• Investigative Magnetic Resonance Imaging
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• v.5 no.1
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• pp.57-65
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• 2001

Purpose : $T_2$-weighted half courier Echo Planar Imaging (T2HEPI) method is proposed to reduce measurement time of existing EPI by a factor of 2. In addition, high $T_2$ contrast is obtained for clinical applications. High resolution single-shot EPI images with $T_2$ contrast are obtained with $128{\times}128$ matrix size by the proposed method. Materials and methods : In order to reduce measurement time in EPI, half courier space is measured, and rest of half courier data is obtained by conjugate symmetric filling. Thus high resolution single shot EPI image with $128{\times}128$ matrix size is obtained with 64 echoes. By the arrangement of phase encoding gradients, high $T_2$ weighted images are obtained. The acquired data in k-space are shifted if there exists residual gradient field due to eddy current along phase encoding gradient, which results in a serious problem in the reconstructed image. The residual field is estimated by the correlation coefficient between the echo signal for dc and the corresponding reference data acquired during the pre-scan. Once the residual gradient field is properly estimated, it can be removed by the adjustment of initial phase encoding gradient field between $70^{\circ}$ and $180^{\circ}$ rf pulses. Results : The suggested T2EPl is implemented in a 1.0 Tela whole body MRI system. Experiments are done with the effective echo times of 72ms and 96ms with single shot acquisitions. High resolution($128{\times}128$) volunteer head images with high $T_2$ contrast are obtained in a single scan by the proposed method. Conclusion : Using the half courier technique, higher resolution EPI images are obtained with matrix size of $128{\times}128$ in a single scan. Furthermore $T_2$ contrast is controlled by the effective echo time. Since the suggested method can be implemented by software alone (pulse sequence and corresponding tuning and reconstruction algorithms) without addition of special hardware, it can be widely used in existing MRI systems.

• The Korean Journal of Nuclear Medicine
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• v.39 no.6
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• pp.445-455
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• 2005

Purpose: We developed an animal SPECT system using clinical Philips ARGUS scintillation camera and pinhole collimator with specially manufactured small apertures. In this study, we evaluated the physical characteristics of this system and biological feasibility for animal experiments. Materials and Methods: Rotating station for small animals using a step motor and operating software were developed. Pinhole inserts with small apertures (diameter of 0.5, 1.0, and 2.0 mm) were manufactured and physical parameters including planar spatial resolution and sensitivity and reconstructed resolution were measured for some apertures. In order to measure the size of the usable field of view according to the distance from the focal point, manufactured multiple line sources separated with the same distance were scanned and numbers of lines within the field of view were counted. Using a Tc-99m line source with 0.5 mm diameter and 12 mm length placed in the exact center of field of view, planar spatial resolution according to the distance was measured. Calibration factor to obtain FWHM values in 'mm' unit was calculated from the planar image of two separated line sources. Te-99m point source with i mm diameter was used for the measurement of system sensitivity. In addition, SPECT data of micro phantom with cold and hot line inserts and rat brain after intravenous injection of [I-123]FP-CIT were acquired and reconstructed using filtered back protection reconstruction algorithm for pinhole collimator. Results: Size of usable field of view was proportional to the distance from the focal point and their relationship could be fitted into a linear equation (y=1.4x+0.5, x: distance). System sensitivity and planar spatial resolution at 3 cm measured using 1.0 mm aperture was 71 cps/MBq and 1.24 mm, respectively. In the SPECT image of rat brain with [I-123]FP-CIT acquired using 1.0 mm aperture, the distribution of dopamine transporter in the striatum was well identified in each hemisphere. Conclusion: We verified that this new animal SPECT system with the Phlilps ARGUS scanner and small apertures had sufficient performance for small animal imaging.

