• Progress in Medical Physics
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• v.11 no.1
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• pp.59-71
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• 2000

It is possible to obtain a fast CT scan during breath holding with spiral technique. But the risk of radiation is increased due to detailed and repeated scans. However, the limitation of X-ray doses is not fully specified on CT, yet. Therefore, the purpose of the present study is to define the limitation of X-ray doses on CT The CT unit was somatom plus 4. Alderson Rando phantom, Solenoid water phantom, TLD, and reader were used. For determining adequate position and size of organs, the measurement of distance(${\pm}$2mm) from the midline of vertebral body was performed in 40 women(20~40 years). On the brain scan for 8:8(8mm slice thickness, 8mm/sec movement velocity of the table) and 10:10(10mm slice thickness, 10mm/sec movement velocity of the table) methods, the absorption doses of exposed area of the 10:10 were slightly higher than those of 8:8. The doses of unexposed uterus were negligible on the brain scan for both 8:8 and 10:10. On the chest scan for 8:8, 8:10(8mm slice thickness, 10mm/sec movement velocity of the table), 10:10, 10:12(10mm slice thickness, 12mm/sec movement velocity of the table) and 10:15(10mm slice thickness, 15mm/sec movement velocity of the table) methods, 8:8 method of the absorption doses of exposure area was the most highest and 10:15 method was the most lowest. The absorption doses of 8:10 method was relatively lower than those of the other methods. In conclusion, the 8:10 method is the most suitable to give a low radiation burden to patient without distorting image quality.

• Progress in Medical Physics
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• v.23 no.1
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• pp.26-32
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• 2012

The magnification technique has recently become popular in bone radiography, mammography and other diagnostic examination. However, because of the finite size of X-ray focal spot, the magnification influences various imaging properties with resolution, noise and contrast. The purpose of study is to investigate the influence of magnification and focal spot size on digital imaging system using eDQE (effective detective quantum efficiency). Effective DQE is a metric reflecting overall system response including focal spot blur, magnification, scatter and grid response. The adult chest phantom employed in the Food and Drug Administration (FDA) was used to derive eDQE from eMTF (effective modulation transfer function), eNPS (effective noise power spectrum), scatter fraction and transmission fraction. According to results, spatial frequencies that eMTF is 10% with the magnification factor of 1.2, 1.4, 1.6, 1.8 and 2.0 are 2.76, 2.21, 1.78, 1.49 and 1.26 lp/mm respectively using small focal spot. The spatial frequencies that eMTF is 10% with the magnification factor of 1.2, 1.4, 1.6, 1.8 and 2.0 are 2.21, 1.66, 1.25, 0.93 and 0.73 lp/mm respectively using large focal spot. The eMTFs and eDQEs decreases with increasing magnification factor. Although there are no significant differences with focal spot size on eDQE (0), the eDQEs drops more sharply with large focal spot than small focal spot. The magnification imaging can enlarge the small size lesion and improve the contrast due to decrease of effective noise and scatter with air-gap effect. The enlargement of the image size can be helpful for visual detection of small image. However, focal spot blurring caused by finite size of focal spot shows more significant impact on spatial resolution than the improvement of other metrics resulted by magnification effect. Based on these results, appropriate magnification factor and focal spot size should be established to perform magnification imaging with digital radiography system.

• Tuberculosis and Respiratory Diseases
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• v.40 no.5
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• pp.584-594
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• 1993

