• Title/Summary/Keyword: Assessment of Accuracy

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The Accuracy of Barr, Blethyn and Leech Scoring Systems on Plain Abdominal Radiographs in Childhood Constipation (소아에서 단순 복부 X-선 사진으로 변비를 진단하는데 있어 Barr, Blethyn과 Leech 점수체계의 정확도)

  • Moon, Ji-Young;Moon, Kyung-Rye
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • v.10 no.1
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    • pp.44-50
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    • 2007
  • Purpose: The role of plain, abdominal radiography in childhood constipation has not been fully evaluated. The aim of this study was to determine the accuracy and reliability of scoring systems assessing a fecal load on plain, abdominal radiographs in children with functional constipation. Methods: Plain, abdominal radiographs from 38 constipated children and 39 control children were examined by four independent inspectors, pediatric residents. Four inspectors independently scored the radiographs according to three different scoring systems Barr, Blethyn, and Leech. No clinical information about the patients was available to the inspectors. Each abdominal radiograph was evaluated on two separate occasions, one week apart. Kappa coefficients were calculated as indicators of inter-and intra-inspector variability, coefficients <0.20, 0.21~0.40, 0.40~0.60, 0.61~0.80 and 0.81~1.00 were considered to indicate poor, fair, moderate, good, and very good agreement, respectively. Results: The Leech score showed the highest reproducibility: the inter-inspector agreement was uniformly very good on two separate occasions (${\kappa}$ values of 0.88, 0.91, 0.92, 0.86 in the first time and 0.81, 0.88, 0.89, 0.84 in the second time). Agreement using the Barr score was good (${\kappa}$ values of 0.66, 0.67, 0.69, 0.66 in the first time and 0.68, 0.65, 0.71, 0.68 in the second time). However, agreement for the Blethyn score was the lowest of the three scoring systems. The Leech scoring system had the highest sensitivity and specificity compared to the Barr scoring system for the diagnosis of functional constipation by plain, abdominal radiographs. Conclusion: The Leech score appeared to be a more accurate and reliable method because of its high sensitivity and specificity for evaluating the fecal load on plain, abdominal radiographs in children with functional constipation. Therefore, the Leech scoring system was found to be the most useful for assessment for the degree of constipation on plain, abdominal radiographs in children.

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A Recidivism Prediction Model Based on XGBoost Considering Asymmetric Error Costs (비대칭 오류 비용을 고려한 XGBoost 기반 재범 예측 모델)

  • Won, Ha-Ram;Shim, Jae-Seung;Ahn, Hyunchul
    • Journal of Intelligence and Information Systems
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    • v.25 no.1
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    • pp.127-137
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    • 2019
  • Recidivism prediction has been a subject of constant research by experts since the early 1970s. But it has become more important as committed crimes by recidivist steadily increase. Especially, in the 1990s, after the US and Canada adopted the 'Recidivism Risk Assessment Report' as a decisive criterion during trial and parole screening, research on recidivism prediction became more active. And in the same period, empirical studies on 'Recidivism Factors' were started even at Korea. Even though most recidivism prediction studies have so far focused on factors of recidivism or the accuracy of recidivism prediction, it is important to minimize the prediction misclassification cost, because recidivism prediction has an asymmetric error cost structure. In general, the cost of misrecognizing people who do not cause recidivism to cause recidivism is lower than the cost of incorrectly classifying people who would cause recidivism. Because the former increases only the additional monitoring costs, while the latter increases the amount of social, and economic costs. Therefore, in this paper, we propose an XGBoost(eXtream Gradient Boosting; XGB) based recidivism prediction model considering asymmetric error cost. In the first step of the model, XGB, being recognized as high performance ensemble method in the field of data mining, was applied. And the results of XGB were compared with various prediction models such as LOGIT(logistic regression analysis), DT(decision trees), ANN(artificial neural networks), and SVM(support vector machines). In the next step, the threshold is optimized to minimize the total misclassification cost, which is the weighted average of FNE(False Negative Error) and FPE(False Positive Error). To verify the usefulness of the model, the model was applied to a real recidivism prediction dataset. As a result, it was confirmed that the XGB model not only showed better prediction accuracy than other prediction models but also reduced the cost of misclassification most effectively.