• The Korean Journal of Health Service Management
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• v.2 no.1
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• pp.105-124
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• 2008

The purpose of this research is to provide the data base for the activation of Quality Improvement operation through investigating the status of Quality Improvement operation, and finding out factors influencing on the goal-orientation of QI performers in the medical centers of more than one hundred beds where are practicing Quality Improvement operation. In order to reach the purpose, document study was carried out grounded on the proceeding researches and formulated statistical data in relation with the status of Quality Improvement performers, and proof study was carried out through questionnaire survey. The subjects of the survey were the Quality Improvement performers working in seventy three medical centers in Pusan-Gyeongnam, Daegu-Gyeongbuk, and Ulsan. Among eighty three Quality Improvement performers, fifty, five were questionnaire surveyed, on the result of which Reliability Analysis, Factor Analysis, and Multiple Regression Analysis were made, using statistical program. The the results of the proof analysis on this research are as follows. First, in the factors influencing the devoting to goal pursuit of QI performers, organization-goal contribution(0.44) had significant positive effects, while organization conflict(-0.25) had significant negative effects. In other words, the higher the organization-goal contribution was, the higher the devoting to goal pursuit was, while the less the organization conflict was, the higher the devoting to goal pursuit was, which was statistically significant.(p<0.05). Second, in the aspect of goal performance types of QI performers, the process-centered type showed high level of the devoting to goal pursuit, which was statistically significant.(p<0.05). Third, in the aspect of QI performance degree, the higher the devoting to goal pursuit was, the higher the QI performance degree was, which was statistically significant.(p<0.05). In addition, the performers who perceived their workplaces organic structure showed much higher QI performance degree, which statistically significant.(p<0.05). Generalizing the results of this research, it is possible to offer a few suggestions as follows. First, as the competition among the medical centers is more severe recently owing to medical center evaluation system, medical centers are practicing various Quality Improvement operation in all of medical services such as clinical performance and management performance, to reach the purpose of both cost-cutting and medical quality improvement. Thus in order to practice Quality Improvement operation more efficiently in medical centers, it is essential to nuke use of problem-solving methods and statistical members. This as the willingness of chief executives and positive attitude and recognition of organization members. This requires the installation of divisions in charge and disposition of persons in charge, not to speak of persistent training of Quality Improvement. Second, the divisions in charge of QI carry out Quality Improvement operation at the medical center level, and take the role of generalizing and adjusting QI performances of various departments. Owing to this role, the division in charge of QI is considered indispensable organization in the QI operation of medical centers along with medical QI committee, while it contributes to the government's goal of reducing quality level gaps among medical centers. Therefore it is necessary for government and QI organizations to give institutional support and resources for the sake of QI operation of medical centers, besides to supply systematic trainning and informations to the divisions and persons in charge of QI. Third, it is certain that disposition of persons in charge should be determined in view of the scale and the scope of QI operation in medical centers.

• Radiation Oncology Journal
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• v.24 no.4
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• pp.255-262
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• 2006

$\underline{Purpose}$: To evaluate the pathological prognostic factors related to local recurrence after radical surgery and adjuvant radiation therapy in advanced rectal cancer. $\underline{Materials\;and\;Methods}$: Fifty-four patients with advanced rectal cancer who were treated with radical surgery followed by adjuvant radiotherapy and chemotherapy between February 1993 and December 2001 were enrolled in this study. Among these patients, 14 patients experienced local recurrence. Tissue specimens of the patients were obtained to determine pathologic parameters such as histological grade, depth of invasion, venous invasion, lymphatic invasion, neural invasion and immunohistopathological analysis for expression of p53, Ki-67, c-erb, ezrin, c-met, phosphorylated S6 kinase, S100A4, and HIF-1 alpha. The correlation of these parameters with the tumor response to radiotherapy was statistically analyzed using the chi-square test, multivariate analysis, and the hierarchical clustering method. $\underline{Results}$: In univariate analysis, the histological tumor grade, venous invasion, invasion depth of the tumor and the over expression of c-met and HIF-1 alpha were accompanied with radioresistance that was found to be statistically significant. In multivariate analysis, venous invasion, invasion depth of tumor and over expression of c-met were also accompanied with radioresistance that was found to be statistically significant. By analysis with hierarchical clustering, the invasion depth of the tumor, and the over expression of c-met and HIF-1 alpha were factors found to be related to local recurrence. Whereas 71.4% of patients with local recurrence had 2 or more these factors, only 27.5% of patients without local recurrence had 2 or more of these factors. $\underline{Conclusion}$: In advanced rectal cancer patients treated by radical surgery and adjuvant chemo-radiation therapy, the poor prognostic factors found to be related to local recurrence were HIF-1 alpha positive, c-met positive, and an invasion depth more than 5.5 mm. A prospective study is necessary to confirm whether these factors would be useful clinical parameters to measure and predict a radio-resistance group of patients.