Background: Among the respiratory diseases, there are a lot of cases of pleural effusion. The most common cause is tuberculosis. But the other cause such as lung malignancy is in an increasing tendency because of the development of diagnostic procedure, the decrease of the prevalence of the tuberculosis and the increase of the longevity. We need to know the accurate diagnosis as soon as possible for the correct therapy. Method: A clinical observation was made on 315 cases of pleural effusion seen at Pusan Adventist Hospital, from Jan, 1989 to Dec, 1992. For diagnostic procedure, thoracentesis, lymph node biopsy, bronchoscopy and percutaneous biopsy of the parietal pleura with Cope needle were performed. The following are parameters used in seperating the exudate from the transudate: pleural protein 3.0 g/dl, pleural protein/serum protein ratio 0.5, pleural LDH 200 IU, pleural LDH/serum LDH ratio 0.6, pleural cholesterol 60 mg/dl and pleural cholesterol/serum cholesterol ratio 0.3. Each parameters were compared, and misclassified rate and diagnostic efficiency were calculated. Results: The most common cause of exudate pleurisy was tuberculosis (82.3%) and malignancy was next (12.2%). The chief complaints of pleural effusion were noted as dyspnea (58.7%), chest pain (54.9%), coughing (50.2%) and fever (36.2%). Location of pleural effusion was noted as right side (51.4%), left side (41.3%) and both sides (7.3%). Amount of pleural effusion of the chest X-ray was minimum (46.8%), moderate (40.5%) and maximum (12.7%). Misclassified rates for each parameters in seperating the exudates from the transudates were as follows; protein: 5.2%, pleural protein/serum protein:7.6%, LDH: 13.9%, pleural LDH/serum LDH: 6.9%, cholesterol: 8.0%, pleural cholesterol/serum cholesterol: 5.6%. On the pleural biopsy, the tuberculosis granuloma was 60.8%, malignancy was 13.6%, infection was 2.3% and nonspecific inflammatory reaction was 23.3%. Conclusion: on the basis of the above results, the most common cause of exudative pleurisy was tuberculosis. We think that the plerual cholesterol/serum cholesterol ratio is the most useful supportive parameter in separating the exudates from the transudates. For accurate diagnosis, the pleural biopsy is the first procedure and repeated pleural biopsy of nonspedcific inflammatory reaction is required.

• Radiation Oncology Journal
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• v.17 no.2
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• pp.100-107
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• 1999

Purpose: This is to evaluate the acute complication, resection rate, and tumor down-staging after pre-operative concurrent chemoradiotherapy for stage IIIA (N2) non-small cell lung cancer. Materials and Methods Fifteen patients with non-small cell lung cancer were enrolled in this study from May 1997 to June 1998 in Samsung Medical Center. The median age of the patients was 61 (range, 45~67) years and male to female ratio was 12:3. Pathologic types were squamous cell carcinoma (11) and adenocarcinoma (4). Pre-operative clinical tumor stages were cT1 in 2 patients, cT2 in T2, and cT3 in 1 and all were N2. Ten patients were proved to be N2 with mediastinoscopic biopsy and five had clinically evident mediastinal Iymph node metastases on the chest CT scans. Pre-operative radiation therapy field included the primary tumor, the ipsilateral hilum, and the mediastinum. Total radiation dose was 45 Gy over 5 weeks with daily dose of 1.8 Gy. Pre-operative concurrent chemotherapy consisted of two cycles of intravenous cis-Platin (100 mg/m$^{2}$) on day 1 and oral Etoposide (50 mg/m$^{2}$/day) on days 1 through 14 with 4 weeks' interval. Surgery was followed after the pre-operative re-evaluation including chest CT scan in 3 weeks of the completion of the concurrent chemoradiotherapy if there was no evidence of disease progression. Results : Full dose radiation therapy was administered to all the 15 patients. Planned two cycles of chemotherapy was completed in 11 patients and one cycle was given to four. One treatment related death of acute respiratory distress syndrome occurred In 15 days of surgery. Hospital admission was required in three patients including one with radiation pneumonitis and two with neutropenic fever. Hematologic complications and other acute complications including esophagitis were tolerable. Resection rate was 92.3% (12/l3) in 13 patients excluding two patients who refused surgery. Pleural seeding was found in one patient after thoracotomy and tumor resection was not feasible. Post-operative tumor stagings were pT0 in 3 patients, pTl in 6, and pT2 in 3. Lymph node status findings were pN0 in 8 patients, pN1 in 1, and pN2 in 3. Pathologic tumor down-staging was 61.5% (8/13) including complete response in three patients ($23.7%). Tumor stage was unchanged in four patients (30.8%) and progression was in one (7.7%). Conclusions : Pre-operative concurrent chemoradiotherapy for Stage IIIA (N2) non-small cell lung cancer demonstrated satisfactory results with no increased severe acute complications. This treatment shceme deserves more patinet accrual with long-term follow-up.