Development of a Model for Analylzing and Evaluating the Suitability of Locations for Cooling Center Considering Local Characteristics (지역 특성을 고려한 무더위쉼터의 입지특성 분석 및 평가 모델 개발)

  • Jieun Ryu;Chanjong Bu;Kyungil Lee;Kyeong Doo Cho
    • Journal of Environmental Impact Assessment
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    • v.33 no.4
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    • pp.143-154
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    • 2024
  • Heat waves caused by climate change are rapidly increasing health damage to vulnerable groups, and to prevent this, the national, regional, and local governments are establishing climate crisis adaptation policy. A representative climate crisis adaptation policy to reduce heat wave damage is to expand the number of cooling centers. Because it is highly effective in a short period of time, most metropolitan local governments, except Jeonbuk, include the project as an adaptation policy. However, the criteria for selecting a cooling centers are different depending on the budget and non-budget, so the utilization rate and effectiveness of the cooling centers are all different. Therefore, in this study, we developed logistic regression models that can predict and evaluate areas with a high probability of expanding cooling centers in order to implement adaptation policy in local governments. In Incheon Metropolitan City, which consists of various heat wave-vulnerable environments due to the coexistence of the old city and the new city, a logistic model was developed to predict areas where heat waves can be cooling centered by dividing it into Ganghwa·Ongjin-gun and other regions, taking into account socioeconomic and environmental differences. As a result of the study, the statistical model for the Ganghwa·Ogjin-gun region showed that the higher the ground surface temperature and the more and more the number of elderly people over 65 years old, the higher the possibility of location of cooling centers, and the prediction accuracy was about 80.93%. The developed logistic regression model can predict and evaluate areas with a high potential as cooling centers by considering regional environmental and social characteristics, and is expected to be used for priority selection and management when designating additional cooling centers in the future.

A Study on Horizontal Reference Planes in Lateral Cephalogram in Korean Children (한국 아동의 측모두부 수평 기준선에 관한 연구)

  • Kim, Kyung-Ho;Choy, Kwang-Chul;Lee, Ji-Yeon
    • The korean journal of orthodontics
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    • v.29 no.2 s.73
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    • pp.251-265
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    • 1999
  • Various types of horizontal reference planes are used for diagnosis, treatment planning and evaluation of treatment results. But these reference Planes lack accuracy and repro-ducibility, and are mainly for Caucasian. Unlike the adult patients who have completed growth, the horizontal reference planes for growing children may change continuously during growth. Therefore this must be considered in selecting the horizontal reference plane. The purpose of this study was to Investigate the angle formed by the Sella-Nasion(SN) plane and Frankfort-Horizontal(FH) plane and evaluate the angle formed by FH plane and other horizontal reference planes in relation to different skeletal maturity and malocclusion types. 540 subjects with no orthodontic treatment history were chosen, and hand -wrist X-rays and lateral cephalometric X-rays were taken. According to SMA(Skeletal Maturity Assessment) of hand-wrist X-rays, the subjects were classified into 3 skeletal maturity groups : SMI 1-4 for group A, SMI 5-7 for group B and SMI 8-11 for group C. A second classification was made according to cephalometric analysis of lateral cephalograms. The subjects were classified into 3 malocclusion groups : Skeletal Class I, II and III malocclusion group. 10 measurements were evaluated. The results were as follows. 1. The angle formed by the SN plane and FH plane showed no difference among skeletal maturity groups, malocclusion groups, and between .sexes. 2. The angles formed by the SN plane and FH plane were $8.27^{\circ}{\pm}2.31^{\circ}$ for males and $8.59^{\circ}{\pm}2.24^{\circ}$ for females. The average value for females and males was $8.42^{\circ}{\pm}2.28^{\circ}$. 3. The angle formed by the FH plane and palatal plane was almost constant showing no difference among skeletal maturity groups, malocclusion groups, and between sexes($1.09^{\circ}{\pm}3.21^{\circ}$).

