• Progress in Medical Physics
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• v.9 no.2
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• pp.65-71
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• 1998

The aims are to evaluate the effects of an 1.0 cm acrylic plate and SSD on the dose profile and depth dose distribution of 9 MeV electron beam and to analyse adequacy for using an acrylic plate to reduce energy of electron beams. An acrylic plate of 1.0 cm thickness was used to reduce energy of 9 MeV electron beam to 7 MeV. The plate was put on an electron applicator at 65.4 cm distance from x-ray target. The size of the applicator was 10${\times}$l0cm at 100 cm SSD. For 100cm, l05cm and 110cm SSD, depth dose on beam axis and dose profiles at d$\_$max/ on two principal axes were measured using a 3D water phantom. From depth dose distributions, d$\_$max/, d$\_$85/, d$\_$50/ and R$\_$p/, surface dose, and mean energy and peak energy at surface were compared. From dose profiles flatness, penumbra width and actual field size were compared. For comparison, 9 MeV electron beams were measured. Surface dose of 7 MeV electron beams was changed from 85.5% to 82.2% increasing SSD from 100 cm to 110 cm, and except for dose buildup region, depth dose distributions were independent of SSD. Flatness of 7 MeV ranged from 4.7% to 10.4% increasing SSD, comparing 1.4% to 3.5% for 9 MeV. Penumbra width of 7 MeV ranged from 1.52 cm to 3.03 cm, comparing 1.14 cm to 1.63 cm for 9 MeV. Actual field size increased from 10.75 cm to 12.85 cm with SSD, comparing 10.32 cm to 11.46 cm for 9 MeV. Virtual SSD's of 7 and 9 MeV were respectively 49.8 cm and 88.5cm. In using energy reducer in electron therapy, depth dose distribution were independent of SSD except for buildup region as well as open field. In case of using energy reducer, increasing SSD made flatness to deteriorate more severely, penumbra width more wide, field size to increase more rapidly and virtual SSD more short comparing with original electron beam. In conclusion, it is desirable to use no energy reducer for electron beam, especially for long SSD.

• Progress in Medical Physics
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• v.17 no.1
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• pp.47-53
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• 2006

The accuracy of the dosimetry in the Cyberknife system is accomplishing important role from all processes of the stereotactic radiosurgery. In this study, we estimated relative output factors for Cyberknife. All measurements were peformed by six different detectors: diode detector, X-Omat V film, Gafchromic EBT film, 0.015 cc, 0.125 cc and 0.6 cc ionization chamber The diode detector and three ionization chambers peformed using water phantom at 80 cm SSD and 1.5 cm depth. When the film measurements were peformed, the water phantom was replaced with a solidwater phantom. Each collimator normalized with respect to the output factor of the largest collimator (60 mm). For the collimators over than 30 mm, the output factors from the different detectors showed a good agreement within 0.5% except 0.6 cc ion chamber For the collimators less than 15 mm, there were substantial differences In the output factors among different detectors. That is, the value of output factor for the 5 mm collimator of a diode and Gafchromic film was each $0.656{\pm}0.009$ and $0.777{\pm}0.013$. In the ion chamber and diode detector, those difference were due to the presence of large dose gradients and lack of electronic equilibrium in narrow megavoltage x-ray beams Therefore, the Gafchromic EBT film were considered more accurate than the others detectors.

• Progress in Medical Physics
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• v.26 no.2
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• pp.93-98
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• 2015

