• Progress in Medical Physics
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• v.11 no.1
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• pp.85-90
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• 2000

In radiation therapy, the effects of radiation are decided total dose, total treatment times and number of radiation dose fractions. We considered that total dose, total treatment times and number of radiation dose fractions in intensity modulation radiation therapy(IMRT) infuence tumor cell killing. The goal of three dimensional conformal radiation therapy(3DCRT) in radiation therapy is to conform the partial distribution of the prescribed radiation dose to the precise 3D configuration of the tumor, and at the same time, to minimize the dose to the surrounding normal tissues. To optimize treatment volume of tumor, treatment volume will be same tumor volume. All IMRT compare to conventional treatment plus boost IMRT when total dose irradiated 75 - 90 Gy. Because of biological effect, total dose are decreased 12.5 - l5Gy in all IMRT.

• Progress in Medical Physics
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• v.8 no.2
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• pp.27-34
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• 1997

In radiation therapy, the goal of three dimensional conformal radiation therapy(3DCRT) is to conform the apatial distribution of the prescribed radiation dose to the precise 3D configuration of the tomor, and at the same time, to minimize the dose to the surrounding normal tissues. To optimize treatment volume of tomor, treatment volume will be same tomor volume. Biological considerations need to be incorporated in the intensity modulation optimization process. Planning of intensity modulated treatment can irradiate more 20％ in tomor compare to conventional 3DCRT. In lung cancer and rectal cancer, planning of intensity modulated treatment showed optimizing dose distribution.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.203-209
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• 2022

One of the typical methods for lowering radiation dose while maintaining image quality of computed tomography (CT) is the use of model-based iterative reconstruction (MBIR). This study is to evaluate the image quality by adjusting the strength of the advanced modeled iterative reconstruction (ADMIRE), which is well known as a representative model of MBIR. The study was conducted using phantom, and CT images were obtained while adjusting the strength of ADMIRE in units of 1 to 5. Quantitative evaluation includes noise levels using coefficient of variation (COV) and contrast to noise ratio (CNR), as well as natural image quality evaluation (NIQE) and blind/referenceless image spatial quality evaluator (BRISQUE). As a result, in both noise level and blind quality evaluation results, the higher the strength of ADMIRE, the better the results were derived. In particular, it was confirmed that COV and CNR were improved 1.89 and 1.75 times at ADMIRE 5 compared to ADMIRE 1, respectively, and NIQE and BRISQUE were proved to be improved 1.35 and 1.22 times at ADMIRE 5 compared to ADMIRE 1, respectively. In conclusion, this study was proved that the reconstruction strength of ADMIRE had a great influence on the noise level and overall image quality evaluation of CT images.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.698-706
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• 2019

Over the last few decades, there have been a lot of efforts to develop soft actuators, which can be external stimuli-responsive and applied to the human body. In order to fabricate medical soft actuators with a dynamic precision control, the 3D crosslinked poly(acrylic acid) (PAAc)/poly(vinyl alcohol) (PVA)/poly(ethylene glycol) (PEG) hydrogels were synthesized in this study by using a radiation technique without noxious chemical additives or initiators. After irradiation, all hydrogels showed high gel fraction over 75% and the ATR-FTIR spectra indicated that PAAc/PVA/PEG hydrogels were successfully synthesized. In addition, the gel fraction, equilibrium water content, and compressive strength were measured to determine the change in physical properties of PAAc/PVA/PEG hydrogels according to the irradiation dose and content ratio of constituents. As the irradiation dose and amount of poly(ethylene glycol) diacrylate (PEGDA) increased, the PAAc/PVA/PEG hydrogels showed a high crosslinking density and mechanical strength. It was also confirmed that PAAc/PVA/PEG hydrogels responded to electrical stimulation even at a low voltage of 3 V. The bending behavior of hydrogels under an electric field can be controlled by changing the crosslinking density, ionic group content, applied voltage, and ionic strength of swelling solution.

