• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2410-2414
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• 2020

Heavy ions have a high potential for destroying deep tumors that carry the highest dose at the peak of Bragg. The peak caused by a single-energy carbon beam is too narrow, which requires special measures for improvement. Here, carbon-12 (¹²C) ion with different energies has been used as a source for calculating the dose distribution in the water phantom, soft tissue and bone by the code of Monte Carlobased FLUKA code. By increasing the energy of the initial beam, the amount of absorbed dose at Bragg peak in all three targets decreased, but the trend for this reduction was less severe in bone. While the maximum absorbed dose per bone-mass unit in energy of 200 MeV/u was about 30% less than the maximum absorbed dose per unit mass of water or soft tissue, it was merely 2.4% less than soft tissue in 400 MeV/u. The simulation result showed a good agreement with experimental data at GSI Darmstadt facility of biophysics group by 0.15 cm average accuracy in Bragg peak positioning. From 200 to 400 MeV/u incident energy, the Bragg peak location increased about 18 cm in soft tissue. Correspondingly, the bone and soft tissue revealed a reduction dose ratio by 2.9 and 1.9. Induced neutrons did not contribute more than 1.8% to the total energy deposited in the water phantom. Also during ¹²C ion bombardment, secondary fragments showed 76% and 24% of primary 200 and 400 MeV/u, respectively, were present at the Bragg-peak position. The combined treatment of carbon ions with neutron or electron beams may be more effective in local dose delivery and also treating malignant tumors.

• Carbon letters
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• v.16 no.1
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• pp.41-44
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• 2015

We report the preparation of sulfonated reduced graphene oxide (SRGO) by the sulfonation of graphene oxide followed by radiation-induced chemical reduction. Graphene oxide prepared by the well-known modified Hummer's method was sulfonated with the aryl diazonium salt of sulfanilic acid. Sulfonated graphene oxide (SGO) dispersed in ethanol was subsequently reduced by ${\gamma}$-ray irradiation at various absorbed doses to produce SRGO. The results of optical, chemical, and thermal analyses revealed that SRGO was successfully prepared by ${\gamma}$-ray irradiation-induced chemical reduction of the SGO suspension. Moreover, the electrical conductivity of SRGO was increased up to 2.94 S/cm with an increase of the absorbed dose.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.55-62
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• 2021

Purpose: This study aims to contribute to the reduction of complications of breast cancer radiation therapy by analyzing skin dose differences due to Set-up error. Materials and Method: Pseudo breast was produced using a 3D printer, applied to the phantom, and images were acquired through CT. Treatment plan was carried out that the PTV, which contains 95% of the prescription dose, could be more than 95% of the volume, so that Dmax did not exceed 107% of the prescription dose. The Set-up error was evaluated by applying ±1mm/±3mm/±5mm to the X-axis, Y-axis, and Z-axis. Results: The dose-variation in skin due to Set-up error was approximately 106% to 123% compared to prescription dose, and the highest dose in skin was 49.24 Gy at 5mm Set-up error in the lateral direction of the X-axis. More than 107% of the prescription dose was the widest at 6.87 cc in skin lateral. Conclusions: If a Set-up error occurs during left breast cancer VMAT, a great difference in skin dose was shown in the lateral direction of the X-axis. If more effort is made to align the X-axis of the breast treated during CBCT registration, the dose-variation of skin will be reduced.

• International Journal of Contents
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• v.8 no.4
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• pp.64-69
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• 2012

The heart is a major dose-limiting organ for radiotherapy of cancer in the thoracic region. The purpose of this study was to examine the protective effect of tranilast on the radiation-induced heart fibrosis model using the C57BL/6 murine strain. A significant reduction in the expression of TGF-${\beta}1$, collagen type I and collagen type III was observed in the radiation plus tranilast group. The authors also suggest the use of tranilast in a clinical trial for the prevention of radiation-induced heart fibrosis.

• Journal of radiological science and technology
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• v.15 no.1
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• pp.79-87
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• 1992

It is a matter of common knowledge that madical radiation is most accented for of radiation is doses applied to the whole of people, and of them the radation dose by radiography diagnosis is mainly prevalent. In applying X-rays to a certain man for radiography diagnosis a radiologyist will have to have an absolute sense of mission concerning the reduction and prevention of the patient's radiation dose as the radiologyist obligation. Accordingly, the radiography conditions of the patient's chest employed 197 medical facilites were surveyed and skin dose was computated by the IPH Bit system and examined. As a result, it was shown that the average skin dose was $288\;{\mu}Sv$, its minimum value was $1600\;{\mu}Sv$, which was over 32 times its minimum value. This shows that the appropriate radiography method has not been applied at applying X-ray to the patient. It comes from the performance of X-ray equipment, the choice of auxiliary equipment materials etc. But the most important thing is to master the appropriate radiography condition, and therefore this point will have to be kept in mind.

• 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.

