• The Journal of Korean Society for Radiation Therapy
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• v.28 no.2
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• pp.87-99
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• 2016

Purpose : This study will evaluate the clinical utility by applying clinical schematic that uses monoenergy or dual energy as according to the location of tumors to the stereotactic radiotherapy to compare the change in actual dose given to the real tumor and the dose that locates adjacent to the tumor. Materials and Methods : CT images from a total of 10 patients were obtained and the clinical planning were planned based on the volumetric modulated arc therapy on monoenergy and dual energy. To analyze the change factor in the tumor, Comformity Index(CI) and Homogeneity Index(HI) and maximum dose quantity were each calculated and comparing the dose distribution on normal tissues, $V_{10}$ and $V_5$, first ~ fourth ribs closest to the tumor ($1^{st}{\sim}4^{th}$ Rib), Spinal Cord, Esophagus and Trachea were selected. Also, in order to confirm the accuracy on which the planned dose distribution is really measured, the 2-dimensional ion chamber array was used to measure the dose distribution. Results : As of the tumor factor, CI and HI showed a number close to 1 when the two energies were used. As of the maximum dose, the front chest wall showed 2% and the dorsal tumor showed equivalent value. As of normal tissue, the front chest wall tumors were reduced by 4%, 5% when both energies were used in the adjacent rib and as of trachea, reduced by 11%, 17%. As of the dose in the lung, as of $V_{10}$, it reduced by 1.5%, $V_5$ by 1%. As of the rear chest wall, when both energies were used, the ribs adjacent to the tumors showed 6%, 1%, 4%, 12% reduction, and in the lung dose distribution, $V_{10}$ reduced by 3%, and $V_5$ reduced by 3.1%. The dose measurement in all energies were in accordance to the results of Gamma Index 3mm/3%. Conclusion : It is considered that rather than using monoenergy, utilizing double energy in the clinical setting can be more effectively applied to the superficial tumors.

• Radiation Oncology Journal
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• v.15 no.2
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• pp.153-158
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• 1997

Purpose : The Dual-Energy Quantitative Computed Tomography(DEQCT) was compared with bone equivalent $K_2HPO_4$ standard solution and ash weight of animal cadaveric trabecular bone in the measurement of bone mineral contents(BMC). Method and Materials : The attenuation coefficient of tissues highly depends on the radiation energy density and effective atomic number of composition, The bone mineral content of DEQCT in this experiments was determined from empirical constants and mass attenuation coefficients of bone,fat and soft tissue equivalent solution in two photon spectra. In this experiments, the BMC of DEQCT with 80 and $120kV_p$ X rays was compared to ash weight of animal trabecular bone. Results : We obtained the mass attenuation coefficient of 0.2409 0.5608 and 0.2206 in $80kV_p$, and 0.2046, 0.3273 and $0.1971cm^2/g$ in $120kV_p$ X-ray spectra for water bone and fat equivalent materials, respectively. The BMC with DEQCT was acomplished with empirical constants $K_1=0.3232,\;K_2$=0.2450 and mass attenuation coefficients has very closed to ash weight of animal trabecular bone The BMC of empirical DEQCT and that of manufacturing DEQCT were correlated with ash weight as a correlation r= 0.998 and r= 0.996, respectively. Conclusion : The BMC of empirical DEQCT using the experimental mass attenuation coefficients and that of manufacture have showed very close to ash weight of animal trabecular bone.

• Journal of radiological science and technology
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• v.41 no.5
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• pp.405-411
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• 2018

We will provide basic data on the evaluation of patient dose in terms of DECT quality control by comparing the equipment-provided dose with the measured dose according to the configuration method of the X-ray generator by the manufacturer of the dual-energy CT unit. For computed tomography (CT) equipment, Discovery 750HD, Aquilion ONE GENESIS Edition, and Somatom Definition Flash were used. The $CTDI_{vol}$ value was measured by inserting the Unfors Xi ion chamber into a 32 cm PMMA acryl Phantom. The results of estimated $CTDI_{vol}$ DECT and measured $CTDI_{vol}$ showed that the dose difference between DECT 80 + 140 kVp of G company was at least 0.51% and -1.90% max, and measured $CTDI_{vol}$ was slightly lower (p<0.05). The difference of 80 + 140 kVp of S company was the minimum of 5.84% and the maximum of 7.52% (p<0.05). The measured $CTDI_{vol}$ was less than estimated $CTDI_{vol}$. The C company's 80 + 135 kVp showed a difference of at least 7.58% and a maximum of 13.58% (P<0.05), and all of measured $CTDI_{vol}$ was less. The linearity of exposure dose for all DECT equipment was very linearly reflected with $R^2$ being 0.97 or above, and the measured dose of the ionization chamber was less than the predicted dose of the monitor.