• Journal of Chest Surgery
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• v.31 no.3
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• pp.233-241
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• 1998

To define the risk factors affecting the early major morbidity and mortality after multiple- valve operations, the preoperative, intraoperative and postoperative informations were retrospectively collected on 124 consecutive patients undergoing a multiple-valve operation between October 1985 and July 1996 at the department of Thoracic and Cardiovascular Surgery of Pusan Paik Hospital. The study population consists of 53 men and 71 women whose mean age was 37.9$\pm$11.5(mean$\pm$SD) years. Using the New York Heart Association(NYHA) classification, 41 patients(33.1%) were in functional class II, 60(48.4%) in class III, and 20(16.1%) in class IV preoperatively. Seven patients(5.6%) had undergone previous cardiac operations. Atrial fibrillations were present in 76 patients(61.3%), a history of cerebral embolism in 5(4.0%), and left atrial thrombus in 13(10.5%). The overall early mortality rate and postoperative morbidity was 8.1% and 21.8% respectively. Among the 124 cases of multiple-valve operation, there were 57(46.0%) of combined mitral valve replacement(MVR) and aortic valve replacement(AVR), 48(38.7%) of combined MVR and tricuspid annuloplasty(TVA), 12(9.7%) of combined MVR, AVR and TVA, 3(2.4%) of combined MVR and aortic valvuloplasty, 2(1.6%) of combined MVR and tricuspid valve replacement, and others. The patients were classified according to the postoperative outcomes; Group A(27 cases) included the patients who had early death or major morbidity such as low cardiac output syndrome, mediastinitis, cardiac rupture, ventricular arrhythmia, sepsis, and others; Group B(97 cases) included the patients who had the good postoperative outcomes. The patients were also classified into group of early death and survivor. In comparison of group A and group B, there were significant differences in aortic cross-clamping time(ACT, group A:153.4$\pm$42.4 minutes, group B:134.0$\pm$43.7 minutes, p=0.042), total bypass time(TBT, group A:187.4$\pm$65.5 minutes, group B:158.1$\pm$50.6 minutes, p=0.038), and NYHA functional class(I:33.3%, II:9.7%, III:20%, IV:50%, p=0.004). In comparison of early death(n=10) and survivor(n=114), there were significant differences in age(early death:45.2$\pm$8.7 years, survivor:37.2$\pm$11.6 years, p=0.036), sex(female:12.7%, male:1.9%, p=0.043), ACT(early death:167.1$\pm$38.4 minutes, survivor:135.7$\pm$43.7 minutes, p=0.030), and NYHA functional class(I:0%, II:4.9%, III:1.7%, IV:35%, p=0.001). In conclusion, the early major morbidity and mortality were influenced by the preoperative clinical status and therefore the earlier surgical intervention should be recommended whenever possible. Also, improved methods of myocardial protection and operative techniques may reduce the risk in patients with multiple-valve operation.

• Tuberculosis and Respiratory Diseases
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• v.45 no.6
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• pp.1143-1153
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• 1998

