• Journal of Radiation Protection and Research
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• v.4 no.1
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• pp.21-28
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• 1979

A calculation is presented of air-scattered gamma rays using the modified single-scattering approximation. The air-scattered tissue dose rates are calculated for a general purpose taking into account (a) the buildup and exponential attenuation, (b) the energy spectrum at the position of question and (c) the geometrical scattering volume in three dimensions. These calculations have been further modified to render them applicable to a typical field irradiation facility which is surrounded by a shield wall and in which the source is fitted with a beam collimating device. The results of the calculation include the energy spectra, angular distribution and tissue does rates at source-receiver separation distances of from 35m to 300m. The comparison shows that the present method developed may be generally adequate for the gamma-ray air-scattering problems in field irradiation facilities if energy and angular distribution at the shield are unimportant.

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4158-4165
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• 2021

In this study, tissue equivalency (TE) of a newly developed epoxy-based phantom to 3-5 years child's tissue was investigated in paediatric energy range. Epoxy-based TE-phantoms were produced at different glandular/adipose (G/A) ratios of 17/83%, 31/69%, 36/64% and 10/90%. A procedure was developed in which specific amounts of boron, calcium, magnesium, sulphur compounds are mixed with epoxy resin, together with other minor substitutes. In paediatric energy range of 40-60 kV_p half-value layer (HVL) values were measured and then Hounsfield Units (HU) were determined from Computed Tomography(CT) scans taken in the X-ray energy range of 80-120kV_p. It is found that radiation absorption properties of these phantoms in terms of the measured HVL values related to linear attenuation coefficients (µ) are very well mimicking a 3 years child's soft tissue in case a ratio of 10/90%G/A. Additionally, the HU values of phantoms were determined from the CT scans. The HU = 47.8 ± 4.8 value was found for the epoxy-based phantom produced at a ratio of 10/90%G/A. The obtained HVL and HU values also support the suitability of the new epoxy based-phantom produced at a ratio of 10/90%G/A for a satisfactory mimicking a 3 years child's soft tissue by 5%. Thus they can have a potential use to perform the quality controls of medical X-ray systems and dose optimization studies.

• Journal of Microbiology and Biotechnology
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• v.29 no.5
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• pp.820-826
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• 2019

This study evaluated the anti-inflammatory potential of a grasshopper ketone (GK) isolated from the brown alga Sargassum fulvellum on lipopolysaccharide (LPS)-induced RAW 264.7 murine macrophage cell line. GK was isolated and purified from the n-hexane fraction and its structure was verified on the basis of NMR spectroscopic data. GK up to $100{\mu}g/ml$ is not cytotoxic to RAW 264.7, and is an effective inhibitor of LPS-induced NO production in RAW 264.7 cells. The production of pro-inflammatory cytokines, including IL-6, $IL-1{\beta}$, and $TNF-{\alpha}$ was found significantly reduced in $0.1-100{\mu}g/ml$ dose ranges of GK treatment (p < 0.05). We confirmed the dose-dependent and significant inhibition of iNOS and COX-2 proteins expression. In addition, it has been shown that GK induces anti-inflammatory effects by inhibiting MAPKs (ERK, JNK, and p38) and $NF-{\kappa}B$ p65 phosphorylation. Our results show that the anti-inflammatory properties of GK may be due to the inhibition of the $NF-{\kappa}B$ and MAPKs pathways, which are associated with the attenuation of cytokine secretion.

• Journal of Radiation Protection and Research
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• v.45 no.4
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• pp.171-177
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• 2020

