• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.225-231
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• 2003

Up-front irradiation technique as 3-dimensional conformation, or intensity modulation has kept large proportion of brain tumors from being complicated with acute radiation reactions in the normal tissue during or shortly after radiotherapy. For years, we've cannot help but counting on 2-D vertex beam technique to reduce acute reactions in the brain tumor patients because we're not equipped with 3-dimensional planning system. We analyzed its advantages and limitations in the clinical application. From 1998 to 2001, vertex or oblique vertex beams were applied to 35 patients with primary brain tumor and 25 among them were eligible for this analysis. Vertex(V) plans were optimized on the reconstructed coronal planes. As the control, we took the bilateral opposed techniques(BL) otherwise being applied. We compared the volumes included in 105% to 50% isodose lines of each plan. We also measured the radiation dose at various extracranial sites with TLD. With vertex techniques, we reduced the irradiated volumes of contralateral hemisphere and prevented middle ear effusion at contralateral side. But the low dose volume increased outside 100%; the ratio of V to BL in irradiated volume included in 100%, 80%, 50% was 0.55+/-0.10, 0.61+/-0.10, and 1.22+/-0.21, respectively. The hot area within 100% isodose line almost disappeared with vertex plan; the ratio of V to BL in irradiated volume included in 103%, 105%, 108% was 0.14+/-0.14, 0.05./-0.17, 0.00, respectively. The dose distribution within 100% isodose line became more homogeneous; the ratio of volume included in 103% and 105% to 100% was 0.62+/-0.14 and 0.26+/-0.16 in BL whereas was 0.16+/-0.16 and 0.02+/-0.04 in V. With the vertex techniques, extracranial dose increased up to $1{\sim}3%$ of maximum dose in the head and neck region except submandibular area where dose ranged 1 to 21%. From this data, vertex beam technique was quite effective in reduction of unnecessary irradiation to the contralateral hemispheres, integral dose, obtaining dose homogeneity in the clinical target. But it was associated with volume increment of low dose area in the brain and irradiation toward the head and neck region otherwise being not irradiated at all. Thus, this 2-D vertex technique can be a useful quasi-conformal method before getting 3-D apparatus.

• Imaging Science in Dentistry
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• v.30 no.3
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• pp.189-198
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• 2000

Purpose: The study was aimed to detect the induction of apoptosis, cell cycle arrest and calcified nodule formation after irradiation on primarily cultured osteoblasts. Materials and Methods: Using rat calvarial osteoblasts, the effects of irradiation on apoptosis, cell cycle arrest, and calcified nodule formation were studied. The single irradiation of 10 and 20 Gy was done with 5.38 Gy/min dose rate using the l37Cs cell irradiator at 4th and 14th day of culture. Apoptosis induction and cell cycle arrest were assayed by the flowcytometry at 1, 2, 3, and 4 days after irradiation. The formation of calcified nodules was observed by alizarin red staining at 1, 3, 10, 14 days after irradiation at 4th day of culture, and at 1, 4, 5 days after irradiation at 14th day of culture. Results: Apoptosis was not induced by 10 or 20 Gy independent of irradiation and culture period. Irradiation did not induced G1 arrest in post-irradiated ostedblasts. After irradiation at 4th-day of culture, G2 arrest was induced but it was not statistically significant after irradiation at 14th-day of culture. In the case of irradiated cells at 4th day of culture, calcified nodules were not formed and at 14th-day of culture after irradiation, calcified nodule formation did not affected. Conclusion: Taken together, these results suggest that irradiation at the dose of 10-20 Gy would not affect apoptosis induction of osteoblasts. Cell cycle and calcified nodule formation were influenced by the level of differentiation of osteblasts.

• Korean Journal of Food Science and Technology
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• v.23 no.4
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• pp.410-413
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• 1991

Prefried chicken patties were irradiated at dose levels of 0, 2, and 4 kGy using $Co^{60}$ source and stored at $3{\pm}1^{\circ}C$ and $-10{\pm}1^{\circ}C$, separately for the evaluation of color and sensory characteristics. Irradiation dose of 4 kGy slightly darkened the internal color of chicken patties. Except for the internal portion of the frozen samples, an increase (p<0.05) in Hunter 'L' values was observed for both the surface and interior of patties during storage. Upon refrigerated storage, Hunter 'a' values, both on the surface and internally, decreased as the storage period progressed. Only storage period affected (p<0.05) the Hunter 'b' values of patty surfaces and interiors. No difference (p<0.05) in odor, taste, color, and texture of the patties was observed for irradiation dose and storage period as evaluated by triangle tests except between 2 kGy and 4 kGy irradiated samples before forzen storage.

