• Progress in Medical Physics
• /
• v.14 no.3
• /
• pp.151-160
• /
• 2003

The application of more complex radiotherapy techniques using multileaf collimation (MLC), such as 3D conformal radiation therapy and intensity-modulated radiation therapy (IMRT), has increased the significance of verifying leaf position and motion. Due to thier reliability and empirical robustness, quality assurance (QA) of MLC. However easy use and the ability to provide digital data of electronic portal imaging devices (EPIDs) have attracted attention to portal films as an alternatives to films for routine qualify assurance, despite concerns about their clinical feasibility, efficacy, and the cost to benefit ratio. In this study, we developed method for daily QA of MLC using electronic portal images (EPIs). EPID availability for routine QA was verified by comparing of the portal films, which were simultaneously obtained when radiation was delivered and known prescription input to MLC controller. Specially designed two-test patterns of dynamic MLC were applied for image acquisition. Quantitative off-line analysis using an edge detection algorithm enhanced the verification procedure as well as on-line qualitative visual assessment. In conclusion, the availability of EPI was enough for daily QA of MLC leaf position with the accuracy of portal films.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2004.11a
• /
• pp.96-99
• /
• 2004

The objective of this study is to assess attenuation correction algorithms utilized in a multipurpose whole-body GSO PET scanner. Four different types of phantoms were tested using different types of attenuation correction techniques. FOV (Field of View) of 256mm was used for brain PET imaging. For compensating attenuation, transmission data of a $^{137}$Cs point source were acquired after the F-18 emission source was infused to the phantoms. Scatter correction were peformed. Reconstructed images of the phantoms were assessed. In addition, reconstructed images of a normal subject were compared and assessed by nuclear medicine physicians. As a result, decreased intensity at the central portion of the attenuation map with cylindrical phantom was noticed during use of the measured attenuation correction. On the other hand, segmentation or remapping attenuation correction provided uniform phantom image. the images reconstructed from the clinical brain data explained the attenuation of a skull, at though reconstructed images of the phantoms couldn't explain it. in conclusion, the complicated and improved attenuation correction methods were required to obtain the better accuracy of the quantitative brain PET images. Our study will be useful in improving quantitative brain PET imaging modalities with attenuation correction of $^{137}$Cs transmission source.

• Korean Journal of Psychosomatic Medicine
• /
• v.26 no.1
• /
• pp.26-34
• /
• 2018

Objectives : This study tried to explore the prevalence of chronic physical diseases in patients with schizophrenia and its effects on total medical costs. Methods : The Health Insurance Review and Assessment Service data in 2014-2015 was employed. Only the injuries and diseases, identically diagnosed 3 times or more as a major or minor injury and disease, were classified into chronic physical diseases to improve data accuracy. Total medical costs included out-of-pocket and insurer's costs from health care system perspective. Results : It was shown that 24.5%, 17.3% and 23.4% of schizophrenia patients had one, two and three or more chronic physical diseases, respectively. There was a high prevalence of not only metabolic, but also musculoskeletal, diseases in those patients. The amount of 2015 total medical costs of patients with schizophrenia in 2014 was about 1.08 trillion won. The factors affecting the costs included sex, age, number of chronic physical diseases, and health insurance status. Conclusions : It is considered that clinical practice guidelines based on personal diseases may not sufficiently solve the problems for comorbidities in schizophrenia patients. Accordingly, it should be required to develop models for new types of medical systems capable of treating and caring varied illnesses at the same time.

• The Journal of Engineering Geology
• /
• v.20 no.3
• /
• pp.243-255
• /
• 2010

The slope design of an open-pit mine must consider economical efficiency and stability. Thus, the overall slope angle is the principal factor because of limited support or reinforcement options available in such a setting. In this study, slope displacement, as monitored by a GPS system, was analyzed for a coal mine at Pasir, Indonesia. Predictions of failure time by inverse velocity analysis showed good agreement with field observations. Therefore, the failure time of an unstable slope can be roughly estimated prior to failure. A GIS model that combines fuzzy theory and the analytical hierarchy process (AHP) was developed to assess slope instability in open-pit coal mines. This model simultaneously considers seven factors that influence the instability of open-pit slopes (i.e., overall slope gradient, slope height, surface flows, excavation plan, tension cracks, faults, and water body). Application of the proposed method to an open-pit coal mine revealed an enhanced prediction accuracy of failure time and failure site compared with existing methods.