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The Role of Camera-Based Coincidence Positron Emission Tomography in Nodal Staging of Non-Small Cell Lung Cancer (비소세포폐암의 림프절 병기 결정에서 Coincidence PET의 역할)

  • Lee, Sun-Min;Choi, Young-Hwa;Oh, Yoon-Jung;Cheong, Seong-Cheoll;Park, Kwang-Joo;Hwang, Sung-Chul;Lee, Yi-Hyeong;Park, Chan-H;Hahn, Myung-Ho
    • Tuberculosis and Respiratory Diseases
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    • v.47 no.5
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    • pp.642-649
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    • 1999
  • Background: It is very important to determine an accurate staging of the non-small cell lung cancer(NSCLC) for an assessment of operability and it's prognosis. However, it is difficult to evaluate tumor involvement of mediastinal lymph nodes accurately utilizing noninvasive imaging modalities. PET is one of the sensitive and specific imaging modality. Unfortunately PET is limited use because of prohibitive cost involved with it's operation. Recently hybrid SPECT/PET(single photon emission computed tomography/positron emission tomography) camera based PET imaging was introduced with relatively low cost. We evaluated the usefulness of coincidence detection(CoDe) PET in the detection of metastasis to the mediastinal lymph nodes in patients with NSCLC. Methods: Twenty one patients with NSCLC were evaluated by CT or MRI and they were considered operable. CoDe PET was performed in all 21 patients prior to surgery. Tomographic slices of axial, coronal and sagittal planes were visually analysed. At surgery, mediastinal lymph nodes were removed and histological diagnosis was performed. CoDe PET findings were correlated with histological findings. Results: Twenty of 21 primary tumor masses were detected by the CoDe PET. Thirteen of 21 patients was correctly diagnosed mediastinal lymph node metastasis by the CoDe PET. Pathological N0 was 14 cases and the specificity of N0 of CoDe PET was 64.3%. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of N1 node was 83.3%, 73.3%, 55.6%, 91.7%, and 76.2% respectively. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of N2 node was 60.0%, 87.5%, 60.0%,87.5%, and 90.0% respectively. There were 3 false negative cases but the size of the 3 nodes were less than 1cm. The size of true positive nodes were 1.1cm, 1.0cm, 0.5cm respectively. There were 1 false positive among the 12 lymph nodes which were larger than 1cm. False positive cases consisted of 1 tuberculosis case, 1 pneumoconiosis case and 1 anthracosis case. Conclusion: CoDe PET has relatively high negative predictive value in the enlarged lymph node in staging of mediastinal nodes in patients with NSCLC. Therefore CoDe PET is useful in ruling out metastasis of enlarged N3 nodes. However, further study is needed including more number of patients in the future.

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Variation on Estimated Values of Radioactivity Concentration According to the Change of the Acquisition Time of SPECT/CT (SPECT/CT의 획득시간 증감에 따른 방사능농도 추정치의 변화)

  • Kim, Ji-Hyeon;Lee, Jooyoung;Son, Hyeon-Soo;Park, Hoon-Hee
    • The Korean Journal of Nuclear Medicine Technology
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    • v.25 no.2
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    • pp.15-24
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    • 2021
  • Purpose SPECT/CT was noted for its excellent correction method and qualitative functions based on fusion images in the early stages of dissemination, and interest in and utilization of quantitative functions has been increasing with the recent introduction of companion diagnostic therapy(Theranostics). Unlike PET/CT, various conditions like the type of collimator and detector rotation are a challenging factor for image acquisition and reconstruction methods at absolute quantification of SPECT/CT. Therefore, in this study, We want to find out the effect on the radioactivity concentration estimate by the increase or decrease of the total acquisition time according to the number of projections and the acquisition time per projection among SPECT/CT imaging conditions. Materials and Methods After filling the 9,293 ml cylindrical phantom with sterile water and diluting 99mTc 91.76 MBq, the standard image was taken with a total acquisition time of 600 sec (10 sec/frame × 120 frames, matrix size 128 × 128) and also volume sensitivity and the calibration factor was verified. Based on the standard image, the comparative images were obtained by increasing or decreasing the total acquisition time. namely 60 (-90%), 150 (-75%), 300 (-50%), 450 (-25%), 900 (+50%), and 1200 (+100%) sec. For each image detail, the acquisition time(sec/frame) per projection was set to 1.0, 2.5, 5.0, 7.5, 15.0 and 20.0 sec (fixed number of projections: 120 frame) and the number of projection images was set to 12, 30, 60, 90, 180 and 240 frames(fixed time per projection:10 sec). Based on the coefficients measured through the volume of interest in each acquired image, the percentage of variation about the contrast to noise ratio (CNR) was determined as a qualitative assessment, and the quantitative assessment was conducted through the percentage of variation of the radioactivity concentration estimate. At this time, the relationship between the radioactivity concentration estimate (cps/ml) and the actual radioactivity concentration (Bq/ml) was compared and analyzed using the recovery coefficient (RC_Recovery Coefficients) as an indicator. Results The results [CNR, radioactivity Concentration, RC] by the change in the number of projections for each increase or decrease rate (-90%, -75%, -50%, -25%, +50%, +100%) of total acquisition time are as follows. [-89.5%, +3.90%, 1.04] at -90%, [-77.9%, +2.71%, 1.03] at -75%, [-55.6%, +1.85%, 1.02] at -50%, [-33.6%, +1.37%, 1.01] at -25%, [-33.7%, +0.71%, 1.01] at +50%, [+93.2%, +0.32%, 1.00] at +100%. and also The results [CNR, radioactivity Concentration, RC] by the acquisition time change for each increase or decrease rate (-90%, -75%, -50%, -25%, +50%, +100%) of total acquisition time are as follows. [-89.3%, -3.55%, 0.96] at - 90%, [-73.4%, -0.17%, 1.00] at -75%, [-49.6%, -0.34%, 1.00] at -50%, [-24.9%, 0.03%, 1.00] at -25%, [+49.3%, -0.04%, 1.00] at +50%, [+99.0%, +0.11%, 1.00] at +100%. Conclusion In SPECT/CT, the total coefficient obtained according to the increase or decrease of the total acquisition time and the resulting image quality (CNR) showed a pattern that changed proportionally. On the other hand, quantitative evaluations through absolute quantification showed a change of less than 5% (-3.55 to +3.90%) under all experimental conditions, maintaining quantitative accuracy (RC 0.96 to 1.04). Considering the reduction of the total acquisition time rather than the increasing of the image acquiring time, The reduction in total acquisition time is applicable to quantitative analysis without significant loss and is judged to be clinically effective. This study shows that when increasing or decreasing of total acquisition time, changes in acquisition time per projection have fewer fluctuations that occur in qualitative and quantitative condition changes than the change in the number of projections under the same scanning time conditions.

