• Journal of the Korean Society of Radiology
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• v.5 no.2
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• pp.93-96
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• 2011

Currently, the development of direct conversion radiation detector using photoconductor materials is progressing in widely. Among of theses photoconductor materials, mercuric iodide compound than amorphous selenium has excellent absorption and sensitivity of high energy radiation. Also, the detection efficiency of signal generated in photoconductor film varies by electric filed and geometric distribution according to top-bottom electrode size. Therefore, in this work, the x-ray detection characteristics are investigated about the size of top electrode in $HgI_2$ photoconductor film. For sample fabrication, to solve the problem that is difficult to make a large area film, we used the spatial paste screen-print method. And the sample thickness is $150{\mu}m$ and an film area size is $3cm{\times}3cm$ on ITO-coated glass substrate. ITO(Indium-Tin-Oxide) electrode was used as top electrode using a magnetron sputtering system and each area is $3cm{\times}3cm$, $2cm{\times}2cm$ and $1cm{\times}1cm$. From experimental measurement, the dark current, sensitivity and SNR of the $HgI_2$ film are obtained from I-V test. From the experimental results, it shows that the sensitivity increases in accordance with the area of the electrode but the SNR is decreased because of the high dark current. Therefore, the optimized size of electrode is importance for the development of photoconductor based x-ray imaging detector.

• Journal of the Korean Society of Radiology
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• v.5 no.2
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• pp.81-92
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• 2011

This study was carried out to improve service efficiency and to cope with a emergency situation in emergency radiography, through analysis of the radiographic distriution and literature cited about emergency care. Data collection of radiographic distribution was surveyed for 1270 emergency outpatients who visit during JAN, 2009at ER of the general hospital in Gwang city. The results is as follows : Emergency radiography rate of simple radiography was 56.6%, special radiography 2. 5%, CT 34.2%, and ultrasonography 6.7%, In simple radiography rate. a high rate was distributed on male(63.6%), thoracicsurgery part(90.0%), admission patient(77.9%), and long stayed patient at ER. In special raiography rate, a high rate was obsurved in urologic part(28.6%), and in CT rate, observed neurosurgerty part(49.2%) and neurologic part(36.7%). Ultrasonography rate was high for female(8.8%) and internal medicine part(15.9%). There are distributed regional radiography rate in radio-graphic type that chest(55.3%) is high in the simple radiography, urinary system(1.2%) in the special study, and brain(40.0%) in the CT. Regional radiography rate according to diagnostic department also was showed highly for head(64.6%) in neuro surgery, chest(90.0%) in thoracic surgery, abdomen(58.0%) in general surgery, spine(40.0%) in neuro surgery, and pelvis(15.9%), upper extrimity(20.5%), and lower extrimity(31.8%) in orthopedic surgery each. Mean radiographic case number per patient of simple radiography was sinificant on sex, age, transfer relation in both total and radiopraphic patients(p<0.05). Mean radiographic case number was highly distributed on male(2.2 case number) in sex, on thirties(2.7) in age, transferred patient(2.7) in patient type, and on nurosurgery(3.4) in diagnostic charged part. Total radiographic case number in regional party was highly distributed on chest(998 case number.) Considering the above results, emergency radiographer should take care of the elder patient in emergency radiography and get hold of injury mechanism to decrease possible secondary injury during radiography. Because of high radiography rate of urinary system in special study, related instrument. All radiographer who take charge emergency patient should cope with a emergency situation during radiography. Because head trauma patients is very important in patient care, especilly in CT at night, charged doctor should be always sitted with CT room and monitoring patient. Radiography was reqested by many diagnostic department in ER. Considering that rate of simple radiography is high, special room for emergency radiopraphy should be established in ER area, and the radioprapher of this room should be stationed radiologic technician who is career and can implement emergency patient care and The disposition of men which is appropriate with emergency patient increase is necessary.

