• Tuberculosis and Respiratory Diseases
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• v.59 no.1
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• pp.39-46
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• 2005

Background : Even though it has been suggested that low-colony, scotochromogen nontuberculous mycobacteria (NTM) are usually contaminants and not true pathogens, evidence for this hypothesis has not been provided. This study investigated the colony characteristics, organism identification, and clinical significance of low-colony scotochromogen. Methods : The laboratory cultured 6,898 respiratory clinical specimens for an examination of mycobacteria over a three-month period. A low-colony count was arbitrarily defined as ${\leq}20$ colonies. This study analyzed the recovery rate of the mycobacteria, the number of colonies and their gross characteristics, and their clinical significance. PCR-restriction fragment length polymorphism analysis was carried out to identify the NTM species. NTM pulmonary disease was defined according to the American Thoracic Society. Results : A total of 6,898 respiratory specimens for mycobacterium were cultured. Of these, 263 (3.8%) grew NTM, and 382 (5.5%) grew M. tuberculosis. Of the 263 cultured NTM specimens, 124 (47.1%) were scotochromogens. The smear-positive rate was significantly lower in these scotochromogens (4.8%) than in the non-scotochromogens (23.7%) (p<0.05). The most common isolates were M. gordonae (83/102, 81.4%) in the scotochromogens, and MAC (52/121, 43.0%) in the non-scotochromogens. Even though three out of 113 patients with a low-colony scotochromogen has been diagnosed with NTM pulmonary disease, the isolated scotochromogen was not considered to be the cause of the NTM disease but was just a contaminant. Conclusion : In this study, the most common isolate of a low-colony count scotochromogen was M. gordonae, which appeared to be contaminants and not true pathogens. Greater efforts in the quality control of a mycobacterium laboratory are needed in cases where there is a high recovery rate of low-colony count scotochromogen.

• Korean Journal of Environmental Agriculture
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• v.27 no.2
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• pp.120-132
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• 2008

Remotely sensed images from a satellite can be applied for detecting and quantifying spatial and temporal variations in terms of landuse & landcover, crop growth, and disaster for agricultural applications. The purposes of this study were to analyze topography using DEM(digital elevation model) and classify landuse & landcover into 10 classes-paddy field, dry field, forest, bare land, grass & bush, water body, reclaimed land, salt farm, residence & building, and others-using Landsat TM images in North Korea. Elevation was greater than 1,000 meters in the eastern part of North Korea around Ranggang-do where Kaemagowon was located. Pyeongnam and Hwangnam in the western part of North Korea were low in elevation. Topography of North Korea showed typical 'east-high and west-low' landform characteristics. Landcover classification of North Korea using spectral reflectance of multi-temporal Landsat TM images was performed and the statistics of each landcover by administrative district, slope, and agroclimatic zone were calculated in terms of area. Forest areas accounted for 69.6 percent of the whole area while the areas of dry fields and paddy fields were 15.7 percent and 4.2 percent, respectively. Bare land and water body occupied 6.6 percent and 1.6 percent, respectively. Residence & building reached less than 1 percent of the country. Paddy field areas concentrated in the A slope ranged from 0 to 2 percent(greater than 80 percent). The dry field areas were shown in the A slope the most, followed by D, E, C, B, and F slopes. According to the statistics by agroclimatic zone, paddy and dry fields were mainly distributed in the North plain region(N-6) and North western coastal region(N-7). Forest areas were evenly distributed all over the agroclimatic regions. Periodic landcover analysis of North Korea based on remote sensing technique using satellite imagery can produce spatial and temporal statistics information for future landuse management and planning of North Korea.

• Radiation Oncology Journal
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• v.24 no.4
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• pp.294-299
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• 2006