Assessment for the Utility of Treatment Plan QA System according to Dosimetric Leaf Gap in Multileaf Collimator (다엽콜리메이터의 선량학적엽간격에 따른 치료계획 정도관리시스템의 효용성 평가)

  • Lee, Soon Sung;Choi, Sang Hyoun;Min, Chul Kee;Kim, Woo Chul;Ji, Young Hoon;Park, Seungwoo;Jung, Haijo;Kim, Mi-Sook;Yoo, Hyung Jun;Kim, Kum Bae
    • Progress in Medical Physics
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    • v.26 no.3
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    • pp.168-177
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    • 2015
  • For evaluating the treatment planning accurately, the quality assurance for treatment planning is recommended when patients were treated with IMRT which is complex and delicate. To realize this purpose, treatment plan quality assurance software can be used to verify the delivered dose accurately before and after of treatment. The purpose of this study is to evaluate the accuracy of treatment plan quality assurance software for each IMRT plan according to MLC DLG (dosimetric leaf gap). Novalis Tx with a built-in HD120 MLC was used in this study to acquire the MLC dynalog file be imported in MobiusFx. To establish IMRT plan, Eclipse RTP system was used and target and organ structures (multi-target, mock prostate, mock head/neck, C-shape case) were contoured in I'mRT phantom. To verify the difference of dose distribution according to DLG, MLC dynalog files were imported to MobiusFx software and changed the DLG (0.5, 0.7, 1.0, 1.3, 1.6 mm) values in MobiusFx. For evaluation dose, dose distribution was evaluated by using 3D gamma index for the gamma criteria 3% and distance to agreement 3 mm, and the point dose was acquired by using the CC13 ionization chamber in isocenter of I'mRT phantom. In the result for point dose, the mock head/neck and multi-target had difference about 4% and 3% in DLG 0.5 and 0.7 mm respectively, and the other DLGs had difference less than 3%. The gamma index passing-rate of mock head/neck were below 81% for PTV and cord, and multi-target were below 30% for center and superior target in DLGs 0.5, 0.7 mm, however, inferior target of multi-target case and parotid of mock head/neck case had 100.0% passing rate in all DLGs. The point dose of mock prostate showed difference below 3.0% in all DLGs, however, the passing rate of PTV were below 95% in 0.5, 0.7 mm DLGs, and the other DLGs were above 98%. The rectum and bladder had 100.0% passing rate in all DLGs. As the difference of point dose in C-shape were 3~9% except for 1.3 mm DLG, the passing rate of PTV in 1.0 1.3 mm were 96.7, 93.0% respectively. However, passing rate of the other DLGs were below 86% and core was 100.0% passing rate in all DLGs. In this study, we verified that the accuracy of treatment planning QA system can be affected by DLG values. For precise quality assurance for treatment technique using the MLC motion like IMRT and VMAT, we should use appropriate DLG value in linear accelerator and RTP system.