The purpose of this study is to see the usefulness of lead apron for critical organs near the breast under examining. For clinical experiment, 30 female volunteers who agreed to their participation in the experiments, were chosen and divided into two groups, 15 in group A and 15 in group B respectively. group A is to see whether each side of breast under mammography affects to other side glandular on the critical organs is same, because it is not allowed to scan the both breast for same person or to scan repeatedly. Group B is to see the effectiveness of lead apron during the mammography of right breast. Glass dosimeters were placed on the thyroid, the contralateral breast, and lower abdomen where near the breast during examining. The average glandular doses on the surface in mammography of the thyroid gland, the contralateral breast, the lower abdomen were 0.0692 mGy, 0.6790 mGy, and 0.0122 mGy, respectively, which was an extremely low level of glandular dose. In group B, as to the thyroid gland, average dose was decreased from 0.0922 mGy to 0.0158 mGy. The average dose of contralateral breast was decreased from 0.8575 mGy to 0.0286 mGy. The average doses of lower abdomen was decrease 0.0150 mGy to 0.0173 mGy. As to the lower abdomen, dose decreased from 0.0150 mGy before the use of an apron down to 0.0173 mGy after the use. As p-value was under 0.05, statistically significant difference was observed between the two groups. Wearing an apron can have the protective effects on the thyroid gland up to 20 times lower than not wearing one. Besides, it is also necessary to protect the other breast during the examination by wearing one.

• Progress in Medical Physics
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• v.24 no.4
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• pp.237-242
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• 2013

In the intracranial regions, an accurate delineation of the target volume has been difficult with only the CT data due to poor soft tissue contrast of CT images. Therefore, the magnetic resonance images (MRI) for the delineation of the target volumes were widely used. To calculate dose distributions with MRI-based RTP, the electron density (ED) mapping concept from the diagnostic CT images and the pseudo CT concept from the MRI were introduced. In this study, the look up table (LUT) from the fifteen patients' diagnostic brain MRI images was created to verify the feasibility of MRI-based RTP. The dose distributions from the MRI-based calculations were compared to the original CT-based calculation. One MRI set has ED information from LUT (lMRI). Another set was generated with voxel values assigned with a homogeneous density of water (wMRI). A simple plan with a single anterior 6MV one portal was applied to the CT, lMRI, and wMRI. Depending on the patient's target geometry for the 3D conformal plan, 6MV photon beams and from two to five gantry portals were used. The differences of the dose distribution and DVH between the lMRI based and CT-based plan were smaller than the wMRI-based plan. The dose difference of wMRI vs. lMRI was measured as 91 cGy vs. 57 cGy at maximum dose, 74 cGt vs. 42 cGy at mean dose, and 94 cGy vs. 53 at minimum dose. The differences of maximum dose, minimum dose, and mean dose of the wMRI-based plan were lower than the lMRI-based plan, because the air cavity was not calculated in the wMRI-based plan. These results prove the feasibility of the lMRI-based planning for brain tumor radiation therapy.

• Journal of agricultural medicine and community health
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• v.29 no.2
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• pp.265-285
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• 2004

Objectives: The acute toxic effects of pesticide are well known. Concern has also been expressed that long-term exposure may result in damage to the central nervous system. This study was conducted to test the hypothesis that central nervous system symptoms might occur due to pesticide exposure. Methods: In a cross-sectional study, first, cumulative exposure index (CEI) was estimated. Neurologic symptoms (Q-16 questionnaire) for 541 farmers (exposed to pesticides) were compared with 119 non-exposed persons in spraying season nine rural areas in Korea. Results: The pesticides poisoning rates for last 3 months were 67.2% for orchard farmers, 55.3%for dry field farmers, and 20.5% for husbandry farmers, respectively, showing significant difference (p<0.001). Compared with non-exposure group, exposure groups (especially, orchard farmers) reported significantly more neurologic symptoms and had a higher overall neurological symptoms score (p<0.001). Factors related to the positive neurological symptoms (answers "yes" to six or more of Q-16 questionnaire) adjusted for age, sex, education level, smoking and alcohol drinking were type of farming (OR 3.08, 95% CI 1.50-6.30 in orchard farmers vs non-exposure group), CEI (OR 2.75, 95% CI 1.12-6.78 in Q3 vs Q1), past poisoning (OR 1.97, 95% CI 1.21-3.20 vs normal), current mild poisoning (OR 3.03, 9500 CI 1.47-6.22 vs normal) and current moderate poisoning (OR 6.34, 95% CI 3.03-13.25 vs normal), respectively. Conclusions: These results suggest that long-term exposure to pesticides appears to be associated with subtle changes in the central nervous system.

