• Polymer(Korea)
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• v.35 no.2
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• pp.161-165
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• 2011

This study is related to the preparation of biocompatible gold nanoparticles (AuNPs) which are stable in aqueous solutions for a long time. Ultrasmall polyethyleneimine (PEI)-capped AuNPs (PEI-AuNPs) with limited agglomeration were prepared in aqueous solutions at room temperature, which were based on the roles of PEI as a reductant and a stabilizer. PEI-AuNPs with an average size of 8~12 nm formed highly stable nanocolloids with an average hydrodynamic cluster size of around 50 nm in aqueous media. At a low concentration of metal precursor hydrogen tetrachloroaurate (III), the particle size was reduced noticeably. The typical peaks of gold were observed in the X-ray diffraction pattern of AuNPs. The cell viability of 98% was obtained in the case of PEI-AuNPs, while PEI was cytotoxic. The PEI-AuNP is considered to be a potential candidate as a contrast agent for computed tomography.

• Clinical and Experimental Pediatrics
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• v.45 no.3
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• pp.339-345
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• 2002

Purpose : The purpose of this study was to evaluate the clinical usefulness of chest high-resolution computed tomography(HRCT) in patients with chronic coughs or persistent wheezing with normal chest X-ray finding. Methods : We reviewed the charts, chest X-rays, and HRCT findings of patients with chronic coughs or persistent wheezing of less than 2 years of age. The records were sourced from the Department of Pediatrics, Inha University Hospital covering the period from July, 1999 to June, 2000. Chronic cough was defined as a cough which was prolonged for more than 3 weeks. Results : The sample consisted of 24 patients(male 15 and female 9, mean age $4.7{\pm}3.8$ months old). Among them, 16 patients showed normal findings(66.7%) and 8 patients showed abnormal (33.3%) in simple chest X-rays. Among 16 patients who had the normal chest X-rays, 13 patients showed abnormal chest HRCT findings(81.3%) such as air space consolidation of the dependent portion(62.5%), bronchiolitis obliterans(12.5%), and bronchopulmonary dysplasia(6.3%). Conclusion : We suggest that the chest HRCT is a useful diagnostic tool in the evaluation of patients with chronic cough or persistent wheezing with normal chest X-ray, especially below 2 years of age.

• The Journal of Korean Society for Radiation Therapy
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• v.23 no.1
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• pp.31-39
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• 2011

Purpose: Helical Tomotherapy allows only coplanar beam delivery because it does not allow couch rotation. We investigated a method to introduce non-coplanar beam by tilting a patient's head for Tomotherapy. The aim of this study was to compare intrafractional movement during Tomotherapy between coplanar and non-coplanar patient's setup. Materials and Methods: Helical Tomotherapy was used for treating eight patients with intracranial tumor. The subjects were divided into three groups: one group (coplanar) of 2 patients who lay on S-plate with supine position and wore thermoplastic mask for immobilizing the head, second group (non-coplanar) of 3 patients who lay on S-plate with supine position and whose head was tilted with Variable Axis Baseplate and wore thermoplastic mask, and third group (non-coplanar plus mouthpiece) of 3 patients whose head was tilted and wore a mouthpiece immobilization device and thermoplastic mask. The patients were treated with Tomotherapy after treatment planning with Tomotherapy Planning System. Megavoltage computed tomography (MVCT) was performed before and after treatment, and the intrafractional error was measured with lateral(X), longitudinal(Y), vertical(Z) direction movements and vector ($\sqrt{x^2+y^2+z^2}$) value for assessing overall movement. Results: Intrafractional error was compared among three groups by taking the error of MVCT taken after the treatment. As the correction values (X, Y, Z) between MVCT image taken after treatment and CT-simulation image are close to zero, the patient movement is small. When the mean values of movement of each direction for non-coplanar setup were compared with coplanar setup group, X-axis movement was decreased by 13%, but Y-axis and Z-axis movement were increased by 109% and 88%, respectively. Movements of Y-axis and Z-axis with non-coplanar setup were relatively greater than that of X-axis since a tilted head tended to slip down. The mean of X-axis movement of the group who used a mouthpiece was greater by 9.4% than the group who did not use, but the mean of Y-axis movement was lower by at least 64%, and the mean of Z-axis was lower by at least 67%, and the mean of Z-axis was lower by at least 67%, and the vector was lower by at least 59% with the use of a mouthpiece. Among these 8 patients, one patient whose tumor was located on left frontal lobe and left basal ganglia received reduced radiation dose of 38% in right eye, 23% in left eye, 30% in optic chiasm, 27% in brain stem, and 8% in normal brain with non-coplanar method. Conclusion: Tomotherapy only allows coplanar delivery of IMRT treatment. To complement this shortcoming, Tomotherapy can be used with non-coplanar method by artificially tilting the patient's head and using an oral immobilization instrument to minimize the movement of patient, when intracranial tumor locates near critical organs or has to be treated with high dose radiation.