Background : Recent outbreaks of pulmonary disease due to drug-resistant strains of Mycobacterium Tuberculosis have resulted in significant morbidity and mortality in patients worldwide. We reviewed our experience to evaluate the effects of pulmonary resection on the management of multidrug-resistant tuberculosis. Method : A retrospective review was performed of 41 patients undergoing pulmonary resection for multidrug-resistant tuberculosis between January 1993 and December 1997. We divided these into 3 groups according to the radiologic findings : (1) patients who have reasonably localized lesion (Localized Lesion Group ; LLG) (2) patients who have cavitary lesions after pulmonary resection on chest roentgenogram (Remained Cavity Group : RCG) (3) patients who have Remained infiltrative lesions postoperatively (Remained infiltrative group : RIG). We evaluated the negative conversion rate after resection and overall response rate of the groups. Then they were compared with the results of the chemotherapy on the multi drug-resistant tuberculosis which has been outcome by Goble et al. Goble et al reported that negative conversion rate was 65% and overall response rate, 56% over a mean period of 5.1 months. Results : Seventy five point six percent were men and 24.4% women with a median age of 31 years (range, 16 to 60 years). Although the patients were treated preoperatively with multidrug regimens in an effort to reduce the mycobacterial burden, 22 of 41 were still sputum culture positive at the time of surgery. 20 of 22 patients(90.9%, p<0.01) responded which is defined as negative sputum cultures within 2 months postoperative. Of 26 patients with the sufficient follow up data, 19 have Remained sputum culture negative for a mean duration of 25.7 months (73.1%, p<0.05). The bulk of the disease was manifest in one lung, but lesser amounts of contralateral disease were demonstrated in 15, consisted of 8 in RIG and 7 in RCG, of 41. 12 of 12 patients (100%, p<0.01) who were sputum positive at the time of surgery in LLG converted successfully. 14 of 15 patients (93.3%, p<0.05) with the follow up have completed treatment and not relapsed for a mean period of 25. 7 months. The mean length of postoperative drug therapy of LLG was 12.2 months. In RIG, postoperative negative conversion rate was 83.3% which was not significant statistically. There was a statistical significance in overall response rate (100%, p<0.05) of RIG for a mean period of 24.4 months with a mean length of postoperative chemotherapy, 11.8 months. In RCG a statistically lower overall response rate (14.3%, p<0.01) has been revealed for a mean duration of follow up, 24.2 months. A negative conversion rate of RCG was 75% which was not significant statistically. Conclusion : Surgery plays an important role in the management of patients with multidrug-resistant Mycobacterium tuberculosis infection. Aggressive pulmonary resection should be performed for resistant Mycobacterium tuberculosis infection to avoid treatment failure or relapse. Especially all cavitary lesions on preoperative chest roentgenogram should be resected completely. If all of them could not be resected perfectly, you should not open the thorax.

• Tuberculosis and Respiratory Diseases
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• v.42 no.1
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• pp.11-18
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• 1995

Background: The natural history of bacillary tuberculosis was studied in India and results showed that at the end of the 5-year period, 49% of the patients were dead, 33% were cured and 18% remained sputum-positive. The aim of this survey is to observe the natural course of the patients with intractable tuberculosis disease who were incurable with all drug regimens of the national tuberculosis programme(NTP). Method: Of the patients who have been found as intractable cases in Kang-Weon Province by the supervisory medical officer during the period from January 1,1987 to December 31,1992, 179 were eligible for this study. Sputum examination was done for those who were survived until October in 1993 at the Kang-Weon provincial laboratory of KNTA. 49 out of 179 patients were transferred to the private sectors and retreated with the combination of prothionamide, cycloserine, ofloxacin, enviomycin, etc. They seemed to have been bacteriologically cured, and so they were excluded from the study. Finally 130 patients were analyzed by modified life table method to calculate the fatality rate and the survival rate during the period of 7 years. Results: 1) 80.8% of intractable cases were male and 19.2%, female. 2) More than 94% of intractable cases showed moderately or far advanced Tb findings on their X-rays at the time of registration at health centres. 3) The cumulative case-fatality rate was 19.74% at the end of 1-year period and has risen to 34.55% by the end of 4-year period(increasing by 4.9% a year on an average). The case-fatality rate has shown no appreciable rise since then until the end of 7-year period. 4) The case-survival rate was 80.26% at the end of 1-year period and has decreased to 65.45% by the end of 4-year period. And then there was no appreciable change in the survival rate until the end of 7-year observation. Conclusion: The case-survival rate of intractable cases was higher than that of untreated pulmonary tuberculosis patients and they may have risk of spreading multidrug resistant organisms. It is time we made an effort to improve case-management qualitatively.

• Journal of Radiation Protection and Research
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• v.27 no.1
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• pp.37-49
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• 2002