• Tuberculosis and Respiratory Diseases
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• v.58 no.4
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• pp.344-351
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• 2005

Background : Both gemcitabine and vinorelbine are effective anticancer drugs with mild toxicity on non-small cell lung cancer, and monotherapy of these drugs are effective as a second-line chemotherapy. The aim of this trial was to assess the response and toxicity of a combination of gemcitabine and vinorelbine in patients of previously treated for non-small cell lung cancer. Materials and Methods : 24 patients, initial stage III A/B,IV and previously treated with platinium and taxane based regimens, were enrolled from June 2000 to March 2004. The regimens consisted of vinorelbine $25mg/m^2$ followed by an infusion of gemcitabine $1000mg/m^2$ on day 1 and day 8 every three weeks. This course was repeated more than twice. Results : Twenty-four patients were analyzed for the response, survival rate, and toxicities. The overall response was 17% with a complete remission rate of 4%. The median time-to progression (TTP) was 3.1 months (95%, CI 1-10months), and the survival time was 8.2 months (95%, CI 1-23 months). The grade 3/4 toxicities encountered were neutropenia (12.5%), anemia (0%), thrombocytopenia (0%). Non-hematological 3/4 toxicities were not observed. Conclusion : A combination of gemcitabine and vinorelbine in patients previously treated for non-small cell lung cancer provides a relatively good response rate, and a low toxicity profile. However, further study will be needed to confirm its effectiveness.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.175-184
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• 2008

Purpose: This study was designed to investigate the fitness of adjustable dental impression trays on the Chinese and the Japanese. Material and methods: Initial design of the adjustable dental trays was developed from the results of the dental arch size of Korean adults. This design was applied to the CAD-CAM process in order to create tray model samples. Simple silicon-base molds were then replicated based on these sample models. Polyurethane injection into the silicon- base molds completed the process of creating a large number of test products. 60 Chinese dental students (male:30, female:30) from the Shanghai Second Medical University and 60 Japanese alumni from the Kumamoto high school (male:30, female:30) were selected for taking irreversible hydrocolloid impression with these trays. The width and length of the impression body were measured on several measuring points by Vernier caliper. The results were analyzed statistically to evaluate the fitness of the trays. Results: 1. Uniform impression material thickness was achieved on the Chinese and Japanese by controlling the width of the tray using stops and beveled guides. The material thickness was generally within the range of 3 mm to 6 mm. 2. In the maxillary tray of the Chinese, average thickness of the impression material of the labial vestibule of the incisal teeth was 6.2 mm, the canine was 5.9 mm and the midpalatal part 10.5 mm and the posterior palatal part 9.7 mm. These were relatively large values. 3. In the mandibular tray of the Chinese, average length of the impression material of the lingual vestibule of first, second premolar contact point was 8.9 mm, the incisal teeth was 7.8 mm and thickness of the labial part of canine was 6.8 mm and premolars 7.0 mm. These were relatively large values. 4. In the maxillary tray of the Japanese, average thickness of the impression material of the labial vestibule of the incisal teeth was 7.4 mm, the canine was 7.7 mm and the midpalatal part 9.1 mm. These were relatively large values. 5. In the mandibular tray of the Japanese, average thickness of the impression material of the labial vestibule of first, second premolar contact point was 8.4 mm, and thickness of the labial part of canine was 7.4 mm. These were relatively large values. Conclusion: This adjustable dental tray shows good accuracy to Korean because it was designed by the analysis of the dental arch size of Korean adult model. With this result, it can be applied to Chinese and Japanese, we can take more easy and accurate dental impressions.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.721-728
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• 2004

