• Radiation Oncology Journal
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• v.27 no.3
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• pp.120-125
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• 2009

Purpose: We wanted to present the preliminary results of intensity-modulated radiotherapy (IMRT) for the treatment of tonsillar cancer. Materials and Methods: We retrospectively analyzed 12 patients who underwent IMRT for tonsillar cancer at Asan Medical Center between November 2002 and February 2007. Seven patients (58%) received definitive treatment, and five (42%) were treated in the postoperative setting. Among the definitively treated patients, 6 patients received cisplatin-based chemotherapy regimens. Simultaneous modulated accelerated radiation therapy (SMART) was used in nine patients. The prescribed dose was 72 Gy at 2.4 Gy/fraction for the definitively treated cases and 61.6 Gy at 2.2 Gy/fraction for the postoperative cases. The median follow-up period was 34 months. Results: All twelve patients completed treatment without interruption, and eleven showed a complete response. One patient had persistent loco-regional disease after treatment. The three-year estimates of loco-regional control, disease-free survival and overall survival were 91.7%, 91.7%, and 100%. The worst acute mucositis was Grade 1 in four patients, Grade 2 in five patients, Grade 3 in two patients and Grade 4 in one patient. Grade 3 xerostomia was observed in six patients. Conclusion: Intensity-modulated radiotherapy was shown to be a safe and effective treatment modality for tonsillar cancer. Further studies with a larger number of patients and a longer follow-up period are needed to evaluate the ultimate tumor control and late toxicity of IMRT for treating tonsillar cancer.

• Radiation Oncology Journal
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• v.22 no.1
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• pp.64-68
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• 2004

Purpose : To study the feasibility of verifying real-time 2-D dose distribution measurement system with the scintillation screen for the quality assurance. Materials and Methods : The water phantom consisted of a scintillation screen (LANEX fast screen, Kodak, USA) that was axially located in the middle of an acrylic cylinder with a diameter of 25 cm. The charge-coupled device (CCD) camera was attached to the phantom In order to capture the visible light from the scintillation screen. To observe the dose distribution In real time, the intensity of the light from the scintillator was converted to a dosage. The isodose contours of the calculations from RTP and those of the measurements using the scintillation screen were compared for the arc therapy and the Intensity modulated radiation therapy (IMRT). Results : The kernel, expressed as a multiplication of two error functions, was obtained in order to correct the sensitivity of the CCD of the camera and the scintillation screen. When comparing the calculated isodose and measured isodose, a discrepancy of less than 8 mm in the high dose region was observed. Conclusion : Using the 2-D dosimetry system, the relationship between the light and the dosage could be found, and real-time verification of the dose distribution was feasible.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.1
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• pp.41-46
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• 2010

Purpose: To analyze differences in the dose uniformity for the computed breast radiation therapy planning with tangential beam between conventional RT using wedge filter and FiF-IMRT using multileaf collimator based onsizes and volumes of breasts. Materials and Methods: Thirty breast cancer patients were classified according to the sizes and volumes of the breasts using Eclipse treatment planning system ($Varian^{TM}$, USA, V8.0). Conformity Index and Homogeneity Index were computed along with Dose Volume Histogram. Results: No differencein CI (${\pm}1.2%$) was observed. However, lower mean HI (1.67%) in FiF-IMRT was observed compared to that of the conventional RT. Statically significant (P<0.01) correlation was identified between the values of ${\Delta}HI$ (%) and physical parameters such as breast volumes and separations. Conclusion: Increase in breast volume and separation improves the dose uniformities in computed radiation therapy planning for FiF-IMRT. Physical dimension of the breast should be considered to optimize the compured radiation therapy planning.

• Radiation Oncology Journal
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• v.29 no.3
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• pp.206-213
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• 2011

Purpose: Intensity modulated radiation therapy (IMRT) is a high precision therapy technique that can achieve a conformal dose distribution on a given target. However, organ motion induced by respiration can result in significant dosimetric error. Therefore, this study explores the dosimetric error that result from various patterns of respiration. Materials and Methods: Experiments were designed to deliver a treatment plan made for a real patient to an in-house developed motion phantom. The motion pattern; the amplitude and period as well as inhale-exhale period, could be controlled by in-house developed software. Dose distribution was measured using EDR2 film and analysis was performed by RIT113 software. Three respiratory patterns were generated for the purpose of this study; first the 'even inhale-exhale pattern', second the slightly long exhale pattern (0.35 seconds longer than inhale period) named 'general signal pattern', and third a 'long exhale pattern' (0.7 seconds longer than inhale period). One dimensional dose profile comparisons and gamma index analysis on 2 dimensions were performed. Results: In one-dimensional dose profile comparisons, 5% in the target and 30% dose difference at the boundary were observed in the long exhale pattern. The center of high dose region in the profile was shifted 1 mm to inhale (caudal) direction for the 'even inhale-exhale pattern', 2 mm and 5 mm shifts to exhale (cranial) direction were observed for 'slightly long exhale pattern' and 'long exhale pattern', respectively. The areas of gamma index >1 were 11.88 %, 15.11%, and 24.33% for 'even inhale-exhale pattern', 'general pattern', and 'long exhale pattern', respectively. The long exhale pattern showed largest errors. Conclusion: To reduce the dosimetric error due to respiratory motions, controlling patient's breathing to be closer to even inhaleexhale period is helpful with minimizing the motion amplitude.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.879-886
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• 1998