• Journal of the Korean Society of Radiology
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• v.5 no.6
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• pp.401-407
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• 2011

The purpose of this study is to know the differences of MR spectra, obtained from normal volunteers by variable TE value, through the quantitative analysis of brain metabolites by peak integral and SNR between 1.5T and 3.0T, together with PRESS and STEAM pulse sequence. Single-voxel MR proton spectra of the human brain obtained from normal volunteers at both 3.0T MR system (Magnetom Trio, SIEMENS, Germany) and 1.5T MR system (Signa Twinspeed, GE, USA) using the STEAM and PRESS pulse sequence. 10 healthy volunteers (3.0T:3 males, 2 females; 1.5T : 3 males, 2 females) with the range from 22 to 30 years old (mean 26 years) participated in our study. They had no personal or familial history of neurological diseases and had a normal neurological examination. Data acquisition parameters were closely matched between the two field strengths. Spectra were recorded in the white matter of the occipital lobe. Spectra were compared in terms of resolution and signal-to-noise ratio(SNR), and echo time(TE) were estimated at both field strengths. Imaging parameters was used for acquisition of the proton spectrum were as follow : TR 2000msec, TE 30ms, 40ms, 50ms, 60ms, 90ms, 144ms, 288ms, NA=96, VOI=$20{\times}20{\times}20mm3$. As the echo times were increased, the spectra obtained from 3.0T and 1.5T show decreased peak integral and SNR at both pulse sequence. PRESS pulse sequence shows higher SNR and signal intensity than those of STEAM. Especially, Spectra in normal volunteers at 3.0T demonstrated significantly improved overall SNR and spectral resolution compared to 1.5T(Fig1). The spectra acquired at short echo time, 3T MR system shows a twice improvement in SNR compared to 1.5T MR system(Table. 1). But, there was no significant difference between 3.0Tand 1.5T at long TE It is concluded that PRESS and short TE is useful for quantification of the brain metabolites at 3.0T MRS, our standardized protocol for quantification of the brain metabolites at 3.0T MRS is useful to evaluate the brain diseases by monitoring the systematic changes of biochemical metabolites concentration in vivo.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.8 no.2
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• pp.194-201
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• 2005

Purpose: Gall bladder (GB) stones in children are rarely observed, and so reports of them have been quite limited in Korea. Therefore, we tried to assess the epidemiology and clinical features of children with GB stone diagnosed at Severance Hospital. Methods: A clinical study was performed on 18 patients below 15 years of age diagnosed with GB stone by abdominal ultrasonography or CT scan at Severance hospital from January 1999 to May 2005. Results: Concerning patients' profile, their sex ratio of male to female in total 18 cases was 2 : 1 with the mean age of $6{\pm}4.3years$. 15 patients (83.3%) were asymptomatic. Inducing factors were found in 14 children (77.8%) including ceftriaxone therapy in 6 cases (33.3%), infection in 4 cases (22.2%), spherocytosis in 3 cases (16.7%), Down syndrome and abdominal operation in 1 case (5.6%) respectively. Single stone was found in 13 cases (76.5%) and multiple in 4 cases (23.5%). 15 cases (88.2%) had the stones less than 5 mm in size, and 2 cases (11.8%) between 5 and 10 mm. 17 patients received conservative treatment, and one patient had cholecystectomy due to Meckel diverticulum. Conclusion: In this report, Pediatric GB stones are predominant in male children, without typical symptoms, having inducing factors, single and small. Recently the diagnosis of them has been increased because of the development of imaging study. But the reports for them were still rare in Korea. Therefore the study for them is more necessary to find it's clinical characteristics.