• Analytical Science and Technology
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• v.27 no.6
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• pp.292-299
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• 2014

Iopromide is an X-ray contrast agent that has been detected frequently with high concentration level in surface waters. Structural characterization of degradation products and measurement of degradation efficiency of iopromide by an electron beam irradiation were performed. For the fortified sample with iopromide, electron beam irradiation (UELV-10-10S, klysotrn, 10 MeV, 1 mA and 10 kW) was performed. The chemical structures of I_D_665 and I_D_663, which are degradation products of iopromide, were proposed by interpretation of mass spectra and chromatograms by LC/ESI-MS/MS. The mass fragmentation pathways of mass spectra in tandem mass spectrometry were also proposed. Iopromide was degraded 30.5~98.4% at dose of 0.3~5 kGy, and 97.8~30% in the concentration range $0.5{\sim}100{\mu}g/kg$ at electron beam dose of 0.3 kGy, respectively. Thus, increased degradation efficiency of iopromide by electron beam irradiation was observed with a higher dose of electron beam and lower concentration.

• Polymer(Korea)
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• v.26 no.1
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• pp.61-70
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• 2002

The effects of molecular weights and rheological properties of polypropylene (PP), on its foam structures in batch process were investigated. The effects of crosslinking process were also considered in this study. The rheological properties of polypropylene, such as storage modulus(G'), loss modulus(G"), zero shear viscosity($\eta_O$), and relaxation time($\lambda$), increased with the increase of molecular weights, and these increases in rheological properties directly affected the stability improvements of the PP foam. The increase of crosslinked PP's gel content stopped at the irradiation dose of 3.2 Mrad. The development of foam structures was more enhanced as the irradiation dose increased up to 3.2 Mrad. When the irradiation dose exceeded 3.2 Mrad, however, it negatively affected the structural development of the foam by diminishing gel contents of the foaming material, which resulted in instability of the foam structure.ture.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.6
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• pp.1025-1029
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• 2000

This study was conducted to investigate whether a DNA comet assay could be applied for identifying irradiated pork and beef. Pork and beef were irradiated with Co-60 gamma rays at 0.1, 0.3, 0.5, 0.7 and 1.0 kGy, and stored in a freezer Cells separated from the samples were embedded in agarose gel on a slide, dissolved in a lysis solution, and electrophoresed at 2 V/cm for 2.0 min by horizontal electrophoesis. The cells were then stained with a silver staining in order to visualize the DNA using a micro-scope. The DNA fragments of the irradiated cells stretched or migrated out of the cells and formed tails towards the anode, giving the appearance of comets, while unirradiated cells formed very short or no tails. The distance of DNA migration increased with irradiation dose. Since the statistical analysis showed a significant correlation between tail length and irradiation dose, a DNA comet assay could provide not only identification but also estimation of the irradiation dose for irradiated beef and pork.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.1
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• pp.16-22
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• 2021

This study investigated the reduction in human norovirus (HNV) GII. 4 count in pacific oyster Crassostrea gigas using electron beam irradiation. Infectious HNV GII. 4 was detected using RT-qPCR (real time reverse transcription-quantitative polymerase chain reaction) with PMA (propidium monoazide)/sarkosyl. At electron beam doses 1, 5, 7, and 10 kGy, the count of HNV GII. 4 was 2.74, 2.37, 2.06, and 1.55 log copies/μL (control, 3.01 log copy/μL), respectively, confirming that as the irradiation dose increased, norovirus count reduced significantly (P<0.05). After PMA/sarkosyl treatment, the counts further reduced at the same irradiation dose, and 10 kGy showed significant differences between the non-treated and PMA/sarkosyl-treated samples (P<0.05). The Ed (decimal reduction dose of electron beam) value based on the first-order kinetic model was 7.33 kGy (R2=0.98). No significant difference was observed in the pH values of the control (6.2) and electron beam-irradiated samples at all doses (6.1). For sensory evaluation, the non-treated sample scored the highest in all categories (5.25-6.17), while the samples treated with 10 kGy showed the lowest score (4.67-5.33), although without statistical significance (P>0.05). Overall, our results suggest that 7 kGy electron beam is sufficient for the non-thermal sterilization of oysters without causing significant changes in quality.

