• Radiation Oncology Journal
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• v.31 no.3
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• pp.147-154
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• 2013

Purpose: To evaluate the role of salvage radiotherapy (RT) for the treatment of regional lymph node recurrence (RLNR) after radical surgery in advanced gastric cancer. Materials and Methods: We retrospectively analyzed medical records of 26 patients who underwent salvage treatment after diagnosis of RLNR between 2006 and 2011. Patients with peritoneal seeding or distant metastasis were excluded. Eighteen patients received RT with or without chemotherapy and the other 8 did chemotherapy only without RT. A three-dimensional conformal RT was performed with median dose of 56 Gy (range, 44 to 60 Gy). Sixteen patients had fluoropyrimidine-based chemotherapy, 5 did taxane-based chemotherapy, and irinotecan was applied in 4. Results: With a median follow-up of 20 months (range, 5 to 57 months), median overall survival (OS) and progression-free survival (PFS) after diagnosis of RLNR were 29 months and 12 months in the entire patients, respectively. Radiotherapy (p = 0.007) and disease-free interval (p = 0.033) were statistically significant factors for OS in multivariate analysis. Median OS was 36 months in patients who received RT and 16 months in those who did not. Furthermore, delivery of RT (p < 0.001), complete remission after salvage treatment (p = 0.040) and performance status (p = 0.023) were associated with a significantly better PFS. Gastrointestinal toxicities from RT were mild in most patients. Conclusion: Salvage RT combined with systemic chemotherapy may be an effective treatment managing RLNR from advanced gastric cancer.

• Radiation Oncology Journal
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• v.35 no.1
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• pp.78-89
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• 2017

Purpose: To determine the optimal radiotherapy technique for gastric mucosa-associated lymphoid tissue lymphoma (MALToma), we compared the dosimetric parameters and the risk of solid secondary cancer from scattered doses among anterior-posterior/ posterior-anterior parallel-opposed fields (AP/PA), anterior, posterior, right, and left lateral fields (4_field), 3-dimensional conformal radiotherapy (3D-CRT) using noncoplanar beams, and intensity-modulated radiotherapy composed of 7 coplanar beams (IMRT_co) and 7 coplanar and noncoplanar beams (IMRT_non). Materials and Methods: We retrospectively generated 5 planning techniques for 5 patients with gastric MALToma. Homogeneity index (HI), conformity index (CI), and mean doses of the kidney and liver were calculated from the dose-volume histograms. Applied the Biological Effects of Ionizing Radiation VII report to scattered doses, the lifetime attributable risk (LAR) was calculated to estimate the risk of solid secondary cancer. Results: The best value of CI was obtained with IMRT, although the HI varied among patients. The mean kidney dose was the highest with AP/PA, followed by 4_field, 3D-CRT, IMRT_co, and IMRT_non. On the other hand, the mean liver dose was the highest with 4_field and the lowest with AP/PA. Compared with 4_field, the LAR for 3D-CRT decreased except the lungs, and the LAR for IMRT_co and IMRT_non increased except the lungs. However, the absolute differences were much lower than <1%. Conclusion: Tailored RT techniques seem to be beneficial because it could achieve adjacent organ sparing with very small and clinically irrelevant increase of secondary solid cancer risk compared to the conventional techniques.

• Radiation Oncology Journal
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• v.35 no.1
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• pp.71-77
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• 2017

Purpose: Although the technical developments of radiotherapy have been remarkable, there are currently few reports on the treatment results of radiotherapy for local recurrence of rectal cancer treated with surgery alone as initial treatment in this three-dimensional conformal radiotherapy era. Thus, we retrospectively evaluated the treatment results of radiotherapy for local recurrence of rectal cancer treated with surgery alone as the initial treatment. Materials and Methods: Thirty-two patients who underwent radiotherapy were enrolled in this study. The dose per fraction was 2.0-3.5 Gy. Because the treatment schedule was variable, the biological effective dose (BED) was calculated. Results: Local control (LC) and overall survival (OS) rates from the completion of radiotherapy were calculated. The 1-, 2-, 3-, 4-, and 5-year LC rates were 51.5%, 24.5%, 19.6%, 19.6%, and 13.1%, respectively. LC rates were significantly higher for the high BED group (${\geq}75Gy_{10}$) than for the lower BED group (<$75Gy_{10}$). All patients who reported pain achieved pain relief. The duration of pain relief was significantly higher for the high BED group than for the lower BED group. The 1-, 2-, 3-, 4-, and 5-year OS rates were 82.6%, 56.5%, 45.2%, 38.7%, and 23.2%, respectively. There was a trend toward higher OS rates in with higher BED group compared to lower BED group. Conclusion: For patients with unresectable locally recurrent rectal cancer treated with surgery alone, radiotherapy is effective treatment. The prescribed BED should be more than $75Gy_{10}$, if the dose to the organ at risk is within acceptable levels.