The Usefulness of 18F-FDG PET to Differentiate Subtypes of Dementia: The Systematic Review and Meta-Analysis

  • Seunghee Na;Dong Woo Kang;Geon Ha Kim;Ko Woon Kim;Yeshin Kim;Hee-Jin Kim;Kee Hyung Park;Young Ho Park;Gihwan Byeon;Jeewon Suh;Joon Hyun Shin;YongSoo Shim;YoungSoon Yang;Yoo Hyun Um;Seong-il Oh;Sheng-Min Wang;Bora Yoon;Hai-Jeon Yoon;Sun Min Lee;Juyoun Lee;Jin San Lee;Hak Young Rhee;Jae-Sung Lim;Young Hee Jung;Juhee Chin;Yun Jeong Hong;Hyemin Jang;Hongyoon Choi;Miyoung Choi;Jae-Won Jang;Korean Dementia Association
    • Dementia and Neurocognitive Disorders
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    • v.23 no.1
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    • pp.54-66
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    • 2024
  • Background and Purpose: Dementia subtypes, including Alzheimer's dementia (AD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD), pose diagnostic challenges. This review examines the effectiveness of 18F-Fluorodeoxyglucose Positron Emission Tomography (18F-FDG PET) in differentiating these subtypes for precise treatment and management. Methods: A systematic review following Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines was conducted using databases like PubMed and Embase to identify studies on the diagnostic utility of 18F-FDG PET in dementia. The search included studies up to November 16, 2022, focusing on peer-reviewed journals and applying the goldstandard clinical diagnosis for dementia subtypes. Results: From 12,815 articles, 14 were selected for final analysis. For AD versus FTD, the sensitivity was 0.96 (95% confidence interval [CI], 0.88-0.98) and specificity was 0.84 (95% CI, 0.70-0.92). In the case of AD versus DLB, 18F-FDG PET showed a sensitivity of 0.93 (95% CI 0.88-0.98) and specificity of 0.92 (95% CI, 0.70-0.92). Lastly, when differentiating AD from non-AD dementias, the sensitivity was 0.86 (95% CI, 0.80-0.91) and the specificity was 0.88 (95% CI, 0.80-0.91). The studies mostly used case-control designs with visual and quantitative assessments. Conclusions: 18F-FDG PET exhibits high sensitivity and specificity in differentiating dementia subtypes, particularly AD, FTD, and DLB. This method, while not a standalone diagnostic tool, significantly enhances diagnostic accuracy in uncertain cases, complementing clinical assessments and structural imaging.

A Study on the Simplification of Questionnaire for Sasang Constitution Classification(QSCC II) (사상체질진단검사(QSCC II) 설문지 간소화 연구)