• Pediatric Infection and Vaccine
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• v.17 no.1
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• pp.23-29
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• 2010

Purpose : Urinary tract infection (UTI) in children is the most common disease during the infantile period, therefore early diagnosis and treatment are important. Pyuria is a useful clinical parameter for the initial diagnosis of a UTI. In this study we aimed to compare the clinical, laboratory, and imaging findings in relation to the duration of pyuria in infants with UTIs. Methods : Three hundred seventy-four infants <12 months of age who were admitted between January 1995 and December 2005 for the first episode of a febrile UTI were retrospectively reviewed. Patients were divided into two groups according to the duration of pyuria as follows: group 1, pyuria resolved <3 days after initial treatment; and group 2, pyuria lasted at least 3 days after initial treatment. Results : There were no significant differences between the two groups in relation to gender, age, total duration of fever, and organisms in the urine. Group 2 had a significantly higher peripheral blood leukocyte count ($14,360.86{\pm}5,526.16cells/mm^3$ vs. $11,822.55{\pm}5,687.26cells/mm^3$, P <0.001), erythrocyte sedimentation rate ($32.81{\pm}19.34mm/hr$ vs. $23.74{\pm}20.43mm/hr$, P <0.001), and C-reactive protein ($6.84{\pm}5.68mg/dL$ vs. $3.78{\pm}3.99mg/dL$, P <0.001) than group 1. There was a significantly higher incidence of hydronephrosis and a higher grade of vesicoureteral reflux (VUR) in group 2 compared to group 1. Conclusion : In infants with UTI, pyuria of longer duration is related to severe UTI and higher grade VUR, therefore aggressive radiologic studies may be necessary.

• Radiation Oncology Journal
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• v.20 no.2
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• pp.123-129
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• 2002

Purpose : The purpose of this study 띤as to determine the potential role of three-dimensional conformal radiotherapy (3D-CRT) in the treatment of primary unresectable hepatocellular carcinoma. The preliminary results on the efficacy and the toxicity of 3D-CRT are reported. Materials and Methods : Seventeen patients were enrolled in this study, which was conducted prospectively from January 1995 to June 1997. The exclusion criteria included the presence of extrahepatic metastasis, liver cirrhosis of Child-Pugh classification C, tumors occupying more than two thirds of the entire liver, and a performance status of more than 3 on the ECOG scale. Two patients were treated with radiotherapy only while the remaining 15 were treated with combined transcatheter arterial chemoembolization. Radiotherapy was given to the field including the tumor plus a 1.5 cm margin using a 3D-CRT technique. The radiation dose ranged from $36\~60\;Gy$ (median; 59.4 Gy). Tumor response was based on a radiological examination such as the CT scan, MR imaging, and hepatic artery angiography at $4\~8$ weeks following the completion of treatment. The acute and subacute toxicities were monitored. Results : An objective response was observed in 11 out of 17 patients, giving a response rate of $64.7\%$. The actuarial survival rate at 2 years was $21.2\%$ from the start of radiotherapy (median survival; 19 months). Six patients developed a distant metastasis consisting of a lung metastasis in 5 patients and bone metastasis in one. The complications related to 30-CRT were gastro-duodenitis $(\geq\;grade\;2)$ in 2 patients. There were no treatment related deaths and radiation induced hepatitis. Conclusion : The preliminary results show that 3D-CRT is a reliable and effective treatment modality for primary unresectable hepatocellular carcinoma compared to other conventional modalities. Further studies to evaluate the definitive role of the 3D-CRT technique in the treatment of primary unresectable hepatocellular carcinoma are needed.

• Journal of Chest Surgery
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• v.41 no.4
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• pp.469-475
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• 2008