• Clean Technology
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• v.19 no.2
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• pp.105-112
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• 2013

In this study, polyaniline (PANI)-based $TiO_2$ (PANI-$TiO_2$) composites calcined at different temperatures were prepared and their applications for control of trichloroethylene (TCE) and tetrachloroethylene (TTCE) at indoor air levels were investigated. For these target compounds, the photocatalytic control efficiencies of PANI-$TiO_2$ composites did not exhibit any trend with varying calcination temperatures (CTs). Rather, the average control efficiencies of PANI-$TiO_2$ composites over 3-h photocatalytic process increased from 61 to 72% and from 21 to 39% for TCE and TTCE, respectively, as the CT increased from 350 to $450^{\circ}C$. However, for both the target compounds, the average control efficiencies of PANI-$TiO_2$ composites decreased gradually as the CT increased further to 550 and $650^{\circ}C$. These results were ascribed to contents of anatase crystal phase and specific surface area of different particle sizes in the PANI-$TiO_2$ composites, which were demonstrated by the X-ray diffraction and scanning electron microscopy images, respectively. At the lowest input concentration (IC, 0.1 ppm), average control efficiencies of TCE and TTCE were 72 and 39%, respectively, whereas at the highest IC (1.0 ppm) they were 52 and 18%, respectively. As stream flow rate increased from 0.1 to 1.0 L $min^{-1}$, the average control efficiencies of TCE and TTCE decreased from ca. 100 to 47% and ca. 100 to 18%, respectively. In addition, the average control efficiencies of TCE and TTCE decreased from ca. 100 to 23% and ca. 100 to 8%, respectively as the relative humidity increased from 20 to 95%. Overall, these findings indicated that as-prepared PANI-$TiO_2$ composites could be used efficiently for control of chlorinated compounds at indoor air levels;if operational conditions were optimized.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.1
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• pp.27-33
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• 2007

Purpose: We have performed SRS (stereotactic radiosurgery) for avm (arterry vein malformation) and brain cancer. In order to verify dose and localization of SRS, dose distributions from TPS ($X-Knife^{(R)}$ 3.0, Radionics, USA) and GafChromic $EBT^{(R)}$ film in a head phantom were compared. Materials and Methods: In this study, head and neck region of conventional humanoid phantom was modified by substituting one of 2.5 cm slap with five 0.5 cm acrylic plates to stack the GafChromic $EBT^{(R)}$ film slice by slice with 5 mm intervals. Four films and five acrylic plates were cut along the contour of head phantom in axial plane. The head phantom was fixed with SRS head ring and adapted SRS localizer as same as real SRS procedure. CT images of the head phantom were acquired in 5 mm slice intervals as film interval. Five arc 6 MV photon beams using the SRS cone with 2 cm diameter were delivered 300 cGy to the target in the phantom. Ten small pieces of the film were exposed to 0, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900 cGy, respectively to calibrate the GafChromic $EBT^{(R)}$ film. The films in the phantom were digitized after 24 hours and its linearity was calibrated. The pixel values of the film were converted to the dose and compared with the dose distribution from the TPS calculation. Results: Calibration curve for the GafChromic $EBT^{(R)}$ film was linear up to 900 cGy. The R2 value was better than 0.992. Discrepancy between calculated from $X-Knife^{(R)}$ 3.0 and measured dose distributions with the film was less than 5% through all slices. Conclusion: It was possible to evaluate every slice of humanoid phantom by stacking the GafChromic EBT film which is suitable for 2 dimensional dosimetry, It was found that film dosimetry using the GafChromic $EBT^{(R)}$ film is feasible for routine dosimetric QA of stereotactic radiosurgery.

