• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.12-27
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• 2004

The contamination pattern of indoor air was simulated when groundwater dissolving benzene was used for household activities. Indoor exposure scenario consisted of inhalation, ingestion, and dermal absorption. Physiologically based pharmacokinetic (PBPK) model was used to analyze how benzene exposed to human body was distributed in internal organs. Main exposure pathways contributing total internal dose were inhalation and ingestion while the contribution of dermal absorption was very small. Man showed higher exposure rate than woman due to his higher breath rate. For a short-term exposure, benzene concentration in venous blood of SPT, RPT and liver changed rapidly while slowly did in venous blood of adipose tissue at a low concentration. For a long-term exposure, woman accumulated about 2.1 times higher than man. Most of benzene exposed to human body was removed by exhalation and metabolism at lung and liver, respectively. For inhalation and ingestion, the benzene removals by exhalation were 69.8 and 48.4%, respectively. Relative importance of removal mechanism was different according to the inflow displacement of benzene. The results obtained from this study would help understand exposure, distribution, and removal phenomena and make plans for the reduction of the health risk associated with the contaminated groundwater by various organic compounds.

• Journal of Trauma and Injury
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• v.20 no.1
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• pp.12-18
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• 2007

Purpose: Recently, trauma is more frequent due to the increases in the population, the number of traffic accident, and the incidence of violence. Especially, abdominal trauma is a leading cause of morbidity and mortality. We analyzed the clinical features and the factors associated with morbidity and mortality. Methods: We analyzed 136 patients of abdominal trauma who were admitted at the Department of Surgery, Chonnam National University Hospital, from January 2003 to June 2005. We analyzed the cause of trauma, the injured organ, combined injuries, mental status, blood pressure, laboratory findings, morbidity, and mortality. The relationships between by variable were assesed by using the independent samples test and the Kruskal?Wallis test. Results: The causes of trauma were traffic accidents (98 cases, 72%), falling accidents (9 cases, 6.6%), violence (6 cases, 4.4%), and stab injuries (6 cases, 4.4%). The injured organs were the small intestines (47 cases, 34.6%), the liver (35 cases, 25.7%), the spleen (26 cases, 19.1%), the mesentery (17 cases, 12.5%), the large intestines (15 cases, 11.0%), the pancreas (14 cases, 10.3%), etc. The most common combined injury was chest injury (53 cases, 39%). Comatose or semicomatose mental status and shock on admission (<60 mmHg in systolic) were related to high mortality (85.7%). In laboratory findings, decreased hemoglobin (<8 g/dL), and platelet count (<$50,000/mm^3$), and increased creatinine level (>1.6 mg/dL) were significant prognostic factors. The incidence of postoperative complications was 40.4%, and frequent complications were wound infection (8.1%) and re-bleeding (8.1%). The overall mortality rate was 18.4%, and most common cause was hypovolemic shock (18 cases, 13.2%), however, there was no statistical difference according to injurd organ. Conclusion: In the multivariate analysis, mental status, hemoglobin, and serum creatinine level were the most significant prognostic factors. When an abdominal trauma patient arrives at the emergency room, a rapid and accurate evaluation of the patient's status and risk factors, and resuscitation, if necessary, have to be performed to lower the morbidity and mortality.

• Journal of Korean Neurosurgical Society
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• v.64 no.5
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• pp.791-798
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• 2021

