• Journal of Biomedical Engineering Research
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• v.36 no.4
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• pp.123-127
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• 2015

Recently, new gamma camera systems enabling low radiation dose imaging have been developed. We reviewed the recent development of these low dose gamma camera systems including high sensitivity detectors, device structures, noise reduction filters, efficient image reconstruction algorithms, low dose protocols, and so on. It is expected that further technological advances reduce both radiation dose and imaging time in gamma camera imaging especially for radiation-sensitive patients such as pediatric patients.

• Journal of the Korean Society of Radiology
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• v.9 no.2
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• pp.109-115
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• 2015

In case of a CT examinations, there is a difference in the distribution of radiation dose from that of general X-ray equipments, and it has been known to cause a great radiation exposure during the examinations. However, owing to its high reliability on the accuracy of a examinations result, its use has increased continuously. In consideration of such a circumstance, the CT equipment, radiation dose during CT examinations, diagnostic reference level, and solutions to reduce radiation dose were mentioned on the basis of previously reported data.

• Proceedings of the Safety Management and Science Conference
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• 2011.11a
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• pp.563-571
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• 2011

The purpose of the study was to evaluation of the radiation dose reduction using various automatic exposure control (AEC) systems in different manufactures multi-detector computed tomography (MDCT). We used three different manufacturers for the study: General Electric Healthcare, Philips Medical systems and Siemens Medical Solutions. The general scanning protocol was created for the each examination with the same scanning parameters as many as possible. In the various AEC systems, the evaluation of reduced-dose was evaluated by comparing to fixed mAs with using body phantom. Finally, when we applied to AEC for three manufacturers, the radiation dose reduction decreased each 35.3% in the GE, 58.2% in the Philips, and 48.6% in the Siemens. This applies to variety of the AEC systems which will be very useful to reduce the dose and to maintain the high quality.

• 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 the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.71-77
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• 2014

In this paper, we investigated the effects of high-energy electron beam irradiation (HEEBI) on the optical transmittance of InGaZnO (IGZO) films grown on transparent Corning glass substrates, with a radio frequency magnetron sputtering technique. The IGZO thin films deposited at low temperature were treated with HEEBI in air at room temperature (RT) with an electron beam energy of 0.8 MeV and doses of $1{\times}10^{14}-1{\times}10^{16}electrons/cm^2$. The optical transmittance of the IGZO films was measured using an ultraviolet visible near-infrared spectrophotometer (UVVIS). The detailed estimation process for separating the transmittance of HEEBI-treated IGZO films from the total transmittance of IGZO films on transparent substrates treated with HEEBI is given in this paper. Based on the experimental results, we concluded that HEEBI with an appropriate dose of $10^{14}electrons/cm^2$ causes a maximum increase in the transparency of IGZO thin films. We also concluded that HEEBI treatment with an appropriate dose shifted the optical band gap ($E_g$) toward the lower energy region from 3.38 to 3.31 eV. This $E_g$ shift suggested that HEEBI in air at RT with an appropriate dose acts like a thermal annealing treatment in vacuum at high temperature.

• Journal of Ginseng Research
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• v.31 no.2
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• pp.109-116
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• 2007

Korean red ginseng has broad efficacious effects against hypertension, diabetes, nociception, and cancer, and it counteracts weakness. It has been reported that Korean red ginseng is able to normalize blood pressure, improve cholesterol and lower blood glucose levels. We have recently reported that Korean red ginseng extract (KRGE) significantly prevented rat carotid arterial thrombosis in vivo, and inhibited platelet aggregation ex vivo and in vitro in a dose-dependent manner. The purpose of this study was to examine the effects of KRGE on blood circulation in human by measuring ex vivo platelet aggregation, plasma coagulation and serum lipid profiles in healthy volunteers. Subjects were randomly divided into three groups (placebo-group, KRGE-low dose group, KRGE-high dose group). Administration of KRGE to subjects significantly inhibited ADP-induced platelet aggregations both in KRGE-low dose group from $72.79{\pm}20.53$ to $62.00{\pm}23.06%$ (p=0.0009), and in KRGE-high dose group from $75.14{\pm}21.86$ to $64.52{\pm}24.72%$ (p=0.0039), respectively. Administration of KRGE to subjects also significantly inhibited collagen-induced platelet aggregations both in KRGE-low dose group from $85.52{\pm}12.57$ to $79.62{\pm}20.47%$ (p=0.0916), and in KRGE-high dose group from $80.24{\pm}18.11$ to $70.31{\pm}25.93%$ (p=0.0565), respectively. Whereas, KRGE has no significant effects on coagulation system, such as prothrombin time (PT) and activated partial thromboplastin time (APTT), and serum lipid profiles, such as total cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol and triglyceride. KRGE also has no significant effects on hematological and serum biochemical profiles. These results suggest that KRGE has a potential to improve blood circulation through antiplatelet activity in human, and KRGE intake may be beneficial for the individuals with high risks of thrombotic and cardiovascular diseases.