• Journal of Radiation Protection and Research
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• v.47 no.3
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• pp.152-157
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• 2022

Background: The hemi-body electron beam irradiation (HBIe^-) technique has been proposed for the treatment of mycosis fungoides. It spares healthy skin using an electron shield. However, shielding electrons is complicated owing to electron scattering effects. In this study, we developed a thimble-like head bolus shield that surrounds the patient's entire head to prevent irradiation of the head during HBIe^-. Materials and Methods: The feasibility of a thimble-like head bolus shield was evaluated using a simplified Geant4 Monte Carlo (MC) simulation. Subsequently, the head bolus was manufactured using a three-dimensional (3D) printed mold and Ecoflex 00-30 silicone. The fabricated head bolus was experimentally validated by measuring the dose to the Rando phantom using a metal-oxide-semiconductor field-effect transistor (MOSFET) detector with clinical configuration of HBIe^-. Results and Discussion: The thimble-like head bolus reduced the electron fluence by 2% compared with that without a shield in the MC simulations. In addition, an improvement in fluence degradation outside the head shield was observed. In the experimental validation using the inhouse-developed bolus shield, this head bolus reduced the electron dose to approximately 2.5% of the prescribed dose. Conclusion: A thimble-like head bolus shield for the HBIe^- technique was developed and validated in this study. This bolus effectively spares healthy skin without underdosage in the region of the target skin in HBIe^-.

• Food Science and Biotechnology
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• v.14 no.2
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• pp.181-184
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• 2005

Effects of irradiation and fumigation on disinfestation and quality attributes of chestnuts during storage were studied. Fresh chestnuts were exposed to gamma irradiation (0-10 kGy) and methyl bromide (MeBr) under commercial conditions and stored at different temperatures for 6 months. Pest of quarantine importance for chestnuts, Curculio sikkimensis Heller showed 100% mortality by MeBr on 3rd day after fumigation and by irradiation at 0.5 kGy in about 3 weeks at $23{\pm}0.5^{\circ}C$. Respiration rates of samples one day after treatments increased in proportion to irradiation dose. Respiration pattern of MeBr group was equal to that of 10 kGy-group. Both MeBr and irradiation at 0.25 kGy or higher showed 100% inhibition of sprouting during storage at $5^{\circ}C$ for 6 months. Flesh firmness was significantly reduced by MeBr or irradiation over 5 kGy (p<0.05) 1 day after treatments. MeBr fumigation resulted in appreciable decrease in flesh weight, reducing sugar and ascorbic acid contents (p<0.05), as compared to irradiated samples. Irradiation at 0.5 kGy was effective as alternative to MeBr in controlling pests while maintaining overall quality of fresh chestnuts during storage.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.153-153
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• 2016

Polyoxymethylene copolymer (POM-C) is an attractive and widely used engineering thermoplastic across many industrial sectors owing to outstanding physical, mechanical, self-lubricating and chemical properties. In this research work, the POM-C blocks were irradiated with 1 MeV electron beam energy in five doses (100, 200, 300, 500 and 700 KGy) in vacuum condition at room temperature. The tribological and physico-chemical properties of electron beam irradiated POM-C blocks have been analyzed using Pin on disk tribometer, Raman spectroscopy, SEM-EDS, Optical microscopy, 3D Nano surface profiler system and Contact angle analyzer. Electron beam irradiation at a dose of 100 kGy resulted in a decrease of the friction coefficient and wear loss of POM-C block due to well suited cross-linking, carbonization, free radicals formation and energetic electrons-atoms collisions (physical interaction). It also shows lowest surface roughness and highest water contact angle among all unirradiated and irradiated POM-C blocks. The irradiation doses at 200, 300, 500 and 700 kGy resulted in increase of the friction coefficient as compared to unirradiated POM-C block due to severe chain scission, chemical and physical structural degradation. The electron beam irradiation transferred the wear of unirradiated POM-C block from the abrasive wear, adhesive wear and scraping to mild scraping for the 1 MeV, 100 kGy irradiated POM-C block which is concluded from SEM-EDS and Optical microscopic observations. The degree of improvement for tribological attribute relies on the electron beam irradiation condition (energy and dose rate).