Objective : The period of mechanical ventilator (MV)-dependent respiratory failure after cervical spinal cord injury (CSCI) varies from patient to patient. This study aimed to identify predictors of MV at hospital discharge (MVDC) due to prolonged respiratory failure among patients with MV after CSCI. Methods : Two hundred forty-three patients with CSCI were admitted to our institution between May 2006 and April 2018. Their medical records and radiographic data were retrospectively reviewed. Level and completeness of injury were defined according to the American Spinal Injury Association (ASIA) standards. Respiratory failure was defined as the requirement for definitive airway and assistance of MV. We also evaluated magnetic resonance imaging characteristics of the cervical spine. These characteristics included : maximum canal compromise (MCC); intramedullary hematoma or cord transection; and integrity of the disco-ligamentous complex for assessment of the Subaxial Cervical Spine Injury Classification (SLIC) scoring. The inclusion criteria were patients with CSCI who underwent decompression surgery within 48 hours after trauma with respiratory failure during hospital stay. Patients with Glasgow coma scale 12 or lower, major fatal trauma of vital organs, or stroke caused by vertebral artery injury were excluded from the study. Results : Out of 243 patients with CSCI, 30 required MV during their hospital stay, and 27 met the inclusion criteria. Among them, 48.1% (13/27) of patients had MVDC with greater than 30 days MV or death caused by aspiration pneumonia. In total, 51.9% (14/27) of patients could be weaned from MV during 30 days or less of hospital stay (MV days : MVDC 38.23±20.79 vs. MV weaning, 13.57±8.40; p<0.001). Vital signs at hospital arrival, smoking, the American Society of Anesthesiologists classification, Associated injury with Injury Severity Score, SLIC score, and length of cord edema did not differ between the MVDC and MV weaning groups. The ASIA impairment scale, level of injury within C3 to C6, and MCC significantly affected MVDC. The MCC significantly correlated with MVDC, and the optimal cutoff value was 51.40%, with 76.9% sensitivity and 78.6% specificity. In multivariate logistic regression analysis, MCC >51.4% was a significant risk factor for MVDC (odds ratio, 7.574; p=0.039). Conclusion : As a method of predicting which patients would be able to undergo weaning from MV early, the MCC is a valid factor. If the MCC exceeds 51.4%, prognosis of respiratory function becomes poor and the probability of MVDC is increased.

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.2
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• pp.181-186
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• 2013

Purpose: This study executed therapy plans on prostate cancer (homogeneous density area) and lung cancer (non-homogeneous density area) using radiation treatment planning systems such as $Pinnacle^3$ (version 9.2, Philips Medical Systems, USA) and Eclipse (version 10.0, Varian Medical Systems, USA) in order to quantify the difference between dose calculation according to density in IMRT. Materials and Methods: The subjects were prostate cancer patients (n=5) and lung cancer patients (n=5) who had therapies in our hospital. Identical constraints and optimization process according to the Protocol were administered on the subjects. For the therapy plan of prostate cancer patients, 10 MV and 7Beam were used and 2.5 Gy was prescribed in 28 fx to make 70 Gy in total. For lung cancer patients, 6 MV and 6Beam were used and 2 Gy was prescribed in 33 fx to make 66 Gy in total. Through two therapy planning systems, maximum dose, average dose, and minimum dose of OAR (Organ at Risk) of CTV, PTV and around tumor were investigated. Results: In prostate cancer, both therapy planning systems showed within 2% change of dose of CTV and PTV and normal organs (Bladder, Both femur and Rectum out) near the tumor satisfied the dose constraints. In lung cancer, CTV and PTV showed less than 2% changes in dose and normal organs (Esophagus, Spinal cord and Both lungs) satisfied dose restrictions. However, the minimum dose of Eclipse therapy plan was 1.9% higher in CTV and 3.5% higher in PTV, and in case of both lungs there was 3.0% difference at V5 Gy. Conclusion: Each TPS according to the density satisfied dose limits of our hospital proving the clinical accuracy. It is considered more accurate and precise therapy plan can be made if studies on treatment planning for diverse parts and the application of such TPS are made.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.89-97
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• 2021

Purpose: The purpose of this study is to compare and evaluate the dose change according to the gas volume variations in the rectum, which was not included in the treatment plan during radiation therapy for cervical cancer. Materials and methods: Static Intensity Modulated Radiation Therapy (S-IMRT) using a 9-field and Volumetric Modulated Arc Therapy (VMAT) using 2 full-arcs were established with treatment planning system on Computed Tomography images of a human phantom. Random gas parameters were included in the Planning Target Volume(PTV) with a maximum change of 2.0 cm in increments of 0.5 cm. Then, the Conformity Index (CI), Homogeneity Index (HI) and PTV D_max for the target volume were calculated, and the minimum dose (D_min), mean dose (D_mean) and Maximum Dose (D_max) were calculated and compared for OAR(organs at risk). For statistical analysis, T-test was performed to obtain a p-value, where the significance level was set to 0.05. Result: The HI coefficients of determination(R²) of S-IMRT and VMAT were 0.9423 and 0.8223, respectively, indicating a relatively clear correlation, and PTV D_max was found to increase up to 2.8% as the volume of a given gas parameter increased. In case of OAR evaluation, the dose in the bladder did not change with gas volume while a significant dose difference of more than D_mean 700 cGy was confirmed in rectum using both treatment plans at gas volumes of 1.0 cm or more. In all values except for D_mean of bladder, p-value was less than 0.05, confirming a statistically significant difference. Conclusion: In the case of gas generation not considered in the reference treatment plan, as the amount of gas increased, the dose difference at PTV and the dose delivered to the rectum increased. Therefore, during radiation therapy, it is necessary to make efforts to minimize the dose transmission error caused by a large amount of gas volumes in the rectum. Further studies will be necessary to evaluate dose transmission by not only varying the gas volume but also where the gas was located in the treatment field.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.73-81
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• 2018