$\underline{Purpose}$: Using cone beam CT, we can compare the position of the patients at the simulation and the treatment. In on-line image guided radiation therapy, one can utilize this compared data and correct the patient position before treatments. Using cone beam CT, we investigated the errors induced by setting up the patients when use only the markings on the patients' skin. $\underline{Materials\;and\;Methods}$: We obtained the data of three patients that received radiation therapy at the Department of Radiation Oncology in Chung-Ang University during August 2006 and October 2006. Just as normal radiation therapy, patients were aligned on the treatment couch after the simulation and treatment planning. Patients were aligned with lasers according to the marking on the skin that were marked at the simulation time and then cone beam CTs were obtained. Cone beam CTs were fused and compared with simulation CTs and the displacement vectors were calculated. Treatment couches were adjusted according to the displacement vector before treatments. After the treatment, positions were verified with kV X-ray (OBI system). $\underline{Results}$: In the case of head and neck patients, the average sizes of the setup error vectors, given by the cone beam CT, were 0.19 cm for the patient A and 0.18 cm for the patient B. The standard deviations were 0.15 cm and 0.21 cm, each. On the other hand, in the case of the pelvis patient, the average and the standard deviation were 0.37 cm and 0.1 cm. $\underline{Conclusion}$: Through the on-line IGRT using cone beam CT, we could correct the setup errors that could occur in the conventional radiotherapy. The importance of the on-line IGRT should be emphasized in the case of 3D conformal therapy and intensity-modulated radiotherapy, which have complex target shapes and steep dose gradients.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.4
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• pp.294-300
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• 2010

Purpose: The template-guided implant surgery offers several advantages over the traditional approach. The purpose of this study was to evaluate the accuracy of coordinate synchronization procedure with 5-axis milling machine for surgical template fabrication by means of reverse engineering through universal CAD software. Materials and methods: The study was performed on ten edentulous models with imbedded gutta percha stoppings which were hidden under silicon gingival form. The platform for synchordination was formed on the bottom side of models and these casts were imaged in Cone beam CT. Vectors of stoppings were extracted and transferred to those of planned implant on virtual planning software. Depth of milling process was set to the level of one half of stoppings and the coordinate of the data was synchronized to the model image. Synchronization of milling coordinate was done by the conversion process for the platform for the synchordination located on the bottom of the model. The models were fixed on the synchordination plate of 5-axis milling machine and drilling was done as the planned vector and depth based on the synchronized data with twist drill of the same diameter as GP stopping. For the 3D rendering and image merging, the impression tray was set on the conbeam CT and pre- and post- CT acquiring was done with the model fixed on the impression body. The accuracy analysis was done with Solidworks (Dassault systems, Concord, USA) by measuring vector of stopping’s top and bottom centers of experimental model through merging and reverse engineering the planned and post-drilling CT image. Correlations among the parameters were tested by means of Pearson correlation coefficient and calculated with SPSS (release 14.0, SPSS Inc. Chicago, USA) ($\alpha$ = 0.05). Results: Due to the declination, GP remnant on upper half of stoppings was observed for every drilled bores. The deviation between planned image and drilled bore that was reverse engineered was 0.31 (0.15 - 0.42) mm at the entrance, 0.36 (0.24 - 0.51) mm at the apex, and angular deviation was 1.62 (0.54 - 2.27)$^{\circ}$. There was positive correlation between the deviation at the entrance and that at the apex (Pearson Correlation Coefficient = 0.904, P = .013). Conclusion: The coordinate synchronization 5-axis milling procedure has adequate accuracy for the production of the guided surgical template.

• Progress in Medical Physics
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• v.22 no.4
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• pp.190-197
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• 2011

Currently, the dose distribution calculation used by commercial treatment planning systems (TPSs) for high-dose rate (HDR) brachytherapy is derived from point and line source approximation method recommended by AAPM Task Group 43 (TG-43). However, the study of Monte Carlo (MC) simulation is required in order to assess the accuracy of dose calculation around three-dimensional Ir-192 source. In this study, geometry factor was calculated using segmented sources integration method by dividing microSelectron HDR Ir-192 source into smaller parts. The Monte Carlo code (MCNPX 2.5.0) was used to calculate the dose rate $\dot{D}(r,\theta)$ at a point ($r,\theta$) away from a HDR Ir-192 source in spherical water phantom with 30 cm diameter. Finally, anisotropy function and radial dose function were calculated from obtained results. The obtained geometry factor was compared with that calculated from line source approximation. Similarly, obtained anisotropy function and radial dose function were compared with those derived from MCPT results by Williamson. The geometry factor calculated from segmented sources integration method and line source approximation was within 0.2% for $r{\geq}0.5$ cm and 1.33% for r=0.1 cm, respectively. The relative-root mean square error (R-RMSE) of anisotropy function obtained by this study and Williamson was 2.33% for r=0.25 cm and within 1% for r>0.5 cm, respectively. The R-RMSE of radial dose function was 0.46% at radial distance from 0.1 to 14.0 cm. The geometry factor acquired from segmented sources integration method and line source approximation was in good agreement for $r{\geq}0.1$ cm. However, application of segmented sources integration method seems to be valid, since this method using three-dimensional Ir-192 source provides more realistic geometry factor. The anisotropy function and radial dose function estimated from MCNPX in this study and MCPT by Williamson are in good agreement within uncertainty of Monte Carlo codes except at radial distance of r=0.25 cm. It is expected that Monte Carlo code used in this study could be applied to other sources utilized for brachytherapy.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.272-278
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• 2013