• Radiation Oncology Journal
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• v.28 no.1
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• pp.50-56
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• 2010

Purpose: We report the results of an external audit on the absorbed dose of radiotherapy beams independently performed by third parties. For this effort, we developed a method to measure the absorbed dose to water in an easy and convenient setup of solid water phantom. Materials and Methods: In 2008, 12 radiotherapy centers voluntarily participated in the external auditing program and 47 beams of X-ray and electron were independently calibrated by the third party’s American Association of Physicists in Medicine (AAPM) task group (TG)-51 protocol. Even though the AAPM TG-51 protocol recommended the use of water, water as a phantom has a few disadvantages, especially in a busy clinic. Instead, we used solid water phantom due to its reproducibility and convenience in terms of setup and transport. Dose conversion factors between solid water and water were determined for photon and electron beams of various energies by using a scaling method and experimental measurements. Results: Most of the beams (74%) were within ${\pm}2%$ of the deviation from the third party's protocol. However, two of 20 X-ray beams and three of 27 electron beams were out of the tolerance (${\pm}3%$), including two beams with a >10% deviation. X-ray beams of higher than 6 MV had no conversion factors, while a 6 MV absorbed dose to a solid water phantom was 0.4% less than the dose to water. The electron dose conversion factors between the solid water phantom and water were determined: The higher the electron energy, the less is the conversion factor. The total uncertainty of the TG-51 protocol measurement using a solid water phantom was determined to be ${\pm}1.5%$. Conclusion: The developed method was successfully applied for the external auditing program, which could be evolved into a credential program of multi-institutional clinical trials. This dosimetry saved time for measuring doses as well as decreased the uncertainty of measurement possibly resulting from the reference setup in water.

• Journal of Chest Surgery
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• v.38 no.10 s.255
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• pp.680-684
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• 2005

Background: With the increasing age of the population, coronary artery bypass grafting in the elderly patients is becoming common. Off-pump coronary artery bypass grafting (OPCAB) has been proven to be less morbidity and to facilitate early recovery. The elderly patients may have benefits by avoiding the adverse effects of the cardiopulmonary bypass. The purpose of this study is to evaluate our results of OPCAB in elderly patients. Material and Method: A retrospective chart review was carried out for 12 patients aged over 80 years who underwent isolated OPCAB from January 2001 and March 2004. Data were collected risk factors for disease, extent of coronary disease, and in-hospital outcomes. Postoperative graft patiency was evaluated in 9 patients by multi-slice computed tomography. Result: Eleven patients had triple vessel disease or left main disease. Four patients were suffered from preoperative CVA, and 4 patients had chronic obstructive pulmonary disease. Two patients had myocardial infarction (MI), among them 1 patient was suffered from pulmonary edema after preoperative MI. There was no perioperative death, perioperative MI, and no ventricular arrhythmia. Also there was no perioperative stroke and renal failure. But there was one deep sternal infection who recovered by treating of muscle flap. Atrial fibrillation was newly developed in 1 patient, but was well controlled by medication. Mean intubation time was $15.9\pm4.4(8\~20hrs)$ hrs and mean ICU stay was $2.9\pm0.8(2\~4 days)$ days. Mean hospital day was $21.6\pm14.3(13\~56 days)$ days. Postoperative mean CK-MS was $11.3\pm14.1\;ng/mL$. Early postoperative graft patency rate was $100\%(24/24)$. Follow-up was completed in all patients. In this time, there was no patients with angina or death. Conclusion: The results of this study suggest that OPCAB reduces morbidity and favors hospital outcomes. Therefore, OPCAB is safe, reasonable and might be preferable operative strategy in elderly patients.