• Journal of radiological science and technology
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• v.40 no.2
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• pp.253-259
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• 2017

The study examines changes in calcium volume on born by comparing two figures; one is measured by dual energy computed tomography(DECT) followed by applying variation in monochromatic energy selection(keV), material decomposition(MD), and material suppressed iodine(MSI) analysis, and the other is measured by conventional single source computed tomography(CSCT). For this study, based on CSCT images taken by using human mimicked phantom, 70, 100, 140 keV and MSI, MD material calcium weighting(MCW) and MD material iodine weighting(MIW) of DECT were applied respectively. Then calculated calcium volume was converted to Agatston score for comparison. Volume of human mimicked phantom was in inverse proportion to keV. The volume decreased while keV increased(p<0.05). The most similar DECT volumes were reconstructed at 70 keV, the difference was showed $35.8{\pm}12.2$ for rib, femur ($16.1{\pm}24.1$), pelvis($13.7{\pm}18.8$), and spine($179.0{\pm}61.8$). However, the volume of MSI was down for each organ; the volume of rib was 5.55%, femur(76.34%), pelvis(55.16%) and spine(87.58%). The volume of MSI decreased 55.9% for rib, femur(80.7%), pelvis(69.6%) and spine(54.2%) while MD MIW reduced for rib(83.51%), femur(87.68%), pelvis(86.64%), and spine(82.62%). With the results, the study found that outcomes were affected by the method which examiners employed. When using DECT, calcium volume of born dropped with keV increased. It also found that the most similar DECT images were reconstructed at 70 keV. The results of experiments implied that the users of MSI and MD should be cautious of errors as there are big differences in scores between those two methods.

• Journal of the Korean Society of Radiology
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• v.15 no.3
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• pp.273-279
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• 2021

Metal material inserted into the body have a large difference in density from human tissues or bones around the Metal during CT scans.. Therefore, the Metal material inserted into the body produces Artifact. Metal Artifact, which occurs around Metals, can degrade the quality of CT images, causing confusion when medical team diagnose lesions. Through this experiment, we confirm that the occurrence of Artifacts decrease by using Dual energy CT and MAR algorithm in Single source Dual energy CT. We also want to present basic data on clinical application methods by comparing and analyzing the characteristics of images obtained by each method. Using GE 750HD CT, artificial implants were scanned using general method and Dual energy. Then we apply the MAR algorithm to each image obtained. And all previously acquired images were compared and analyzed the characteristics of the examination, such as image quality evaluation and dose evaluation. Images with MAR algorithm and Dual Energy confirmed a decrease in Metal Artifact. Images with MAR algorithm have reduced Metal Artifact, but have the disadvantage of distorting the details of artificial joint implants. On the other hand images teseted with Dual Energy have the advantage of being able to implement details than those applied with MAR algorithms, it takes longer to reconstruct the image and the exposure dose was about four times higher than those applied with MAR algorithm. In order to locate Metals, such as the post-operative follow-up period, it is useful to apply MAR algorithm to obtain images. And it is more useful to examine with Dual Energy when micro lesion identification, such as cardiac examination, and surgical planning or when tests are performed in diagnostic way.

• Membrane Journal
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• v.33 no.4
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• pp.211-221
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• 2023

This study presents a comprehensive study on the synthesis and characterization of PVI-PGMA/LiTFSI polymeric membrane electrolytes and CxNy-C flexible electrodes for energy storage applications. The dual-functional PVI-PGMA copolymer exhibited excellent ionic conductivity, with the PVI-PGMA73/LiTFSI200 membrane electrolyte achieving the highest conductivity of 1.0 × 10^-3 S cm^-1. The electrochemical performance of the CxNy-C electrodes was systematically investigated, with C3N2-C demonstrating superior performance, achieving the highest specific capacitance of 958 F g^-1 and lowest charge transfer resistance (R_ct) due to its highly interconnected hybrid structure comprising nanowires and polyhedrons, along with binary Co/Ni oxides, which provided abundant redox-active sites and facilitated ion diffusion. The presence of a graphitic carbon shell further contributed to the enhanced electrochemical stability during charge-discharge cycles. These results highlight the potential of PVI-PGMA/LiTFSI polymeric membrane electrolytes and CxNy-C electrodes for advanced energy storage devices, such as supercapacitors and lithium-ion batteries, paving the way for further advancements in sustainable and high-performance energy storage technologies.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.7-11
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• 2012