To evaluate the effect of surface contaminated with Escherichia coli O157:H7 (E. coli O157:H7) on the microbiological safety of lettuce, this study was conducted to investigate the attachment, biofilm producing, survival, and cross-contamination of E. coli O157:H7 on stainless steel and polyvinyl chloride (PVC). The attachment rate of E. coli O157:H7 on PVC was 10 times higher than that on stainless steel after exposure 1 h in cell suspension. However, there was not a difference between two types of surface after exposure for 6 h and 24h. The biofilm producing of E. coli O157:H7 was TSB > 10% lettuce extracts > 1% lettuce extracts > phosphate buffer. When two kinds of materials were stored at various conditions ($20^{\circ}C$ and $30^{\circ}C$, relative humidity (RH) 43%, 69%, and 100%), the numbers of E. coli O157:H7 at $30^{\circ}C$, RH 43% or RH 69% were reduced by 5.0 log CFU/coupon within 12 h regardless of material type. Conversely, the survival of E. coli O157:H7 at RH 100% was lasted more than 5 days. In addition, the reduction rate of E. coli O157:H7 was decreased in the presence of organic matter. The transfer efficiency of E. coli O157:H7 from the contaminated surface to lettuce was dependent upon the water amount of the surface of lettuce. Especially, the transfer rate of E. coli O157:H7 was increased by 10 times in the presence of water on the lettuce surface. From this study, the retention of E. coli O157:H7 on produce contact surfaces increase the risk cross-contamination of this pathogen to produce. Thus, it is important that the surface in post harvest facility is properly washed and sanitized after working for prevention of cross-contamination from surface.

• Korean journal of applied entomology
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• v.49 no.3
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• pp.219-226
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• 2010

This paper presents the occurrence and damage characteristics of the rice leaf-folder populations in the paddy fields of Dangsu-dong, Suwon from 2004 to 2007, and also reports the insecticide response of rice leaf-folder populations, which were collected from 2005 to 2006 in Korea and Vietnam. Laboratory measurements of the head capsule width and body length data enabled the identification of the rice leaf-folder larva stages collected in the field. The rice leaf-folder population in Suwon from 2004 to 2007 has a clear pattern consisting of two different group: the low and high density years. During the low density years (2004 and 2006), only one adult peak was noted in late August, with the damaged-hill percent less than 10% in late July, and the damaged-leaf percent around 2% in September. In contrast, during the high density years (2005 and 2007), two adult peaks were noted in early August and mid-September, with the damaged-hill percent was around 30% in late July, and the damaged-leaf percent 15 to 30% in September, which was beyond the economic injury level of rice leaf-folder. High correlations existed between the occurrence of rice leaf-folder in late July and early August and damages to rice during September. Based on these results, we suggest that the information on the rice leaf-folder population monitored by the adult density or damaged-hill percent in late July and early August would be very useful for predicting the damages later in the season for aiding in decision-making for timely control. In addition, the regional populations of rice leaf-folder showed the similar responses to the insecticides tested: high susceptibility to IGRs (tebufenozide and methoxyfenozide) and organophosphates (chlorpyrifos-methyl, pyridaphenthion), but relatively low to cartap.

• Progress in Medical Physics
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• v.22 no.3
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• pp.107-116
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• 2011