• Nuclear Engineering and Technology
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• v.15 no.1
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• pp.1-10
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• 1983

By controlling both the means of grafting and the cast-solution components, no degradation and dimensional change of radiation-induced graft polymerization were found. The electric resistance of styrene-cellulose acetate grafts increases with increasing styrene content, while those for the hydrophilic monomers show no marked effect. In comparison with the grafted cellulose acetate membrane by simultaneous irradiation method, the appearance of the grafted membrane by post-polymerization method was not markedly changed irrespective of the percent of grafting and radiation dose of electron beam or ${\gamma}$-ray. The combination of crosslinking agents such as divinyl benzene (OB) or trimethyl propane triacrylate (TMPT) in the VP:St:BPO system leads to gradual increase of the percent of grafting. The activation energy for grafting of St:VP:BPO solution onto cellulose acetate membrane was determined to be about 21.8 Kcal/mole over the range of 55$^{\circ}$-8$0^{\circ}C$. The initial rate of grafting (in %/hr) is proportional to the power 0.76 for dose intensities.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.71-75
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• 2001

In this paper, a three-dimensional measuring system of thermoluminescence(TL) spectra based on temperature, wavelength and luminescence intensity was introduced. The system was composed of a spectrometer, temperature control unit for thermal stimulation, photon detector and personal computer for control the entire system. Temperature control was achieved by using feedback to ensure a linear-rise in the sample temperature. Digital multimeter(KEITHLEY 195A) measures the electromotive force of Copper-Constantan thermocouple and then transmits the data to the computer through GPIB card. The computer converts this signal to temperature using electromotive force-temperature table in program, and then control the power supply through the D/A converter. The spectrometer(SPEX 1681) is controlled by CD-2A, which is controlled by the computer through RS-232 communication port. For measuring the luminescence intensity during the heating run, the electrometer(KEITHLEY 617) measures the anode current of photomultiplier tube(HAMAMATSU R928) and transmits the data to computer through the A/D converter. And, we measured and analyzed thermoluminescence of $CaSO_4$ : Dy, P using the system. The measuring range of thermoluminescence spectra was 300K-575K and 300~800 nm, $CaSO_4$ : Dy. P was fabricated by the Yamashita's method in Korea Atomic Energy Research Institute(KAERI) for radiation dosimeter. Thermoluminesce spectra of the $CaSO_4$ : Dy, P consist of two main peak at temperature of $205^{\circ}C$, wavelength 476 nm and 572 nm and with minor ones at 658 nm and 749 nm.

• Radiation Oncology Journal
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• v.28 no.3
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• pp.133-140
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• 2010

Purpose: We retrospectively investigated the effect of irradiation using helical tomotherapy in recurrent pelvic tumors that underwent prior irradiation. Materials and Methods: Fourteen patients with recurrent pelvic tumors consisting of rectal cancer (57.1%), cervical cancer (35.7%) and cancer with an unknown origin (7.1%) were treated with tomotherapy. At the time of irradiation, median tumor size was 3.5 cm and 7 patients complained of pain originating from a recurrent tumor. The median radiation dose delivered to the gross tumor volume, clinical target volume, and planning target volume was 50 Gy, 47.8 Gy and 45 Gy, respectively and delivered at 5 fractions per week over the course of 4 to 5 weeks. Treatment response and duration of local disease control were evaluated using the Response Evaluation Criteria in Solid Tumors (ver. 1.0) and the Kaplan-Meyer method. Treatment-related toxicities were assessed through Common Terminology Criteria for Adverse Events (ver. 3.0). Results: The median follow-up time was 17.3 months, while the response rate was 64.3%. Symptomatic improvement appeared in 6 patients (85.7%). The median duration time of local disease control was 25.8 months. The rates of local failure, distant failure, and synchronous local and distant failure were 57.1%, 21.4%, and 7.1%, respectively. Acute toxicities were limited in grade I or II toxicities, except for one patient. No treatment related death or late toxicity was observed. Conclusion: Helical tomotherapy could be suggested as a feasible palliative option in recurrent pelvic tumors with prior radiotherapy. However, to increase treatment effect and overcome the limitation of this outcome, a large clinical study should be performed.