• Journal of Chest Surgery
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• v.38 no.8 s.253
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• pp.564-569
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• 2005

Background: Thymic carcinoma is a rare malignant disease with sparse data for treatment and prognosis. We intended to investigate the prognostic factors of thymic carcinoma. Material and Method: Data of 42 patients, who were diagnosed and treated for thymic carcinoma from January of 1986 to August of 2003 were reviewed retrospectively. Influences of characteristics of patients, Masaoka stage, histologic grade, completeness of resection and adjuvant treatment on survival were evaluated. Result: There were 30 male and 12 female patients and their mean age was $52.0\pm15.7$ years old. There were 28 patients with low-grade histology and 13 patients with high-grade histology. Clinical stage according to Masaoka stage were I in 2, II in 2, III in 15 $(35.7\%)$, IVa in 10 $(23.8\%),\;and\;IVb\;in\;13\;(31\%)$ patients. Surgical resection was done in 22 patients, Complete resection was possible in 13 patients and incomplete resection was done in 9 patients. Among 20 patients without resection, 8 patients received chemotherapy, 7 patients received radiotherapy and 5 patients received combined therapy. Median survival time was $31.7\pm6.1$ months and 5 year survival rate was $28.5\%$. High grade histology (hazard ratio=3.009, $95\%\;confidence\;interval=1.178\sim7.685,$ p=0.021) and incompleteness of resection (hazard ratio=3.605, $95\%$ confidence interval= $1.1541\sim1.580$, p=0.023) were the prognostic factors of thymic carcinoma. Conclusion: In thymic carcinoma, low grade histology is a good prognostic factor and complete resection can prolong the survival of patients.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.200-208
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• 2011

Most problematic antibiotic resistance mechanism for MLS (macrolide-lincosamide-streptogramn B) antibiotics encountered in clinical practice is mono- or dimethylation of specific adenine residue at 2058 (E. coli coordinate) of 23S rRNA which is performed by Erm (erythromycin ribosome resistance) protein through which bacterial ribosomes reduce the affinity to the antibiotics and become resistant to them. ErmSF is one of the four gene products produced by Streptomyces fradiae to be resistant to its own antibiotic, tylosin. Unlike other Erm proteins, ErmSF harbors idiosyncratic long N-terminal end region (NTER) 25% of which is comprised of arginine well known to interact with RNA. Furthermore, NTER was found to be important because when it was truncated, most of the enzyme activity was lost. Based on these facts, capability of NTER peptide to inhibit the enzymatic activity of ErmSF was sought. For this, expression system for two different proteins to be expressed in one cell was developed. In this system, two plasmids, pET23b and pACYC184 have unique replication origins to be compatible with each other in a cell. And expression system harboring promoter, ribosome binding site and transcription termination signal is identical but disparate amount of protein could be expressed according to the copy number of each vector, 15 for pACYC and 40 for pET23b. Expression of NTER peptide in pET23b together with ErmSF in pACYC 184 in E. coli successfully gave more amounts of NTER than ErmSF but no inhibitory effects were observed suggesting that there should be dynamicity in interaction between ErmSF and rRNA rather than simple and fixed binding to each other in methylation of 23S rRNA by ErmSF.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.1 no.1
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• pp.90-99
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• 1998