The accuracy of radiation dose delivery to target volume is one of the most important factors for good local control and less treatment complication. In vivo dosimetry is an essential QA procedure to confirm the radiation dose delivered to the patients. Transmission dose measurement is a useful method of in vivo dosimetry and it's advantages are non-invasiveness, simplicity and no additional efforts needed for dosimetry. In our department, in vivo dosimetry system using measurement of transmission dose was manufactured and algorithms for estimation of transmission dose were developed and tested with phantom in various conditions successfully. This system was applied in clinic to test stability, reproducibility and applicability to daily treatment and the accuracy of the algorithm. Transmission dose measurement was performed over three weeks. To test the reproducibility of this system, X-tay output was measured before daily treatment and then every hour during treatment time in reference condition(field size; $10 cm{\times} 10 cm$, 100 MU). Data of 11 patients whose pelvis were treated more than three times were analyzed. The reproducibility of the dosimetry system was acceptable with variations of measurement during each day and over 3 week period within ${\pm}2.0%$. On anterior- posterior and posterior fields, mean errors were between -5.20% and +2.20% without bone correction and between -0.62% and +3.32% with bone correction. On right and left lateral fields, mean errors were between -10.80% and +3.46% without bone correction and between -0.55% and +3.50% with bone correction. As the results, we could confirm the reproducibility and stability of our dosimetry system and its applicability in daily radiation treatment. We could also find that inhomogeneity correction for bone is essential and the estimated transmission doses are relatively accurate.

• Tuberculosis and Respiratory Diseases
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• v.40 no.3
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• pp.259-266
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• 1993

Background: To evaluate the risk factor of pneumothorax (PNX) which is the most common complication of CT-guided needle aspiration of the lung, we have examined the frequency of PNX according to the presence of obstructive ventilatory impairment determined by pulmonary function tests. Methods: A comparative study of analysis of forecd expiratory volume and folw-volume curves, and determinations of diffusing capacity taken before procedure were made between each 16 cases with PNX and controls with no PNX. Each of the control group was matched for sex, age, height, and size and depth of lesion with the former. Results: 1) In comparison of vital capacity and parameters derived from forced expiratory volume curve between two groups, VC and FVC were not significantly different, whereas $FEV_1$, $FEV_1$/FVC%, and FEF25-75% showed a significant decrease in the PNX gorup. Also, in the PNX group, all the observed values of parameters analyzed from flow-volune curve were siginificantly reduced in the PNX group compared with those in the control group. 2) The diffusing capacity tended to decrease along with varying individual differences in the PNX group. 3) Patients who had obstructive ventilatory impairment according to the results of pulmonary function tests experienced a twofold increase in the frequency of PNX and a sixfold increase in the frequency of chest tube drainage for treatment of PNX compared with those whose results were normal. Conclusion: These findings suggest that the exact evaluation of obstructive lung disease determined by pulmonary function test be considered assessing a pastient's risk for PNX in the patients who will take the CT-guided needle aspiration of the lung.

• Tuberculosis and Respiratory Diseases
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• v.48 no.5
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• pp.709-719
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• 2000

Background : The different features of high-resolution CT(HRCT) findings of active pulmonary tuberculosis(TB) were studied between acid fast bacilli(AFB) smear or culture positive and negative group. Methods : We prospectively evaluated 36 patients who had been confirmed for active pulmonary tuberculosis by the smear or culture of AFB in sputum(n=25), and changes on serial chest radiographs(n=11). The patients were divided into 3 groups by the results of sputum AFB stain and culture. Group 1(n= 11) is negative in both AFB stain and culture; group 2(n=13) is negative in AFB stain but positive in culture ; and group 3(n=12) is positive in both AFB stain and culture. We evaluated the findings of HRCT in each group randomly. Result : On the HRCT scans, acinar nodule(100%), macronodule(75%), and cavity(75%) in group 3 were more frequently found than group 1(63%. 18%, 9%) and group 2(46%, 15%, 23%)(p<0.05). The centrilobular nodule and branching structure were more frequently observed in group 3(92%) than in group 1(54%)(p<0.05), but were similarly observed in group 2(77%)(p>0.05). AFB positive group was statistically different than the negative group in the HRCT findings with to acinar nodule(100% vs 54%), macronodule(75% vs 17%), and cavity(75% vs 17%)(p<0.05). TB culture positive group was statistically different than the negative group in the HRCT findings with respect to acinar nodule(72% vs 45%) and cavity(48% vs 9%)(p<0.05). Conclusions : HRCT scans are helpful in determining disease acitivity in sputum AFB stain-negative pulmonary tuberculosis. When HRCT shows centrilobular nodule and branching structure, acinar nodule, macronodule, cavity, further studies as sputum induction and bronchoscopy can be performed to determine the presence of bacilli in patients of AFB stain-negative tuberculosis.