• Radiation Oncology Journal
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• v.37 no.3
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• pp.193-200
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• 2019

Purpose: To explore the role of salvage radiotherapy (RT) for recurrent thymoma as an alternative to surgery. Materials and Methods: Between 2007 and 2015, 47 patients who received salvage RT for recurrent thymoma at Yonsei Cancer Center were included in this study. Recurrent sites included initial tumor bed (n = 4), pleura (n = 19), lung parenchyma (n = 10), distant (n = 9), and multiple regions (n = 5). Three-dimensional conformal and intensity-modulated RT were used in 29 and 18 patients, respectively. Median prescribed dose to gross tumor was 52 Gy (range, 30 to 70 Gy), with equivalent doses in 2-Gy fractions (EQD₂). We investigated overall survival (OS), progression-free survival (PFS), and patterns of failure. Local failure after salvage RT was defined as recurrence at the target volume receiving >50% of the prescription dose. Results: Median follow-up time was 83 months (range, 8 to 299 months). Five-year OS and PFS were 70% and 22%, respectively. The overall response rate was 97.9%; complete response, 34%; partial response, 44.7%; and stable disease, 19.1%. In multivariate analysis, histologic type and salvage RT dose (≥52 Gy, EQD₂) were significantly associated with OS. The high dose group (≥52 Gy, EQD₂) had significantly better outcomes than the low dose group (5-year OS: 80% vs. 59%, p = 0.046; 5-year PFS: 30% vs. 14%, p=0.002). Treatment failure occurred in 34 patients; out-of-field failure was dominant (intra-thoracic recurrence 35.3%; extrathoracic recurrence 11.8%), while local failure rate was 5.8%. Conclusion: Salvage RT for recurrent thymoma using high doses and advanced precision techniques produced favorable outcomes, providing evidence that recurrent thymoma is radiosensitive.

• Radiation Oncology Journal
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• v.30 no.1
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• pp.43-48
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• 2012

Purpose: To develop the dose volume histogram (DVH) management software which guides the evaluation of radiotherapy (RT) plan of a new case according to the biological consequences of the DVHs from the previously treated patients. Materials and Methods: We determined the radiation pneumonitis (RP) as an biological response parameter in order to develop DVH management software. We retrospectively reviewed the medical records of lung cancer patients treated with curative 3-dimensional conformal radiation therapy (3D-CRT). The biological event was defined as RP of the Radiation Therapy Oncology Group (RTOG) grade III or more. Results: The DVH management software consisted of three parts (pre-existing DVH database, graphical tool, and $Pinnacle^3$ script). The pre-existing DVH data were retrieved from 128 patients. RP events were tagged to the specific DVH data through retrospective review of patients' medical records. The graphical tool was developed to present the complication histogram derived from the preexisting database (DVH and RP) and was implemented into the radiation treatment planning (RTP) system, $Pinnacle^3$ v8.0 (Phillips Healthcare). The software was designed for the pre-existing database to be updated easily by tagging the specific DVH data with the new incidence of RP events at the time of patients' follow-up. Conclusion: We developed the DVH management software as an effective tool to incorporate the phenomenological consequences derived from the pre-existing database in the evaluation of a new RT plan. It can be used not only for lung cancer patients but also for the other disease site with different toxicity parameters.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.508-513
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• 2015

A capacitive-type touch screen panel (TSP) composed of silver nanowire (AgNW) crossing electrodes and transparent bridge structures was fabricated on a polycarbonate film. The transparent bridge structure was formed with a stack of Al-doped ZnO (AZO) electrodes and SU-8 insulator. The stable and robust continuity of the bridge electrode over the bridge insulator was achieved by making the side-wall slope of the bridge insulator low and depositing the conformal AZO film with atomic layer deposition. With an extended exposure time of photolithography, the lower part of the SU-8 layer around the region uncovered by the photomask can be exposed enough to the UV light scattered from the substrate. This leads to the low side-wall slope of the bridge insulator. The fabricated TSP sample showed a large capacitance change of 22.71% between with and without touching. Our work supplies the technological clue for ensuring long-term reliability to the highly flexible and transparent TSP made by using conventional fabrication processes.

