• 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.

• Progress in Medical Physics
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• v.22 no.2
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• pp.72-78
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• 2011

The aim of this study is to evaluate the patient's setup errors in TomoTherapy (Hi-Art II, TomoTherapy, USA) Bodyfix system (Medical Intelligence, Ele-kta, Schwabmuchen, Germany) pressure in the vacuum compression, depending on and were evaluated. Bodyfix immobilization system and vacuum pressure was compression applied to the patients who received Tomotherapy thoracic and abdominal area, 21 patients were selected and TomoTehpay treatment total 477 of MVCT images were obtained. The translational (medial-lateral: ML, anterior-posterior: AP, superior-inferior: SI directions) and rolling were recorded and analyzed statistically. Using Pearson's product-moment coefficient and One-way ANOVA, the degree of correlation depending on the different vacuum pressure levels were statistically analyzed for setup errors from five groups (p<0.05). The largest average and standard deviation of systematic errors were 6.00, 5.95 mm in the AP and SI directions, respectively. The largest average of random errors were 4.72 mm in the SI directions. The correlation coefficients were 0.485, 0.244, and 0.637 for the ML-Roll, AP-Vector, and SI-Vector, respectively. SI-Vector direction showed the best relationship. In the results of the different degree of vacuum pressure in five groups (Pressure range: 30~70 mbar), the setup errors between the ML, SI in both directions and Roll p=0.00 (p<0.05) were shown significant differences. The average errors of SI direction in the vacuum pressure of 40 mbar and 70 mbar group were 4.78 mm and -0.74 mm, respectively. In this study, the correlation between the vacuum pressure and the setup-errors were statistically analyzed. The fact that setup-errors in SI direction is dependent in vacuum pressure considerly setup-errors and movement of interal organs was identified. Finally, setup-errors, and it, based on the movement of internal organs in Bodyfix system we should apply more than 50 mbar vacuum pressure. Based on the results of this study, it is suggested that accuracy of the vacuum pressure and the quantitative analysis of movement of internal organs and the tumor should be studied.

• Progress in Medical Physics
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• v.20 no.1
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• pp.21-29
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• 2009

Breast cancer is the most common form of cancer among korean woman. Therefore, the early detection activities of breast cancer such as breast self-examinations, clinical breast examinations, mammography are important. A yearly mammography examination has been recommended for women aged 40 and older for the early detection of breast cancer in asymptomatic periods. However, the glandular tissue of breast is the most radiation-sensitive tissue, and the determination of average glandular dose (AGD) forms an important part of the quality control of the mammographic systems. Because of the difficulty of estimating AGD directly, it is often estimated from the measurements of the incident air kerma and by applying the appropriate conversion factors. The primary objective of this study was to standardize the method of measuring AGD. The secondary objective was to evaluate the relationships between AGD per various composition and thickness of the breast using Monte Carlo simulations. As a result, we standardized the method of measuring AGD according to International Atomic Energy Agency (IAEA) guidelines (CoP: an international code of practice). Overall, AGD for mammographic practice in Korea was less than 3.0 mGy recommended by the Korea Food and Drug Adminstration (KFDA) protocol, and Korean Institute for Accreditation of Medical Image (KIAMI). The measured and simulated AGD for a given condition were calculated as 1.7 and 1.6 mGy, respectively. For the AGDs obtained, there was no significant difference between them. The simulated AGD was dependent on the fraction of glandular tissue of the breast. The AGD increases with increasing of the breast glandularity due to increasing absorption of low energy photons. The AGD also increases as a function of breast thickness. In conclusion, the results of this study could be used as a baseline to establish a reference level of radiation dose in mammography.

