• Journal of Radiation Protection and Research
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• v.36 no.1
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• pp.1-7
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• 2011

A simple mathematical model of simultaneous combined action of environmental agents has been proposed to describe the synergistic interaction of microwave and high ambient temperature treatment on animal heating. The model suggests that the synergism is caused by the additional effective damage arising from an interaction of sublesions induced by each agent. These sublesions are considered to be ineffective if each agent is taken individually. The additional damage results in a higher body temperature increment when compared with that expected for an independent action of each agent. The model was adjusted to describe the synergistic interaction, to determine its greatest value and the condition under which it can be achieved. The prediction of the model was shown to be consistent with experimental data on rabbit heating. The model appears to be appropriate and the conclusions are valid.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.269-274
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• 2023

In this paper, we proposed a new UNet 3+ model for medical image segmentation. The proposed ensemble(E) UNet 3+ model consists of UNet 3+s of varying depths into one unified architecture. UNet 3+s of varying depths have same encoder, but have their own decoders. They can bridge semantic gap between encoder and decoder nodes of UNet 3+. Deep supervision was used for learning on a total of 8 nodes of the E-UNet 3+ to improve performance. The proposed E-UNet 3+ model shows better segmentation results than those of the UNet 3+. As a result of the simulation, the E-UNet 3+ model using deep supervision was the best with loss function values of 0.8904 and 0.8562 for training and validation data. For the test data, the UNet 3+ model using deep supervision was the best with a value of 0.7406. Qualitative comparison of the simulation results shows the results of the proposed model are better than those of existing UNet 3+.

• Journal of Biomedical Engineering Research
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• v.43 no.6
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• pp.369-374
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• 2022

Purpose: Focused ultrasound is an emerging technology for treating the brain locally in a noninvasive manner. In this study, we have investigated the influence of skull properties on simulating transcranial pressure field. Methods: A 3D computational model of transcranial focused ultrasound was constructed using female and male CT data to solve for intracranial pressure. For heterogeneous model, the acoustic properties were calculated from CT Hounsfield units based on a porosity. The homogeneous model assigned constant acoustic properties for the single-layered skull. Results: A computational model was validated against empirical data. The homogeneous models were then compared with the heterogeneous model, resulted in 10.87% and 7.19% differences in peak pressure for female and male models respectively. For the focal volume, homogeneous model demonstrated more than 94% overlap compared with the heterogeneous model. Conclusion: Homogeneous model can be constructed using MR images that are commonly used for the segmentation of the skull. We propose the possibility of the homogeneous model for the simulating transcranial pressure field owing to comparable focal volume between homogeneous model and heterogeneous model.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7785-7788
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• 2015

Utilization of high energy photons (>10MV) with an optimal weight using a mixed energy technique is a practical way to generate a homogenous dose distribution while maintaining adequate target coverage in intact breast radiotherapy. This study represents a model for estimation of this optimal weight for day to day clinical usage. For this purpose, treatment planning computed tomography scans of thirty-three consecutive early stage breast cancer patients following breast conservation surgery were analyzed. After delineation of the breast clinical target volume (CTV) and placing opposed wedge paired isocenteric tangential portals, dosimeteric calculations were conducted and dose volume histograms (DVHs) were generated, first with pure 6MV photons and then these calculations were repeated ten times with incorporating 18MV photons (ten percent increase in weight per step) in each individual patient. For each calculation two indexes including maximum dose in the breast CTV ($D_{max}$) and the volume of CTV which covered with 95% Isodose line ($V_{CTV,95%IDL}$) were measured according to the DVH data and then normalized values were plotted in a graph. The optimal weight of 18MV photons was defined as the intersection point of $D_{max}$ and $V_{CTV,95%IDL}$ graphs. For creating a model to predict this optimal weight multiple linear regression analysis was used based on some of the breast and tangential field parameters. The best fitting model for prediction of 18MV photons optimal weight in breast radiotherapy using mixed energy technique, incorporated chest wall separation plus central lung distance (Adjusted R2=0.776). In conclusion, this study represents a model for the estimation of optimal beam weighting in breast radiotherapy using mixed photon energy technique for routine day to day clinical usage.

• Korean Medical Education Review
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• v.16 no.3
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• pp.126-131
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• 2014

The purpose of this study is to analyze the medical education system of Korea and to propose a method of curriculum redesign. Although there have been many attempts by medical educators to improve the quality of medical education, the results have not been fruitful. First, there exists a limitation to the dualistic curriculum design based on Flexnerianism, and thus, this model does not provide an integrated experience to medical students. Therefore, we propose a unidimensional model for curriculum redesign. Second, it is impossible to promote excellence in medical education without solving the structural problems of teaching and learning, such as the teaching competency of the faculty, large-scale lectures, and team teaching systems. A curricular strategy that emphasizes mutual interaction and teaching accountability is necessary to promote meaningful learning. Third, the current clinical training system, the circulation model, provides incomplete training as well as a lack of sequence and articulation experiences. This system needs to be redesigned in a way that allows only those students who have mastered both the knowledge and the application of medical education to advance to the next step. Fourth, norm-referenced assessments of a medical college distort the learning process and create unconstructive system energy. A criterion-referenced assessment that values cooperation, independent study, and intrinsic motivation is more important for the reliability and validity of the assessment. Medical students should not focus on formative and informative learning. Medical colleges should investigate the multifaceted potential of the students and provide transformative learning to grow students into change agents. For this to take place, curriculum redesign-not new methods of medical education-is required.