Purpose: The aim of this study was to clarify the serum cytokine pattern in patients with chronic HBV infection in terms of their clinical state. Methods: Intravenous blood samples were taken from 35 patients who were seropositive for HBsAg for at least 6 months and 7 healthy controls. Samples were initially tested for serum aminotransferases and serologic markers for hepatitis B virus by EIA. Serum levels of interleukin(IL)-2, tumor necrosis factor-alpha (TNF-${\alpha}$), interferon-gamma (IFN-${\gamma}$), IL-4, and IL-10 were measured by ELISA. Results: Among 35 patients, seropositive for HBeAg was 20 and for anti-HBe was 15. The histologic diagnosis of 19 patients underwent liver biopsy were chronic persistent hepatitis (CPH) in 10 and chronic active hepatitis (CAH) in 9. Serum IL-10 level in patients seropositive for HBeAg was significantly higher than that in patients seropositive for anti-HBe (p<0.05). All measured cytokine levels in patients with CAH were higher than those of patients with CPH. High values of all measured cytokines except IL-4 were seen in patients with AST and ALT > 100 U/L. High level of IL-4 was seen in patients with normal aminotransferase levels. Conclusion: These results were thought to indicate that anti-inflammatory Th2-like cytokine (IL-10) production in chronic HBV infection is related to circulating HBeAg rather than activity of hepatitis and that Th1 cytokines seem to be associated with the increasing activity of hepatitis.

• Journal of Oral Medicine and Pain
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• v.35 no.4
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• pp.245-258
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• 2010

Smoking has been identified not as a major risk factor for circulatory and respiratory diseases but also as causes of various oral diseases. A number of clinical studies and regional health surveys have found an association between smoking and poor oral health status and between smoking and prognosis of dental treatments. However, there is few studies about status of smoking cessation treatment and policies in dentistry in Korea. The purpose of this study was to investigate the smoking patterns of outpatients and outcomes of short-term smoking cessation treatment in dental hospitals in Korea and, subsequently, to seek further smoking cessation services in dentistry. This study was sponsored by Korean Dental Association (KDA) and department of culture and welfare. 825 dental patients were voluntarily participated in a 4-week smoking cessation program with nicotine patch and 297 participants of them completed on smoking-related questionnaires. All participants were recruited from outpatients of 11 dental university hospitals (primarily in the department of oral medicine, oral surgery and periodontology) in Korea during 3-month period from October 2009 to January 2010. The Questionnaires included demographics, duration of smoking, heavy smoking index (HSI), number of thinking of quit smoking, duration of stop smoking and reasons to smoking, awareness of smoking effects on oral health, and their success rate after 4 weeks of nicotine patch program was investigated. The statistical analysis was carried by SPSS version 18.0 program and Chi-square test. According to the results of this study, male in their 30s to 50s were the most prevalent of all the participants and duration of smoking increased with age. Attempt rate to quit smoking (Quit smoking) was the highest in 30s and 40s with duration of quit smoking ranging 1 to 3 months. Emotional stresswas the most frequently reported reason for smoking, followed by habit and pleasure in order. All age group showed high HIS over 71% and awareness of smoking effects on oral diseases such as oral soft tissue diseases, periodontal diseases and dental caries was found relatively high (50~60%) Periodontal implant was the main reason for participation in the smoking cessation services in dental clinics and the success rate of, 4-week nicotine patch program of all the participants was 29.4%, extremely low compared to that of medical clinics. Systemic education for dentists to be able to provide interventions to quit smoking including counseling with the 5As'and development of available measures for smokers is needed as considered that the low success rate of the smoking cessation services in dentistry could be explained mainly by lack of dentists' strategies, experience and attention. Awareness and attention of dentists should be emphasized and their participation be encouraged by long-term, multidisciplinary policies such as establishment of insurance fee, which would made a considerable progress in preventing smoking-related oral diseases and promoting public oral health.