• Progress in Medical Physics
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• v.19 no.1
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• pp.14-20
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• 2008

Accounting for tumor motion in treatment planning and delivery is one of the most recent and significant challenges facing radiotherapy. The purpose of this study was to investigate the correlation and clarified the relationship between the motion of an external marker using the Real-Time Position Management (RPM) System and an internal organ motion signal obtained fluoroscope. We enrolled 10 patients with locally advanced lung cancer and liver cancer, retrospectively. The external marker was a plastic box, which is part of the RPM used to track the patient's respiration. We investigated the quantitatively correlation between the motions of an external marker with RPM and internal motion with fluoroscope. The internal fiducial motion is predominant in the caraniocaudal direction, with a range of $1.3{\sim}3.5cm$ with fluoroscopic unit. The external fiducial motion is predominant in the caraniocaudal direction, with a range of $0.43{\sim}2.19cm$ with RPM gating. The two measurements ratio is from 1.31 to 5.56. When the regularization guided standard deviation is from 0.08 to 0.87, mean 0.204 cm, except only for patients #3 separated by a mean 0.13 cm, maximum of 0.23 cm. This result is a good correlation between internal tumor motion imaged by fluoroscopic unit and external marker motion with RPM during expiration within 0.23 cm. We have demonstrated that gating may be best performed but special attention should be paid to gating for patients whose fiducials do not move in synchrony, because targeting on the correct phase difference alone would not guarantee that the entire tumor volume is within the treatment field.

• Geotechnical Engineering
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• v.12 no.4
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• pp.157-178
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• 1996

Current design methods for reinforced earth structures take no account of the magnitude of the strains induced in the tensile members as these are invariably manufactured from high modulus materials, such as steel, where straits are unlikely to be significant. With fabrics, however, large strains may frequently be induced and it is important to determine these to enable the stability of the structure to be assessed. In the present paper internal design method of analysis relating to the use of fabric reinforcements in reinforced earth structures for both stress and strain considerations is presented. For the internal stability analysis against rupture and pullout of the fabric reinforcements, a strain compatibility analysis procedure that considers the effects of reinforcement stiffness, relative movement between the soil and reinforcements, and compaction-induced stresses as studied by Ehrlich 8l Mitchell is used. I Bowever, the soil-reinforcement interaction is modeled by relating nonlinear elastic soil behavior to nonlinear response of the reinforcement. The soil constitutive model used is a modified vertsion of the hyperbolic soil model and compaction stress model proposed by Duncan et at., and iterative step-loading approach is used to take nonlinear soil behavior into consideration. The effects of seepage pressures are also dealt with in the proposed method of analy For purposes of assessing the strain behavior oi the fabric reinforcements, nonlinear model of hyperbolic form describing the load-extension relation of fabrics is employed. A procedure for specifying the strength characteristics of paraweb polyester fibre multicord, needle punched non-woven geotHxtile and knitted polyester geogrid is also described which may provide a more convenient procedure for incorporating the fablic properties into the prediction of fabric deformations. An attempt to define improvement in bond-linkage at the interconnecting nodes of the fabric reinforced earth stracture due to the confining stress is further made. The proposed method of analysis has been applied to estimate the maximum tensions, deformations and strains of the fabric reinforcements. The results are then compared with those of finite element analysis and experimental tests, and show in general good agreements indicating the effectiveness of the proposed method of analysis. Analytical parametric studies are also carried out to investigate the effects of relative soil-fabric reinforcement stiffness, locked-in stresses, compaction load and seepage pressures on the magnitude and variation of the fabric deformations.

• Sleep Medicine and Psychophysiology
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• v.19 no.1
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• pp.27-34
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• 2012

Objectives: The analysis of heart rate variability (HRV) is a useful non-invasive tool to investigate the autonomic nerve function. Previous studies on the relationship between HRV and depression have been reported controversial results. Similarly, the correlation between the serum lipids and depression is debatable. The purpose of this study is to examine the relationship between heart rate variability, lipid profile and depression. Methods: A total of 42 patients with major depressive disorder (MDD) and 32 age and sex-matched normal subjects who had no previous history of major medical and mental illnesses were recruited for this study. A structured-interview was used to assess the general characteristics and psychiatric illness. HRV measures were assessed by time-domain and frequency-domain analyses. Psychological symptoms were measured using the Hamilton rating scale for anxiety (HAM-A), Hamilton rating scale for depression (HAM-D). In addition, the evaluation for lipid profile was performed by blood test. Results: In serum lipid profile test, MDD group showed higher cholesterol ($197.68{\pm}42.94$ mg/dL vs. $176.85{\pm}34.68$ mg/dL, p=0.044), TG ($139.45{\pm}92.54$ mg/dL vs. $91.4{\pm}65.68$ mg/dL, p=0.018), LDL ($130.03{\pm}33.18$ vs. $106.62{\pm}27.08$, p=0.004) level than normal control group. In HRV time domain analyses, the standard deviation of the NN interval (SDNN) was decreased in MDD group than normal control group, but was not significant ($32.82{\pm}14.33$ ms vs. $40.36{\pm}21.40$ms, p=0.078). ApEn (Approximate Entrophy) was significantly increased in MDD group than normal control group ($1.13{\pm}0.11$ vs. $0.91{\pm}0.18$, p<0.001). ApEn was correlated with LDL level (r=0.277, p=0.028), HAM-D scores (r=0.534, p<0.001) and HAM-A scores (r=0.470, p<0.001). Conclusions: MDD patients showed increased ApEn, one of the HRV measurement. And this ApEn was correlated with LDL, HAM-D and HAM-A scores. In this study, the analysis of ApEn would be a useful test of MDD.