• The Journal of Korean Society for Radiation Therapy
• /
• v.11 no.1
• /
• pp.53-59
• /
• 1999

The aim of this study is to improve the accuracy of field placement and junction between adjacent fields and block shielding through the use of a computed tomography(CT) simulator and virtual simulation. The information was acquired by assessment of Alderson Rando phantom image using CT simulator (I.Q. Xtra - Picker), determination of each field by virtual fluoroscopy of voxel IQ workstation AcQsim and colored critical structures that were obtained by contouring in virtual simulation. And also using a coronal, sagittal and axial view can determine the field and adjacent field gap correctly without calculation during the procedure. With the treatment planning by using the Helax TMS 4.0, the dose in the junction among the adjacent fields and the spinal cord and cribriform plate of the critical structure was evaluated by the dose volume histogram. The pilot image of coronal and sagittal view took about 2minutes and 26minutes to get 100 images. Image translation to the virtual simulation workstation took about 6minutes. Contouring a critical structure such as cribriform plate, spinal cord using a virtual fluoroscopy were eligible to determine a correct field and shielding. The process took about 20 minutes. As the result of the Helax planning, the dose distribution in adjacent field junction was ideal, and the dose level shows almost 100 percentage in the dose volume histogram of the spinal cord and cribriform plate CT simulation can get a correct therapy area due to enhancement of critical structures such as spinal cord and cribriform plate. In addition, using a Spiral CT scanner can be saved a lot of time to plan a simulation therefore this function can reduce difficulties to keep the patient position without any movements to the patient, physician and radiotherapy technician.

• Journal of Korean Institute of Industrial Engineers
• /
• v.41 no.2
• /
• pp.121-127
• /
• 2015

A reduction of motor performance due to brain disorders can be screened by evaluating force tracking capabilities (FTCs). Existing studies have examined FTCs mainly using simple sinusoidal waves, of which repeated profiles have a critical limitation due to a learning effect in force tracking. The present study examined the effects of personal factors (age and gender) and sinusoidal wave factors (central force and complexity) on FTCs of healthy adults using composite sinusoidal wave profiles (CSWPs). FTCs were measured using Finger $Touch^{TM}$ for 30 seconds and quantified in terms of time within the target range (TWR, accuracy measure) and relative RMSE (RRMSE, variability measure). A total of 90 healthy adults in 20s to 70s with the equal gender ratio participated in the experiment consisting of combinations of 2 central force levels (6 N and 10 N) and 2 complexity levels (approximate entropy, ApEn = 0.03 and 0.06) of CSWPs. Significantly decreased FTCs (lower TWR and higher RRMSE) were found in aged adults, females, the low central force, and the high complexity. The detailed FTC decrements include a 43% reduced TWR and a 85% increased RRMSE of older adults in 70s as compared to those in 20s, a 17% reduced TWR and a 17% increased RRMSE of female as compared to those of male, a 30% reduced TWR and a 108% increased RRMSE at central force = 6N when compared to those at central force = 10N, and a 19% reduced TWR and a 30% increased RRMSE at ApEn = 0.06 as compared to those at ApEn = 0.03. The characteristics of FTCs for CSWPs can be of use in establishing an assessment protocol of motor performance for screening brain disorders.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.1
• /
• pp.105-109
• /
• 2010