Velopharyngeal closure is a sphincter mechanism between the activities of the soft palate, lateral pharyngeal wall and the posterior pharyngeal wall, which divides the oral and nasal cavity. It participates in physiological activities such as swallowing, breathing and speech. It is called a velopharyngeal dysfunction when this mechanism malfunctions. The causes of this dysfunction are defects in (1) length, function, posture of the soft palate, (2) depth and width of the nasopharynx and (3) activity of the posterior and lateral pharyngeal wall. The purposes of this study are to analyze the nasopharynx of cleft palate patients using cephalometry and to evaluate the degree of hypernasality using nasometry to find its relationship with velopharyngeal dysfunction. The following results were obtained : 1. In cephalometry, there were significant differences in soft palate length, soft palate thickness, nasopharyngeal depth, nasopharyngeal area, and adequate ratio between two groups. 2. In nasometry, there were significant differences between two groups in vowel /o/ and sentences including oral consonants. 3. In cleft palate patients, though no general correlation was found between Anatomic VPI and nasalance scores, vowel /i/ and sentences including oral consonants were slightly correlated. In conclusion, cephalometry and nasometer results were significantly different between the two groups. Though in the cleft palate group, Anatomic VPI and nasalance scores, which are indices for velopharyngeal closure, excluding the vowel /i/ and sentences including oral consonants show generally no significance.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.636-644
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• 2004

Recently, self-etching adhesive system have been developed and bonding procedures simplified into one or two steps, which are simultaneously applied to both enamel and dentin. These systems are easy to use and have the potential for good clinical success. The purpose of this study is to evaluate in vitro the microleakage on the cementum/dentin and enamel walls in composite resin restoration of Class V cavities, regarding the use of different adhesive systems. 30 human premolars were divided into 3 groups. A standardized Class V preparation was prepared on the buccal and lingual surface of each premolar. The preparation were made parallel to the cementoenamel junctions, with the gingival half of the preparation extending 1mm apical to the cementoenamel junction. After adhesive system was applied to teeth as manufacture's recommendation, hybrid resin composite was filled in bulk into the preparation and light polymerized according to manufacturer's recommendations. Specimen were stored in distilled water at $37^{\circ}C$ for 5 days and thermocycled 1000 times ($5^{\circ}C{\pm}2^{\circ}C\;and\;55^{\circ}C{\pm}2^{\circ}C)$, then immersed in a 2% methylene blue solution for 12 hours. After sectioning mesio distally through the restorations, the degree of dye penetration was scored under a stereomicroscope at ${\times}\;25$ magnification. The data were analyzed statistically using t-test and one-way ANOVA. The results were as follows: ${\cdot}$ There is no adhesive system which can prevent microleakage perfectly. ${\cdot}$ There is significant difference in microleakage between enamel margin and dentin margin (p<0.0001). ${\cdot}$ In enamel margin, self-etching primer systems did not show any significant difference comparing total-etching system. In denin margin, self-etching primer systems did not show any significant difference comparing one-bottle adhesive system used in combination with total-etching.

• Food Science and Preservation
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• v.16 no.5
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• pp.605-611
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• 2009

Korean Baechu cabbage(known as Chinese cabbage) brined in 0%, 5% and 10% (all w/v) salt solutions were packed using high-density polyethylene film (HDPE-film), low-density polyethylene film (LDPE-film), or Mirafresh film (MF-film, US patent No. 5972815), and stored at 4C for 4 weeks. Changes in pH and salinity, and microorganism counts (lactic acid bacteria and total bacteria), were investigated. There was no significant difference in the pH change in cabbage stored using various films when the vegetables were not salted. However, the pH was most stable in Baechu cabbage prepared using 10% salt solution. Cabbage treated with 0%, 5%, and 10% salt showed salinity values of 0.83%, 1.17% and 1.62%(all w/w), respectively, after 4 weeks of storage by LDPE-film. When cabbage was treated with the highest concentration of salt solution, the count of lactic acid bacteria increased but that of total bacteria decreased. The pH from pH 6.10 to pH 4.32, pH 5.68, and pH 5.92 in brined cabbage packed in HDPE-film, LDPE-film, and MF-film, respectively, after 4 weeks. When MF-film was used, the pH showed the greatest stability of all films tested, regardless of the concentration of salt solution employed in brining. The counts of lactic acid bacteria and total bacteria increased by all tested films during storage. Cabbage packed by MF-film showed the lowest increase in bacterial counts. In conclusion, MF-film was found to be the most effective packaging material for Baechu cabbage and brining in 10% salt solution was optimal to enhance the shelf life of the vegetable. LDPE-film was more effective than was HDPE-film for storage of brined cabbage.