Purpose : The effect of concomitant use of $^{18}F$-FDG and intravenous contrast agent (CA) on dual-energy X-ray absorptiometry (DXA), was rarely reported. We had investigated these potentially confounding effects. Materials and Methods : Twenty-two patients had undergone DXA before and immediately after $^{18}F$-FDG PET/CT scans. Two DXA and 1 PET/CT scans had performed within one-day. $^{18}F$-FDG PET/CT scans had been performed with CA in 17 patients and without CA in 5 patients. Whole body bone mineral content (BMC), whole body bone mineral density (BMD), total fat mass (TFM), and lean body mass (LBM) were measured by DXA scanner before and after the $^{18}F$-FDG PET/CT scans. Results : BMC, BMD, TFM and LBM had significantly affected by $^{18}F$-FDG PET/CT with CA (BMC, +13.7%, from $2061.3{\pm}393.7$ to $2343.4{\pm}373.3$; BMD, +9.3%, from $1.07{\pm}0.09$ to $1.17{\pm}0.08$; TFM, -34.1%, from $17052.1{\pm}4049.9$ to $11237.1{\pm}2990.3$; LBM, +13.6%, from $45834.5{\pm}5662.1$ to $52094.0{\pm}6335.4$). However, $^{18}F$-FDG PET/CT without CA had no effect on the measurement of DXA (BMC, +2.4%, from $2197.7{\pm}391.6$ to $2251.5{\pm}380.9$; BMD, +1.8%, from $1.13{\pm}0.09$ to $1.15{\pm}0.07$; TFM, -6.8%, from $14585.6{\pm}3455.9$ to $13591.3{\pm}4351.4$; LBM, +2.2%, from $47360.5{\pm}8381.8$ to $48441.1{\pm}8488.1$). Conclusion : The measurements of DXA are affected by using CA. However, DXA scans might be unaffected by the presence of $^{18}F$-FDG administered for PET/CT.

• Journal of the Korean Society of Radiology
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• v.83 no.5
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• pp.1032-1045
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• 2022

Peripheral arterial disease (PAD) is common in elderly patients. Lower-extremity CT angiography (LE-CTA) can be useful for detecting PAD and planning its treatment. PAD can also be accurately evaluated on reconstructed monoenergetic images (MEIs) from low kiloelectron volt (keV) to high keV images using dual-energy CT. Low keV images generally provide higher contrast than high keV images but also feature more severe image noise. The noise-reduced virtual MEI reconstruction algorithm, called the Mono+ technique, was recently introduced to overcome such image noise. Therefore, this pictorial review aimed to present the imaging findings of PAD on LE-CTA and compare low and high keV images with those subjected to the Mono+ technique. We found that, in many cases, the overall and segmental image qualities were better and metal artifacts and venous contamination were decreased in the high keV images.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.3
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• pp.292-298
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• 2011

This study examines the effects of the ambient temperature (AT), methanol feeding temperature (MFT), methanol concentration (MC) and methanol flow rate (MFR) on the performance and cell temperature (CT) of a 5-stacked direct methanol fuel cell (DMFC). The AT, MFT, MC, and MFR are varied from $-10^{\circ}C$ to $+40^{\circ}C$, $50^{\circ}C$ to $90^{\circ}C$, 0.5M to 3.0M and 11.7 mL $min^{-1}$ to 46.8 mL $min^{-1}$, respectively. The performance of the DMFC under various operating conditions is analyzed from the I-V polarization curve, and the methanol crossover is estimated by gas chromatography (GC). The performance of the DMFC improves significantly with increasing AT. The open circuit voltage (OCV) decreases with increasing MC due to the enhanced likelihood of methanol crossover. The cell performance is improved significantly when the MFR is increased from 11.7 mL $min^{-1}$ to 28.08 mL $min^{-1}$. The change in cell performance is marginal with further increases in MFR. The CT increases significantly with increasing AT. The effect of the MFT and MFR is moderate, and the effect of MC is marginal on the CT of the DMFC.

• Journal of the Korean Society of Radiology
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• v.83 no.6
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• pp.1286-1297
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• 2022

Purpose To assess the usefulness of various metal artifact reduction (MAR) methods in patients with hip prostheses. Materials and Methods This retrospective study included 47 consecutive patients who underwent hip arthroplasty and dual-energy CT. Conventional polyenergetic image (CI), orthopedic-MAR (OMAR), and virtual monoenergetic image (VMI, 50-200 keV) were tested for MAR. Quantitative analysis was performed in seven regions around the prostheses. Qualitative assessments included evaluation of the degree of artifacts and the presence of secondary artifacts. Results The lowest amount of image noise was observed in the O-MAR, followed by the VMI. O-MAR also showed the lowest artifact index, followed by high-keV VMI in the range of 120-200 keV (soft tissue) or 200 keV (bone). O-MAR had the highest contrast-to-noise ratio (CNR) in regions with severe hypodense artifacts, while VMI had the highest CNR in other regions, including the periprosthetic bone. On assessment of the CI of pelvic soft tissues, VMI showed a higher structural similarity than O-MAR. Upon qualitative analysis, metal artifacts were significantly reduced in O-MAR, followed by that in VMI, while secondary artifacts were the most frequently found in the O-MAR (p < 0.001). Conclusion O-MAR is the best technique for severe MAR, but it can generate secondary artifacts. VMI at high keV can be advantageous for evaluating periprosthetic bone.