While numerous information services are provided on the Web as a core infrastructure of information society, semantic services using the Semantic Web technologies still stay deployed number and application range. This situation would be mainly originated from the failure of securing reliability to the user. Thus, this paper introduces an evaluation method for measuring reliabilities of the semantic services comparatively. To measure the reliability of the compared systems, the observer assesses 'precision in task performance' as a quantitative analysis and 'reliability of expectation-result' as a qualitative analysis described by the test persons. On the other hand, the test person should rate the functional reliability and reliability of the served information on the vector graph by himself with a scale from 0 to 5. Experimental results show that assessment by the observer is very similar to rating value by test persons, and that the accuracy of the served information has a close effect on the functional reliability. Through this paper, we can verify the essential factors for evaluating the reliability of semantic service systems. These are functional reliability and reliability of served information resulting from function execution. In particular, it has been proven that the reliability of the semantic information services largely influences the "Quality in Use" and therefore determines the major factors of the semantic service reliability.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.10 no.2 s.21
• /
• pp.35-39
• /
• 2004

Ship structures are basically an assembly of plate elements and the load-carrying capacity or the ultimate strength is one of the most important criteria for safety assessment and economic design. Also, Structural elements making up ship plated structures do not work separately, resulting in high degree of redundancy and complexity, in contrast to those of steel framed structures. To enable the behavior of such structures to be analyzed simplifications or idealizations must essentially be made considering the accuracy needed and the degree of complexity of the analysis to be used On this study, to investigate effect of modeling range, the finite element method are used and their results are compared varying the analysis ranges. The model has been selected from bottom panels of merchant ship structures. For FHA, three types of structural modeling are adopted in terms of the extent of the analysis. The purpose of the present study is to numerically calculate the characteristics of ultimate strength behavior according to the analysis ranges of stiffened panels subject to uniaxial compressive loads.

• Journal of Yeungnam Medical Science
• /
• v.33 no.1
• /
• pp.8-12
• /
• 2016

Background: The decision to administer oral anticoagulation therapy depends on accurate assessment of stroke risk in patients with atrial fibrillation (AF). Various stroke risk stratification schemes have been developed to help inform clinical decision making. The CHADS2 and CHA2DS2-VASc scores have been used in estimating the risk of stroke in patients with AF. Recently R2CHA2DS2-VASc score was developed. The objective of the current study is to validate the usefulness of the R2CHA2DS2-VASc score and to compare the accuracy of the CHADS2, CHA2DS2-VASc, and R2CHA2DS2-VASc scores in predicting a patient's risk of stroke. Methods: Based on medical records, we conducted a retrospective study of patients hospitalized with AF from March 2011 to July 2013. A total of 448 AF patients were included in this study. The receiver operating characteristic (ROC) curve analysis in MedCalc was used for comparison with respective diagnostic values. Results: The patient characteristics showed male predominance (60.9%). Among the 448 AF patients, 131 (29.2%) patients had strokes during the study. A R2CHA2DS2-VASc score of more than 5 is the optimal cut-off value for prediction of stroke. A risk score of three, the area under the ROC curve (AUC) of R2CHA2DS2-VASc score (AUC 0.631; 95% confidence interval, 0.585-0.679) was the highest. A significant difference was observed between AUC for R2CHA2DS2-VASc, CHADS2, and CHA2DS2-VASc scores, but no meaningful difference between CHADS2 and CHA2DS2-VASc scores. Conclusion: We determined the usefulness of the R2CHA2DS2-VASc score, which showed better association with stroke than the CHADS2 and CHA2DS2-VASc scores.

• Journal of Conservation Science
• /
• v.36 no.2
• /
• pp.73-81
• /
• 2020

Considering the difficulties associated with the creation of deterioration maps for stone cultural heritages, quantitative determination of chemical and biological contaminants in them is still challenging. Hyperspectral image analysis has been proposed to overcome this drawback. In this study, hyperspectral imaging was performed on Stone Buddhas Temple in Four Directions at Gulbulsa Temple Site(Treasure 121), and several surface contaminants were observed. Based on the color and shape, these chemical and biological contaminants were classified into ten categories. Additionally, a method for establishing each class as a reference image was suggested. Simultaneously, with the help of Spectral Angle Mapper algorithm, two classification methods were used to classify the surface contaminants. Method A focused on the region of interest, while method B involved the application of the spectral library prepared from the image. Comparison of the classified images with the reference image revealed that the accuracies and kappa coefficients of methods A and B were 52.07% and 63.61%, and 0.43 and 0.55, respectively. Additionally, misclassified pixels were distributed in the same contamination series.