Respiratory gated radiation therapy and stereotactic body radiation therapy require identical tumor motions during each treatment with the motion detected in treatment planning CT. Therefore, this study developed a tumor motion monitoring and analysis system during the treatments employing RPM data, gated setup OBI images and a data analysis software. A respiratory training and guiding program which improves the regularity of breathing was used to patients. The breathing signal was obtained by RPM and the recorded data in the 4D console was read after treatment. The setup OBI images obtained gated at 0% and 50% of breathing phases were used to detect the tumor motion range in crenio-caudal direction. By matching the RPM data recorded at the OBI imaging time, a factor which converts the RPM motion to the tumor motion was computed. RPM data was entered to the institute developed data analysis software and the maximum, minimum, average of the breathing motion as well as the standard deviation of motion amplitude and period was computed. The computed result is exported in an excel file. The conversion factor was applied to the analyzed data to estimate the tumor motion. The accuracy of the developed method was tested by using a moving phantom, and the efficacy was evaluated for 10 stereotactic body radiation therapy patients. For the sine wave motion of the phantom with 4 sec of period and 2 cm of peak-to-peak amplitude, the measurement was slightly larger (4.052 sec) and the amplitude was smaller (1.952 cm). For patient treatment, one patient was evaluated not to qualified to SBRT due to the usability of the breathing, and in one patient case, the treatment was changed to respiratory gated treatment due the larger motion range of the tumor than treatment planed motion. The developed method and data analysis program was useful to estimate the tumor motion during treatment.

• Progress in Medical Physics
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• v.16 no.1
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• pp.24-31
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• 2005

The stereotactic radiosurgery (SRS) describes a method of delivering a high dose of radiation to a small tar-get volume in the brain, generally in a single fraction, while the dose delivered to the surrounding normal tissue should be minimized. To perform automatic plan of the SRS, a new method of multi-isocenter/shot linear accelerator (linac) and gamma knife (GK) radiosurgery treatment plan was developed, based on a physical lattice structure in target. The optimal radiosurgical plan had been constructed by many beam parameters in a linear accelerator or gamma knife-based radiation therapy. In this work, an isocenter/shot was modeled as a sphere, which is equal to the circular collimator/helmet hole size because the dimension of the 50% isodose level in the dose profile is similar to its size. In a computer-aided system, it accomplished first an automatic arrangement of multi-isocenter/shot considering two parameters such as positions and collimator/helmet sizes for each isocenter/shot. Simultaneously, an irregularly shaped target was approximated by cubic structures through computation of voxel units. The treatment planning method by the technique was evaluated as a dose distribution by dose volume histograms, dose conformity, and dose homogeneity to targets. For irregularly shaped targets, the new method performed optimal multi-isocenter packing, and it only took a few seconds in a computer-aided system. The targets were included in a more than 50% isodose curve. The dose conformity was ordinarily acceptable levels and the dose homogeneity was always less than 2.0, satisfying for various targets referred to Radiation Therapy Oncology Group (RTOG) SRS criteria. In conclusion, this approach by physical lattice structure could be a useful radiosurgical plan without restrictions in the various tumor shapes and the different modality techniques such as linac and GK for SRS.

• Radiation Oncology Journal
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• v.14 no.1
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• pp.77-85
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• 1996

Purpose : Multileaf collimator(MLC) is very suitable tool for conformal radio-therapy and commissioning measurements for a multileaf collimator installed on a dual energy accelerator with 6 and 10MV photons are required, For modeling the collimator with treament planning software, detailed dosimetric characterization of the multileaf collimator including the penumbra width, leaf transmission between leaf leakage and localization of the leaf ends and sides is an essential requirement. materials and Methods : Measurement of characteristic data of the MLC with 26 pair block leaves installed on CLINAC 2100C linear accelerator was performed. Low sensitive radiographic film(X-omatV) was used for the penumbra measurement and separate experiments using radiographic film and thermoluminescent dosimeters were performed to verify the dose distribution, Measured films were analized with a photodensitometer of WP700i scanner. Results : For 6 & 10 MV x-ray energies, approximately $2.0\%$ of photons incident on the multileaf collimator were transmitted and an additional $0.5\%$ leakage occurs between the leaves. Localizing the physical end of the leaves showed less than 1mm deviation from the $50\%$ decrement line and this difference is attributed to the curved shaped end on the leaves One side of a sin히e leaf corresponded to the $50\%$ decrement line, but the opposite face was aligned with a lower value. This difference is due to the tongue and groove used to decrease between leaf leakage. Alignment of the leaves to form a straight edge resulted larger penumbra at far position from isocenter as compare with divergent alloy blocks. When the MLC edge is stepped by sloping field, the isodose lines follow the leaf pattern and Produce scalloping isodose curves in tissue. The effective penumbra by 45 degree stepped MLC is about 10mm at 10cm depth for 6MV x-ray. The difference of effective penumbra in deep tissue between MLC and divergent alloy blocks is small (5mm). Conclusion : Using the characteristic data of MLC, the MLC has the clinlical acceptability and suitability for 3-D conformal radiotherapy except small field size.