• Tuberculosis and Respiratory Diseases
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• v.39 no.1
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• pp.7-14
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• 1992

Background: Cognitive deficit by hypoxia and/or hypercapnia is one of neuropsychological impairments frequently observed in patients with chronic obstructive pulmonary disease (COPD). The degree of cognitive deficit is variable among patients with similar level of hypoxia and/or hypercapnia, although a cause of this individual difference is well not known. COPD can be divided into two characteristic clinical entities including predominant emphysema and predominant bronchitis. This study was designed to evaluate the individual difference in cognitive deficit respond to hypoxia and/or hypercapnia in patients with COPD. Method: Sixteen patients with COPD (9 emphysema-dominant and 7 bronchitis-dominant) participated in this study. On admission arterial blood gas analysis and trail-making B (TMB) test for the evaluation of cognitive function were done in all patients. Mean TMB scores and the correlations between TMB scores and arterial blood gases were compared between two clinical groups. Results: 1) Mean TMB scores and arterial blood gases between two clinical groups were not different. 2) There was a tendency to be higher TMB score in hypoxemia, acidemia, and hypercapnia. However these findings were not statistically significant. 3) In emphysema-dominant group, $PaCO_2$ was mostly well correlated with TMB score (r=0.693). 4) In bronchitis-dominant group, arterial pH was mostly well correlated with TMB score (r=-0.526). Conclusion: Our data suggest that the individual difference in cognitive deficit respond to hypoxia and/or hypercapnia in patients with COPD may be dependent on their clinical entities, and arterial blood gases mostly well correlated with cognitive function that may be different according to their clinical entities.

• Tuberculosis and Respiratory Diseases
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• v.43 no.1
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• pp.22-29
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• 1996

Background: Abnormalities of the peripheral blood are frequent and varied in patients with miliary tuberculosis. Anemia, leukopenia, thrombocytopenia, pancytopenia, monocytosis, basophilia, eosinophilia and leukemoid reactions have been reported. These abnormalities are more frequent in patients with positive bone marrow study. In this report, we evaluated clinical, hematological and immunological features in patients with miliary tuberculosis in order to know whether difference is existed between "bone marrow biopsy positive group(pathologically proven to miliary tuberculosis)" and "negative group". Method: Clinical evaluation, serum ADA, sIL-2R, and T-lymphocyte subsets were measured in 40 patients with miliary tuberculosis who received bone marrow biopsy. Results: 1) The average age of patients was 39 year-old. There were 23 male and 17 female patients. Associated extrapulmonary tuberculosis are 9 CNS tuberculosis, 6 joint tuberculosis, and 2 tuberculous pleurisy. 2) Sixteen of the 40 patients were positive bone marrow biopsy(60%). 3) Sixteen of the 40 patients(60%) had anemia(11 positive patients: 13 negative patients). Leukopenia occurred in 12 per cent(4:1). Thrombocytopenia was noted in 10%(3:1). 4) The mean value of serum ADA was 83 U/L(90 U/L: 70.6 U/L, p=0.23). 5) The mean activity of Soluble IL-2 receptor was 4,643 pmol/L($6840{\pm}7446\;pmol/L$: $1,897{\pm}1,663\;pmol/L$, p=0.06). 6) In the T lymphocyte subsets, the percent of T-lymphocytes was 64%(62%:73%, p=0.2). In some patients(9), $T_4$ and $T_8$ ratio in BAL fluid($1.97{\pm}1.2$) was higher than that in the peripheral blood($1.16{\pm}0.5$). Conclusion: Bone marrow examination are diagnostic in 60% of cases of miliary tuberculosis. Percents of the total T lymphocyte and helper T cell in BAL are more elevated than in peripheral blood. There was no significant difference in peripheral blood abnormalities and marker of T lymphocyte activation between the bone marrow biopsy positive and negative group.