• Radiation Oncology Journal
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• v.25 no.2
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• pp.63-69
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• 2007

[ $\underline{Purpose}$ ]: We performed this prospective randomized study to evaluate the efficacy and the complications of radiotherapy for Subfoveal CNV in ARMD and to compare the treatment results at two dosages (14.4 Gy and 19.8 Gy). $\underline{Materials\;and\;Methods}$: 60 eyes of 55 patients were enrolled, and randomized into 14.4 Gy (31 eyes) or 19.8 Gy (29 eyes) groups. CT was used to plan the radiotherapy. All patients received radiotherapy with a 1.8 Gy daily dose using 4 MV photon. We categorized treatment results as improved, stable, or deteriorated based on visual acuity changes of more than 2 lines on the ETDRS chart. $\underline{Results}$: Median follow-up period was 33.5 months. At 12 months, visual acuity improved in 9 (16.7%), stable in 41 (75.9%), and aggravated in 4 (7.4%) of 54 evaluated eyes. At 24 months, 49 eyes (81.7%) were evaluated. Visual acuity improved in 6 (12.2%), was stable in 33 (67.4%), and deteriorated in 10 (20.4%). At 36 months, 37 eyes were evaluated. Six (16.2%) eyes were improved, 21 (56.8%) stable, and 10 (27.0%) deteriorated. No significant difference in response was observed between the 14.4 Gy and 19.8 Gy groups (Mantel-Haenszel $x^2=0.4756$). The proportion of eyes with a vision of $20/100{\leq}increased$ from 28.3% initially to 32.7% after 24 months of radiotherapy. There were no severe acute or chronic complications. $\underline{Conclusion}$: External beam radiotherapy with doses of 14.4 or 19.8 Gy may be an effective treatment for subfoveal CNV in ARMD. No dose-response relationships with respect to treatment response or toxicity were observed between the 14.4 Gy and 19.8 Gy groups.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.1
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• pp.43-50
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• 2014

In case of all patients who receive radiation therapy, a treatment plan is established and all steps of treatment are planned in the same geometrical condition. In case of head and neck cancer patients who undergo simulated treatment through computed tomography (CT), patients are fixed onto a table for planning, but laid on the top of the treatment table in the radiation therapy room. This study excogitated and fabricated an adjustable holder for head and neck cancer patients to fix patient's position and geometrical discrepancies when performing radiation therapy on head and neck cancer patients, and compared the error before and after adjusting the position of patients due to difference in weight to evaluate the correlation between patients' weight and range of error. Computed tomography system(High Advantage, GE, USA) is used for phantom to maintain the supine position to acquire the images of the therapy site for IMRT. IMRT 4MV X-rays was used by applying the LINAC(21EX, Varian, U.S.A). Treatment planning system (Pinnacle, ver. 9.1h, Philips, Madison, USA) was used. The setup accuracy was compared with each measurement was repeated five times for each weight (0, 15, and 30Kg) and CBCT was performed 30 times to find the mean and standard deviation of errors before and after the adjustment of each weight. SPSS ver.19.0(SPSS Inc., Chicago, IL,USA) statistics program was used to perform the Wilcoxon Rank test for significance evaluation and the Spearman analysis was used as the tool to analyze the significance evaluation of the correlation of weight. As a result of measuring the error values from CBCT before and after adjusting the position due to the weight difference, X,Y,Z axis was $0.4{\pm}0.8mm$, $0.8{\pm}0.4mm$, 0 for 0Kg before the adjustment. In 15Kg CBCT before and after adjusting the position due to the weight difference, X,Y,Z axis was $0.2{\pm}0.8mm$, $1.2{\pm}0.4mm$, $2.0{\pm}0.4mm$. After adjusting position was X,Y,Z axis was $0.2{\pm}0.4mm$, $0.4{\pm}0.5mm$, $0.4{\pm}0.5mm$. In 30Kg CBCT before and after adjusting the position due to the weight difference, X,Y,Z axis was $0.8{\pm}0.4mm$, $2.4{\pm}0.5mm$, $4.4{\pm}0.8mm$. After adjusting position was X,Y,Z axis was $0.6{\pm}0.5mm$, $1.0{\pm}0mm$, $0.6{\pm}0.5mm$. When the holder for the head and neck cancer was used to adjust the ab.0ove error value, the error values from CBCT were $0.2{\pm}0.8mm$ for the X axis, $0.40{\pm}0.54mm$ for Y axis, and 0 for Z axis. As a result of statistically analyzing each value before and after the adjustment the value was significant with p<0.034 at the Z axis with 15Kg of weight and with p<0.038 and p<0.041 at the Y and Z axes respectively with 30Kg of weight. There was a significant difference with p<0.008 when the analysis was performed through Kruscal-Wallis in terms of the difference in the adjusted values of the three weight groups. As it could reduce the errors, patients' reproduction could be improved for more precise and accurate radiation therapy. Development of an adjustable device for head and neck cancer patients is significant because it improves the reproduction of existing equipment by reducing the errors in patients' position.