It is very important to understand the vibration and noise characteristics of a structure to developed quiet machines and lessen their noise. In this paper, the vibration and sound radiation characteristics of a simple and a bar-stiffened plate have been investigated using numerical and experimental techniques. In numerical process, FEM analysis has been performed for the vibration level ; the time-space squared and averaged velocity and BEM analysis for sound radiation parameters ; sound power and radiation efficiency. In experimental process, FFT signal processing method has been used. While a power from an exiciter is applied to the structure by using a point contact, sound intensity and vibration level has been measured. Based on these two data, the radiation efficiency has been calculated. Results show that the radiation efficiency for the stiffened structure increases compared to the simple plate, due to the extra edges provided by the stiffener.

• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.101-112
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• 2000

An Experimental study of oxygen enriched double inversed diffusion flame was conducted to understand the flame characteristics and radiation heat transfer. The infrared radiation meter was used to measure of various combination of fuel, air and pure oxygen. The results show that oxygen enriched double inversed diffusion flame is very effective to increase of thermal radiation and proper addition of pure oxygen in air flow can intensity thermal radiation of flame. And it can be found that oxygen enriched double inversed diffusion flame could give benefits of cost effective and very high energy saving.

• 대한방사선방어학회:학술대회논문집
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• 2011.11a
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• pp.346-347
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• 2011

• 대한방사선방어학회:학술대회논문집
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• 2011.11a
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• pp.340-341
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• 2011

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.129.2-129.2
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• 2011

Knowledge of the detailed solar radiation components are essential for modeling many solar systems. This is particularly the case for applications that concentrate the incident energy to attain high photo-dynamic efficiency achievable only at the higher intensities. In order to estimate the performance of concentrating solar systems, it is necessary to know the intensity of the beam radiation, as only this component can be concentrated. The Korea Institute of Energy Research(KIER) has began collecting detailed solar radiation component data since August, 1988. KIER's component data will be extensively used by solar system users or designers as well as by research institutes.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.8
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• pp.3257-3265
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• 2015

Background: Radiotherapy is an important treatment of choice for breast cancer patients after breast-conserving surgery, and we compare the feasibility of using dual arc volumetric modulated arc therapy (VMAT2), single arc volumetric modulated arc therapy (VMAT1) and Multi-beam Intensity Modulated Radiotherapy (M-IMRT) on patients after breast-conserving surgery. Materials and Methods: Thirty patients with breast cancer (half right-sided and half left-sided) treated by conservative lumpectomy and requiring whole breast radiotherapy with tumor bed boost were planned with three different radiotherapy techniques: 1) VMAT1; 2) VMAT2; 3) M-IMRT. The distributions for the planning target volume (PTV) and organs at risk (OARs) were compared. Dosimetries for all the techniques were compared. Results: All three techniques satisfied the dose constraint well. VMAT2 showed no obvious difference in the homogeneity index (HI) and conformity index (CI) of the PTV with respect to M-IMRT and VMAT1. VMAT2 clearly improved the treatment efficiency and can also decrease the mean dose and V5Gy of the contralateral lung. The mean dose and maximum dose of the spinal cord and contralateral breast were lower for VMAT2 than the other two techniques. The very low dose distribution (V1Gy) of the contralateral breast also showed great reduction in VMAT2 compared with the other two techniques. For the ipsilateral lung of right-sided breast cancer, the mean dose was decreased significantly in VMAT2 compared with VMAT1 and M-IMRT. The V20Gy and V30Gy of the ipsilateral lung of the left-sided breast cancer for VMAT2 showed obvious reduction compared with the other two techniques. The heart statistics of VMAT2 also decreased considerably compared to VMAT1 and M-IMRT. Conclusions: Compared to the other two techniques, the dual arc volumetric modulated arc therapy technique reduced radiation dose exposure to the organs at risk and maintained a reasonable target dose distribution.