• Tuberculosis and Respiratory Diseases
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• v.42 no.1
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• pp.42-49
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• 1995

Background: Hemoptysis always merits thorough investigation because even minimal bleeding may be an early indicator of the presence of significant bronchopulmonary disease. But in patients with hemoptysis & a normal chest roentgenogram, there are no clear guidelines for a diagnostic approach, including the indications of bronchoscopy. Methods: Eighty patients with hemoptysis and a normal chest roentgenogram were involved in this study. We evaluated the cause of hemoptysis in these patients by bronchoscopy and/or bronchogram or high-resolution CT of the lung and we analyzed the relationship of clinical features, such as age, sex, smoking and properties of hemoptysis, to the cause of hemoptysis. Results: 1) They were 34 men and 46 women, with the mean age of 46.7 and 41.8 years old, respectively. 2) Initial bronchoscopy provided a diagnosis in 8 patients - bronchogenic carcinoma in 3 patients (3.8%), metastatic cancer in 1 patient(1.3%) and endobronchial tuberculosis in 4 patients(5.0%). 3) Two clinical findings of patients over 50 years and/or with more than 30 pack-year smoking history were associated with bronchogenic carcinoma, and among these two factors, a more than 30 pack-year smoking history was the best predictor for diagnosis of bronchogenic cancer. 4) The 72 patients in whom no specific cause of hemoptysis was identified by initial bronchoscopy underwent bronchogram and/or high resolutional CT of the lung. Then, 6 patients were diagnosed as bronchiectasis and 5 patients rebleeded in the follow up period of 9 to 90 weeks. Of the remaining 66 patients, 33 were followed for 7 to 80 weeks. Among these patients, only 5 patients had recurrent episodes of hemoptysis & they were diagnosed as bronchiectasis in 1 patient, tuberculosis in 2 patients and catamenial hemoptysis in 2 patients. Conclusion: We conclude that patients with hemoptysis and a normal chest roentgenogram who are more than 50 years old or have more than 30 pack-year smoking history should undergo bronchoscopy to exclude possible bronchogenic carcinoma. In patients without these clinical features, a conservative approach with observation appears justified. If hemoptysis recurs to these patients, bronchogram or high-resolutional CT of the lung with sputum examination are necessary.

• Tuberculosis and Respiratory Diseases
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• v.42 no.1
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• pp.50-57
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• 1995

Background: Transcather arterial embolization has been established as an effective means to control hemoptysis, especially in patients with decreased pulmonary function such as postpneumonectomy patients and those with advanced chronic obstructive pulmonary disease. We evaluated the effect of arterial embolization and analysed the correlation of the clinical and angiographic characteristics and investigated the clinical course and outcome after arterial embolization in the patients with significant hemoptysis. Method: 58 patients with massive or recurrent hemoptysis underwent transcatheter arterial embolization for the treatment of hemoptysis from April 1992 to Sept. 1993. Results: Most common cause of hemoptysis was pulmonary tuberculosis(34 cases, 58.3%). Embolized vessels responsible for hemoptysis were 56 bronchial arteries and 32 nonbronchial systemic arteries. Initial most common angiographic findings were hypervascularity and shunt. Initial success rate of hemoptysis control revealed 81.1%. However, 15 of 58 patients(25.9%) showed recurrence of hemoptysis after transcatheter arterial embolization. The complications(18 cases, 31%) such as chest pain, fever, voiding difficulty, atelectasis, paralytic ileus and unwanted embolization were occured. Conclusion: Transcatheter arterial embolization is useful and relatively safe treatment modality for immediate bleeding control of patients with massive hemoptysis or inoperable cases. The further evaluation of the long term results according to the embolized material and underlying pulmonary disease will be required.