• The Korean Journal of Nuclear Medicine
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• v.35 no.3
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• pp.117-124
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• 2001

Serum thyroglobulin measurement and I-131 whole-body scintigraphy (WBS) are well-established methods for the detection of recurrence in the follow-up of patients with thyroid carcinoma. However, inconsistent results are observed frequently, and these two methods are not always able to detect recurrence. In some patients, serum thyroglobulin level is elevated but the WBS is negative, because the recurrent tumor is too small and below the sensitivity of the diagnostic scan, or there is a dissociation between thyroglobulin synthesis and the iodine frapping mechanism. In such cases, various nuclear imaging methods including Tl-201 Tc-99m-sestamibi, and F-18-FDG PET can be used besides anatomical imaging methods. Among them, FDG PET localizes recurrent lesions in WBS-negative thyroid carcinoma with high accuracy. Several studies have suggested that empirical high-dose I-131 therapy resulted in a high rate of visualization in post-therapy scans with evidence of subsequent improvement. An important question is when to operate on patients with recurrent tumor. We believe that surgical removal is the best means of treatment for patients with localized persistent tumor, despite the high-dose I-131 therapy. with tumor in thyroid remnant, and with isolated recurrence in the lymph node, lung or bone. In addition, we recommend palliative resection of locally unresectable mass with subsequent treatment with high-dose I-131 therapy. Before I-131 therapy, the evaluation of sodium-iodide symporter expression in thyroid carcinoma can predict iodine uptake. Retinoic acid is known to induce redifferentiation, and to enhance I-131 uptake in thyroid carcinoma. Retinoic acid therapy may represent an alternative approach before high-dose I-131 therapy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3412-3418
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• 2013

The Purpose of this study was to evaluate by comparing the dose change and build up characteristic according to delay time in 30 days of glass dosimeter processed preheat and non preheat when measuring accumulation dose of radiation by using glass dosimeter over the long haul. For obtaining low dose with 0.1 mGy, 1 mGy and 5 mGy, we employed diagnostic generator AccuRay-650R. We compared the build up characteristic over the long haul by exposuring radiation to 30 glass dosimeters sorted into 10 glass dosimeters per tube voltage and current. In Non preheat glass dosimeter, initial measured dose was inferior to exposed dose but as time goes on, was close to exposed dose steadily. In 72 hour after experiment end, non preheat glass dosimeters were not indicated the difference from preheat glass dosimeters and statistical analysis were meaningful (p>0.05). Initial measured dose for low glass dosimeter processed preheat was close to exposed dose and stable. After 15 days dose was gradually increased. Previous study characteristics of glass dosimeter were with respect to characteristic of glass dosimeter in high dose of high energy area. However, in this study, we make a judgment to measure the dose of glass dosimeter without preheat processing when measuring the accumulation dose of low dose in conclusion.

• Journal of Preventive Medicine and Public Health
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• v.38 no.4
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• pp.431-436
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• 2005

Objectives : We investigated the seroprevalence of the measles antibody and its at tributable factors for the students who underwent routine 2-dose Schedule Era. Methods : The subjects were 996 students of the national measles seroepidemiologic study in December 2000 who had vaccination records. We conducted a questionnaire survey and we performed serologic testing for the measlesspecific IgG by using an enzyme linked immunosorbent assay. Results : The coverage for the first dose of the MMR vaccination at 12-15 months of age was 95.1% and the coverage for the second dose of MMR at 4-6 years of age was 35.0%. The proportion of subjects undergoing 2-dosesof MMR dec reased as the age of the subjects increased. The seropositive rate of the measles antibody was significantly high in the second dose vaccinees (93.5% in the second dose group, 84.7% in the non-second dose group, p<0.001) and it was 72.0% in the 0-dose group, 85.4% in the 1-dose group and 93.7% in the 2-dose group (p<0.001). Two point eight percent of the subjects had a past history of measles infection. On the multiple logistic regression analysis, the first and second dose (odds ratio, 8.54; 95% CI.=3.05-23.91), the first dose (odds ratio, 3.06; 95% CI.=1.20-7.81) and the outbreak in the year 2000 (odds ratio, 1.89; 95% CI.=1.24-2.88) were the significant factors for the seropositivity. Conclusions : Maintaining high coverage with a 2-dose vaccination program would be the decisive factor to prevent an outbreak of measles and to eliminate measles in Korea.

• Journal of Yeungnam Medical Science
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• v.6 no.2
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• pp.113-119
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• 1989

In recent years there has been a growing interest in total body, hemibody, total lymphoid irradiation. For refractory leukemia or lymphoma patients, various techniques and dose regimens were introduced, including high dose total body irradiation for destruction of leukemic or bone marrow cells and immunosuppression prior to bone marrow transplantation, and low dose total body irradiation for treatment of lymphocytic leukemia or lymphomas. Accurate provision for specified dose and the desired homogeneity are essential before clinical total body irradiation. Purposes of this paper are to discuss calibrating Cobalt Unit in 3m distance using Rando Phantom, to compare calculated dose, calibrated dose, and compensating filters for homogeneous dose distribution in the head and neck, the lung, and the pelvis. Results were following. 1. Measured dose on the lung was 6% higher than on the abdomen. Measured dose on the head (10%) and neck (18%) were higher than the abdomen because of thinness. Pelvic dose was measured 12% less than the abdomen. Those data suggest that compensating filter was essential. 2. Measured dose according to distance was 3% less than calculated dose which suggest that all doses in clinical use should be compared with calculated dose for minimizing error.