Background: Video-assisted thoracic sympathicotomy is a definitive minimally invasive treatment for axillary hyperhidrosis. Different techniques exist for controlling axillary hyperhidrosis, but they are temporary and expensive. We compared the results after using two different levels of sympathicotomy for treating axillary hyperhidrosis: T3-T4 and T4. Material and Method: Between June 2002 and May 2007, 30 patients with isolated axillary hyperhidrosis underwent either T3-T4 or T4 thoracoscopic sympathicotomy in the Department of Thoracic & Cardiovascular Surgery at Wonkwang University Hospital. The patients were divided into two groups. Group I (n=15) was composed of patients who underwent T3-T4 sympathicotomy (thermal ablation), and Group II (n=15) was composed of patients who underwent T4 sympathicotomy (thermal ablation). The procedures were bilateral and simultaneous, involving the use of two 2-mm trocars and a 0-degree 2-mm thoracoscope under general anesthesia with single endotracheal intubation. Outcome parameters included satisfaction rate of treatment, degree of compensatory sweating, and postoperative complications. Patients were interviewed by telephone regarding satisfaction and compensatory hyperhidrosis. Result: There were no differences in age between group I and group II. The mean follow-up for the T3-T4 group was $38.7{\pm}2.3$ months, and the mean follow-up for the T4 group was $18.7{\pm}3.6$ months. The immediate therapeutic success rate (within 2 weeks postoperative) was 100% in both groups, and there were no recurrences in either group during the long-term follow-up period. The satisfaction rate was higher (93.3%) in the T4 group than in the T3-T4 group (53.3%), and the incidence of compensatory hyperhidrosis was lower in the T4 group (6.7%) than in the T3-T4 group (46.7%). Postoperative complications included one mild pneumothorax and two instances of intercostal neuralgia. Digital infrared thermographic imaging (DITI) correlated well with postoperative satisfaction. Conclusion: Both techniques proved effective for controlling isolated axillary hyperhidrosis. The T4 group had a higher satisfaction rate and lower severity of compensatory hyperhidrosis. Hence, thermal ablation of the lower interganglionic fibers of the third thoracic sympathetic ganglion on the fourth rib is a more practical and minimally invasive treatment than is the T3-T4 surgical method, according to the degree of compensatory sweating in isolated axillary hyperhidrosis.

• Tuberculosis and Respiratory Diseases
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• v.41 no.2
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• pp.97-102
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• 1994

Objectives : Since Mountain proposed the new staging system of non-small cell lung cancer in 1986, the indications for operation of NSCLC have been extended. However, operative mortality is from 3 to 6%. Therefore it is important to reduce unnecessary operation and to evaluate unresectability of tumor correctly, preoperatively. The purpose of this study is to find out the causes of unresectability in patients who were initially thought to be resectable preoperatively. Methods : By retrospective analysis, 64 patients out of 291 NSCLC patients who were undergone operation for curative resection in Seoul National University Hospital from Jan. of 1987 to Dec. of 1991, were found to be unresectable at operating room, were selected for this study. Out of 64 patients, 42 were evaluable. The analysis was focused on the change of pre- & post-operative staging and the causes of unresectability of tumors. Results : Among 42 patients with unresectable tumor who could be evaluated, preoperative CT finding showed resectable tumors in 55%(23 patients) and suspicious for unresectable tumors in 45%(19 patients). The causes of unresectability were technically unresectable T3 lesions in 7%(3 patients), T4 lesions in 62%(26 patients), N2 lesions in 17%(7 patients) and N3 lesions in 14%(6 patients). Conclusion : The major causes of unresectability of NSCLC were pulmonary artery invasions. It is suggested that careful evaluation of mediastinal structure, especially great vessels by additional imaging technique other than CT(like MRI) is indicated in selected NSCLC cases.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.9
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• pp.117-124
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• 2015

In this paper, we introduce how to control TR, TE physical MR parameters for managing $H_1$ spin's SI(Signal Intensity) which is combined with gadolinium following administration MR agent in T1 effect for diagnostic usefulness. we used MRI phantom made with 0.5 mol Gadoteridol. This phantom was scanned by FSE sequence with different TR, TE parameters. In this study, to make T1 effect, TR was 200, 250, 300, 350, 400, 450, 500, 550, 600 msec. In addition to, TE was 6.2, 12.4, 18.6, 21.6 msec. The results were as follows ; Each RSP(Reaction Starting Point) was 100, 50, 40, 30 mmol in TE 6.2, 12.4, 18.6, 21.6 msec being irrelevant to TR. In MPSI(Max Peak Signal Intensity), 4 mmol was showed in TR 200 msec while peak signal was decreased to low concentration mol in TR 250-600 msec. In terms of RA(Reaction Area), the highest SI was TE 6.2 msec in TR 200-600msec. According to the study, we are able to recognize it is possible to control enhance rates by managing TR and TE of MR parameters; moreover, we expect that enhanced T1 image in MR clinical field can be performed in a practical way with this quantitative data.