• Radiation Oncology Journal
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• v.17 no.2
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• pp.100-107
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• 1999

Purpose: This is to evaluate the acute complication, resection rate, and tumor down-staging after pre-operative concurrent chemoradiotherapy for stage IIIA (N2) non-small cell lung cancer. Materials and Methods Fifteen patients with non-small cell lung cancer were enrolled in this study from May 1997 to June 1998 in Samsung Medical Center. The median age of the patients was 61 (range, 45~67) years and male to female ratio was 12:3. Pathologic types were squamous cell carcinoma (11) and adenocarcinoma (4). Pre-operative clinical tumor stages were cT1 in 2 patients, cT2 in T2, and cT3 in 1 and all were N2. Ten patients were proved to be N2 with mediastinoscopic biopsy and five had clinically evident mediastinal Iymph node metastases on the chest CT scans. Pre-operative radiation therapy field included the primary tumor, the ipsilateral hilum, and the mediastinum. Total radiation dose was 45 Gy over 5 weeks with daily dose of 1.8 Gy. Pre-operative concurrent chemotherapy consisted of two cycles of intravenous cis-Platin (100 mg/m$^{2}$) on day 1 and oral Etoposide (50 mg/m$^{2}$/day) on days 1 through 14 with 4 weeks' interval. Surgery was followed after the pre-operative re-evaluation including chest CT scan in 3 weeks of the completion of the concurrent chemoradiotherapy if there was no evidence of disease progression. Results : Full dose radiation therapy was administered to all the 15 patients. Planned two cycles of chemotherapy was completed in 11 patients and one cycle was given to four. One treatment related death of acute respiratory distress syndrome occurred In 15 days of surgery. Hospital admission was required in three patients including one with radiation pneumonitis and two with neutropenic fever. Hematologic complications and other acute complications including esophagitis were tolerable. Resection rate was 92.3% (12/l3) in 13 patients excluding two patients who refused surgery. Pleural seeding was found in one patient after thoracotomy and tumor resection was not feasible. Post-operative tumor stagings were pT0 in 3 patients, pTl in 6, and pT2 in 3. Lymph node status findings were pN0 in 8 patients, pN1 in 1, and pN2 in 3. Pathologic tumor down-staging was 61.5% (8/13) including complete response in three patients ($23.7%). Tumor stage was unchanged in four patients (30.8%) and progression was in one (7.7%). Conclusions : Pre-operative concurrent chemoradiotherapy for Stage IIIA (N2) non-small cell lung cancer demonstrated satisfactory results with no increased severe acute complications. This treatment shceme deserves more patinet accrual with long-term follow-up.