• Journal of radiological science and technology
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• v.16 no.2
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• pp.27-38
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• 1993

To investigate relationships between image guality and exposure dose, Chest X-ray films were evaluated for the following points:how much scattered radiation can affect reduction in image quality and can be permissible diagnostically? For this purpose using a test charts and Burger's phantoms. The visual evaluation of their X-ray films and the measurements of scattered radiation were carried out. The dose of scattered radiation ranging from 20 to 25% was found to be for nothing in any diagnostic obstacle. In this range, surface doses were low of 17, 21, and $25{\mu}Gy$ for The thickness of the chest of 15, 20 and 25 cm respectively. Comparison of these high voltage X-ray films with low voltage ones showed a surface dose rate of 1:11.7. Therefore, X-ray quality, photosensitive materials(film and screen) and grid should be selected very carefully for the purpose of reduction in exposure dose.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.7
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• pp.2889-2894
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• 2015

Background: To investigate the impact of the breast size, shape, maximum heart depth (MDH), and chest wall hypotenuse (the distance connecting middle point of the sternum and the length of lung draw on the selected transverse CT slice) on the volumetric dose to heart with whole breast irradiation (WBI) of left-sided breast cancer patients. Materials and Methods: Fifty-three patients with left-sided breast cancer undergoing adjuvant intensity-modulated radiotherapy (IMRT) were enrolled in the study. The primary breast size and shape, MHD and DCWH (chest wall hypotenuse) were contoured on radiotherapy (RT) planning CT slices. The dose data of hearts were obtained from the dose-volume histograms (DVHs). Data were analyzed by one-way analysis of variance (ANOVA), Student's t-test and linear regression analysis. Results: Breast size was independent of heart dose, whereas breast shape, MHD and DCWH were correlated with heart dose. The shapes of breasts were divided into four types, as the flap type, hemisphere type, cone type and pendulous type with heart mean dose being $491.8{\pm}234.6cGy$, $752.7{\pm}219.0cGy$, $620.2{\pm}275.7cGy$, and $666.1{\pm}238.0cGy$, respectively. The flap type of breasts shows a strong statistically reduction in heart dose, compared to others (p=0.008 for V30 of heart). DCWH and MHD were found to be the most important parameters correlating with heart dose in WBI. Conclusions: More attention should be paid to the heart dose of non-flap type patients. The MHD was found to be the most important parameter to correlate with heart dose in tangential WBI, closely followed by the DCWH, which could help radiation oncologists and physicsts evaluate heart dose and design RT plan in advance.

• Radiation Oncology Journal
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• v.17 no.3
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• pp.238-248
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• 1999

Purpose : To assess the histomorphologic changes in the rat lung injury induced by radiation, to determine whether captopril reduces the rat lung injury and to evaluate change in TNF-${\alpha}$ and TGF-${\beta}$ in rat lung damage by radiation and captopril Methods and material : Right lungs in male Sprague-Dawley rats were divided irradiation alone (10, 20, 30 Gy) or radiation (same dose with radiation alone group) with captopril (500 mg/L). Radiation alone group were sacrificed at twelve hours and eleven weeks after radiation and radiation with captopril group (captopril group) were sacrificed at eleven weeks after radiation with captopril. We examined the light microscope and electron microscopic features in the groups. Results : In radiation alone group, there were patch parenchymal collapse and consolidation at twelve hours after radiation. The increase of radiation dose shows more prominent the severity and broader the affected areas. Eleven weeks after radiation, the severity and areas of fibrosis had increased in proportion to radiation dose given in the radiation alone group. There was notable decrease of lung fibrosis in captopril group than in radiation alone group. The number of mast cells rapidly increased with increase of radiation dose in radiation alone group and the degree of increase of mast cell number and severity of collagen accumulation more decreased in captopril group than in radiation alone group. In radiation alone group, expression of TNF-${\alpha}$ and TGF-${\beta}$ increased according to increase of radiation dose at twelve hours after radiation in both group. At eleven weeks after radiation, expression of TGF-${\beta}$ increased according to increase of radiation dose in radiation group but somewhat decreased in captopril group. In the captopril group the collagen deposition increased but less dense than those of radiation alone group. The severity of perivascular thickening, capillary change, the number and degranulation of mast cells more decreased in the captopril group than in the radiation alone group. Conclusion : It is concluded that the effect of captopril in the rat lungs after radiation was considered to be due to its effect on inhibition of mast cells and reduction of collagen deposition, and captopril may be protect in lung damage after radiation. We observed expression of TNF-${\alpha}$ and TGF-${\beta}$ increased at the early phase after radiation and expression of TGF-${\beta}$ increased in proportion to increase of radiation dose at the chronic phase after radiation. This results will contribute to future investigation in reduction mechanism of captopril in lung damage after radiation.

• The Korean Journal of Food & Health Convergence
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• v.4 no.1
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• pp.23-31
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• 2018

The main issue of CT is radiation dose reduction to patient. The purpose of this study was to estimate the image quality and dose by iterative reconstruction (IR) for adults and pediatrics. Adult and pediatric images of phantom were obtained with 120 and 140 kV, respectively, in accordance with radiation dose in terms of volume CT dose index ($CTDI_{vol}$): 10, 15, 20, 25, 30, 35 mGy. Then, the adult and the pediatric images are reconstructed by filtered-backprojection (FBP) and iterative reconstruction (IR). The images were analyzed by signal-to-noise ratio (SNR). SNR is improved when IR and 140 kV are applied to acquire adult and pediatric images. In the adult abdomen, according to diagnostic reference level, the SNR values of bone were increased about 27.84 % and 27.77 % at 120 kV and 140 kV, and the tissue's SNR values of the IR were increased about 29.84 % and 33.46 % 120 and 140 kV, respectively. Dose is reduced to 40% in adults abdomen images when using IR reconstruction. In pediatric images, the bone's SNR were also increased about 17.70% and 18.17 % at 120 kV and 140 kV. The tissue's SNR were increased about 26.73 % and 26.15 % at 120 kV and 140 kV. Radiation dose is reduced from 30% to 50% for bone and tissue images. In the case of examinations for adult and pediatric CT, IR technique reduces radiation dose to patient, and it could be applied to adult and pediatric imaging.