• Korea Journal of Hospital Management
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• v.2 no.1
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• pp.1-21
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• 1997

In order to analyze the shifts in the volume and profits of Computed Tomography(CT) and Magnetic Resonance Imaging(MRI) utilization for a year before and after the implementation of insurance coverage for CT, this study has been undertaken examining CT and MRI cost data from 'Y' University Hospital situated in Seoul, Korea. Following are the results of this study: 1. The medical insurance payment for CT, implemented on January 1, 1996, increased CT utilization from January 1996 to April 1996 due to low insurance premiums: however, from May 1996 the number of CT cases significantly decreased as a result of strengthened medical cost reviews and the new 'Detailed standards for approval of CT' announced near the end of April 1996 by the insurer. 2. Since the implementation of insurance coverage for CT, CT fee reduction rates for reimbursements by the insurer to the hospital were 50% and 40% for January and February, respectively, and 31% and 15% for March and April. A significant point in the lowering of the reduction rate was reached in May at 11%; furthermore, since June the reduction rate fell below the average reduction rate for reimbursements for all procedures. If the 'Detailed standards for approval of CT' had been announced before the implementation of insurance coverage for CT, CT utilization would not have been so high due to the need to meet those 'standards'. In addition, loss of hospital profits resulting from the reduction for reimbursements would not have occurred. 3. The shifts in MRI utilization showed that there was no particular change with the beginning of insurance coverage for CT, and the introduction of the 'Detailed standards for approval of CT' made MRI utilization increase because MRI is free of restrictions imposed by the insurer. 4. The relationship between CT utilization and MRI utilization showed that they were supplementary to each other before insurance coverage for CT, but that CT was substituted for MRI because of strengthened medical cost reviews after t~e beginning of insurance coverage for CT. 5. The shifts in volume by patient characteristics showed that the number of inappropriate case patients, according to the insurer's "Standards for approval", decreased more than the number of appropriate case patients after the introduction of insurance coverage for CT. Therefore, the health insurance fee schemes for CT have influenced patient care. 6. The shifts in profits from CT utilization showed a net profit decrease of 31.6%. In order to match the pre-coverage profit level, 5,471 more cases would need to be seen and productivity would need to be increased by 32.7%. This profit decrease resulted from a decrease of CT utilization and low reimbursements. With insurance coverage, net profits from CT were 24.4%, and a margin of safety ratio was 39.6%. Because of the net profits and margin of safety ratio, CT utilization fees for insured appropriate cases could not be considered inappropriate. 7. The shifts in profits from MRI utilization before and after the introduction of CT coverage showed that in order to match pre-CT coverage profit levels, 2,011 more cases would need to be seen and productivity would need to be increased by 9.2%. The reasons for needing to increase the number of cases and productivity result from cost burdens created by adding new MRI units. But with CT coverage already begun, MRI utilization increased. Combined with a minor increase in the MRI fee schedule, MRI utilization showed a net profit increase of 18.5%. Net profits of 62.8% and a 'margin of safety ratio' of 43.1% for MRI utilization showed that the hospital relied on this non-covered procedure for profits. 8. The shifts in profits from CT and MRI utilization showed the net profits from CT decreased by 2.33billion Won while the net profits from MRI increased by 815.7million Won. Overall, these two together showed a net profit decrease of 1.51billion Won. The shifts in utilization showed a functional substitutionary relationship, but the shifts in profits did not show a substitutionary relationship. From these results, We can conclude that if insurance is to be expanded to include previously uncovered procedures using expensive medical equipment, detailed standards should be prepared in advance. The decrease in profits from the shifts in coverage and changes in fees is a difficult burden that should be shared, not carried by the hospital alone. Also, a new or improved fee schedule system should include revised standards between items listed and the appropriateness of the fee schedule should constantly be ensured. This study focused on one university hospital in Seoul and is therefore limited in general applicability. But it is valuable for considering current issues and problems, such as the influence of CT coverage on hospital management. Future studies will hopefully expand the scope of the issues considered here.