Purpose : The aims of this study were to compare and assess the effectiveness of Volumetric Modulated Arc Therapy(VMAT) using jaw tracking(JT) and fixed jaw(FJ) in radiation therapy of multiple brain metastasis. Methode and material : Among the patients with Multiple Brain Metastasis treated with jaw tracking, 10 patients with more than 6 tumors and with the size of radiation field $14{\times}14cm^2$ or more were included. Each Treatment plans with jaw tracking(JT) and fixed jaw(FJ) was established with Eclipse (Ver. 13.6 Varian, USA). Gamma Index (3 mm, 3 % confidence interval - 95 %) and maximum dose difference were measured with an electronic portal imaging device(EPID). The $D_{max}$ and $D_{mean}$ of Organ At Risk(OAR) were assessed and compared, and the Conformity Index(CI) and Homogeneity Index(HI) were evaluated. Result : Evaluating jaw tracking(JT) and fixed jaw(FJ) outcomes, in all cases, Gamma Index met the permissible standard of 3 mm, 3 % confidence intervals of 95 %. The maximum dose difference value from the areas with leaf end transmission was measured at a maximum of 98.4 % and an average of 43.6 % in clockwise(CW), and 67.9 % and 41.0 % for each in Counter-Clockwise(CCW). With jaw tracking, the maximum value of $D_{max}$ for each normal organ in OAR decreased in 15.36 %~74.59 % with the average value decreasing in 2.84 %~39.80 %. The maximum value of $D_{mean}$ in OAR decreased in 27.90 %~65.23 %, with the average value decreasing in 7.70 %~41.71 %. No change has been found in Conformity Index and Homogeneity Index values. Conclusion : When Jaw tracking is used in treating patients with multiple brain metastasis with VMAT, the unnecessary exposure due to leakage and transmission of radiation in unspecified areas was reduced, without affecting the dose distribution of the planning target volume(PTV), and the availability of radiation therapy with lower doses in normal organs is expected.

• Progress in Medical Physics
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• v.28 no.3
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• pp.100-105
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• 2017

The purpose of the present study was to develop and evaluate patient-customized helmets with a three-dimensional (3D) printer for radiation therapy of malignant scalp tumors. Computed tomography was performed in a case an Alderson RANDO phantom without bolus (Non_Bolus), in a case with a dental wax bolus on the scalp (Wax_Bolus), and in a case with a patient-customized helmet fabricated using a 3D printer (3D Printing_Bolus); treatment plans for each of the 3 cases were compared. When wax bolus was used to fabricate a bolus, a drier was used to apply heat to the bolus to make the helmet. $3-matic^{(R)}$ (Materialise) was used for modeling and polyamide 12 (PA-12) was used as a material, 3D Printing bolus was fabricated using a HP JET Fusion 3D 4200. The average Hounsfield Unit (HU) for the Wax_Bolus was -100, and that of the 3D Printing_Bolus was -10. The average radiation doses to the normal brain with the Non_Bolus, Wax_Bolus, and 3D Printing_Bolus methods were 36.3%, 40.2%, and 36.9%, and the minimum radiation dose were 0.9%, 1.6%, 1.4%, respectively. The organs at risk dose were not significantly difference. However, the 95% radiation doses into the planning target volume (PTV) were 61.85%, 94.53%, and 97.82%, and the minimum doses were 0%, 77.1%, and 82.8%, respectively. The technique used to fabricate patient-customized helmets with a 3D printer for radiation therapy of malignant scalp tumors is highly useful, and is expected to accurately deliver doses by reducing the air gap between the patient and bolus.