Background: This study aims to determine the effective atomic number (Zeff) from dual-energy image sets obtained using a conventional computed tomography (CT) simulator. The estimated Zeff can be used for deriving the stopping power and material decomposition of CT images, thereby improving dose calculations in radiation therapy. Materials and Methods: An electron-density phantom was scanned using Philips Brilliance CT Big Bore at 80 and 140 kVp. The estimated Zeff values were compared with those obtained using the calibration phantom by applying the Rutherford, Schneider, and Joshi methods. The fitting parameters were optimized using the nonlinear least squares regression algorithm. The fitting curve and mass attenuation data were obtained from the National Institute of Standards and Technology. The fitting parameters obtained from stopping power and material decomposition of CT images, were validated by estimating the residual errors between the reference and calculated Zeff values. Next, the calculation accuracy of Zeff was evaluated by comparing the calculated values with the reference Zeff values of insert plugs. The exposure levels of patients under additional CT scanning at 80, 120, and 140 kVp were evaluated by measuring the weighted CT dose index (CTDIw). Results and Discussion: The residual errors of the fitting parameters were lower than 2%. The best and worst Zeff values were obtained using the Schneider and Joshi methods, respectively. The maximum differences between the reference and calculated values were 11.3% (for lung during inhalation), 4.7% (for adipose tissue), and 9.8% (for lung during inhalation) when applying the Rutherford, Schneider, and Joshi methods, respectively. Under dual-energy scanning (80 and 140 kVp), the patient exposure level was approximately twice that in general single-energy scanning (120 kVp). Conclusion: Zeff was calculated from two image sets scanned by conventional single-energy CT simulator. The results obtained using three different methods were compared. The Zeff calculation based on single-energy exhibited appropriate feasibility.

• Journal of radiological science and technology
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• v.44 no.4
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• pp.367-373
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• 2021

A quality assurance of computed tomography(CT) have done seven items that were water attenuation coefficient, noise, homogeneity, spatial resolution, contrast resolution, slice thickness, artifact using by standard phantom. But there is no quality assurance items and methods for CT simulator at domestic institutions yet. Therefore the study aimed to access the CT dose index(CTDI), table tilting, image distortion, laser accuracy, table movement accuracy and CT seven items for CT simulator quality assurance. The CTDI at the center of the head phantom was 0.81 for 80 kVp, 1.55 for 100 kVp, 2.50 for 120 mm, 0.22 for 80 kVp at the center of the body phantom, 0.469 for 100 kVp, and 0.81 for 120 kVp. The table tilting was within the tolerance range of ±1.0° or less. Image distortion had 1 mm distortion in the left and right images based on the center, and the laser accuracy was measured within ±2 mm tolerance. The purpose of this study is to improve the quality assurance items suitable for the current situation in Korea in order to protect the normal tissues during the radiation treatment process and manage the CT simulator that is implemented to find the location of the tumor more clearly. In order to improve the accuracy of the CT simulator when looking at the results, the error range of each item should be small. It is hoped that the quality assurance items of the CT simulator will be improved by suggesting the quality assurance direction of the CT simulator in this study, and the results of radiation therapy will also improve.

• Journal of Radiation Industry
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• v.17 no.2
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• pp.173-181
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• 2023

3D printing is a technology that can transform and process computerized data obtained through modeling or 3D scanning via CAD. In the medical field, studies on customized 3D printing technology for clinical use or patients and diseases continue. The importance of research on filaments and molding methods is increasing, but research on manufacturing methods and available raw materials is not being actively conducted. In this study, we compare the characteristics of each material according to the manufacturing method of the phantom manufactured with 3D printing technology and evaluate its usefulness. We manufactured phantoms of the same size using poly methyl meta acrylate (PMMA), acrylonitrile butadiene styrene (ABS), and Poly Lactic Acid (PLA) based on the international standard phantom of aluminum step wedge. We used SITEC's radiation generator (DigiRAD-FPC R-1000-150) and compared the shielding rate and line attenuation coefficient through the average after shooting 10 times. As a result, in the case of the measured dose transmitted through each phantom, it was confirmed that the appearance of the dose measured for phantoms decreased linearly as the thickness increased under each condition. The sensitivity also decreased as the steps increased for each phantom and confirmed that it was different depending on the thickness and material. Through this study, we confirmed that 3D printing technology can be usefully used for phantom production in the medical field. If further development of printing technology and studies on various materials are conducted, it is believed that they will contribute to the development of the medical research environment.

• IMMUNE NETWORK
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• v.24 no.4
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• pp.32.1-32.13
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• 2024

Low-dose radiotherapy (LDRT) has been explored as a treatment option for various inflammatory diseases; however, its application in the context of rheumatoid arthritis (RA) is lacking. This study aimed to elucidate the mechanism underlying LDRT-based treatment for RA and standardize it. LDRT reduced the total numbers of immune cells, but increased the apoptotic CD4⁺ T and B220⁺ B cells, in the draining lymph nodes of collagen induced arthritis and K/BxN models. In addition, it significantly reduced the severity of various pathological manifestations, including bone destruction, cartilage erosion, and swelling of hind limb ankle. Post-LDRT, the proportion of apoptotic CD4⁺ T and CD19⁺ B cells increased significantly in the PBMCs derived from human patients with RA. LDRT showed a similar effect in fibroblast-like synoviocytes as well. In conclusion, we report that LDRT induces apoptosis in immune cells and fibro-blast-like synoviocytes, contributing to attenuation of arthritis.