• Radiation Oncology Journal
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• v.28 no.3
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• pp.155-165
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• 2010

Purpose: In order to evaluate the positional uncertainty of internal organs during radiation therapy for treatment of liver cancer, we measured differences in inter- and intra-fractional variation of the tumor position and tidal amplitude using 4-dimentional computed radiograph (DCT) images and gated orthogonal setup kilovolt (KV) images taken on every treatment using the on board imaging (OBI) and real time position management (RPM) system. Materials and Methods: Twenty consecutive patients who underwent 3-dimensional (3D) conformal radiation therapy for treatment of liver cancer participated in this study. All patients received a 4DCT simulation with an RT16 scanner and an RPM system. Lipiodol, which was updated near the target volume after transarterial chemoembolization or diaphragm was chosen as a surrogate for the evaluation of the position difference of internal organs. Two reference orthogonal (anterior and lateral) digital reconstructed radiograph (DRR) images were generated using CT image sets of 0% and 50% into the respiratory phases. The maximum tidal amplitude of the surrogate was measured from 3D conformal treatment planning. After setting the patient up with laser markings on the skin, orthogonal gated setup images at 50% into the respiratory phase were acquired at each treatment session with OBI and registered on reference DRR images by setting each beam center. Online inter-fractional variation was determined with the surrogate. After adjusting the patient setup error, orthogonal setup images at 0% and 50% into the respiratory phases were obtained and tidal amplitude of the surrogate was measured. Measured tidal amplitude was compared with data from 4DCT. For evaluation of intra-fractional variation, an orthogonal gated setup image at 50% into the respiratory phase was promptly acquired after treatment and compared with the same image taken just before treatment. In addition, a statistical analysis for the quantitative evaluation was performed. Results: Medians of inter-fractional variation for twenty patients were 0.00 cm (range, -0.50 to 0.90 cm), 0.00 cm (range, -2.40 to 1.60 cm), and 0.00 cm (range, -1.10 to 0.50 cm) in the X (transaxial), Y (superior-inferior), and Z (anterior-posterior) directions, respectively. Significant inter-fractional variations over 0.5 cm were observed in four patients. Min addition, the median tidal amplitude differences between 4DCTs and the gated orthogonal setup images were -0.05 cm (range, -0.83 to 0.60 cm), -0.15 cm (range, -2.58 to 1.18 cm), and -0.02 cm (range, -1.37 to 0.59 cm) in the X, Y, and Z directions, respectively. Large differences of over 1 cm were detected in 3 patients in the Y direction, while differences of more than 0.5 but less than 1 cm were observed in 5 patients in Y and Z directions. Median intra-fractional variation was 0.00 cm (range, -0.30 to 0.40 cm), -0.03 cm (range, -1.14 to 0.50 cm), 0.05 cm (range, -0.30 to 0.50 cm) in the X, Y, and Z directions, respectively. Significant intra-fractional variation of over 1 cm was observed in 2 patients in Y direction. Conclusion: Gated setup images provided a clear image quality for the detection of organ motion without a motion artifact. Significant intra- and inter-fractional variation and tidal amplitude differences between 4DCT and gated setup images were detected in some patients during the radiation treatment period, and therefore, should be considered when setting up the target margin. Monitoring of positional uncertainty and its adaptive feedback system can enhance the accuracy of treatments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1714-1720
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• 2012

The purpose of the study was to evaluation of the radiation dose reduction and the possibility of the maintainability of the adequate image quality using various automatic exposure control (AEC) systems in multi-detector computed tomography (MDCT). We used three AEC systems for the study: General Electric Healthcare (Auto-mA 3D), Philips Medical systems (DoseRight) and Siemens Medical Solutions (Care Dose 4D). The general scanning protocol was created for the each examination with the same scanning parameters as many as possible. In the various AEC systems, the evaluation of reduced-dose was evaluated by comparing to fixed mAs with using human phantom. The image quality of the phantom was evaluated with measuring the image noise (standard deviation) by insert regions of interests. Finally, when we applied to AEC for three manufacturers, the radiation dose reduction decreased each 35.3% in the Auto-mA 3D, 58.2% in the DoseRight, and 48.6% in the Care Dose 4D. And, there was not statistical significant difference among the image quality in the Strong/Weak of the Care Dose 4D(P=.269). This applies to variety of the AEC systems which will be very useful to reduce the dose and to maintain the high quality.