  • Park, Jee-Won;Kim, Jeong-Ah;Wang, Myung-Ja
    • Research in Community and Public Health Nursing
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    • v.14 no.2
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    • pp.334-350
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    • 2003
  • The purpose of this descriptive study was to evaluate the clinical validity of QSCCII (Questionnaire for the Sasang Constitution Classification), whose high accuracy as a constitutional diagnostic tool has been recognized by medical professionals. The subjects of this study were 568 clients from an A university hospital in Suwon. Of the subjects, 259 were health center visitors and 292 were ambulatory clinic visitors. Data were collected using self-reported questionnaire and were analyzed by $X^2$-test and one-way ANOVA. The results of this study as follows: 1. In 4 types of constitution, Soeumin type was found in 41.5% of the subjects. Taeumin type in 39.2%.,and Soyangin type in 19.2%, respectively. There was no Tayangin type found in this study. There were no significant differences on types of constitution by demographic characteristics such as age, sex, marital status, education, religion, and economic status. 2. As for 15 item-selective questionnaire, there were statistically significant differences on the response rate of the 12 items, except items such as A4, A11 and A14, by the types of constitution. When the subjects' own criteria on their constitution were compared to the given constitutional criteria on each item, 4 items such as A6, A11, A13 and A14 were advisable to be excluded from the questionnaire or to be reunited to the other criteria. In the meanwhile, 3 items such as A7, A18 and A15 were desirable to be re-categorized to the other constitutional types and reconstructed to the QSCC II questionnaire. 3. In terms of 106 true-false questionnaire, there were statistically significant differences on the response rate of 46 items by the types of constitution. The 46 items include 15 items (32.6%) of the domain of 'handling something/strength and weakness', 4 items (8.7%) of the domain of 'interpersonal relationship', 9 items (19.6%) of the domain of 'state of mind at ordinary times', 2 items (4.3%) of the domain of 'distinctive emotional characteristics' area, 11 items (23.9%) of the domain of 'specific behavioral trait' and 5 items (10.9%) of the domain of 'physical characteristics'. Therefore, the areas of 'handling something/strength and weakness' and' specific behavioral trait' mainly contributed to the classification of constitutional type. 4. When the 106 true-false items were simplified to the 46 items, statistically significant differences were found on the rate of items allocated to the 3 types of constitution. The rate of selection assigned to the 3 constitutional types of the simplified 46-item questionnaire was higher than that of the original 106-item questionnaire. Conclusions; It was concluded that the rate of selection of each lay person about his own constitutional type would be still higher even though the simplified items of QSCC II questionnaire were applied. If more replicated studies are conducted on the diverse population using the simplifying QSCC II questionnaire in the future, a more simplified standardized Sasang Constitution Questionnaire that is available to the public rather than to medical staffs in the clinical settings could be developed. Moreover, the simplified scale will help nurses deliver more efficient nursing care by providing a more rapid way of health assessment.

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The Effectiveness Evaluation of Reconstruction Method Using DFOV Position Changes for Reduction of Artifact Around Hotspot in PET/CT Images (PET/CT 검사에서 열소 주변 인공물 감소를 위한 DFOV 위치 변화 재구성 방법의 유용성 평가)

  • Han, Dong Chan;Hong, Gun Chul;Choi, Choon ki;Lee, Hyeok;Choi, Seong Wook
    • The Korean Journal of Nuclear Medicine Technology
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    • v.17 no.2
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    • pp.90-94
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    • 2013
  • Purpose: In the PET/CT images, various artifacts cause degradation of the quantitative assessment. Most hotspot generated by radiopharmaceutical injection errors cause an artifact and degrade the quality of the images as well as the accuracy of the quantitative evaluation. The purpose of this study is to assess effectiveness of the elimination of the hotspot at the injection sites using shifting the center of DFOV (Display Field of View, DFOV) method and evaluate the quantitative evaluation of result. Materials and Methods: GE Discovery STE 16 (GE Healthcare, Milwaukee, USA) and 1994 NEMA phantom were used for imaging acquisition. Phantom was filled with 0.005 MBq/mL of $^{18}F-FDG$. A hotspot was artificially placed on the outside of the phantom. The ratio of hotspot area activity to background area activity was regulated as 200:1. After image acquisition with routine protocol, all of the images were reconstructed using the shifting the center of DFOV method that wasn't overlapped with hotspot. Those images obtained before and after applying the shifting reconstruction method were compared. ROIs (Region Of Interests) were set in the hotspot areas, meanSUVs and standard deviations were calculated. Percentage differences were calculated with those meanSUVs and standard deviations. The evaluation on the effects of the shifting reconstruction method was done by comparison of the meanSUVs and the standard deviations, which were calculated for background areas unaffected by hotspot. Results: In the areas of unaffected by hotspot, meanSUVs before and after applying the shifting of center of DFOV method were $0.67{\pm}0.06g/mL$ and $0.65{\pm}0.06g/mL$, respectively. In the artifact areas affected by hotspot, meanSUVs before and after applying the shifting of center of DFOV method were $0.32{\pm}0.08g/mL$ and $0.56{\pm}0.12g/mL$, respectively. The percentage differences of the area adjacent to the hotspot and the area distant from the hotspot were 65.3% and 97.4%, respectively. Conclusion: In the PET/CT images, meanSUV was improved by 32.1% when the effect of artifact was removed with application of the shifting the center of DFOV methode. In other areas unaffected by artifacts, meanSUVs were not significantly different after applying DFOV center shift method. As shown in the result, adverse effects of hotspot made by swelling in the injection site can be reduced by applying DFOV center shift method. Therefore, DFOV center shift method can be applied for the more precise quantitative evaluation, and contribute to the increase of the diagnostic value of the images.

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