• Proceedings of the KOSOMBE Conference
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• v.1991 no.11
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• pp.113-118
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• 1991

Hypertension is a medical problem with no permanent cure. Extended hypertension can cause various cardio vascular diseases, cerebral vascular diseases, and circulatory system trouble. Medical treatment at present does not consider circadian variation of blood pressure in patients ; therefore, the problem of over-reduction of blood pressure through drugs sometimes occurs. This paper presents a prediction model of circadian variation or moon blood pressure employing the endocrine grand and the autonomic nervous system.

• Safety and Health at Work
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• v.13 no.4
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• pp.469-474
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• 2022

Background: Nowadays, counter-productive work behaviors (CWBs) have turned into a common and costly position for many organizations and especially health centers. Therefore, the study was carried out to examine and compare the demand-control-support (DCS) and effort-reward imbalance (ERI) models as predictors of CWBs. Methods: The study was cross-sectional. The population was all nurses working in public hospitals in Hamadan, Iran of whom 320 were selected as the sample based on simple random sampling method. The instruments used were Job Content Questionnaire, Effort-Reward Imbalance Questionnaire, and Counterproductivity Work Behavior Questionnaire. Data were analyzed using correlation and regression analysis in SPSS18. Results: The findings indicated that both ERI and DCS models could predict CWB (p ≤ 0.05); however, the DCS model variables can explain the variance of CWB-I and CWB-O approximately 8% more than the ERI model variables and have more power in predicting these behaviors in the nursing community. Conclusion: According to the results, job stress is a key factor in the incidence of CWBs among nurses. Considering the importance and impact of each component of ERI and DCS models in the occurrence of CWBs, corrective actions can be taken to reduce their incidence in nurses.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.11
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• pp.6857-6862
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• 2013

Background: Breast cancer is the most common cancer in women. All ages are susceptible and more than 90% of the patients can be cured with early diagnosis. Breast self-examination (BSE) and mammography can be useful for this aim. In this study we examined the components of the Champion health belief model to identify if they could predict the intentions of women to perform such screening. Materials and Methods: A total of 380 women aged 30 and above who had referred to health-care centers were assessed for use of breast cancer screening over the past year with a modified health belief model questionnaire. Logistic regression was applied to identify leading independent predictors. Results: In this study 27% of the women performed BSE in the last year but only 6.8% of them used mammography as a way of screening. There were significant differences regarding all components of the model except for perceived severity between women that underwent BSE. over the past year and those that did not. Findings were similar for mammography. Regression analysis revealed that intentions to perform BSE were predicted by perceived self-efficacy and perceived barriers to BSE while intentions to perform mammography were predicted by perceived barriers. Conclusions: This study indicated that self-efficacy can support performance of BSE while perceived barriers are important for not performing both BSE and mammography. Thus we must educate women to increase their self-efficacy and decrease their perceived barriers.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.8
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• pp.3747-3752
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• 2014

Background: Gallbladder carcinoma (GBC) is the most common carcinoma of the biliary system. Among its research models, orthotopic xenograft models, important research tools, have been rarely reported in the literature however. Aim: To explore establishment of an orthotopic xenograft model and to evaluate the advantage and disadvantage as compared with other models. Materials and Methods: Subcutaneous xenograft and orthotopic xenograft models of gallbladder carcinoma in nude mice were established and compared with human gallbladder carcinomas. Results: For the orthotopic xenograft model and clinical gallbladder carcinomas, the lymph node metastatic rates were 69.2% and 53.3% (p>0.05); ascites generation rates, 38.5% and 11.7%(p<0.05); liver invasive rates, 100% and 61.7%(p<0.05); and lymphatic vessel densities (LVD), $10.4{\pm}3.02$ and $8.77{\pm}2.92$ (p>0.05), respectively. In the subcutaneous xenograft model, no evidence of ascites generation, lymph node metastasis and liver metastasis were found, and its LVD was lower ($4.56{\pm}1.53$, p<0.05). Conclusions: Compared with the subcutaneous xenograft model, the orthotopic xenograft model better simulates clinical gallbladder carcinoma in terms of metastasis and invasion, which may be attributed to the difference in microenvironment and LVD.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5349-5353
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• 2014

Statistical methods to analyze and predict the related risk factors of nosocomial infection in lung cancer patients are various, but the results are inconsistent. A total of 609 patients with lung cancer were enrolled to allow factor comparison using Student's t-test or the Mann-Whitney test or the Chi-square test. Variables that were significantly related to the presence of nosocomial infection were selected as candidates for input into the final ANN model. The area under the receiver operating characteristic (ROC) curve (AUC) was used to evaluate the performance of the artificial neural network (ANN) model and logistic regression (LR) model. The prevalence of nosocomial infection from lung cancer in this entire study population was 20.1% (165/609), nosocomial infections occurring in sputum specimens (85.5%), followed by blood (6.73%), urine (6.0%) and pleural effusions (1.82%). It was shown that long term hospitalization (${\geq}22days$, P= 0.000), poor clinical stage (IIIb and IV stage, P=0.002), older age (${\geq}61days$ old, P=0.023), and use the hormones were linked to nosocomial infection and the ANN model consisted of these four factors. The artificial neural network model with variables consisting of age, clinical stage, time of hospitalization, and use of hormones should be useful for predicting nosocomial infection in lung cancer cases.