• Korean Journal of Materials Research
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• v.22 no.11
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• pp.636-641
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• 2012

In this study, we have investigated highly efficient nanoscale surface corrugated light emitting diodes (LEDs) for the enhancement of light extraction efficiency (LEE) of nitride semiconductor LEDs. Nanoscale indium tin oxide (ITO) surface corrugations are fabricated by using the conformal nanoimprint technique; it was possible to observe an enhancement of LEE for the ITO surface corrugated LEDs. By incorporating this novel method, we determined that the total output power of the surface corrugated LEDs were enhanced by 45.6% for patterned sapphire substrate LEDs and by 41.9% for flat c-plane substrate LEDs. The enhancement of LEE through nanoscale surface corrugations was studied using 3-dimensional Finite Different Time Domain (FDTD) calculation. From the FDTD calculations, we were able to separate the light extraction from the top and bottom sides of device. This process revealed that light extraction from the top and bottom sides of a device strongly depends on the substrate and the surface corrugation. We found that enhanced LEE could be understood through the mechanism of enhanced light transmission due to refractive index matching and the increase of light scattering from the corrugated surface. LEE calculations for the encapsulated LEDs devices also revealed that low LEE enhancement is expected after encapsulation due to the reduction of the refractive index contrast.

• Korean Journal of Materials Research
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• v.19 no.8
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• pp.437-442
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• 2009

This paper describes an improved strategy for controlling the adhesion force using both the antiadhesion and adhesion layers for a successful large-area transfer process. An MPTMS (3-mercaptopropyltrimethoxysilane) monolayer as an adhesion layer for Au/Pd thin films was deposited on Si substrates by vapor self assembly monolayer (VSAM) method. Contact angle, surface energy, film thickness, friction force, and roughness were considered for finding the optimized conditions. The sputtered Au/Pd ($\sim$17 nm) layer on the PDMS stamp without the anti-adhesion layer showed poor transfer results due to the high adhesion between sputtered Au/Pd and PDMS. In order to reduce the adhesion between Au/Pd and PDMS, an anti-adhesion monolayer was coated on the PDMS stamp using FOTS (perfluorooctyltrichlorosilane) after $O_2$ plasma treatment. The transfer process with the anti-adhesion layer gave good transfer results over a large area (20 mm $\times$ 20 mm) without pattern loss or distortion. To investigate the applied pressure effect, the PDMS stamp was sandwiched after 90$^{\circ}$ rotation on the MPTMS-coated patterned Si substrate with 1-${\mu}m$ depth. The sputtered Au/Pd was transferred onto the contact area, making square metal patterns on the top of the patterned Si structures. Applying low pressure helped to remove voids and to make conformal contact; however, high pressure yielded irregular transfer results due to PDMS stamp deformation. One of key parameters to success of this transfer process is the controllability of the adhesion force between the stamp and the target substrate. This technique offers high reliability during the transfer process, which suggests a potential building method for future functional structures.

• Radiation Oncology Journal
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• v.38 no.1
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• pp.11-17
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• 2020

Purpose: Definitive radiotherapy remains a primary treatment option for early stage glottic cancer. Intensity-modulated radiation therapy (IMRT) has emerged as the standard treatment technique for advanced head and neck cancers, whereas three-dimensional conformal radiotherapy (3D-CRT) has remained standard for early glottic cancers. We used the National Cancer Database (NCDB) to identify predictors of IMRT use and effect on outcome in these patients. Materials and Methods: We queried the NCDB from 2004-2015 for squamous cell carcinoma of the glottic larynx staged Tis-T2N0 treated with radiation alone. Logistic regression was used to identify predictors of IMRT. Cox regression was used to identify factors predictive of overall survival. Propensity matching was conducted to account for indication bias. Results: We identified 15,627 patients, of which 11% received IMRT. IMRT use rose from 2% in 2004 to 16% in 2015. Predictors of IMRT include: increased comorbidity, T2 stage, urban location, chemotherapy, treatment at an academic center, and later treatment year. Predictors of improved survival were female gender, higher income, lower stage, no chemotherapy, academic facility, and more remote year. There was no difference in survival between 3D-CRT and IMRT across all stages. Conclusions: The rate of IMRT use for early stage glottic laryngeal cancer has increased over time. There was no difference in outcome in patients receiving IMRT versus 3D-CRT across the cohort.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.3 s.21
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• pp.41-51
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• 2002

Recently, many studies extracting the geography information using digital aerial image have been implemented. But it is very difficult that automatically recognizing objects using edge detection method on the aerial image, and so that work have practiced manually or semi-automatically. Therefore, in this study, we have removed impedimental elements for recognition using the image which overlapped the significant information bands of brightness-sliced aerial images, then have developed the algorithm which can automatically recognize and extract road information and we will try to apply that method when we develope a system. For this, first of all, we have developed the 'template conformal-transformation moving operator' for automatically recognizing crosswalk area from crosswalk band image and the 'window normal search algorithm' which is able to track road area based on long-side length of crosswalk, so that we have proposed the method that can extract directly the road information from the aerial image.