• The Korean Journal of Pesticide Science
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• v.11 no.4
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• pp.289-298
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• 2007

In order to set ADIs for pesticides registered for use in Korea, an analysis of guidelines on setting ADIs and ADIs established by international bodies and advanced countries was conducted General guidelines on the derivation ADIs are very similar among regulatory authorities. However, there were large differences in the ADIs' setting status and ADI values set for some individual pesticides. ADIs were established for 213 pesticides in UN, 332 in USA, 230 in Japan, 219 in UK and 435 in EU and Australia. Of the established ADIs in other countries, 87 to 252 pesticides were the pesticides registered in Korea depending countries. The number of lowest ADIs depending countries was 32 in USA, 23 in Japan, 6 in EU and Australia. The key target organs and endpoints used for setting ADIs were in the order of enzyme inhibition, body weight change and adverse effect on liver. The number of ADIs used for setting MRLs in Korea was high in the order of JMPR, Japan and USA. ADIs of EU and JMPR had highest similarity among bodies investigated. By referring to the guidances investigated at this study, guideline for setting ADI and ADIs for 64 pesticides registered in Korea were proposed.

• Journal of Biomedical Engineering Research
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• v.38 no.2
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• pp.62-73
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• 2017

To identify a solution for the restricted availability of healthy lungs and the high risk of immune rejections following organ transplantation, tissue engineering techniques for culturing lungs have been studied by many research groups. The most promising method for culturing lungs is the utilization of a bio-scaffold that was prepared using harvested organs from human donors or other animals by removing their original cells. In this study, a pulsatile perfusion pump was used to alleviate the cell removal effect with the high fluid-dynamic power of the perfusion stream during the decellularization process, while other conventional studies focused on chemical methods to identify efficient detergents. The purpose of this study was to analyze the developed device by using energy equivalent pressure (EEP), which is an indicator of pulsatility, to understand the characteristics of pulsatile energy transmitted according to the load size by using the artificial model and compare it with the measured EEP. The pulsatility of the device can be estimated with the concept of fluid-dynamic energy during a particular constant time period or fluid-dynamic power represented as EEP and EEP increment. Because the measured EEP of perfusion flow during decellularization can be changed by the amount of fluid leakage and the degree of clogging in the capillary vessels, EEP should be measured to determine whether the decellularization is progressing without problems. The decrement of EEP caused by the high perfusion resistance was observed from some experimental results that were obtained with artificial models. EEP can be used to monitor the decellularization process after analyzing the varying EEP according to the amount of load. It was confirmed that the EEP was maintained at a high level in the experiment using the harvested lungs from 12-13-week-old rats. In addition, it was confirmed that the cell removal time was faster than when continuous perfusion was performed. In this study, pulsatile power delivered to the lungs was measured to monitor the process of cell removal, and it serve as the evidence for efficient decellularization.

• Radiation Oncology Journal
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• v.31 no.4
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• pp.252-259
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• 2013

Purpose: To report the results of dosimetric comparison between intensity-modulated radiotherapy (IMRT) using Tomotherapy and four-box field conformal radiotherapy (CRT) for pelvic irradiation of locally advanced rectal cancer. Materials and Methods: Twelve patients with locally advanced rectal cancer who received a short course preoperative chemoradiotherapy (25 Gy in 5 fractions) on the pelvis using Tomotherapy, between July 2010 and December 2010, were selected. Using their simulation computed tomography scans, Tomotherapy and four-box field CRT plans with the same dose schedule were evaluated, and dosimetric parameters of the two plans were compared. For the comparison of target coverage, we analyzed the mean dose, $V_{nGy}$, $D_{min}$, $D_{max}$, radical dose homogeneity index (rDHI), and radiation conformity index (RCI). For the comparison of organs at risk (OAR), we analyzed the mean dose. Results: Tomotherapy showed a significantly higher mean target dose than four-box field CRT (p = 0.001). But, $V_{26.25Gy}$ and $V_{27.5Gy}$ were not significantly different between the two modalities. Tomotherapy showed higher $D_{max}$ and lower $D_{min}$. The Tomotherapy plan had a lower rDHI than four-box field CRT (p = 0.000). Tomotherapy showed better RCI than four-box field CRT (p = 0.007). For OAR, the mean irradiated dose was significantly lower in Tomotherapy than four-box field CRT. Conclusion: In locally advanced rectal cancer, Tomotherapy delivers a higher conformal radiation dose to the target and reduces the irradiated dose to OAR than four-box field CRT.