal conditions survival rate seemed a large reduction. As the cumulative dose of X-ray normal conditions and hyperglycemia were all relatively rapid cell death. But the rate of decreased survivals by almost parallel to the reduction proceed and it didn't show synergistic effect.

• Journal of Korean Neurosurgical Society
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• v.42 no.4
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• pp.286-292
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• 2007

Objective : Gamma Knife Stereotactic Radiosurgery (GK SRS) has become an important treatment modality for vestibular schwannomas. We evaluated the tumor control rate, patterns of tumor volume change and preservation of hearing following low-dose radiation for vestibular schwannomas in a homogeneous cohort group in which the mean marginal dose was 12 Gy. Methods : A total of 59 patients were enrolled in this study. All enrolled patients were followed-up for at least 5 years and the radiation dose was 11-13 Gy. Regular MRI, audiometry and clinical evaluations were done and tumor volumes were obtained from MRI using the OSIRIS program. Results : The tumor control rate was 97%. We were able to classify the patterns of change in tumor volume into three categories. Transient increases in tumor volume were detected in 29% of the patients and the maximum transient increase in tumor volume was identified at 6 to 30 months after GK SRS. The transient increases in tumor volume ranged from 121% to 188%. Hearing was preserved in 4 of the 12 patients who had serviceable hearing prior to treatment. There were no other complications associated with GK SRS. Conclusion : Low-dose GK SRS was an effective and safe mode of treatment for vestibular schwannomas in comparison to the previously used high-dose GK SRS. Transient increases in tumor volume can be identified during the follow-up period after low-dose GK SRS for vestibular schwannomas. Physicians should be aware that these increases are not always indicative of treatment failure and that close observation is required following treatments. Unfortunately, a satisfactory hearing preservation rate was not achieved by reducing the radiation dose. It is thought that hearing preservation is a more sophisticated problem and further research is required.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.242-242
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• 2010

Si(100) 표면에 이온을 일정한 에너지로 dose량을 동일하게 유지하고, dose rate만을 변화시켜가며 주입한 후에 depth profile과 damage, 그리고 sheet resistance를 조사하였다. 일정한 에너지로 이온을 주입하여도 dose rate의 변화에 따라서 depth profile에 변화를 보이는 것을 확인할 수 있었고 sheet resistance역시 dose rate변화에 비례하여 변화하는 것을 확인할 수 있었다. 본 연구는 Crystal-TRIM program으로 computer simulation 하여 damage profile의 결과를 통해 dose rate가 클수록 시료 표면 근처에 잔류 damage의 양이 높게 나타나는 것을 알 수 있었고 그 잔류 damage의 표면근방 분포가 sheet resistance에 직접적인 영향을 미친다는 것을 확인할 수 있었다.

• Journal of Radiation Protection and Research
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• v.34 no.2
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• pp.77-81
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• 2009

An Area Radiation Monitoring System (ARMS) ionization chamber, which had an 11.8 L active volume, was fabricated and performance-tested at KAERI. Low leakage currents, linearities at low and high dose rates were achieved from performance tests. The correlation coefficients between the ionization currents and the dose rates are 1 at high dose rate and 0.99 at low dose rate. In this study, an integration-type ARMS ionization chamber was tested over a year for an evaluation of its long-term stability at a radioisotope (RI) repository of the Young-gwang nuclear power plant. The standard deviation of dose rate of 1 day data and over a 100-days mean value were 6.2 $\mu$R/h and 2.9 $\mu$R/h, respectively. The fabricated ARMS ionization chamber showed stable performance from the results of the long-term tests. Design and performance characteristics of the fabricated ionization chamber for the ARMS from performance-tests are also addressed.