• Journal of radiological science and technology
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• v.25 no.2
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• pp.47-55
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• 2002

We came to the following conclusion as the results of experiment on the image quality of mammography and the average glandular dose using 4 apparatuses at 3 hospitals in Seoul. 1. Whereas the measurement of half value layer showed no differences among the apparatuses, the measurement by an attenuation curve method showed some differences by 5.9%. There were 9.1% differences in the measurement by aluminum conversion method. 2. The basic density of an automatic exposure control unit must be D = 1.40, but there was no automatic exposure unit adjusted precisely at any hospitals. The unit at the B hospital exceeded the allowable limit by ${\pm}0.15$. 3. In the photographing using an automatic exposure control unit and the management of an automatic film processor using a sensitometer, most automatic film processors were well kept. But in some cases the mean value of a fluctuation coefficient exceeded the allowable limit. There is a need for more cautious management. 4. The image quality of breast phantom photography was affected by the screen/film system among the hospitals. 5. The average glandular dose at a breast of 4.2 cm thickness depended on the tube voltage, In the case of Mo/Mo, it was measured $0.26{\sim}1.39\;mGy$ less than ACR standard 3.0 mGy.

• Journal of radiological science and technology
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• v.39 no.1
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• pp.71-79
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• 2016

The purpose of this study is computed tomography contrast agent at low concentrations and low tube voltage technique to evaluate the usefulness on the phantom image. By varying the degree of mixture by the contrast medium concentration it was inserted in phantom. It was taken by changing the tube voltage and tube current step by step, and to evaluate the dose and the CT value obtained from the phantom image. As a result, low-contrast, low tube voltage(300 mgI/ml, 100 kV) was reduced by an average 21%(CTDIvol; computed tomography dose indexvol) more standard condition(350 mgI/ml, 120 kV). SNR was increased at all depths of the phantom, respectively 1:10 and 1:20(by diluting a contrast agent and normal saline) 12.2(26%) 6.2(17%). CNR was increased at all depths of the phantom, respectively 1:10 and 1:20(by diluting a contrast agent and normal saline) 11.5(32%), 6.3(26%). Research work on the CT scan is necessary in a variety of studies on the low contrast concentration and low tube voltage techniques for dose reduction and reducing of side effects the contrast agent.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.134-139
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• 2014

Purpose: Adaptive statistical iterative reconstruction (ASIR) technique is a reconstruction method of CT image using statistical noise modeling which is known to reduce image noise and to preserve image quality despite reducing radiation dose. The aim of this study is to evaluate images using ASIR on bone SPECT/CT which is primarily performed in our hospital. Materials and Methods: We compared the images of applied ASIR (ASIR level: 20-80%) and none ASIR by changing the mA based on 120 kVp, 100 mA using Discovery NM/CT 670 (GE, U.S.A). First, we evaluated attenuation correction in SPECT image by changing the ASIR level using Anthropomorphic phantom. Second, we compared the contrast to noise ratio (CNR), image noise and spatial resolution in CT image using ACR phantom. Third, after selecting the ASIR level applicable patient using lower torso phantom, we examined 2 patients who followed up bone SPECT/CT and we performed blind test. Results: The degree of attenuation correction in SPECT image showed no significant difference between applied ASIR and none ASIR (P>0.05). When applied ASIR, the noise of CT image were reduced at least 17 up to 52% by changing the mA. The CNR of image with ASIR was maintained more than 0.8 at 40 mA (ASIR 60%) while those without ASIR showed 0.42 at standard 40 mA. In comparison of the high contrast object, we distinguished 12 line pairs/cm at 40 mA regardless of appling ASIR. Comparison of the patients image applied ASIR level 60% (40 mA) which found out by spine image of lower torso phantom showed no signigicant difference between applied ASIR and none ASIR in blind test. The CTDIvol and DLP for applied ASIR 60% showed decreased by 60%, 60% on average than using standard mA. Conclusion: The study show that the radiation dose in SPECT/CT using ASIR can be reduced despite degradation of SPECT and CT images. In addition, higher ASIR level could be possibly applied characteristics of SPECT/CT that region of interest is limited to bone.